Difference between revisions of "1732: Earth Temperature Timeline"
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| rowspan="3"| 19500 <small>BCE</small> | | rowspan="3"| 19500 <small>BCE</small> | ||
− | | But the world is about to warm up. || 19500 BCE|| -4 | + | | But the world is about to warm up. || 19500 BCE|| -4.3 || The warming process actually takes thousands of years, which this comic will portray down thousands of pixels to come. |
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− | | By this time, humans have already spread across {{w|Africa}}, {{w|Eurasia}}, and {{w|Australia}}. || 19300 BCE || -4 | + | | By this time, humans have already spread across {{w|Africa}}, {{w|Eurasia}}, and {{w|Australia}}. || 19300 BCE || -4.3 || {{w|Homo Sapiens}} successfully {{w|Recent_African_origin_of_modern_humans#Movement_out_of_Africa|migrated out of Africa}} somewhere between {{w|Recent_African_origin_of_modern_humans#Dating:_pre-or_post-Toba|130,000}} and {{w|Recent_African_origin_of_modern_humans#Coastal_route|70,000}} BCE. |
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− | | They’ve created {{w|painting}}, {{w|pottery}}, {{w|rope}}, and {{w|Bow and arrow|bows and arrows}}, but haven’t developed {{w|writing}} or {{w|farming}}. || 19100 BCE || -4 | + | | They’ve created {{w|painting}}, {{w|pottery}}, {{w|rope}}, and {{w|Bow and arrow|bows and arrows}}, but haven’t developed {{w|writing}} or {{w|farming}}. || 19100 BCE || -4.3 || The {{w|History of painting#Pre-history|oldest known paintings}} date back to about 38,000 BCE. The {{w|Ceramic_art#History|oldest known pottery}} date back to about 20,000 BCE. The {{w|Rope#History|oldest known rope}} date back to about 26,000 BCE. The {{w|History_of_archery#Stone_Age_and_Bronze_Age_archery|oldest known arrows}} date back to about 70,000 BCE, but Randall seems to be mistaken about the bows which seems to be {{w|History_of_archery#Stone_Age_and_Bronze_Age_archery|at most 10,000 years old}}. Writing is mentioned again at 3500 BCE and farming at 10,000 BCE. |
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| rowspan="2"| 19000 <small>BCE</small> | | rowspan="2"| 19000 <small>BCE</small> | ||
− | | Changes in the Earth’s orbit mean that more sunlight reaches the polar ice… || || ||{{w|Milankovitch cycles}} are repeated climate variations on a timescale of tens of millennia. | + | | Changes in the Earth’s orbit mean that more sunlight reaches the polar ice… || 18600 BCE || -4.2 ||{{w|Milankovitch cycles}} are repeated climate variations on a timescale of tens of millennia caused by cyclic variations in {{w|Orbital eccentricity|eccentricity}}, {{w|axial tilt}}, and {{w|precession}} of the {{w|Earth's orbit}}, which thus then determined climatic patterns on Earth. At this time the cycles reaches a point where more sun reached the polar ice and this will begin the melting that (after thousands of years) ends the glaciation. Next to this is a chart showing the solar input, see next entry. |
+ | |||
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− | | [A line chart with a labeled Y-axis "Summer sun W/m<sup>2</sup> at 60°N" with three labeled ticks ranging from 450-550. The curve starts up and then goes down five times and up four times ending down. There is one plateau towards the end compared to the rest of the curve where the ups and downs are quite alike.] || || || | + | | [A line chart with a labeled Y-axis "Summer sun W/m<sup>2</sup> at 60°N" with three labeled ticks ranging from 450-550. The curve starts up and then goes down five times and up four times ending down. There is one plateau towards the end compared to the rest of the curve where the ups and downs are quite alike.] || 18600 BCE || -4.2 || The chart shows the input of sun during summer time in the {{w|Northern hemisphere}} (at {{w|60° northern latitude}}) as the effect (W) per square meter (m<sup>2</sup>) which fluctuated in the range from 450-550 during the time shown in the chart. There is, however, no scale for the time between the peaks. This chart relates to the text about increasing sun to the polar ice in the entry above. |
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| rowspan="1"| 18500 <small>BCE</small> | | rowspan="1"| 18500 <small>BCE</small> | ||
− | | [A map of the world. At the top is a light gray area covering North America, Greenland and northern Europe and most of the northern part of Russia. A similar gray area covers Antarctica. The gray areas are labeled as ice.] || || || | + | | [A map of the world. At the top is a light gray area covering North America, Greenland and northern Europe and most of the northern part of Russia. A similar gray area covers Antarctica. The gray areas are labeled as ice.] || 18300 BCE || -4.2 || |
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| rowspan="1"| 18000 <small>BCE</small> | | rowspan="1"| 18000 <small>BCE</small> | ||
− | | …And the ice sheets start to melt. || || || | + | | …And the ice sheets start to melt. || 17900 BCE || -4.1 || |
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| rowspan="1"| 17500 <small>BCE</small> | | rowspan="1"| 17500 <small>BCE</small> | ||
− | | Temperatures have been creeping upward, but around this point, CO<sub>2</sub> levels start to climb…|| || || | + | | Temperatures have been creeping upward, but around this point, CO<sub>2</sub> levels start to climb…|| 17300 BCE || -4.1 || |
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| rowspan="1"| 17000 <small>BCE</small> | | rowspan="1"| 17000 <small>BCE</small> | ||
− | | …And then the warming speeds up. || || || Sarcasm about the rate of natural climate change compared to modern anthropogenic warming. | + | | …And then the warming speeds up. || 16700 BCE || -4.1 || Sarcasm about the rate of natural climate change compared to modern anthropogenic warming. |
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| rowspan="1"| 16500 <small>BCE</small> | | rowspan="1"| 16500 <small>BCE</small> | ||
− | | [Cueball is standing with a spear just the right of the graph talking to a rabbit.]<br>Cueball: Still pretty cold. || || || True. | + | | [Cueball is standing with a spear just the right of the graph talking to a rabbit.]<br>Cueball: Still pretty cold. || 16200 BCE || -4.0 || True, because although the temperature has risen with 0.3°C over the last 4000 years the temperature is still 4°C below the 1961-1990 average. |
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| rowspan="2"| 16000 <small>BCE</small> | | rowspan="2"| 16000 <small>BCE</small> | ||
− | | [Megan points to the graph to the right of her and between her and Ponytail standing on the other side. Mean is the first drawing on the left side of the dotted curve, which has hardly moved since the beginning, only to just on the other side of 4°C below the 1961-1990 average.] || || || | + | | [Megan points to the graph to the right of her and between her and Ponytail standing on the other side. Mean is the first drawing on the left side of the dotted curve, which has hardly moved since the beginning, only to just on the other side of 4°C below the 1961-1990 average.] || 15600 BCE || -3.9 || Megan seems to be pushing the temperature up, and this is the first time the temperature is less than 4°C below the 1961-1990 average. |
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− | | [In the right part of the chart is an explanation of the data. Below the first two lines there are four drawings each showing possible temperature swings in reality compared to the smoothed data that represents the dotted curve of the entire chart. The dotted curve is shown in all four drawings and a thin line is shown running along it but with much more fluctuation left and right on the first two, a large spike right on the third and a large bump way right on the fourth. Above these there are two labels. The first labels is inside a bracket that covers the first three, and the last label is for the last drawing. Below is a list of sources.] <br>Limits of this data: <br> Short warming or cooling spikes might be “smoothed out” by these reconstructions but only if they’re small or brief enough. <br> Possible Unlikely<br>Reconstructions are from Shakun (2012) and Marcott (2013), scaled to Annan + Hargreaves (2013) estimate for the last glacial period. || || || This is Randall's pre-emptive response to skepticism about the accuracy of prehistoric data. Ice cores and similar records might miss individual year-to-year variation, but should catch sustained changes lasting many decades, which is the time scale that matters for climate. | + | | [In the right part of the chart is an explanation of the data. Below the first two lines there are four drawings each showing possible temperature swings in reality compared to the smoothed data that represents the dotted curve of the entire chart. The dotted curve is shown in all four drawings and a thin line is shown running along it but with much more fluctuation left and right on the first two, a large spike right on the third and a large bump way right on the fourth. Above these there are two labels. The first labels is inside a bracket that covers the first three, and the last label is for the last drawing. Below is a list of sources.] <br>Limits of this data: <br> Short warming or cooling spikes might be “smoothed out” by these reconstructions but only if they’re small or brief enough. <br> Possible Unlikely<br>Reconstructions are from Shakun (2012) and Marcott (2013), scaled to Annan + Hargreaves (2013) estimate for the last glacial period. || 15600 BCE || -3.9 || This is Randall's pre-emptive response to skepticism about the accuracy of prehistoric data. Ice cores and similar records might miss individual year-to-year variation, but should catch sustained changes lasting many decades, which is the time scale that matters for climate. See links to the [[#Sources|sources below]]. |
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| rowspan="1"| 15500 <small>BCE</small> | | rowspan="1"| 15500 <small>BCE</small> | ||
− | | In what is now France, humans paint murals on the walls of the Lascaux caves <br> [Hairy paints three animals, two with horns, and two humans, Cueball holding hand with Hairy who has a spear. On the other side of the central line Megan writes three letters, the last of which is reversed:] | + | | In what is now France, humans paint murals on the walls of the Lascaux caves <br> [Hairy paints three animals, two with horns, and two humans, Cueball holding hand with Hairy who has a spear. On the other side of the central line Megan writes three letters, the last of which is reversed:] NIИ || 15200 BCE || -3.8 || A reference to the industrial techno band {{w|Nine Inch Nails}} as Megan writes the bands stylized name NIИ on the wall next to Hairy who is in the process of painting the {{w|cave painting}} at {{w|Lascaux}} in France. |
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| rowspan="1"| 15000 <small>BCE</small> | | rowspan="1"| 15000 <small>BCE</small> | ||
− | | Ice sheets around Alaska shrink, exposing a land bridge between Asia and North America <br> [From around the bottom if this section and down to 11500 BCE the dotted curve moved steadily to the right towards warmed temperature peaking close to 1.5°C below the 1961-1990 average. Before this the temperature had not moved much away from that at the start.] || || || | + | | Ice sheets around {{w|Alaska}} shrink, exposing a land bridge between Asia and North America <br> [From around the bottom if this section and down to 11500 BCE the dotted curve moved steadily to the right towards warmed temperature peaking close to 1.5°C below the 1961-1990 average. Before this the temperature had not moved much away from that at the start.] || 14600 BCE || -3.5 || This land bridge is known as {{w|Beringia}}. |
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| rowspan="1"| 14500 <small>BCE</small> | | rowspan="1"| 14500 <small>BCE</small> | ||
− | | [Cueball walks right looking back at the graph behind him. Megan walks in front of him pointing further right.]<br>| Cueball: Cool.<br> Humans reach North America. || || || This is approximately when the ancestors of the Inuit crossed the land bridge from what is now Russia to what is now Alaska. However, evidence of humans in North America over 20,000 years ago suggests that humans reached North America by boat prior to the formation of the land bridge. | + | | [Cueball walks right looking back at the graph behind him. Megan walks in front of him pointing further right.]<br>| Cueball: Cool.<br> Humans reach North America. || 14200 BCE || -3.3 || This is approximately when the ancestors of the Inuit crossed the land bridge from what is now Russia to what is now Alaska. However, evidence of humans in North America over 20,000 years ago suggests that humans reached North America by boat prior to the formation of the land bridge. Cueball's comment can either be directed at the fact that it was cool that people migrated this far, or it could be related to the fact that he looks back at the temperature curve and observes that even though the temperature has increased one degree since the start of the chart it is still 3.3°C below the 1961-1990 average, i.e. it is still very cold. |
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| rowspan="2"| 14000 <small>BCE</small> | | rowspan="2"| 14000 <small>BCE</small> | ||
− | | The edge of the ice withdraws from New York City and retreats North. || || || | + | | The edge of the ice withdraws from New York City and retreats North. || 13700 BCE || -3.1 || |
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− | | [A large glacier front speaks in a speech bubble with an arrow pointing at it. Behind is there are four peaks in the horizon and in front of it three small melting pools and some rocks on the ground.] <br> Glacier: ''That’s it! I’m moving to Canada!'' || || || When US citizens are unhappy with changes in their country, they sometimes say they will move to Canada in protest. | + | | [A large glacier front speaks in a speech bubble with an arrow pointing at it. Behind is there are four peaks in the horizon and in front of it three small melting pools and some rocks on the ground.] <br> Glacier: ''That’s it! I’m moving to Canada!'' || 13600 BCE || -3.0 || When US citizens are unhappy with changes in their country, they sometimes say they will move to Canada in protest. Here it is the glacier that is unhappy with the climate changes. And since the ice withdraws north when it gets hotter this glacier didn't have much of a choice. However this is a slow process and according to the chart the glacier first retreated over the Canadian border around 8400 BCE more than 5000 years later. |
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| rowspan="2"| 13500 <small>BCE</small> | | rowspan="2"| 13500 <small>BCE</small> | ||
− | | Humans domesticate dogs <br> (Date uncertain, may be much earlier) || || || | + | | Humans domesticate dogs <br> (Date uncertain, may be much earlier) || 13400 BCE || -3.0 || See {{w|Origin of the domestic dog}}. Here it is {{w|Origin_of_the_domestic_dog#Time_of_domestication|mentioned}} that {{w|dogs}} separated from {{w|wolfs}} about 23,500 years ago, but that there was an event around 15,000 years ago (13,00 BCE) which increased the population size and that may be attributable to domestication events. But if humans are responsible for the creation of the dog species it may have occurred several thousands of years before. |
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− | || [Megan and Cueball is watching a wolf looking at them.]<br>Megan: Okay, you can live in our homes and we’ll feed you, but we’ll still get mad if you poop on the floor. <br> Wolf: Deal. <br> Cueball: And we get to breed you to be tiny and dress you in little costumes. <br>Wolf: …Wait. || || || | + | || [Megan and Cueball is watching a wolf looking at them.]<br>Megan: Okay, you can live in our homes and we’ll feed you, but we’ll still get mad if you poop on the floor. <br> Wolf: Deal. <br> Cueball: And we get to breed you to be tiny and dress you in little costumes. <br>Wolf: …Wait. || 13100 BCE || -2.8 || Megan is making a deal with the wolf that it can eat and sleep with the humans as long as they can yell at it for pooping indoor. This sounds like a sweat deal for the wolf until Cueball mentions that they will {{w|Dog breeding|breed}} it to be {{w|Chihuahua (dog)|very small}} and then dress it up in small {{w|Dog's fashion|costumes}}. The wolf says wait, but it is already too late... |
|- | |- | ||
| rowspan="2"| 13000 <small>BCE</small> | | rowspan="2"| 13000 <small>BCE</small> | ||
− | | {{w|Woolly Rhino}} goes extinct || || || Actually only true for mainland woolly rhinos. Some survived on a small island until | + | | {{w|Woolly Rhino}} goes extinct || 12900 BCE || -2.7 || Actually only true for mainland woolly rhinos. Some survived on a small island until {{w|Woolly_rhinoceros#Extinction|around 8000 BCE}}. |
|- | |- | ||
− | | Oregon is scoured by huge floods as glacial dams burst and lakes of meltwater flow to the sea || || || See {{w|Missoula Floods}} | + | | Oregon is scoured by huge floods as glacial dams burst and lakes of meltwater flow to the sea || 12600 BCE || -2.2 || See {{w|Missoula Floods}} |
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| rowspan="1"| 12500 <small>BCE</small> | | rowspan="1"| 12500 <small>BCE</small> | ||
− | | Ice sheets withdraw from Chicago || || || | + | | Ice sheets withdraw from Chicago || 12200 BCE || -1.8 || |
|- | |- | ||
| rowspan="1"| 12000 <small>BCE</small> | | rowspan="1"| 12000 <small>BCE</small> | ||
− | | Humans settle {{w|Abu Hureyra}} in Syria | + | | Humans settle {{w|Abu Hureyra}} in {{w|Syria}} || 11550 BCE || -1.6 || A well-preserved prehistoric village that lasted over 4000 years, allowing archaeologists to study how their culture developed. |
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| rowspan="1"| 11500 <small>BCE</small> | | rowspan="1"| 11500 <small>BCE</small> | ||
− | | [An arrow on the left side of the dotted curve is pointing down along the dotted curve and to the left indicate temperature is declining again, meaning the dotted curve now moves left to colder temperatures. This only continues until 10500 BCE. It is only the second time something is noted on the left side after Megan at 16000 BCE] <br> Temperatures start to decline, mainly in the Northern hemisphere<br> This may be caused by changes in ocean circulation due to the floods of cold fresh meltwater flowing into the Atlantic as the North American ice sheet melts. <br> This cooler period is called the {{w|Younger Dryas}} || || || | + | | [An arrow on the left side of the dotted curve is pointing down along the dotted curve and to the left indicate temperature is declining again, meaning the dotted curve now moves left to colder temperatures. This only continues until 10500 BCE. It is only the second time something is noted on the left side after Megan at 16000 BCE] <br> Temperatures start to decline, mainly in the Northern hemisphere<br> This may be caused by changes in ocean circulation due to the floods of cold fresh meltwater flowing into the Atlantic as the North American ice sheet melts. <br> This cooler period is called the {{w|Younger Dryas}} || 11300 BCE || -1.6 || The temperature almost reached 1.5°C below the 1961-1990 average before it got colder. The mentioning of the melting water causing a cooling in the northern hemisphere references a similar event that could also happen today. If the ice on Greenland melts too quickly it could mess the pump that runs the {{w|Gulf Stream}} and cause a {{w|shutdown of thermohaline circulation}}, which would actually end up cooling Europe, especially the northern part and the British Island (and everything in the North Atlantic), in spite of possibly still generally increasing temperatures on a global scale. This could be a major problem for farming in Europe! The movie {{w|The Day After Tomorrow}} was based on this shutdown, although it then took it to an (impossible) extreme with super cyclones that cooled down the entire northern hemisphere into an ice age in a few days... In the Younger Dryas this effect caused the Earth to cool down less than one degree over 1000 years before the warm up began again. |
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| rowspan="1"| 11000 <small>BCE</small> | | rowspan="1"| 11000 <small>BCE</small> | ||
− | | [This is the first text to the left of the dotted curve:] <br> Humans reach Argentina || || || | + | | [This is the first text to the left of the dotted curve:] <br> Humans reach {{w|Argentina}} || 10900 BCE || -1.8 || || |
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Revision as of 19:39, 17 September 2016
Earth Temperature Timeline |
↓ Skip to explanation ↓ |
Title text: [After setting your car on fire] Listen, your car's temperature has changed before. |
Explanation
Contents
This explanation may be incomplete or incorrect: Table for explanations now ready to be filled out. Please remove this tag only when everything is explained. If you can address this issue, please edit the page! Thanks. |
In the past 100 years, human action produced lots of CO₂ emissions, which have caused a rise in average global temperature through the greenhouse effect. This is called global warming and is part of a climate change, a subject that has become a recurrent subject on xkcd. There are still many people who claim that this is not happening, or at least that it is not caused by any human actions, called climate change deniers. One argument of theirs is that global warming is happening for natural causes, summarized with the phrase "temperature has changed before". This comic is a direct, but much more thorough, follow up on the previous global warming comic: 1379: 4.5 Degrees.
This comic shows that while temperature changes have indeed occurred before, the speed of the current temperature rise is much, much faster than those seen (actually: estimated) in the previous thousands of years. It seemed to touch on something in peoples consciousness, because it became so popular that Randall postponed the release of his next comic to keep this one on the front page one day longer.
This comic is a timeline on how the temperature has changed since 20,000 BCE (Before Common Era) to the present day and extrapolated 84 years on from present day of the release of the comic (2016) to 2100 CE depending on the choice of actions to stop CO₂ emission that is taken now or never. It is meant to contrast the slow-paced natural changes with the rapid temperature rise in the recent years. The effect is achieved by forcing the reader to scroll endlessly through slow, building-up changes and then face them with an almost instantaneous, quick rise towards the end. The temperature curve is a dotted line most of the time, but from about 1850 to present day (2016) the measurement data is good enough to let the curve become a solid line indicating that this is not an estimate. Before 1850 the temperature is an estimate based on the sources given. And likewise into the future the curve is also dotted as this is predictions. And here there are even three possible outcomes depending on how seriously politicians and other influential people (and the population of Earth) take knowledge (and comics) like this.
Although this is a topic Randall obviously takes very seriously, and by far most of the facts fit with known history, he still includes several jokes in the comic (see list below) He even included one at the base of the comic where the serious human caused temperature increase is at display. By placing the invention of the internet at 1990 in the chart, just where the temperature curve starts its most rapid increase, he humorously implies that the internet caused the rise in temperature. Randall has before been after incidents where cause and effects like this has been used without any proof that it was not a coincidence.
Below in the table each entry will be noted and explained (in time). This is one of the comics where Randall cites his sources like he did for one of his other very large comics 980: Money.
The title text compares the saying that "the temperature has changed before" comparing temperature changes over thousands of years to the rapid global warming over the last century with saying that the "small" changes to the temperature a car experiences over the years of normal usage should not make you worried over the rapid temperature increase that happens when someone sets your car on fire. A related joke was used recently in 1693: Oxidation.
Jokes in the comic
- Above the joke about the internet causing the global warming is mentioned.
- Other "silly" jokes included in the comic are:
- At 13600 BCE it is mentioned that humans domesticate dogs. Megan talks to a wolf about to be tamed making a deal with it, that it can eat and sleep with the humans as long as they can yell at it for pooping indoor. This sounds like a sweat deal for the wolf until Cueball mentions that they will breed it to be very small and then dress it up in small costumes. The wolf says wait, but it is already too late...
- The Pokémon reference at 9000 BCE about them going extinct in North America (although Megan does proclaim that this is not a real fact). As the writing stated that Pokémon go extinct this can also be seen as a reference to the recently released Pokémon Go game and hence also the recent comic 1705: Pokémon Go.
- At 4500 BCE, next to "Proto-Indo-European language develops", Ponytail gets the idea to develop the language heavily inflected to make it difficult to remember all the verb endings for future students. A direct reference to the recent comic 1709: Inflection.
- The reference to the mockumentary about the fake rock band This Is Spinal Tap in conjunction with Stonehenge at 2300 BCE. In the movie the band ordered a giant 18 feet Stonehenge megalith but a writing mistake gives them one that is only 18 inches high.
- Another real band Nine Inch Nails is referenced 16000 BCE where Megan writes the bands stylized name NIИ on the wall next to Hairy who is in the process of painting the cave painting at Lascaux in France.
- Around the setting of the Iliad and the Odyssey (1200 BCE) a drawing of the Trojan Horse has writing on it that states: Not a trap.
- Just below the previous entry also at 12000 BCE is the mentioning of the invasion of the Sea Peoples. This sounds so much like a reference to mermaids, often called sea people that Randall feels the need to note that this invasion and these sea people is a real thing in a foot note. This is opposed to the Pokémon reference above where he notes that it is not a real fact. The sea people was a seafaring confederation of groups known to have attacked ancient Egypt around this time.
- At 500 BCE a reference to the Battle of Thermopylae (also known as 300 Spartans) he references this by comparing the event with the 2007 movie 300 about this battle. But notes that in the real world the fighting of course occurred at regular speed and that they probably had more clothing on in the real world than in the fictionalized action movie.
- There are other minor jokes but this list mentiones all the major jokes.
Table of all elements
- Here is table (to be filled out) of all elements with explanations including reading of temperature and year for each event from the curve.
- Table ready for use:
- The year group is just an easy way to find the section.
- The actual year of an event should be read off more precisely on the chart.
- Suggestion for doing this:
- Top part of element
- Central part of element
- Other?
- Element is a description mainly taken from the transcript. Feel free to remove redundant information, but the guess was that getting the table ready was the most important feature for getting the explanation started.
- T (°C) is the number of degrees above or below the 1961-1990 average, which on this graph is set to zero.. (i.e. not the number of physical degrees above or below 0°C).
- Explanation explains itself.
Year group | Element | Year | T (°C) | Explanation | |
---|---|---|---|---|---|
20000 BCE | [An arrow goes from the dotted line to the central line at 0°C (representing the 1961-1990 average). In the middle of the line there is a temperature label:] 4.3°C At the start of our timeline, 22,000 years ago, Earth is 4°C colder than during the late 20th century. |
20000 BCE | -4.3 | The temperature at the beginning of the chart compared to the average from 1961-1990 that in general are used to compare temperatures with today as well as in the rest of this chart. As a rule climate changes are compared with a 30 year interval, and recently the 1961-1990 average was chosen as the "normal" to compare temperature changes with. The timeline staring at 20,000 BCE fits with Wikipedia's article on Last glacial period (or the last ice age) stating that the the maximum extent of glaciation was approximately 22,000 years ago. However, in the article on the Last Glacial Maximum it states that this maximum occurred 24,500 BCE 4,500 years before the other article (even though they link to each other). | |
Boston is buried under almost a mile of ice, and the glaciers reach as far south as New York City. [The Statue of Liberty is shown in front of a glacier front. A guy with a white knit cap is seen walking in a snowy landscape. The skyline of Boston is shown under a half a mile of ice.] |
19700 BCE | -4.3 | The Boston image is directly taken from 1225: Ice Sheets about the ice age glacier coverage and the guy with the white knit cap could be the guy from 1321: Cold also about global warming. It shows what a difference 4 degree in global temperature means (massive effect), as opposed to what four degree means on a daily weather wise scale (nothing!). Randall lives in Boston. It was also shown buried in ice in 1379: 4.5 Degrees. Knit caps have only been used a few times in xkcd, most prominently on Knit Cap Girl in 1350: Lorenz, see her section for more details. | ||
19500 BCE | But the world is about to warm up. | 19500 BCE | -4.3 | The warming process actually takes thousands of years, which this comic will portray down thousands of pixels to come. | |
By this time, humans have already spread across Africa, Eurasia, and Australia. | 19300 BCE | -4.3 | Homo Sapiens successfully migrated out of Africa somewhere between 130,000 and 70,000 BCE. | ||
They’ve created painting, pottery, rope, and bows and arrows, but haven’t developed writing or farming. | 19100 BCE | -4.3 | The oldest known paintings date back to about 38,000 BCE. The oldest known pottery date back to about 20,000 BCE. The oldest known rope date back to about 26,000 BCE. The oldest known arrows date back to about 70,000 BCE, but Randall seems to be mistaken about the bows which seems to be at most 10,000 years old. Writing is mentioned again at 3500 BCE and farming at 10,000 BCE. | ||
19000 BCE | Changes in the Earth’s orbit mean that more sunlight reaches the polar ice… | 18600 BCE | -4.2 | Milankovitch cycles are repeated climate variations on a timescale of tens of millennia caused by cyclic variations in eccentricity, axial tilt, and precession of the Earth's orbit, which thus then determined climatic patterns on Earth. At this time the cycles reaches a point where more sun reached the polar ice and this will begin the melting that (after thousands of years) ends the glaciation. Next to this is a chart showing the solar input, see next entry. | |
[A line chart with a labeled Y-axis "Summer sun W/m2 at 60°N" with three labeled ticks ranging from 450-550. The curve starts up and then goes down five times and up four times ending down. There is one plateau towards the end compared to the rest of the curve where the ups and downs are quite alike.] | 18600 BCE | -4.2 | The chart shows the input of sun during summer time in the Northern hemisphere (at 60° northern latitude) as the effect (W) per square meter (m2) which fluctuated in the range from 450-550 during the time shown in the chart. There is, however, no scale for the time between the peaks. This chart relates to the text about increasing sun to the polar ice in the entry above. | ||
18500 BCE | [A map of the world. At the top is a light gray area covering North America, Greenland and northern Europe and most of the northern part of Russia. A similar gray area covers Antarctica. The gray areas are labeled as ice.] | 18300 BCE | -4.2 | ||
18000 BCE | …And the ice sheets start to melt. | 17900 BCE | -4.1 | ||
17500 BCE | Temperatures have been creeping upward, but around this point, CO2 levels start to climb… | 17300 BCE | -4.1 | ||
17000 BCE | …And then the warming speeds up. | 16700 BCE | -4.1 | Sarcasm about the rate of natural climate change compared to modern anthropogenic warming. | |
16500 BCE | [Cueball is standing with a spear just the right of the graph talking to a rabbit.] Cueball: Still pretty cold. |
16200 BCE | -4.0 | True, because although the temperature has risen with 0.3°C over the last 4000 years the temperature is still 4°C below the 1961-1990 average. | |
16000 BCE | [Megan points to the graph to the right of her and between her and Ponytail standing on the other side. Mean is the first drawing on the left side of the dotted curve, which has hardly moved since the beginning, only to just on the other side of 4°C below the 1961-1990 average.] | 15600 BCE | -3.9 | Megan seems to be pushing the temperature up, and this is the first time the temperature is less than 4°C below the 1961-1990 average. | |
[In the right part of the chart is an explanation of the data. Below the first two lines there are four drawings each showing possible temperature swings in reality compared to the smoothed data that represents the dotted curve of the entire chart. The dotted curve is shown in all four drawings and a thin line is shown running along it but with much more fluctuation left and right on the first two, a large spike right on the third and a large bump way right on the fourth. Above these there are two labels. The first labels is inside a bracket that covers the first three, and the last label is for the last drawing. Below is a list of sources.] Limits of this data: Short warming or cooling spikes might be “smoothed out” by these reconstructions but only if they’re small or brief enough. Possible Unlikely Reconstructions are from Shakun (2012) and Marcott (2013), scaled to Annan + Hargreaves (2013) estimate for the last glacial period. |
15600 BCE | -3.9 | This is Randall's pre-emptive response to skepticism about the accuracy of prehistoric data. Ice cores and similar records might miss individual year-to-year variation, but should catch sustained changes lasting many decades, which is the time scale that matters for climate. See links to the sources below. | ||
15500 BCE | In what is now France, humans paint murals on the walls of the Lascaux caves [Hairy paints three animals, two with horns, and two humans, Cueball holding hand with Hairy who has a spear. On the other side of the central line Megan writes three letters, the last of which is reversed:] NIИ |
15200 BCE | -3.8 | A reference to the industrial techno band Nine Inch Nails as Megan writes the bands stylized name NIИ on the wall next to Hairy who is in the process of painting the cave painting at Lascaux in France. | |
15000 BCE | Ice sheets around Alaska shrink, exposing a land bridge between Asia and North America [From around the bottom if this section and down to 11500 BCE the dotted curve moved steadily to the right towards warmed temperature peaking close to 1.5°C below the 1961-1990 average. Before this the temperature had not moved much away from that at the start.] |
14600 BCE | -3.5 | This land bridge is known as Beringia. | |
14500 BCE | Cueball: Cool. Humans reach North America. |
14200 BCE | -3.3 | This is approximately when the ancestors of the Inuit crossed the land bridge from what is now Russia to what is now Alaska. However, evidence of humans in North America over 20,000 years ago suggests that humans reached North America by boat prior to the formation of the land bridge. Cueball's comment can either be directed at the fact that it was cool that people migrated this far, or it could be related to the fact that he looks back at the temperature curve and observes that even though the temperature has increased one degree since the start of the chart it is still 3.3°C below the 1961-1990 average, i.e. it is still very cold. | |
14000 BCE | The edge of the ice withdraws from New York City and retreats North. | 13700 BCE | -3.1 | ||
[A large glacier front speaks in a speech bubble with an arrow pointing at it. Behind is there are four peaks in the horizon and in front of it three small melting pools and some rocks on the ground.] Glacier: That’s it! I’m moving to Canada! |
13600 BCE | -3.0 | When US citizens are unhappy with changes in their country, they sometimes say they will move to Canada in protest. Here it is the glacier that is unhappy with the climate changes. And since the ice withdraws north when it gets hotter this glacier didn't have much of a choice. However this is a slow process and according to the chart the glacier first retreated over the Canadian border around 8400 BCE more than 5000 years later. | ||
13500 BCE | Humans domesticate dogs (Date uncertain, may be much earlier) |
13400 BCE | -3.0 | See Origin of the domestic dog. Here it is mentioned that dogs separated from wolfs about 23,500 years ago, but that there was an event around 15,000 years ago (13,00 BCE) which increased the population size and that may be attributable to domestication events. But if humans are responsible for the creation of the dog species it may have occurred several thousands of years before. | |
[Megan and Cueball is watching a wolf looking at them.] Megan: Okay, you can live in our homes and we’ll feed you, but we’ll still get mad if you poop on the floor. Wolf: Deal. Cueball: And we get to breed you to be tiny and dress you in little costumes. Wolf: …Wait. |
13100 BCE | -2.8 | Megan is making a deal with the wolf that it can eat and sleep with the humans as long as they can yell at it for pooping indoor. This sounds like a sweat deal for the wolf until Cueball mentions that they will breed it to be very small and then dress it up in small costumes. The wolf says wait, but it is already too late... | ||
13000 BCE | Woolly Rhino goes extinct | 12900 BCE | -2.7 | Actually only true for mainland woolly rhinos. Some survived on a small island until around 8000 BCE. | |
Oregon is scoured by huge floods as glacial dams burst and lakes of meltwater flow to the sea | 12600 BCE | -2.2 | See Missoula Floods | ||
12500 BCE | Ice sheets withdraw from Chicago | 12200 BCE | -1.8 | ||
12000 BCE | Humans settle Abu Hureyra in Syria | 11550 BCE | -1.6 | A well-preserved prehistoric village that lasted over 4000 years, allowing archaeologists to study how their culture developed. | |
11500 BCE | [An arrow on the left side of the dotted curve is pointing down along the dotted curve and to the left indicate temperature is declining again, meaning the dotted curve now moves left to colder temperatures. This only continues until 10500 BCE. It is only the second time something is noted on the left side after Megan at 16000 BCE] Temperatures start to decline, mainly in the Northern hemisphere This may be caused by changes in ocean circulation due to the floods of cold fresh meltwater flowing into the Atlantic as the North American ice sheet melts. This cooler period is called the Younger Dryas |
11300 BCE | -1.6 | The temperature almost reached 1.5°C below the 1961-1990 average before it got colder. The mentioning of the melting water causing a cooling in the northern hemisphere references a similar event that could also happen today. If the ice on Greenland melts too quickly it could mess the pump that runs the Gulf Stream and cause a shutdown of thermohaline circulation, which would actually end up cooling Europe, especially the northern part and the British Island (and everything in the North Atlantic), in spite of possibly still generally increasing temperatures on a global scale. This could be a major problem for farming in Europe! The movie The Day After Tomorrow was based on this shutdown, although it then took it to an (impossible) extreme with super cyclones that cooled down the entire northern hemisphere into an ice age in a few days... In the Younger Dryas this effect caused the Earth to cool down less than one degree over 1000 years before the warm up began again. | |
11000 BCE | [This is the first text to the left of the dotted curve:] Humans reach Argentina |
10900 BCE | -1.8 | ||
10500 BCE | [An arrow pointing down along the right side of the dotted curve and to the right indicate temperature is increasing again, meaning the dotted curve now moves right to hotter temperatures. This continues until 8000 BCE where it levels out just above the 1961-1990 average.] Warming resumes |
||||
Human settlements at Jericho | |||||
10000 BCE | First development of farming | See History of agriculture | |||
9500 BCE | Saber-toothed cat goes extinct | They were not tigers. | |||
Horses disappear from North America | The evolution of the horse began millions of years ago in North America; early species migrated across Beringia into Eurasia. | ||||
9000 BCE | Last North American Pokémon go extinct [Cueball with a spear and Megan is looking up at this last “fact”.] Megan: That is not a real fact. |
As prehistoric Megan states, this is not a real fact. Pokémon are still thriving throughout the entire world (see 1705: Pokémon Go), and are most commonly found near affluent first world neighborhoods. | |||
Temperatures reach modern levels | |||||
Rising seas cut off the land bridge between North America and Asia | |||||
Cattle domesticated | |||||
8500 BCE | Ice sheets retreat across the Canadian border | ||||
Temperatures start to level out slightly above 1961-1990 levels | |||||
8000 BCE | [The above sentence breaks over the 8000 BCE line. From here a maximum in temperature on the chart is reached at 0.5°C above the 1961-1990 average, which will not be overtaken until 2000 CE. It stays almost constant here until 5000 BCE where a slight cooling begins.] |
| |||
7500 BCE | This warm, stable period is called the Holocene Climate Optimum | Some skeptics like to say "it was warmer in the Holocene." This is no longer true. Global temperature began encroaching Holocene levels in 1998, and has equalled or possibly exceeded them since 2014. | |||
Jiahu settled in China | |||||
7000 BCE | Final collapse of the North American ice sheet leads to rapid 2-4m sea level rise… | ||||
[A small arrow points down and left to the right of the dotted curve. There is a small decrease in temperature but it is very small and would have been missed without the arrow and label.] …And a period of cooling in the Northern hemisphere |
|||||
6500 BCE | As seas rise to near their modern levels, Britain is cut off from mainland Europe | This is a reference to the flooding of Doggerland. | |||
6000 BCE | Humans develop copper metalworking | The copper age was relatively brief before humans discovered how to make bronze. | |||
5500 BCE | Massive volcanic eruption in Oregon creates crater lake | ||||
Gold metalworking | Ooh, shiny! | ||||
5000 BCE | Invention of the wheel | ||||
[To the right of the dotted curve is an arrow pointing down and slightly left. From here temperature decreases very slowly but steadily from 0.5°C above the 1961-1990 average until 1000 BCE where a stable plateau is reached around the 1961-1990 average.] Earth begins to cool slowly mainly due to regular cycles in its orbit |
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4500 BCE | Proto-Indo-European language develops | ||||
[To the right of the curve Ponytail holds up a hand towards Cueball.] Ponytail: Let’s make out language heavily inflected, so future students have to memorize a zillion verb endings! Cueball: Okay! |
Ponytail refers to 1709: Inflection. | ||||
Permanent settlements in the fertile crescent | |||||
4000 BCE | Horses domesticated | ||||
Minoan culture arises on Crete | |||||
3500 BCE | Egyptian mummification | ||||
Rise of the Indus Valley civilization | |||||
Invention of writing in Sumer “prehistory” ends, “history” begins | Kids these days with their new-fangled stone tablets, instead of using their memory... | ||||
Earliest human whose name we know (Pharaoh Iry-Hor in Egypt) | |||||
3000 BCE | Three Sovereigns and Five Emperors period in China | ||||
Gilgamesh | |||||
Imhotep | |||||
Mayan culture emerges | |||||
Great Pyramid constructed | |||||
2500 BCE | Corded Ware culture in Europe | ||||
[To the left of the curve two rock musicians with long hair and electrical guitars are standing on either side of a small gate made of three slabs of stone, one on top of the other two standing stones.] Stonehenge completed |
2250 | The drawing is a reference to the 1984 movie "This is Spinal Tap" (A documentary/parody featuring the fake metal band "Spinal Tap", http://www.imdb.com/title/tt0088258/), the musicians order a Stone Henge prop for the stage, which turns out to be too small (https://www.youtube.com/watch?v=qAXzzHM8zLw) | |||
Chariots developed | |||||
2000 BCE | Alphabetic writing developed in Egypt | ||||
Last mammoths on a tiny Siberian island go extinct | |||||
Minoan eruption | |||||
1500 BCE | Iron smelting | ||||
Olmec civilization develops in Central America | |||||
[A Trojan horse with two Cueball-like guys in front and a third standing on its back. Its back is at three Cueball’s height and its head rises to the level of the Cueball on its back. It stands on a platform with four wheel on the visible side. There is text on the horse] Setting of the Iliad and the Odyssey Text on horse: Not a trap |
The Trojan War | ||||
Invasion of the Sea peoples* * A real thing |
|||||
Polynesians explore the Pacific Ocean | |||||
1000 BCE | [From 1000 BBC to 1000 CE the temperature is stable and very close to the 1961-1990 average.] | ||||
Solomon | |||||
Iliad and Odyssey composed | |||||
Rise of Greek city-states | |||||
Neo-Assyrian empire | |||||
First Olympics | |||||
Zapotec writing in modern Mexico | |||||
Confucius | |||||
500 BCE | movie 300, but regular speed and with more clothing | ||||
Buddha | |||||
Nazca Lines | |||||
Alexander the Great | |||||
Mayan hieroglyphics | |||||
Ashoka the Great | |||||
Paper invented | |||||
Asterix | |||||
Teotihuacán metropolis | |||||
Julius Caesar | |||||
1 BCE 1 CE |
[At the year 0, there is instead two numbers for each of the two scales before (1 BCE) and after Christ (1 CE)] | ||||
Roman Empire | |||||
Jesus | |||||
[To the left and erupting volcano.] Pompeii |
|||||
Three Kingdoms period | |||||
Gupta empire | |||||
Various groups take turns sacking Rome | |||||
Attila the Hun | |||||
500 CE | Muhammad | ||||
Tang Dynasty | |||||
[An arrow to the right of the dotted curve pointing down, takes a swing far out from the curve and then bends back again. The text label next to it breaks into the next 500 period. The dotted curve stays stable at the 1961-1990 average along this arrow.] Medieval warm period in Europe and some northern regions (too regional to affect the global average much) |
|||||
Leif Eriksson | |||||
1000 CE | [The dotted curve moves to the left towards lower temperature reaching a minimum around 1650 of about 0.6°C below the 1961-1990 average at the Little Ice Age.] | ||||
[To the left a drawing of a compass with needle pointing the black end towards north east. There are labels for the four main directions (N, S, W, E) and a label next to it:] Magnetic compass navigation |
|||||
Ghengis Khan | |||||
Zheng He’s fleet explores Asia and Africa | |||||
Aztec Alliance | |||||
Printing press | |||||
Columbus | |||||
1500 CE | European Renaissance | ||||
Shakespeare | |||||
1600 | Newton | ||||
[To the right of the dotted curve there is an arrow pointing down that makes a swing in towards the curve and then back out again. At 0.6°C below the 1961-1990 average, this is the coldest it has been since 9500 BCE. It is labeled:] ”Little Ice Age” |
This was not a true geologic Ice Age, just a slightly chilly period. | ||||
1700 | Steam engines | ||||
Unites States Independence | |||||
1800 | Industrial Revolution | ||||
Telegraphs | |||||
[After this the dotted curve becomes solid.] | In the late 1800s, weather records became sufficiently accurate and widespread to greatly improve the precision of climate measurements. | ||||
1900 | Airplanes | ||||
World Wars | |||||
[The solid line takes a step to the right close to the 1961-1990 average. Over the rest of the 1900s it moves closer to the 1961-1990 average, crossing it before 2000 where it almost reaches the maximum temperature of 0.5 °C above the 1961-1990 average from earlier in 8000 BCE.] | This is what the previous 14000 pixels of comic has been leading up to. After a laborious 20 millennia of gradual and meandering climate change, it should be clear that a full degree of warming in a single century is unprecedented in human history, and very unlikely to be natural variation. | ||||
Fossil fuel CO2 emissions start rapidly increasing | |||||
Nuclear weapons | The Working Group on the 'Anthropocene' suggests dating the Anthropocene epoch from ~1950. | ||||
Internet |
| ||||
2000 | Northwest Passage opens | ||||
[From here to present day the solid line increases rapidly and in 2016 present day is almost reaches 1°C above the 1961-1990 average, with about 0.8°C above the 1961-1990 average.] | No, warming did not stop in 1998. | ||||
2016 | Present day | ||||
[From here the curve once again becomes dotted as this is the future. After one dot it splits in two and after the first two dots another split between them occurs forming three possible future dotted curves.] | |||||
The first curve bending down before the others, and thus to the right of the other two reaches about 1.2°C above the 1961-1990 average and then goes straight down and stops at the 2100 line. An arrow points to it from the left and a label is written partly before and the rest after the 2100 line to the left of the curve:] Best-case scenario assuming immediate massive action to limit emissions |
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2100 | [The middle curve bends a little down after reaching 1.3°C above the 1961-1990 average, and then continues this path reaching 2°C above the 1961-1990 average in 2100. An arrow point from below to it and a label is written below the curve and below 2100 line:] Optimistic scenario |
||||
[The last line continues along the path from the last 16 years of the solid line reaching 4.2°C above the 1961-1990 average at 2100, almost as far on the other side of the 1961-1990 average in 150 years as it took 14,000 years to move from the other side from the start of the chart. Another arrow point to this from below with a label below the curve and below 2100 line:] Current Path |
Randall has warned about the hazards of Extrapolating, but this line is in fact below the worst case prediction. |
Sources
The image attributes climate data sources as "Shakun et al. (2012), Marcott et al. (2013), Annan and Hargreaves (2013), HadCRUT4, IPCC":
- Shakun et al. (2012) - Nature, (pdf)
- Marcott et al. (2013) - Science, (pdf)
- Annan and Hargreaves (2013) - Climate of the Past (pdf)
- HadCRUT4 - Official site
- IPCC -Official site
Transcript
Note there are several spelling errors in the comic, so please do only correct spelling errors that are not part of the comic! See more in the trivia section.
- [A large heading, followed by a sub-caption. Below that two lines with a statement in between:]
- A timeline of Earth’s average temperature
- since the last ice age glaciation
- When people say “The climate has changed before,” these are the kinds of changes they’re talking about.
- [A very long chart below the headings above is headed with a label for the scale of the X-axis above the chart. Below that a sub-caption. To the left an arrow down to the top of the chart pointing to the dotted curves starting point (at -4.3°C below the 1961-1990 average) with a label above the arrow. And arrow pointing left to the left of the center and another pointing right to the right of the center has labels. Below these is the temperature scale of the X-axis, with 9 ticks between the borders each with a label ranging from -4 to +4°C compared to the 1961-1990 average, but with another step in each direction not labeled towards to axis so the chart covers -5 to +5°C compared to the 1961-1990 average.]
- Temperature
- Compared to the 1961-1990 average
- Start
- Colder
- Warmer
- -4°C -3°C -2°C -1°C 0°C +1°C +2°C +3°C +4°C
- [To the right of the chart is a gray text standing on the side down along the outer boarder of the chart with the sources for the chart:]
- Source: Shakun et. al. (2012) , Marcott et. al. (2013), Annan and Hargreaves (2013) , HadCRUT4, IPCC
- [The chart is split in 10 columns by the temperature scale and the borders. The two central columns are white, and then from there to the left the background becomes a faded color that changes from light blue to blue at the edge in four steps. Similarly to the right the color changes from light red to red. To the left there is a time scale taking 500 years leaps from 20,000 BCE all the way to year 1, where there are two years, one for BBC and one for CE. The 500 year leaps continue until 1500 CE and from there the steps are down to 100 years until 2100 with also present day 2016 labeled. After 1500 the CE is omitted. The labels stop there, but there is space below covering down to 2200 CE. There is clearly visible division line across the chart on the level of each of the 500 step, and fainter lines for each of the 100 steps all the way even though only the last 5 of these 100 steps are labeled. There is a similar clear line at 2016. Below each step on the Y-axis is noted, and then any text starting before the next step is noted below indented. If there are extra image belonging to text this is indented once more. The graph that the whole chart is about is a dotted line that begins at the “start” point mentioned above at -4.3°C and then begins to go straight down. It will change left and right all the way down. To being with all text and most drawings are to right of the dotted curve. Whenever something is to the left it will be noted. When it says to the left above something, and then nothing over the next, then the next will be to the right. Only at the very bottom are there more entries to the left than right. ]
- 20000 BCE
- [An arrow goes from the dotted line to the central line at 0°C. In the middle of the line there is a temperature label:]
- 4.3°C
- At the start of our timeline, 22,000 years ago, Earth is 4°C colder than during the late 20th century.
- Boston is buried under almost a mile of ice, and the glaciers reach as far south as New York City.
- [The Statue of Liberty is shown in front of a glacier front. A very tiny Cueball is on top of the glacier. The drawing is labeled and so is also the glacier.]
- New York
- Ice
- [A guy with a white knit cap is seen walking in a snowy landscape leaving black footprints behind him. He walks through the white central part of the chart.]
- [The skyline of Boston is shown with two clear buildings among all the other. Above it is a line and in between this area has been filled with thin lines. The drawing is labeled and so is this area. Also the skyline has an arrow pointing at it with a label:]
- Boston
- Ice
- Modern skyline
- 19500 BCE
- But the world is about to warm up.
- By this time, humans have already spread across Africa, Eurasia, and Australia.
- They’ve created painting, pottery, rope, and bows and arrows, but haven’t developed writing or farming.
- 19000 BCE
- Changes in the Earth’s orbit mean that more sunlight reaches the polar ice…
- [A line chart with a labeled Y-axis with three labeled ticks. The curve starts up and then goes down five times and up four times ending down. There is one plateau towards the end compared to the rest of the curve where the ups and downs are quite alike.]
- Summer sun W/m2 at 60°N
- 550
- 500
- 450
- Changes in the Earth’s orbit mean that more sunlight reaches the polar ice…
- 18500 BCE
- [A map of the world. At the top is a light gray area covering North America, Greenland and northern Europe and most of the northern part of Russia. A similar gray area covers Antarctica. There are two labels in the gray area above and one in the gray area below:]
- Ice Ice
- Ice
- 18000 BCE
- …And the ice sheets start to melt.
- 17500 BCE
- Temperatures have been creeping upward, but around this point, CO2 levels start to climb…
- 17000 BCE
- …And then the warming speeds up.
- 16500 BCE
- [Cueball is standing with a spear just the right of the graph talking to a rabbit.]
- Cueball: Still pretty cold.
- 16000 BCE
- [Megan points to the graph to the right of her and between her and Ponytail standing on the other side. Mean is the first drawing on the left side of the dotted curve, which has hardly moved since the beginning, only to just on the other side of 4°C.]
- [In the right part of the chart is an explanation of the data. Below the first two lines there are four drawings each showing possible temperature swings in reality compared to the smoothed data that represents the dotted curve of the entire chart. The dotted curve is shown in all four drawings and a thin line is shown running along it but with much more fluctuation left and right on the first two, a large spike right on the third and a large bump way right on the fourth. Above these there are two labels. The first labels is inside a bracket that covers the first three, and the last label is for the last drawing. Below is a list of sources.]
- Limits of this data:
- Short warming or cooling spikes might be “smoothed out” by these reconstructions but only if they’re small or brief enough.
- Possible Unlikely
- Reconstructions are from Shakun (2012) and Marcott (2013), scaled to Annan + Hargreaves (2013) estimate for the last glacial period.
- 15500 BCE
- In what is now France, humans paint murals on the walls of the Lascaux caves
- [Hairy paints three animals, two with horns, and two humans, Cueball holding hand with Hairy who has a spear. On the other side of the central line Megan writes three letters, the last of which is reversed.]
- NIИ
- 15000 BCE
- Ice sheets around Alaska shrink, exposing a land bridge between Asia and North America
- [From around the bottom if this section and down to 11500 BCE the dotted curve moved steadily to the right towards warmed temperature peaking close to -1.5°C. Before this the temperature had not moved much away from that at the start.]
- 14500 BCE
- [Cueball walks right looking back at the graph behind him. Megan walks in front of him pointing further right.]
- Cueball: Cool.
- Humans reach North America.
- 14000 BCE
- The edge of the ice withdraws from New York City and retreats North.
- [A large glacier front speaks in a speech bubble with an arrow pointing at it. Behind is there are four peaks in the horizon and in front of it three small melting pools and some rocks on the ground.]
- Glacier: That’s it! I’m moving to Canada!
- 13500 BCE
- Humans domesticate dogs
- (Date uncertain, may be much earlier)
- [Megan and Cueball is watching a wolf looking at them.]
- Megan: Okay, you can live in our homes and we’ll feed you, but we’ll still get mad f you poop on the floor.
- Wolf: Deal.
- Cueball: And we get to breed you to be tiny and dress you in little costumes.
- Wolf: …Wait.
- 13000 BCE
- [Randall did not use the normal spelling for Woolly Rhino, but this is an accepted alternative spelling:]
- Wooly Rhino goes extinct
- Oregon is scoured by huge floods as glacial dams burst and lakes of meltwater flow to the sea
- 12500 BCE
- Ice sheets withdraw from Chicago
- 12000 BCE
- Humans settle Abu Hureyra in Syria
- 11500 BCE
- [An arrow on the left side of the dotted curve is pointing down along the dotted curve and to the left indicate temperature is declining again, meaning the dotted curve now moves left to colder temperatures. This only continues until 10500 BCE. It is only the second time something is noted on the left side after Megan at 16000 BCE]
- Temperatures start to decline, mainly in the Northern hemisphere
- This may be caused by changes in ocean circulation due to the floods of cold fresh meltwater flowing into the Atlantic as the North American ice sheet melts.
- This cooler period is called the Younger Dryas
- 11000 BCE
- [This is the first text to the left of the dotted curve:]
- Humans reach Argentina
- 10500 BCE
- [An arrow pointing down along the right side of the dotted curve and to the right indicate temperature is increasing again, meaning the dotted curve now moves right to hotter temperatures. This continues until 8000 BCE where it levels out just above 0°C.]
- Warming resumes
- Human settlements at Jericho
- 10000 BCE
- First development of farming
- 9500 BCE
- Saber-toothed cat goes extinct
- [To the left:]
- Horses disappear from North America
- 9000 BCE
- [To the left, Randall spelled Pokémon wrong:]
- Last North American Pokemon go extinct
- [Cueball with a speak and Megan is looking up at this last “fact”.]
- Megan: That is not a real fact.
- Temperatures reach modern levels
- Rising seas cut off the land bridge between North America and Asia
- Cattle domesticated
- [To the left, Randall spelled Pokémon wrong:]
- 8500 BCE
- Ice sheets retreat across the Canadian border
- Temperatures start to level out slightly above 1961-1990 levels
- 8000 BCE
- [The above sentence breaks over the 8000 BCE line. From here a maximum in temperature on the chart is reached at 0.5°C which will not be overtaken until 2000 CE. It stays almost constant here until 5000 BCE where a slight cooling begins.]
- 7500 BCE
- [To the left:]
- This warm, stable period is called the Holocene Climate Optimum
- [To the left:]
- Jiahu settled in China
- 7000 BCE
- Final collapse of the North American ice sheet leads to rapid 2-4m sea level rise…
- [A small arrow points down and left to the right of the dotted curve. There is a small decrease in temperature but it is very small and would have been missed without the arrow and label.]
- …And a period of cooling in the Northern hemisphere
- 6500 BCE
- [To the left:]
- As seas rise to near their modern levels, Britain is cut off from mainland Europe
- 6000 BCE
- Humans develop copper metalworking
- 5500 BCE
- [To the left:]
- Massive volcanic eruption in Oregon creates crater lake
- Gold metalworking
- 5000 BCE
- [To the left:]
- Invention of the wheel
- [To the left. To the right of the dotted curve is an arrow pointing down and slightly left. From here temperature decreases very slowly but steadily from 0.5°C until 1000 BCE where a stable plateau is reached around 0°C.]
- Earth begins to cool slowly mainly due to regular cycles in its orbit
- 4500 BCE
- [To the left:]
- Proto-Indo-European language develops
- [To the right of the curve Ponytail holds up a hand towards Cueball.]
- Ponytail: Let’s make out language heavily inflected, so future students have to memorize a zillion verb endings!
- Cueball: Okay!
- [To the left:]
- Permanent settlements in the fertile crescent
- 4000 BCE
- Horses domesticated
- [To the left:]
- Minoan culture arises on Crete
- 3500 BCE
- Egyptian mummification
- Rise of the Indus Valley civilization
- [To the left:]
- Invention of writing in Sumer “prehistory” ends, “history” begins
- Earliest human whose name we know
- (Pharaoh Iry-Hor in Egypt)
- 3000 BCE
- Three Sovereigns and five emperors period in China
- Gilgamesh
- [To the left:]
- Imhotep
- Mayan culture emerges
- [To the left:]
- Great Pyramid constructed
- 2500 BCE
- Corded Ware culture in Europe
- [To the left of the curve two rock musicians with long hair and electrical guitars are standing on either side of a small gate made of three slabs of stone, one on top of the other two standing stones.]
- Stonehenge completed
- Chariots developed
- 2000 BCE
- [To the left:]
- Alphabetic writing developed in Egypt
- Last mammoths on a tiny Siberian island go extinct
- [To the left:]
- Minoan eruption
- 1500 BCE
- [To the left:]
- Iron smelting
- Olmec civilization develops in Central America
- [A Trojan horse with two Cueball-like guys in front and a third standing on its back. Its back is at three Cueball’s height and its head rises to the level of the Cueball on its back. It stands on a platform with four wheel on the visible side. There is text on the horse]
- Setting of the Iliad and the Odyssey
- Text on horse: Not a trap
- [To the left:]
- Invasion of the Sea peoples*
- * A real thing
- Polynesians explore the Pacific Ocean
- 1000 BCE
- [From 1000 BBC to 1000 CE the temperature is stable and very close to 0°C.]
- [To the left:]
- Solomon
- [Randall spelled Iliad wrongly this time:]
- Illiad and Odyssey composed
- [To the left:]
- Rise of Greek city-states
- Neo-Assyrian empire
- [To the left:]
- First Olympics
- Zapotec writing in modern Mexico
- [To the left:]
- Confucius
- 500 BCE
- [To the left:]
- The stuff in the 300 (film)|movie 300, but regular speed and with more clothing
- Buddha
- Nazca Lines
- [To the left:]
- Alexander the Great
- [To the left:]
- Mayan hieroglyphics
- Ashoka the Great
- [To the left:]
- Paper invented
- [To the left:]
- Asterix
- Teotihuacán metropolis
- [To the left:]
- Julius Caesar
- [At the year 0, there is instead two numbers for each of the two scales before and after Christ:]
- 1 BCE
- 1 CE
- [To the left:]
- Roman Empire
- Jesus
- [To the left and erupting volcano.]
- Pompeii
- Three Kingdoms period
- [To the left:]
- Gupta empire
- [To the left:]
- Various groups take turns sacking Rome
- [Randall spelled Attila wrong:]
- Atilla the Hun
- 500 CE
- Muhammad
- [To the left:]
- Tang Dynasty
- [An arrow to the right of the dotted curve pointing down, takes a swing far out from the curve and then bends back again. The text label next to it breaks into the next 500 period. The dotted curve stays stable at 0°C along this arrow.]
- Medieval warm period in Europe and some northern regions (too regional to affect the global average much)
- [To the left:]
- Leif Eriksson
- 1000 CE
- [The dotted curve moves to the left towards lower temperature reaching a minimum around 1650 of about -0.6°C at the Little Ice Age.]
- [To the left a drawing of a compass with needle pointing the black end towards north east. There are labels for the four main directions and a label next to it:]
- N
- W E
- S
- Magnetic compass navigation
- [To the left:]
- Ghengis Khan
- Zheng He’s fleet explores Asia and Africa
- [To the left:]
- Aztec Alliance
- [To the left:]
- Printing press
- [To the left:]
- Columbus
- 1500 CE
- European Renaissance
- [To the left:]
- Shakespeare
- 1600
- [To the left:]
- Newton
- [To the right of the dotted curve there is an arrow pointing down that makes a swing in towards the curve and then back out again. At -0.6°C this is the coldest it has been since 9500 BCE. It is labeled:]
- ”Little Ice Age”
- 1700
- Steam engines
- [To the left:]
- Unites States Independence
- 1800
- Industrial Revolution
- [To the left:]
- Telegraphs
- [After this the dotted curve becomes solid.]
- 1900
- [To the left, and on the line for 1900:]
- Airplanes
- [To the left:]
- World Wars
- [The solid line takes a step to the right close to 0°C. Over the rest of the 1900s it moves closer to 0°C crossing it before 2000 where it almost reaches the maximum temperature of 0.5 °C from earlier in 8000 BCE.]
- Fossil fuel CO2 emissions start rapidly increasing
- [To the left:]
- Nuclear weapons
- [To the left:]
- Internet
- 2000
- Northwest Passage opens
- [From here to present day the solid line increases rapidly and in 2016 present day is almost reaches 1°C, with about 0.8°C.]
- 2016
- [To the left on the line for 2016:]
- Present day
- [From here the curve once again becomes dotted as this is the future. After one dot it splits in two and after the first two dots another split between them occurs forming three possible future dotted curves. The first curve bending down before the others, and thus to the right of the other two reaches about 1.2°C and then goes straight down and stops at the 2100 line. An arrow points to it from the left and a label is written patly before and the rest after the 2100 line to the left of the curve:]
- Best-case scenario assuming immediate massive action to limit emissions
- 2100
- [The middle curve bends a little down after reaching 1.3°C and then continues this path reaching 2°C in 2100. An arrow point from below to it and a label is written below the curve and below 2100 line:]
- Optimistic scenario
- [The last line continues along the path from the last 16 years of the solid line reaching 4.2°C at 2100, almost as far on the other side of 0°C in 150 years as it took 14000 years to move from the other side from the start of the chart. Another arrow point to this from below with a label below the curve and below 2100 line:]
- Current Path
Trivia
- There have been several large drawings in the history of xkcd, and also some that are bigger than this one (for instance 1110: Click and Drag).
- But among those that can be viewed in one go, without downloading a larger file or moving around, this is by far the longest.
- The next longest is probably 482: Height.
- The timeline starts at 20,000 BCE (22,000 years ago) and ends at 2100 CE, thus covering 22,100 years.
- There are several spelling mistakes.
- Most obvious is the second time Randall wrote the word "Iliad," because he just spelled it correctly at 1500 BCE and then spelled it Illiad at 1000 BCE with two "L"s.
- Attila the Hun becomes Atilla the Hun with one T and two L's.
- Pokémon is spelled Pokemon, but then again that is not so strange for Randall (see 1647: Diacritics). But he usually spells it correctly as in the recent comic 1705: Pokémon Go.
- Note that the fact that Woolly rhinoceros becomes Wooly rhino with only one l is not a spelling mistake but an alternative spelling of the word.
- Notably absent are the following facts
- 1850: methodical temperature record begins. Although this fact is indirectly indicated when the temperature curve becomes solid around 1850 and until present day.
- The entire swing period between 20 and 200 thousand years prior to now, which would depict temperature swings with increasing frequency and amplitude (ref geological record).
- But of course this could not be included in a comic that only goes back to 20,000 BCE. And as is clear from the curve the temperature has been very stable these last 10,000 years which may explain why human civilization has peace from rapid changes in the environment to develop in the first place. And now it seems that we are causing this stable plateau to come to an end, and that was the point of the comic.
- The 300 million years prior to that, during which the earth was significantly warmer than now, underwent much more extreme temperature changes, and during which time it is presumed that life was present on the earth (but that cars were not).
- The comment for the previous entry also goes for this entry.
Popularity of comic
- This comic became so popular with a broader audience that Randall decided to push the release of the next comic 1733: Solar Spectrum one day back for a rare Thursday release instead of the scheduled Wednesday release.
- He noted this above all the comics in the header text on xkcd:
- Note: Since a lot of new people are here looking for this chart today,
- I'll be posting Wednesday's comic on Thursday instead.
- Before that the normal heading with the release day of xkcd was shown.
- This was (of course) still there Tuesday the day after the release, because it was first on Wednesday there were reason to note the delay.
- It stayed in place even for some time after the "Wednesday" comic was released on Thursday, but was then removed before noon (EST) on Thursday.
- Randall did thus not post a link to this comic in the header text for new visitors to use, only giving them that one extra day.
- Even though the next comic was released on a Thursday, the scheduled Friday comic 1734: Reductionism was still released as planned.
- This was also the first time this occurred on xkcd - see this trivia item from the Friday comic.
Discussion
As this is a controversial topic, there may be several denialist trolls lurking below. Beware of feeding them. |
Well, never mind then. Oh well. -- JayRulesXKCD (talk) 1:02, 12 September 2016
- I acknowledge that the picture is WAY too long, so I added a "skip to explanation" bar, to speed things up. --JayRulesXKCD (talk) 17:32, 12 September 2016 (UTC)
- Thank you Run, you clever boy (talk)
Is it just me or does the picture not render all the way down in full resolution on firefox? I found it worked on Chrome and explorer... And Wauw, just after I had created the new Category:Climate change... Was also just watched a QandA program yesterday where Brian Cox tried to convince some Australian politician about global warming, but the other one just cried conspiracy... Will take some time to make this one complete I guess? Great ;-) --Kynde (talk) 17:53, 12 September 2016 (UTC)
- That's the thing with this kind of stuff. It takes a LONG time to make it just right. --JayRulesXKCD (talk) 19:08, 12 September 2016 (UTC)
Please delete the ridiculous trivia
- The colors used to represent temperature vary from blue (the perceived hue of a black body at 20000K) to pale red (perceived at 2200K).
108.162.221.139 19:44, 12 September 2016 (UTC)
Of course you can pretty much ignore the part of the diagram that is in dotted line, you can't rely on that data. 108.162.246.119 20:40, 12 September 2016 (UTC)
- Note that even if we ignore the extrapolated future, the warming in the past century is already a vastly more abrupt climate shift than anything that happened in the preceding 219 centuries. - Frankie (talk) 21:15, 12 September 2016 (UTC)
- Actually we don't know what the shifts were on that scale in the past. The dotted line before modern measurement is a very limited estimate. We have no idea what the year to year changes were in the past, at best we can work out an average. I am reminded of a house mouse(life span of about 1 year) looking at the leaves fall from the tress and saying "Surely this is the end of the world". 108.162.246.119 14:44, 13 September 2016 (UTC)
- Randall explicitly addresses your specious complaint at 15900 BCE. Year-to-year fluctuations are not the same as the current century-long surge. Either show scientific evidence or go away, Mr Troll from Seattle Cloudflare. - Frankie (talk) 16:11, 13 September 2016 (UTC)
- I should have known better to enter into a religious debate on the internet. 108.162.246.119 00:17, 14 September 2016 (UTC)
- No it is not that which is the problem, but that you try to disqualify the data without even bothering to look through them. Aa mentioned Randall tries to let us know that such a high fluctuation as we have in these last 100 years would not be hidden in the old data. As mentioned by Fankie this is explained between 16000 and 15500 BCE... --Kynde (talk) 14:30, 14 September 2016 (UTC)
- I refuse to debate a matter of faith with you. Note that 15500-16000 is 500 years, perhaps when we have 500 years of accurate temperature measurements we will know more. 108.162.246.119 03:54, 15 September 2016 (UTC)
- I'm not surprised that you can't even read a chart. 16000-15500 BCE is where the explanation is placed on the chart. The fluctuations he shows that would not register are small fluctuations over a decade or two. A fluctuation of a century would "unlikely" be smoothed out. The examples are even drawn to scale... 3rd grade level stuff here. 108.162.221.145 17:28, 16 September 2016 (UTC)
- Why even bring your faith into this? 108.162.212.92 16:29, 15 September 2016 (UTC)
- I call Troll. Talking about the significance of where the subchart/Legend/footnote lies? Like what years it's next to actually has any significance? Either he's too dim to actually look, or he's trolling. The standard recommendation is "Don't feed the trolls". :) - NiceGuy1 108.162.218.118 02:55, 16 September 2016 (UTC) I finally signed up! This comment is mine. (Heh, seems I was right, looks like the troll stopped after I called him out) :) NiceGuy1 (talk) 11:03, 9 June 2017 (UTC)
- I refuse to debate a matter of faith with you. Note that 15500-16000 is 500 years, perhaps when we have 500 years of accurate temperature measurements we will know more. 108.162.246.119 03:54, 15 September 2016 (UTC)
- No it is not that which is the problem, but that you try to disqualify the data without even bothering to look through them. Aa mentioned Randall tries to let us know that such a high fluctuation as we have in these last 100 years would not be hidden in the old data. As mentioned by Fankie this is explained between 16000 and 15500 BCE... --Kynde (talk) 14:30, 14 September 2016 (UTC)
- Frankie, funny how the nonaveraged plots [and even the averaged plot] linked to below invalidates Randall's plot, "Hence the comparison is not comparing like with like and is scientifically invalid." The temperature rate between 1859 (coincident with America's discovery of petroleum and the Carrington Event) and today does not exceed that within the past 2,000, 20,000, or 100,000s of years. The present surge (the tip of the "hockey stick") concerns not 100 years but almost 40 years (36 years in Randall's plot) which does not successfully meet the three fluctuation disclaimers. As mentioned in the Wikimedia discussion the temperature resolution is about 300 years; therefore it should take another 150 years to see whether this slope corrects itself. Lysdexia (talk) 13:04, 5 January 2019 (UTC)
- I should have known better to enter into a religious debate on the internet. 108.162.246.119 00:17, 14 September 2016 (UTC)
- Randall explicitly addresses your specious complaint at 15900 BCE. Year-to-year fluctuations are not the same as the current century-long surge. Either show scientific evidence or go away, Mr Troll from Seattle Cloudflare. - Frankie (talk) 16:11, 13 September 2016 (UTC)
- Actually we don't know what the shifts were on that scale in the past. The dotted line before modern measurement is a very limited estimate. We have no idea what the year to year changes were in the past, at best we can work out an average. I am reminded of a house mouse(life span of about 1 year) looking at the leaves fall from the tress and saying "Surely this is the end of the world". 108.162.246.119 14:44, 13 September 2016 (UTC)
- Have you read the referenced papers? Well you fit well with the people he refers to between the two lines at the top. ;-) We are heading for troublesome times :-( 164: Playing Devil's Advocate to Win... --Kynde (talk) 21:22, 12 September 2016 (UTC)
- the use unqualified of the words "still many people" is exactly the kind of weasely nonsense that this comic is designed to refute. there are "still many people" who claim the earth is flat, that they have been abducted by aliens, or that the MMR jab made their children autistic. those people are deluded or insincere. the difference with deniers of climate change is that there are in their ranks scientists who are clear-sighted but who have decided that funding at any price is better than none. this site should be better than that. --141.101.98.84
- You're absolutely right, the ranks of climate deniers do indeed include a few scientists willing to sell their voices to the highest bidder (e.g. http://www.polluterwatch.com/heartland-institute ). But is that what you meant to say? - Frankie (talk) 11:50, 13 September 2016 (UTC)
- that the wording be changed to reflect that. --141.101.98.84 11:59, 13 September 2016 (UTC)
- You're absolutely right, the ranks of climate deniers do indeed include a few scientists willing to sell their voices to the highest bidder (e.g. http://www.polluterwatch.com/heartland-institute ). But is that what you meant to say? - Frankie (talk) 11:50, 13 September 2016 (UTC)
For a large post like this, it's a wonder that we can all keep up and edit something like this all at once. Wow. --JayRulesXKCD (talk) 11:56, 13 September 2016 (UTC)
- Also, anyone else notice that this was a top trending post on Facebook last night? I don't know if I could call it a milestone but it's still pretty cool. And WE edited it! :D --JayRulesXKCD (talk) 12:06, 13 September 2016 (UTC)
Maybe someone should add the fact that the transcript may be a reference to oxidation?Transuranium (talk) 19:21, 13 September 2016 (UTC)Transuranium
- I think you mean the "title text" not the transcript? And that you refer to the recent comic 1693: Oxidation which is indeed referened in the title text, then that has been written at the bottom of the main explanation and has been there already since the 12th edit less than 1½ hour after the comic came out... --Kynde (talk) 20:02, 13 September 2016 (UTC)
Is nobody else having a problem seeing the comic? Both here and on XKCD I get an "Image not found" icon, a blue question mark. I thought maybe this was an interactive comic that doesn't work on my iPad (like that garden thing, though that did nothing on my computer either). If I tap it on XKCD nothing happens, here it leads to the picture's Wiki page - also with the question mark - which says it's a PNG, which I know this iPad can show. It's 11pm EST, maybe night maintenance on XKCD? Or the file got renamed without updating the sites? - NiceGuy1 162.158.126.227 03:12, 14 September 2016 (UTC) I finally signed up! This comment is mine. NiceGuy1 (talk) 11:03, 9 June 2017 (UTC)
- I had trouble seeing it on my own PC using Firefox but not the other browsers I have. See my early comment above. I guess the file is too big for your iPad as it is a very huge file. I tried to download it but it failed. --Kynde (talk) 14:07, 14 September 2016 (UTC)
- It's weird that I got what is clearly an "Image not found" icon, though. Maybe my 1st Gen iPad's Safari saw the file, decided "No way I'm loading that!"(or "that size can't be right", LOL!) and chose to show the error icon instead. When I force the issue, by going directly to the image URL listed on XKCD, the first time Safari crashed rather than load the image (but it crashes on a regular basis, so that didn't deter me), the second time it crashed, the third time it actually loaded, and I was able to see it. After seeing mentions here of spelling errors (though I have to disagree on "Pokemon", generally only people connected to the show bother with the accent. Like how I'm the only one who spells Hallowe'en correctly, with the apostrophe), I thought maybe the comic was taken down to correct it, but guess not. LOL! - NiceGuy1 108.162.218.239 20:54, 14 September 2016 (UTC) So's this! NiceGuy1 (talk) 11:03, 9 June 2017 (UTC)
I feel that the missing bottom axis is a usability problem, so I fixed it. See it here. Hananc (talk) 10:42, 14 September 2016 (UTC)
- Nice but I'm sure it was on purpose to indicate that time continues down,as well as a possible even worse temperature change. As shown in the previous global warming comic 1379 Earth has been 8 degree hotter than now... And apart from the last small segment (albeit a very important one) you either remember that white is normal and bluer is colder redder is warmer or else you cannot use the chart in between the top and bottom, and since this is the longest xkcd comic so far it would be a shame. :-) --Kynde (talk) 14:07, 14 September 2016 (UTC)
Okay, now that I've managed to SEE the damn thing, I have a question. There's no mention of why this is using "BCE" and "CE" instead of the standard "BC" and "AD", never mind what these stand for (thinking and thinking about it, my guess is "Before Christ Era" and "Christ Era"). This is the kind of thing that should be mentioned on ExplainXKCD, LOL! Fun fact: when I searched this page for "BCE", to confirm it wasn't explained, I got "Over 100 matches". :) Anyway, I figure maybe those are currently accepted scientific terminology, especially since "AD" is Latin, unlike "BC", but the average person still uses BC and AD. In fact, I think this is the first time I've ever seen BCE and CE (unless it's been on XKCD before and I just dismissed it as a typo or something. This time there are WAY too many for it to be a mistake every time, including here in the explanation!) - NiceGuy1108.162.218.239 21:20, 14 September 2016 (UTC) I finally signed up! This comment is mine. NiceGuy1 (talk) 11:03, 9 June 2017 (UTC)
- It's "Before Common Era" and "Common Era", an alternative to BC/AD. Pretty common alternative, though I don't know why off-hand - probably to remove the religious connotations of "Christ" and "Year of our Lord". --108.162.215.236 23:23, 14 September 2016 (UTC)
- Because they're the standards in the scientific community. The guy above assumed his way is standard, but that's inaccurate. 108.162.212.92 00:26, 15 September 2016 (UTC)
- I assume nothing. My statements are completely accurate. I OBSERVE it is the standard, the only standard anybody (else) seems to use. BC/AD is the "standard" because it is standard practice to use it. For good reason, since I would estimate just about everybody knows what it means, while I am sure I am in the majority in having never heard BCE/CE. It is also not "my" way, I made no choice here, it is the established convention, it is the way accepted and adopted by society. While I would normally be more inclined towards terminology devoid of religion (as seems to be the point here, now that someone kindly clarified these acronyms for me), I feel this would be a losing fight, one it would be foolish to attempt, the classic terminology is too ingrained in society. Sorry. - NiceGuy1 108.162.218.118 02:44, 16 September 2016 (UTC) Also mine! NiceGuy1 (talk) 11:03, 9 June 2017 (UTC)
- For the convenience of archeologists working in the Middle East. Wwoods (talk) 01:16, 15 September 2016 (UTC)
- Thank you! Yes, it sounds to me like the point would be to remove the religious aspect. Personally, I don't really mind the religious terminology, I just see it as historical, keeping a record of where the names and numbering came from. - NiceGuy1 108.162.218.118 02:44, 16 September 2016 (UTC) Also mine! NiceGuy1 (talk) 11:03, 9 June 2017 (UTC)
- Well, "it is the established convention" isn't quite correct either.. checking Wikipedia suggests to me that it's a large argument, and that people that aren't Christian or Muslim (i.e. just under half of all people) really never used the AD/BC notation in the first place. BCE/CE appears to have originated in Jewish European communities some point before the 1700s. 172.70.100.192 20:12, 5 April 2023 (UTC)
- Because they're the standards in the scientific community. The guy above assumed his way is standard, but that's inaccurate. 108.162.212.92 00:26, 15 September 2016 (UTC)
What this comic doesn't show is what kind of changes occurred in the previous interglacial period as opposed to the current one. Since the current one is not yet over there could still be a stage of an interglacial with rapid temperature rise which we are only now reaching, but has happened in previous interglacial periods. 108.162.219.54 02:32, 15 September 2016 (UTC)
- Check out this 400k year comparison of temperature variations from two ice core projects in Antarctica, Lake Vostok and EPICA. https://commons.wikimedia.org/wiki/File:Ice_Age_Temperature.png (Note that Randall's timeline matches up pretty well with the last 20k years on the far right of the graph) 162.158.69.98 13:23, 16 September 2016 (UTC)
I think this would be first time where I see global thermonuclear war described as "best case scenario". There was and still is lot of discussion about how much is current warming caused by humans, but that's not important. Important question is "can we stop it?" and the answer is "not without literally billions of dead" (and even that might not suffice). Any money currently used for most plans to reduce CO2 (which usually fails to reduce CO2, not speaking about global warming, but succeed in their main goal, which is moving the money into pockets of their proponents) would be better spent on ADAPTING to the change. Only plans for reducing CO2 actually worth doing are the ones related to stopping burning fossil fuels, because we will soon need fossil fuels to make food (and other stuff) from. Oh, and also stop burning FOOD. So we should replace fossil fuel power plants with only viable alternative - NUCLEAR. So called renewable power sources like solar are good addition, but doesn't scale to the amount of power and stability we need. -- Hkmaly (talk) 14:12, 15 September 2016 (UTC)
So disappointing to see that Randall Hitler Munroe subscribes to the obviously false "global warming" religion. He should know better. 172.68.55.83 00:11, 16 September 2016 (UTC)
- Troll troll trolly trolly troll troll troll 162.158.214.217 03:07, 16 September 2016 (UTC)
- https://www.explainxkcd.com/wiki/index.php/261:_Regarding_Mussolini 141.101.98.126 (talk) (please sign your comments with ~~~~)
I understand the concept behind this comic, but why doesn't the graph include atmospheric CO2, sulfur aerosols, and solar 10.7cm radio flux for comparison? Also, for the person who suggested we look at previous interglacial periods, I may be wrong, but I believe a lot of that data comes from ice cores, that would make it hard to look at time periods before the present ice sheets existed. IIRC, there were periods not too long ago (geologically speaking) where Antarctica was covered in lakes, tundra, and sparse forests instead of ice sheets.172.68.65.127 05:08, 16 September 2016 (UTC)
The jump of 0.5 degrees from 2000 to 2016 has been shown to be false. It exists because "scientists" went back and changed (or "seasonally adjusted") their data to fit their preconceived conclusions. Just look at Al Gore's 'Inconvenient [Non]Truth', pretty much every doomsday scenario has not occurred. I expect better of XKCD.173.245.48.77 20:58, 15 September 2016 (UTC)
It would be very nice if they wouldn't spread climate change misinformation. 22,000 year Time line [20,000 BC to 2000 AD] versus 2.5 to 3 billion years of Evolution on a 4 Billion year old Planet
22,000 / 2,500,000,000 = 0.0000088 Using 0.00088 % of Evolutionary History do decide what the weather is supposed to look like. Now an atmospheric history lesson - Cambrian Oxygen 12.5% - Carbon Dioxide 0.45% - Average Temp. 21 °C - sea level 30 - 90 meters - Ordovician Oxygen 13.5% - Carbon Dioxide 0.42% - Average Temp. 16 °C - sea level 180 - 220 - 140 meters - Silurian Oxygen 14% - Carbon Dioxide 0.45% - Average Temp. 17 °C - sea level 180 meters - Devonian Oxygen 15% - Carbon Dioxide 0.22% - Average Temp. 20 °C - sea level 189 - 120 meters - Carboniferous Oxygen 32.5% - Carbon Dioxide 0.08% - Average Temp. 14 °C - sea level 120 - 0 - 80 meters - Permian Oxygen 23% - Carbon Dioxide 0.09% - Average Temp. 16 °C - sea level 60 - 0 - -20 meters - Triassic Oxygen 16% - Carbon Dioxide 0.1750% - Average Temp. 17 °C - sea level 0 meters - Jurassic Oxygen 26% - Carbon Dioxide 0.1950% - Average Temp. 16.5 °C - Cretaceous Oxygen 30% - Carbon Dioxide 0.17% - Average Temp. 18 °C - Paleogene Oxygen 26% - Carbon Dioxide 0.05% - Average Temp. 18 °C - Neogene Oxygen 21.5% - Carbon Dioxide 0.028% - Average Temp. 14 °C - Current Oxygen 20.9% - Carbon Dioxide 0.039% - Average Temp. 15 °C
As you can see an atmosphere when healthy should have Oxygen 25 - 32% Carbon dioxide 0.1 - 0.15% Average Temperature 14 - 18 °C Sea level 60 - 180 meters and there should be no polar ice caps
our sea level is at extinction levels our carbon dioxide is almost too low for plants to survive and our oxygen level is almost suffocatingly low
Less Carbon Dioxide means less Plants Less plants means less Oxygen Less Oxygen means less Life108.162.246.112 07:24, 17 September 2016 (UTC)
- I think the point of comics is that while there were changes in temperature before, they were never this rapid. Although I wouldn't be sure about THAT either ... granted, the previous rapid changes were accompanied with mass extinction ... -- Hkmaly (talk) 15:16, 17 September 2016 (UTC)
- Yeah, the long sample intervals and best fit curves from pre-industrial temperature estimates tend to smooth out any rapid changes that may have occurred over the time period (Think of an ECG/EKG that took a single instantaneuos microvolt sample once every 15 minutes of your life from birth to death, the resulting deflection graph would not look like anything like a normal heart rhythm, but it could be interpreted as the average electrical activity of your heart over the course of a lifetime). It's true that the rapid climate shifts we are able see in geological records usually coincide with things like supervolcano eruptions and asteroid impacts. But those shifts are usually to the negative end from the nuclear winter effect. Idea for reversing global warming without affecting CO2 emissions, just send a couple of hypervelocity rods or a gravity-tractored asteroid into a dormant supervolcano caldera every few years and... instant winter. 173.245.51.75 02:38, 18 September 2016 (UTC)
Very interesting and important work.
Actually.... Solomon and Jesus are not historical figures. Outside the Old and the New Testament, there is no archaeological or other evidence for their existence. I suppose, Jesus has played a significant role in history. So, you may be justified to add an entry saying something like "Date that religious traditions hold as the date of birth of Jesus."
Then, if you mention, say, Shakespeare, then you should also mention the estimated composition of the Bible, an event with more important historical influences.
Roman empire was continued for more than thousand years (Eastern Roman Empire, today reffered as Byzantium).
Current scholarly wisdom is that the Homeric epics, (the Iliad and the Odussey) were composed at the second half of the 8th century, perhaps around 720 BCE. Konstantas (talk) 05:14, 19 September 2016 (UTC)
- Except that no historical evidence has ever contradicted the Bible, and many archaeological discoveries were predicted by it.
- According to proper scientific analysis, it is the most accurate historical document(s) in existence. 172.70.51.173 02:19, 11 August 2021 (UTC) Darryl
I wonder if it is getting to be a good time to make a followup, showing the further warming over the last several years and the rightward movement of the 'if we...' paths. 21-Feb-2020
~5000 BCE is higher slightly lower then now User:Squishmallow fan (talk) 01:47, 10 February 2011 2024 (UTC)
Actual best-case scenario
The actual best-case scenario is far better than Randall's depiction; please see. However, the URLs below in that linked Imgur gallery's first caption were rendered unclickable, probably for spam protection measures, so I reproduce them here:
- Actual "best-case scenario assuming immediate massive action to limit emissions"
- From https://www.theguardian.com/environment/2013/apr/17/why-cant-we-give-up-fossil-fuels
- What will it take to get to this scenario? https://www.solveforx.com/explorations/foghorn/ with http://freenights.txu.com/ and http://co2-chemistry.eu/ for ocean carbonate-sourced plastic composite structural lumber allowing reforestation.
JSalsman (talk) 15:02, 22 September 2016 (UTC)
- First, the Guardian is a newspaper, not a science journal. Second, that article is from 2013, before the latest upsurge. Third, even ignoring those things, the article doesn't say what you claim it does. The single most optimistic sentence I see is "If we are lucky, the impact of burning all that oil, coal and gas could turn out to be at the less severe end of the plausible spectrum." The rest of the article is quite pessimistic, such as "it is overwhelmingly likely that we would shoot well past 2C and towards 3C or even 4C of warming."
- Please post exact quotes where your links talk about a better scenario. Please do not post URLs and expect us to figure out what you mean. You are making the claim, the burden of proof is on you. - Frankie (talk) 17:13, 5 October 2016 (UTC)
- How do you expect me to quote from the graphs? I can't upload images, maybe I need more edits. Please ask any questions you like. JSalsman (talk) 06:14, 1 November 2016 (UTC)
- please explain how the Guardian graph you posted on imgur has to do with better scenarios. The title: "Cuts required for 50% chance of not exceeding 2°C". The footer: "CO2 emissions since 1850 (red); exponential growth (blue); cuts to hit climate target (dashed)." It says that in order to possibly reach the "optimistic" +2° scenario (Randall's 2nd line, not the 1st one), we would need to cut anthropogenic CO2 to about 1/10th our current level, which is ridiculously unlikely to happen. The other graphs you posted are just hypothetical extrapolations about energy production that, even if they're trustworthy (which I doubt) don't reference any climate scenarios at all, much less ones better than the timeline. Until you can post a cogent explanation, I will assume you are trolling and undo your edits. - Frankie (talk) 17:19, 2 November 2016 (UTC)
- If you extrapolate [1] to 2023-4, renewables dominate, right? Wind has been in competitive equilibrium with coal since 1995, and solar hit grid parity early this year and is expected to continue falling in price about as fast at least until 2035. Is there any reason to believe fossil fuels won't be abandoned by 2030? JSalsman (talk) 02:01, 3 November 2016 (UTC)
- Exactly zero words in your explanation discuss how the linked graphs show the existence of a better scenario than the ones listed in the timeline. Your very first graph, from the Guardian, explicitly says 50% chance of not exceeding 2°C, which is Randall's middle scenario. That means it supports exactly what Randall is saying. It says absolutely nothing about a scenario better than the "best case" timeline. - Frankie (talk) 21:06, 3 November 2016 (UTC)
- Do you understand the words that I am saying? The words that I have been saying from the start of this conversation? I don't f***ing care about pie in the sky energy projects. Even if your energy claims are correct, they don't say a single d**n thing about beating the +1.2°C curve.. - Frankie (talk) 21:13, 3 November 2016 (UTC)
- If you extrapolate [1] to 2023-4, renewables dominate, right? Wind has been in competitive equilibrium with coal since 1995, and solar hit grid parity early this year and is expected to continue falling in price about as fast at least until 2035. Is there any reason to believe fossil fuels won't be abandoned by 2030? JSalsman (talk) 02:01, 3 November 2016 (UTC)
- please explain how the Guardian graph you posted on imgur has to do with better scenarios. The title: "Cuts required for 50% chance of not exceeding 2°C". The footer: "CO2 emissions since 1850 (red); exponential growth (blue); cuts to hit climate target (dashed)." It says that in order to possibly reach the "optimistic" +2° scenario (Randall's 2nd line, not the 1st one), we would need to cut anthropogenic CO2 to about 1/10th our current level, which is ridiculously unlikely to happen. The other graphs you posted are just hypothetical extrapolations about energy production that, even if they're trustworthy (which I doubt) don't reference any climate scenarios at all, much less ones better than the timeline. Until you can post a cogent explanation, I will assume you are trolling and undo your edits. - Frankie (talk) 17:19, 2 November 2016 (UTC)
- How do you expect me to quote from the graphs? I can't upload images, maybe I need more edits. Please ask any questions you like. JSalsman (talk) 06:14, 1 November 2016 (UTC)
Joanne Nova
- http://www.skepticalscience.com/How-Jo-Nova-doesnt-get-past-climate-change.html
- http://blog.hotwhopper.com/2014/03/almost-everything-we-know-about-fake.html
- http://skeptico.blogs.com/skeptico/2009/02/global-warming-denial.html
- http://www.desmogblog.com/joanne-nova-climate-skeptics-handbook
- http://rationalwiki.org/wiki/Joanne_Nova
- http://itsnotnova.wordpress.com/
- Frankie (talk) 23:41, 8 October 2016 (UTC)
Interesting Ways to Look at it.
Hey, I had a great time scrolling down and watching the earth heat up :).108.162.245.115 19:47, 17 October 2016 (UTC)
ICYMI, Cato provides an IPCC MAGICC climate model simulator for anyone to examine. FWIW, I side with Bjorn Lomborg, who famously champions a middle way in climate science for the sake of downtrodden peoples around the world. Should we reconsider this explanation in this light? Run, you clever boy (talk)
Fact checking the chart on Stack Exchange
I posted a question on Earth Sciences Stack Exchange about how the Younger Dryas fits into this comic: http://earthscience.stackexchange.com/q/9103/6973
There was also an existing question about the chart's general accuracy: http://earthscience.stackexchange.com/q/8746/6973
--Aaron Rotenberg (talk) 02:53, 14 November 2016 (UTC)
Translation of the Morse code message
The translation of the explanation in "Telegraph", written in Morse code, is: "Now, the mother of Samuel Morse always sent the lad out on a horse." Agusbou2015 (talk) 15:56, 28 May 2017 (UTC)
"Sad comics"
...So after the election of a climate change denier later in the year of this comic's release, several sad comics have been posted. Some of the reason could be that Randall no longer believes that even his worst fears (as expressed by the current path at the bottom) will hold up, when USA gets a president, who will on purpose act in a way that scientist claims will make the temperature rise even more. See more here.
I've mentioned this on the talk page for 2137: Text Entry, but I'll reiterate it here: this observation is not factual, not relevant to the explanation, and does not belong in the description of this comic. If you read it in context, you will see that it is also a non-sequitur, clumsily inserted after one or two factual sentences - it does not follow from anything prior in the discussion. It is poorly expressed and the point being made is unclear in any case.
While the user doing this may well have honest intentions, they are simply defacing articles with their own anti-Trump projections and spamming a link to their own, misleadingly-titled page (Sad comics) which has no clear meaning or explanatory value. Hawthorn (talk) 16:38, 26 April 2019 (UTC)
The industrial revolution and its consequences have been a disaster for the human race, and this graph shows it.172.68.50.19
- I agree that it has probably been a disaster (certainly a gamechanger) for the ecosystems, causing changes and challenges that are so much different to what everything else woupd have experienced without such a heavy hand of humans upon the planet. But for "the human race",vI wonder if there'd be so many billions of us if industrial (and post-malthusian) developments had never arisen. By a simplistic numbers game, we are (currently) ranking higher than it seems likely a more nature-tuned alternative 20th/21st-Century would have looked like.
- A higher population doesn't guarantee "success", I know, and only hindsight will say for sure whether unprecedented growth leads to unprecedented decline in the same 'scoring' value (indicating that it isn't the best score to use long-term), but some would say this. (Not me, I'm just philosophising here.)
- Beyond this, if only by entering the Industrial Age do we have the ability to foresee and forestall some asteroid impact..? Perhaps then the (somewhat damaged) ecosystem actually lives on 'better' (subjectively) from our flawed attempt to industrially improve the planet, to our own ends, the rediscovery of ecoprinciples and then the successful aversion of another planet-killing asteroid (or at least the development of "arks" to let the current biodiversity to ride out the problem, here or elsewhere). Unless you have the view that the post-now changes (like the post-dinosaur/etc changes) are themselves higher scoring on the nature-scale. (But then if an unaverted asteroid is equal to a prior one, then is our polluion of the world equal to when earlier organisms started to fill the atmosphere with deadly oxygen and convert the world to an entirely different phase of life?)
- What can definitely be said is that we're doing something, but expect some people (who aren't actually full-on deniers) to suggest that it isn't really a bad thing. Which it probably is, of course. Or at least not the best thing, and there's probably better outcomes than the one we're tumbling into, by whatever measure. 172.70.86.31 09:03, 1 May 2023 (UTC)
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