Title text: Though 100 years is longer than a lot of our resources.
This is a simple scatterplot showing how often the word "sustainable" has been used in English texts in the US each year. As can be seen, the y-axis is given a logarithmic scale, meaning that the apparently linear trend is actually exponential. Randall humorously attempts to extend the graph to the point the frequency exceeds 100% about a century from now, which obviously makes no sense (hence the quip that the word's usage is itself "unsustainable").
The use of the word "sustainable" has been increasing as people become more aware of the steadily increasing use of nonrenewable resources and need to ensure that the Earth's resources do not become totally exhausted, through sustainable development. Sustainable development refers to the practice of using resources that simultaneously aims to meet human needs while preserving the environment so that these needs can be met not only in the present time, but also for generations to come.
As Randall somewhat depressingly mentions in the title text, the ~100 years that it will supposedly take for the word "sustainable" to become unsustainable is actually a lot longer than most of our nonrenewable resources will last on the Earth. The idea that all of the Earth's coal, oil, natural gas, etc. that has built up over the past millions of years may be completely gone within the century is unsettling.
More realistically, the actual use of "sustainable" is likely to be logistic rather than exponential growth. A logistic curve describes a trend that at first behaves exponentially, but then tapers off and reaches a cap. Logistic growth is commonly used to model data that naturally increases exponentially but has a limiting factor, such as population growth.
- [A large two-axis scatterplot graph with a caption below. The y-axis displays percentages on a logarithmic scale from 0.000001% to 1,000%, and is labeled "Frequency of use of the word "sustainable" in US English text, as a percentage of all words, by year. Source: Google NGrams." The x-axis displays years from 1950 to 2140, and is labeled "Year". Plotted data points show a high linear correlation (effectively exponential due to being a log scale), ranging from approximately 0.000005% in 1960 to approximately 0.003% in 2012. A linear trend line is drawn through the data points, and is extrapolated to the end of the graph. Four points on this trend line are marked and labled:]
- (2012, ~0.003%): Present Day
- (2036, ~0.03%): 2036: "Sustainable" occurs an average of once per page
- (2061, ~0.5%): 2061: "Sustainable" occurs an average of once per sentence
- (2109, 100%): 2109: All sentences are just the word "sustainable" over and over.
- [The trend line continues past the year 2109, exceeding 100% and breaking up into question marks.]
- Caption: The word "sustainable" is unsustainable.