Global Warming

As summer approaches and Trump considers withdrawing from the Paris Climate Agreement, it is worth looking at some data on global warming. The graph on the left shows global temperature change over the past 100 years measured by both NASA and the National Oceanic and Atmospheric Administration (NOAA). Though the temperature bounces around year-to-year, the overall trend is clearly a steady and dramatic rise from about 1970 on. Based on these and other data, a staggering 97% of climate scientists and scientific studies endorse human-caused global warming that is directly related to CO₂ and other greenhouse gases. This scientific consensus means that finding a climate scientist who denies human-caused global warming is just as fluky as flipping a coin five times, and getting heads each and every time. In stark contrast, only 69% of Democrats and a mere 23% of Republicans agree with this scientific consensus.

For the Data Wonks

1. Global temperature data from the National Oceanic and Atmospheric Administration (NOAA) can be downloaded at goo.gl/iQu8C9. Global temperature information and data from the National Aeronautics and Space Administration (NASA) can be found at goo.gl/HgqOlI.
2. The graph on the left plots individual yearly average temperature anomalies (as compared to the 20^th century average) in degrees Fahrenheit from years 1916 through 2016. These individual data points were smoothed to visualize overall trends using locally weighted scatterplot smoothing (LOESS) in ggplot2 with a local weighting span of 0.3.
3. Multiple surveys of scientists and scientific research reports suggest that around 97% of climate scientists and climate science studies support the statement that human activity, mostly through increased concentrations of greenhouse gases such as CO₂, is driving global warming at a rate unseen in previous eras. More information about the scientific consensus can be found at goo.gl/y1XU2N and goo.gl/JjHTR8. A recent scientific paper compiling and examining all the surveys of climate scientists can be found at goo.gl/NFzuYs.
4. The probability of flipping a coin five times and getting five heads can be calculated by exponentiating the probability of one heads (50%, or 0.5) by the number of tosses. For five heads, it would be 0.5⁵ or 0.5 × 0.5 × 0.5 × 0.5 × 0.5 which equals 0.03125 or 3.125%.
5. Pew has been tracking public belief in human-caused global warming and other climate change topics for the past 10 years (goo.gl/Ix44sU) In 2016, only 69% of self-identified Democrats or Democrat leaning independents and only 23% of self-identified Republicans or Republican leaning independents endorsed the idea that “the earth is getting warmer mostly because of human activity.”