The journey that took the Curiosity rover from the surface of the Earth to Mars was a remarkable achievement. However, a much more important achievement from NASA took place this week, though it didn’t include parachutes, roaring rockets, and heat shields (if only it had included heat shields). This week, the Proceedings of the National Academy of Sciences released the results of a statistical analysis of summer temperatures over time, from the 1950s to today. These statistics provide “a high degree of confidence” that the extremely hot temperatures of this summer would not have occurred if the long-term trend of global warming was not present, says the study’s author, Dr. James Hansen.
Many politicians in Washington D.C., however, are refusing to accept the validity of this statistical evidence. It isn’t that they have an alternative statistical model that disproves Hansen’s analysis. They simply can’t bring their minds to accept the reality of global warming, because it subjectively feels like an outrageous idea to them. It’s like a member of Congress refusing to believe that NASA really was able to land the Curiosity rover on the surface of Mars, because the technical achievement seems too intricate to have been accomplished.
Senator James Inhofe, who calls the global warming the “greatest hoax” of all times, is one of the dwindling number of members of Congress who still insists that global warming isn’t happening. “Look at the patterns. It gets cold, it gets warmer, it gets colder, gets warmer,” he says.
Actually, NASA did look at the patterns. That’s what the Hansen study was all about. But, if Senator Inhofe isn’t capable of understanding the statistical analysis underlying that study, maybe a visual representation of the data could help convince him, just as photographs of the Martian surface from the Curiosity rover might convince people who doubt the reality of the new Mars rover mission.
NASA has provided two forms of visualizing the temperature data examined by Dr. Hansen. The first, below, is a map of the Northern hemisphere, showing extreme temperature events during the summer, year by year. You’ll find a more complete video of this data, moving from the 1950s up to last summer at the NASA web site, but as you can see just from these three years selected in the image below, the summers we’re having now have many more extreme heat events than used to take place. Extreme heat, beyond two standard deviations above the 1950s norm, was found over just one percent of the surface of the Earth in the Northern Hemisphere’s summertime back in the 1950s, but is found over 10 percent of the Northern Hemisphere in summer today.
The second visualization of the summer temperature data scrutinized in the Hansen study, also available on video, shows the shift over the last seven decades of summertime temperature extremes strikingly out of the predictable bell curve of 1950s temperatures, becoming much hotter over time.
These visual models, as well as the statistical data that they’re based upon, show that Senator James Inhofe is clearly wrong. We looked at the patterns, and there has not been a cycle of warming and cooling between the 1950s and today. There has been a trend in one direction: The planet has been getting hotter. Most worrisome is that the heating trend appears to be accelerating.
The science of anthropogenic global warming has been clear for many years now, and this new study simply expands that body of scientific understanding, showing the highly probable link between the extreme weather events we’re seeing this year and the larger trend of global warming. Cold Earthers like James Inhofe like to protest that no single extreme weather event can with absolute knowledge be linked to a larger global warming trend, and that’s true, but it’s also not the point.
The massive problem of drought, wildfires, deadly heat waves and resulting crop failures this year would be an isolated tragedy, if it weren’t for the fact that these problems have been coming with increasing frequency over the last few generations. The important story isn’t a single wildfire or area of parched earth. The important story is that what used to be extreme heat and drought are becoming a regular part of our new climate.