Last week, the government released the Climate Science Special Report, the first volume of the Fourth National Climate Assessment. It makes grim reading – or perhaps more accurately, grim reaper – reading. Here’s what we might call the executive summary of the Executive Summary. First, the bottom line:
This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.
In addition to warming, many other aspects of global climate are changing, primarily in response to human activities. Thousands of studies conducted by researchers around the world have documented changes in surface, atmospheric, and oceanic temperatures; melting glaciers; diminishing snow cover; shrinking sea ice; rising sea levels; ocean acidification; and increasing atmospheric water vapor.
And the highlights (or lowlights):
Global annually averaged surface air temperature has increased by about 1.8°F (1.0°C) over the last 115 years (1901–2016). This period is now the warmest in the history of modern civilization.
global average sea level has risen by about 7–8 inches since 1900, with almost half (about 3 inches) of that rise occurring since 1993.
Heavy rainfall is increasing in intensity and frequency across the United States and globally.
Heatwaves have become more frequent in the United States since the 1960s.
The incidence of large forest fires in the western United States and Alaska has increased since the early 1980s.
Since this recitation has something of the ten plagues about it, at this point, I’ll say “Dayenu!”
It’s certainly more than enough for me, but what about this administration? I’m not going to begin to speculate on how the administration will go about ignoring the Report, though I’m confident that it will. I’ll only add that, at the very least, this report makes abandonment of the endangerment finding by EPA even more infeasible than it already was. When the government itself says that it is extremely likely that release of GHGs is the dominant cause of warming, it would seem to be the definition of arbitrary and capricious were the government somehow still to conclude that the endangerment finding should be withdrawn.
Of course, this is an administration that has already abandoned years of GOP support for cost-benefit analysis in favor of cost-only analysis, so nothing would really surprise me at this point.