Final report warns, “Waiting for unacceptable impacts to occur before taking action is imprudent because … many of these changes will persist for hundreds or even thousands of years.”
“The number of days per year in which temperatures are projected to exceed 100°F by late this century” on our current (high) emissions path, A1FI
Last May, the U.S. National Academy of Sciences released the first of its “America’s Climate Choices” reports (see NAS labels as “settled facts” that “the Earth system is warming and that much of this warming is very likely due to human activities”). Today, they released their final ACC report.
The good news is that the Academy is clear about the need to start reducing greenhouse gas emissions “as soon as possible” (for some reason the acronym, ASAP, sounds stronger). The AP story got that message: “Panel Says US Must Act Now to Curb Global Warming.”
The bad news is that the report is otherwise rather bland and conservative in that classic NAS style. If your house were on fire, the NAS would take three months to write a report that says you should put out the fire “as soon as possible” (and, of course, you should do some adaptation planning for the potential loss of your home).
Dr. Kevin Trenberth, distinguished senior scientist at NCAR, wrote in an email that, while he agrees generally with the findings, “my quick summary is that there is a lot here that is good but it doesn’t seem to go far enough.”
The NAS also makes a mistake that is emblematic of its conservative approach, as we will see.