Humanity’s choice (via IPCC): Aggressive climate action ASAP (left figure) minimizes future warming. Continued inaction (right figure) results in catastrophic levels of warming, 9°F over much of U.S. The UN Intergovernmental Panel on Climate Change (IPCC) now says we are as certain that humans are dramatically changing the planet’s climate as we are that smoking causes cancer. So perhaps the best way to think about the IPCC, which has issued a summary of its latest report reviewing the state of climate science, is as a super-cautious team of brilliant diagnosticians and specialists (who, like many doctors, aren’t the best communicators). They are are the best in the world — the climate equivalent of the Cleveland Clinic or Mayo Clinic or Johns Hopkins — where you and the rest of humanity have just gone through a complete set of medical tests and are awaiting the diagnosis, prognosis, and recommended course of treatment. (It has a big waiting room — called planet Earth.) The diagnosis is that humans are suffering from a fever (and related symptoms) caused by our own actions — primarily emissions of carbon pollution. Indeed, team IPCC is more certain than the last time we came in 6 years ago and ignored their advice. They are 95% to 100% certain we are responsible for most of the added fever since 1950. Indeed, they explain: The best estimate of the human-induced contribution to warming is similar to the observed warming over this period. To clarify the diagnosis, the best estimate is that humans are responsible for all of the warming we have suffered since 1950. You may ask why team IPCC buried this bombshell at the end of a paragraph on page 12 of their report in very dry language. You might think that with a patient who has as serious a condition as we do but who has simply refused the obvious treatment for two decades (!), they might be a tad blunter. But like I said, communications is not their strong suit and I am afraid that is a terminal condition. After all, they made you get up at 4 in the morning on a Friday to get this diagnosis! Yes, their bedside manner isn’t that great either. So what is the prognosis? As they told us 6 years ago (and 6 years before that), if we keep ignoring their recommended course of treatment, then, on average, total warming from preindustrial levels by 2100 is headed toward 4°C (7°F). And although they don’t come out and directly say so, team IPCC shows you a figure (top) that upon close examination reveals Americans face warming in the range of 5°C (9°F). Again, it’s kind of big news to bury in a chart at the end of a report that you are supposed to read while you are anxiously (and groggily) awaiting your diagnosis. Note that the figure at the top is average temperature change from 1986-2005 to 2081-2100. For some reason these doctors like to tell us how much higher our fever will get rather than simply tell us what our total fever will be. You can add about 1°F to get the total fever. Like I said, they are brilliant doctors but lousy communicators. There is other alarming news in the report: Sea level rise is speeding up and it’s going to be bigger in the future that they told us last time. This is true even though the doctors are so super-cautious they have thrown out some of the reports they were given that suggest we may see suffer even higher levels of sea rise. To be even more cautious, they have included some highly contested reports that suggest our sensitivity to carbon pollution may be slightly lower than they had thought. As the NY Times explains: “The I.P.C.C. is far from alarmist — on the contrary, it is a highly conservative organization,” said Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research in Germany, whose papers on sea level were among those that got discarded. “That is not a problem as long as the users of the I.P.C.C. reports are well aware of this. The conservatism is built into its consensus structure, which tends to produce a lowest common denominator on which a large number of scientists can agree.” So even though the IPCC is not alarmist, its prognosis still is. Rahmstorf explains on RealClimate: This is perhaps the biggest change over the 4th IPCC report: a much more rapid sea-level rise is now projected (28-97 cm by 2100). This is more than 50% higher than the old projections (18-59 cm) when comparing the same emission scenarios and time periods. With unabated emissions (and not only for the highest scenario), the IPCC estimates that by the year 2300 global sea levels will rise by 1-3 meters. Already, there are likely more frequent storm surges as a result of sea level rise, and for the future this becomes very likely. A great many of the glaciologists I talk to expect one meter (39 inches) of sea level rise (or more by 2100 in the no-action case. The report also warns that dry areas are likely to get drier and wet areas wetter. More intense deluges are very likely. Buried on page 18 is another alarming prognosis: It is virtually certain that near-surface permafrost extent at high northern latitudes will be reduced as global mean surface temperature increases. By the end of the 21st century, the area of permafrost near the surface (upper 3.5 m) is projected to decrease by between 37% (RCP2.6) to 81% (RCP8.5) for the model average (medium confidence). In the no-action case, the top 10 feet of permafrost are headed towards oblivion. Given that the permafrost contains twice as much carbon as the atmosphere does today, you’d think team IPCC would warn us about this more bluntly. You’d certainly think that they would factor in some of that carbon in their prognosis. But, like I said, they are super-cautious (see “IPCC’s Planned Obsolescence: Fifth Assessment Report Will Ignore Crucial Permafrost Carbon Feedback”). Last fall, a major study found that the carbon feedback from thawing permafrost will likely add 0.4°F – 1.5°F to total global warming by 2100. All team IPCC does is make a broad statement that “Climate change will affect carbon cycle processes in a way that will exacerbate the increase of CO2 in the atmosphere (high confidence). Further uptake of carbon by the ocean will increase ocean acidification.” That is, our fever is making our body release toxins that will make our fever even worse — but the doctors are not going to factor that into their prognosis. A study from August found “Ocean Acidification May Amplify Global Warming This Century Up To 0.9°F.” But then team IPCC takes so long to work that they have a stated policy of completely ignoring the most recent studies (don’t worry, you signed a waiver years ago agreeing to all this, assuming you read the fine print). Of course, for two decades, their patients (humanity) have completely ignored the recommended treatment even though it is quite inexpensive relative to the cost of dealing with the ever-worsening symptoms, many of which are going to be irreversible. So we have a super-conservative team of doctors who are bad communicators and a patient who, like most addicts, is self-destructive, very bad at listening, and focused on short-term pleasure over long-term health. That is a prescription for disaster. The post Alarming IPCC Prognosis: 9°F Warming For U.S., Faster Sea Rise, More Extreme Weather, Permafrost Collapse appeared first on ThinkProgress.
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