UPDATE: Andy Revkin’s comment (here) may be the single most head-exploding and revisionist thing he has ever written. I reply. The adaptation expert, Dr. Richard Klein, offers a defense of the IPCC process in the comments (here).
Fortunately, the public already understands that global warming makes extreme weather more severe, as new polling reveals:
September polling by ecoAmerica found that 57% of Americans already understand “If we don’t do something about climate change now, we can end up having our farmland turned to desert.” Duh:
The Palmer Drought Severity Index on a “moderate” warming path (via NCAR, click to enlarge). “A reading of -4 or below is considered extreme drought.” During the 1930s Dust Bowl, the PDSI spiked briefly to -6 but rarely exceeded -3. We probably can’t stop this, but we can avert far, far worse post-2050 (see below).
The UN’s Intergovernmental Panel on Climate Change is coming out Friday with its umpteenth watered down report on climate science, in this case on extreme weather. The thing to remember about IPCC reports is that pretty much everyone involved has to sign off on every word, so it is inevitably a least common denominator document.
The actual scientific literature from 2011 is far more useful than this report — see “Study Finds 80% Chance Russia’s 2010 July Heat Record Would Not Have Occurred Without Climate Warming” and “NOAA Study Finds Human-Caused Climate Change Already a Major Factor in More Frequent Mediterranean Droughts.” I will provide the links to as many recent studies as possible in this post.
Indeed we already know from a major 2011 study that “human-induced increases in greenhouse gases have contributed to the observed intensification of heavy precipitation events found over approximately two-thirds of data-covered parts of Northern Hemisphere land areas.” As predicted, the warming has put more water vapor in the air, making deluges more intense. Climatologist Kevin Trenberth explains:
There is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms,
Obviously, since it’s getting hotter, we’re worsening extreme heat waves — both in intensity and duration and scale (the area the heat wave covers). For the same reason, we know humans are making droughts worse — in intensity, duration, and scale. The earlier snow melts also makes summer droughts worse.
Actual observations reveal that since 1950, the global percentage of dry areas has increased by about 1.74% of global land area per decade (see here). Heck, our best scientists are already using global warming to help them predict dangerous extreme weather (see “USGS Expert Explains How Global Warming Likely Contributes to East Africa’s Brutal Drought“).
The reinsurance industry understands all this (see Munich Re: “The only plausible explanation for the rise in weather-related catastrophes is climate change”).
Again, much if not most of the public appear to have a better sense of what’s happening right now than you’ll find in the summaries of a typical IPCC report, to go by Yale’s 2011 polling and the September poll from ecoAmerica quoted at the top, which also found:
69% of Americans Know “Weather Conditions (Such as Heat Waves and Droughts) Are Made Worse by Climate Change”
The American public can’t miss the extreme weather because it is everywhere now and increasingly off the charts (see “A New Record: 14 U.S. Billion-Dollar Weather Disasters in 2011“) and links below.
Of course, what’s to come is the real issue, since we still have control over that. We’re facing 5 to 10 times the warming this century that we’ve seen in the past half century.
Unfortunately, the IPCC continues to conflate uncertainty in future emissions of greenhouse gases with uncertainty in the climate’s sensitivity to those emissions. This means they present a very large range of possible overall impacts — and that allows the deniers to trumpet the low range with their powerful fossil-fuel-funded megaphone and induces the media to provide “balance” in their stories between the mid-range and the low range.
The reality is we are on the highest emissions trends (see “Biggest Jump Ever in Global Warming Pollution in 2010 means “levels of greenhouse gases are higher than the worst case scenario outlined by climate experts just four years ago”). And the latest science and observation points towards the high end of the climate’s sensitivity (see Journal of Climate: New cloud feedback results “provide support for the high end of current estimates of global climate sensitivity”).
Most climate scientists know what is coming if we don’t act quickly– and more and more are shedding their reticence to speak out, even if that is not yet reflected in bland, least-common-denominator IPCC reports (see Lonnie Thompson on why climatologists are speaking out: “Virtually all of us are now convinced that global warming poses a clear and present danger to civilization”).
And as long as the deniers, inactivists and climate ignorati rule the debate, inaction is assured, which means that we are risking extreme weather beyond imagination, extreme events on top of an average warming this century that could hit 13-18°F over most of U.S. and 25°F in the Arctic: