Yes, the science says on our current emissions path we are projected to warm most of U.S. 10 – 15°F by 2100, with sea level rise of 5 feet or more, and the SW will be a permanent Dust Bowl
"Yes, the science says on our current emissions path we are projected to warm most of U.S. 10 – 15°F by 2100, with sea level rise of 5 feet or more, and the SW will be a permanent Dust Bowl"
What is the best, most accurate soundbite for climate science advocates asked about projected climate impacts on this country by 2100 assuming we stay on business-as-usual emissions — according to the latest science?
I suggest some version of
On our current emissions path we are projected to warm most of the United States 10 – 15°F by 2100, with sea level rise of 5 feet or higher, the U.S. Southwest a permanent Dust Bowl, half or more species extinct, and much of the ocean a hot, acidic dead zone.
I say that, of course, because that is what the latest science says, as I document at length with links to the literature here: An introduction to global warming impacts: Hell and High Water.
You can quibble with the word choice, and sometimes I don’t remember to say every word or phrase I’d like to, such as “from preindustrial levels” [or "from Kansas and Oklahoham to California"]. But this is now the median projection for business-as-usual emissions and warming. It might not be that bad, but it could be much worse.
If you like to err on the conservative side, you can throw in “up to” — i.e. “we are projected to warm most of the U.S. up to 15°F or more by 2100, with sea level rise of up to 5 feet or more….”
Now conservatives, who err all the time, don’t like blunt progressives who know their science. So they are trying to shout down this soundbite by misstating the science.
“On our current emissions path we are going to warm the United States 10-15 degrees Fahrenheit by the end of the century and sea level rise will be 5 feet or higher and a third of the planet will be desert.”
Sheppard labels this “grossly exaggerating the already hyped predictions of his fellow climate hysterics” and “blatant fabrications and misrepresentations in the three predictions of his opening salvo.”
Readers here know the statement is an accurate representation of the latest science, though the part on the desert needs the kind of elaboration this blog provides.
I am going to respond to the American Thinker here not because they are a credible source worth wasting time on — they aren’t — but for two other reasons:
- The misunderstanding and misapplication of basic climate science by Marc Sheppard is quite typical of deniers, and I have been meaning to post on this.
- I haven’t blogged on the American Thinker or Marc Sheppard , and I do try to cover each denier website and denier at least once so that somebody searching this website or the Internet will find a commentary and/or response.
Here is how Sheppard makes his “case”:
Even the overly venerated Intergovernmental Panel on Climate Change (IPCC) 2007 Fourth Assessment Report (AR4) predicted that climate sensitivity (change in mean global temperatures resulting from a sustained doubling of atmospheric CO2 concentration) would likely range between 2 and 4.5°C, and would most probably border on 3°C.
Based on his syntax, Romm implies future warming — which translates to a 90 year period. Yet to achieve Romm’s lowest warming figure of 10°F (5.8°C) even at AR4′s highest sensitivity figure of 4.5°C, would require more than doubling the current level of 386ppm in just 9 decades, which is beyond absurd. Keep in mind that in the 50 years between 1958 and 2008, atmospheric carbon dioxide, as measured at the Mauna Loa Observatory in Hawaii, rose only 70ppm.
It has always amazed me that deniers who don’t believe the IPCC reports and therefore don’t actually read them closely enough to understand them continue to quote the IPCC on their behalf.
Marc Sheppard makes several beginner mistakes that are quite common on denier websites:
- He simply has no idea what the IPCC AR4 actually says or what “our current emissions path” is. Through most of this decade, we have been exceeding the most extreme emissions scenario, A1F1, and that means we are headed toward 1000 ppm [see "U.S. media largely ignores latest warning from climate scientists: "Recent observations confirm "¦ the worst-case IPCC scenario trajectories (or even worse) are being realised" "” 1000 ppm"]. Actually, if you read the IPCC closely, then you know they project we will probably hit 1000 ppm even if our emissions trajectory is well below A1F1 — because of the amplifying carbon cycle feedbacks (see “Nature publishes my climate analysis and solution“). For the record, the IPCC said in 2007 that for A1F1 the “best estimate” temperature change from 1990 to 2095 is 4°C.
- He is apparently unaware of the latest science. Most of the science inputs to the IPCC AR4 were stopped by 2006, so it is already about three years out of date. With more recent emissions data and a better understanding of feedbacks, the UK’s Hadley Center predicts median warming from preindustrial levels of 5.5°C by 2100 (see here), and MIT’s Joint Program on the Science and Policy of Climate Change predicts median warming from 1990 levels of 5.1°C by 2100 (see here) .
- He apparently has no clue that a basic prediction of climate science is that the vast majority of the United States is projected to warmed considerably faster than the rest of the world — see A (Hopefully) Clarifying Note on Temperature.
- He apparently has failed to notice that the rate of rise of carbon dioxide concentrations has accelerated — and continues to do so under all high emissions scenarios the IPCC looks at. This is another basic prediction of climate science, which is already coming true. Global warming is not linear!
And so Sheppard labels “beyond absurd” the notion we would more than double the current level of CO2 concentrations in just 9 decades, when in fact it is a prediction of the IPCC AR4 that he cites. Indeed, MIT said in January that its median projection for the atmospheric concentration of carbon dioxide in 2095 on the business-as-usual emissions trajectory is 866 ppm. So I guess MIT joins the “beyond absurd” club.
Thus, even with the IPCC’s most likely climate sensitivity, the median projected warming for the vast majority of the United States (including Alaska) by 2100 is indeed around 10°F to 15°F — depending on whether you use the IPCC’s A1f1 scenario or the recent MIT and Hadley projections.
SEA LEVEL RISE
Marc Sheppard the continues his uninformed assault:
And from what sci-fi flick did Romm draw his assertion of a 5 foot or higher sea level rise? Referring again to AR4, even the IPCC’s intentionally alarm-biased models only projected figures running from 0.18 to 0.59 meters by 2100.
The “sci-fi flick” is, of course, the recent scientific literature, of which Sheppard apparently knows nothing about:
- Science 2008: “On the basis of calculations presented here, we suggest that an improved estimate of the range of SLR to 2100 including increased ice dynamics lies between 0.8 and 2.0 m.” The IPCC famously ignored increased ice dynamics in its projection.
- Nature Geoscience 2007 looked at the last interglacial period (the Eemian, about 120,000 years ago) — the last time the planet was as warm as it soon will be again. Seas rose 1.6 meters (5 feet) per century “when the global mean temperature was 2 °C higher than today,” a rather mild version of where we are headed in the second half of this century.
- Science 2007 used empirical data from last century to project that sea levels could be up to 5 feet higher in 2100 and rising 6 inches a decade.
Again, it is so amusing that the deniers hide behind the AR4 when they don’t even believe it or basic climate science. In any case, Sheppard’s beloved Bush administration itself explained in great detail that the IPCC’s projection, rather than being “alarm-biased,” in fact low-balled the sea level rise number — see US Geological Survey stunner: Sea-level rise in 2100 will likely “substantially exceed” IPCC projections, which concluded “based on an assessment of the published scientific literature” is:
Recent rapid changes at the edges of the Greenland and West Antarctic ice sheets show acceleration of flow and thinning, with the velocity of some glaciers increasing more than twofold. Glacier accelerations causing this imbalance have been related to enhanced surface meltwater production penetrating to the bed to lubricate glacier motion, and to ice-shelf removal, ice-front retreat, and glacier ungrounding that reduce resistance to flow. The present generation of models does not capture these processes. It is unclear whether this imbalance is a short-term natural adjustment or a response to recent climate change, but processes causing accelerations are enabled by warming, so these adjustments will very likely become more frequent in a warmer climate. The regions likely to experience future rapid changes in ice volume are those where ice is grounded well below sea level such as the West Antarctic Ice Sheet or large glaciers in Greenland like the Jakobshavn Isbrae that flow into the sea through a deep channel reaching far inland. Inclusion of these processes in models will likely lead to sea-level projections for the end of the 21st century that substantially exceed the projections presented in the IPCC AR4 report (0.28 ± 0.10 m to 0.42 ± 0.16 m rise).
And just for the record, that report, Abrupt Climate Change, has the signature of those well known “sci-fi flick”-watching radicals:
- Carlos Gutierrez, Bush’s Sec. of Commerce
- Samuel Bodman, Bush’s Sec. of Energy
- John Marburger III, Director of Bush’s Office of Science and Technology Policy
So now you know why climate science advocates don’t like to debate anti-scientific deniers. The deniers sound genuinely believable when they insist you are wrong and exaggerating because they believe the disinformation they are pushing because they have no friggin’ clue what the science says (or no interest in accurately reporting it).
I have come to realize that using the words “desert” and “desertification” lack clarity because people have many different definitions of desert. The USGS believes one-third of the land is desert already (see here) whereas the University of California Museum of Paleontology says it is one fifth (see here).
I got the original quote from the UK’s prestigious Hadley Center, by way of the Guardian newspaper, which often reports on their research. In 2006, the Environmental Editor wrote an article with this headline and sub-head:
Obviously the editor meant “one third of the land,” but the statement is clearly inadequate anyway as a stand-alone statement given the various definitions of the word “desert.” So let’s go back to what the non-alarmist Hadley Center actually concluded back in 2006 (before they upped their temperature target for 2100, I might add):
Reiterating findings published last month, Dr. Pope will highlight the likely major increases in the areas affected by drought right across the globe. Extreme drought is likely to increase from under 3% of the globe today to 30% by 2100 – areas affected by severe drought could see a five-fold increase from 8% to 40%.
So the Hadley Center and the Guardian were talking about extreme drought, which it is probably best characterized as a Dust Bowl, rather than a desert.
Their is no word “Dust-Bowl-ification” to replace desertification, but I think desertification does not do justice to what global warming has started to do in parts of Australia and ultimately will do over a large fraction of the now-habited land (see “Australia today offers horrific glimpse of U.S. Southwest, much of planet, post-2040, if we don’t slash emissions soon“). I will do another post with useful PowerPoint slides on the expansion of the subtropics and the rise of permanent Dust Bowls shortly.
But for a U.S. audience, what happens in this country is naturally more salient. Here, the science is solid — and troublesome. In 2007, Science (subs. req’d) published research that “predicted a permanent drought by 2050 throughout the Southwest” “” levels of aridity comparable to the 1930s Dust Bowl would stretch from Kansas to California.
Philip Mote, an atmospheric scientist at the University of Washington who was not involved in the study, added, “There is a convergence of the models that is very strong and very worrisome.”
And the Science researchers were only looking at a 720 ppm case! The Dust Bowl was a sustained decrease in soil moisture of about 15% (“which is calculated by subtracting evaporation from precipitation”). Princeton has done an analysis on “Century-scale change in water availability: CO2-quadrupling experiment,” which is to say 1100 ppm. The grim result: Most of the South and Southwest ultimately sees a 20% to 50% (!) decline in soil moisture.
Again, even the Bush Administration signed off on this conclusion in its Abrupt Climate Change report:
The serious hydrological changes and impacts known to have occurred in both historic and prehistoric times over North America reflect large-scale changes in the climate system that can develop in a matter of years and, in the case of the more severe past megadroughts, persist for decades. Such hydrological changes fit the definition of abrupt change because they occur faster than the time scales needed for human and natural systems to adapt, leading to substantial disruptions in those systems. In the Southwest, for example, the models project a permanent drying by the mid-21st century that reaches the level of aridity seen in historical droughts, and a quarter of the projections may reach this level of aridity much earlier.
The deniers try to shout down every effort to warn the public of what the science clearly says we are risking our current emissions path. Whatever motivation they have for their self-destructive behavior, they must not be allowed to succeed. The health and well-being of countless billions of people over the coming decades and centuries depend on it.