Posted by The incredible words that spilled from my radio this morning were spoken by NASA Administrator Michael Griffin. Asked on NPR’s Morning Edition to respond to an attack on his agency’s competence the previous day by Gregg Easterbrook, who wrote Wired magazine’s “How NASA Screwed up,” Griffin said some pretty strange things. Among the most bizarre was his response to host Steve Inskeep’s question: “Do you think climate change is a problem?” Believe it or not this is what he said:
I have no doubt that … a trend of global warming exists. I am not sure that it is fair to say that it is a problem we must wrestle with.
Not sure we should wrestle with it? Amazing. Truly amazing. Sounds like more like Dick Cheney than the boss at NASA. But that’s not all.
To assume that it is a problem is to assume that the state of Earth’s climate today is the optimal climate, the best climate that we could have or ever have had and that we need to take steps to make sure that it doesn’t change. First of all, I don’t think it’s within the power of human beings to assure that the climate does not change, as millions of years of history have shown. And second of all, I guess I would ask which human beings — where and when — are to be accorded the privilege of deciding that this
a level change.
Wow. I hardly know where to begin. Fortunately, Janet over at Adventures in Ethics and Science, does. As she notes, “I’m not sure this is an argument you can sell in an island nation that’s on a trajectory to being underwater.” But more importantly, almost everything Griffin seems to be believe about the threat of climate change is directly and explicitly contradicted by his own chief climatologist, Jim Hansen.
In a paper published May 7, “Dangerous human-made interference with climate: a GISS modelE study” (Atmos. Chem. Phys., 7, 2287-2312, 2007), Hansen and veritable army of colleages from NASA’s Goddard Institute for Space Studies and Columbia University’s Earth Institute, report on the fusion of two computer climate models and conclude that we are closer to dangerous climate change than previously thought. While the Intergovernmental Panel on Climate Change, which earlier this year reported that we can allow only 2 or 3 degrees C of further warming before the really bad stuff kicks in, Hansen et al. say it’s more like 1 C.
What follows are a series of excerpts from the paper, which isn’t freely available, but I have a copy I feel obliged to share the more salient points. It’s also interesting to note that the paper, which has been out for three weeks, attracted almost no press. But suddenly, today of all days, NASA decided to put out a press release on the paper. Hmmm. Anyway, here’s the meat of the matter:
The [IPCC] diagram is sometimes taken as suggesting that global warming of 2-3 C relative to recent temperatures, is likely to be dangerous … Hansen (2004, 2005a, b) asserts that the dangerous level of global warming is closer to 1 C or less, his principal rationale being evidence from the Earth’s history that greater warmings are likely to cause large sea level change, which, he argues, will occur on a time scale of centuries.
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it is unlikely that the response time for significant ice sheet change could exceed centuries, because such response times (with sea level change of meters per century) have occurred during the Pleistocene with much smaller forcings
…
GHG climate forcings in the IPCC BAU (business as usual) scenarios, such as A1FI, A2 and A1B, are far outside the range that has existed on Earth in millions of years. The rate of change of this sustained forcing exceeds that of known forcings in at least millions of years.
…
We suggest that the conclusion that a “tipping point” has been passed, such that it is not possible to avoid a warm-season ice-free Arctic, with all that might entail for regional climate and the Greenland ice sheet, is not warranted yet. Better information is needed on the present magnitude of all anthropogenic forcings and on the potential for their reduction. If CO2 growth is kept close to that of the alternative scenario [requiring implementation of an agressive and immediate program of GHG emissions reductions], and if strong efforts are made to reduce positive non-CO2 forcings, it may be possible to minimize further Arctic climate change.
What happens to the Arctic, and the north polar ice cap, is key, thanks to their role in maintaining the equilibria and overall climate we now enjoy. And it’s important to keep in mind that, since this paper was written, concerns about the accelerating melt of the north polar ice cap have only grown. Some estimates would see it disappear entirely in the summer by 2020. All that extra warm air over the North Polar is certain to affect the Greenland ice sheet, which in turn will cause serious increases in sea level. And when we talk about “dangerous,” a rising sea level is the most obvious danger.
The strong positive feedback between sea ice area and surface albedo makes the Arctic one of the most sensitive regions on Earth to global warming. In the middle Pliocene,
with global temperature 2-3 degrees C warmer than today, the Arctic was ice-free in the warm season. Such drastic climate change would have deleterious effects on wildlife and indigenous people (ACIA, 2004), constituting what many people would agree is dangerous anthropogenic interference with nature. … we can conclude that the world is already close to the dangerous level.…
If equilibrium sea level rise is many meters, a response time of centuries provides little consolation to coastal dwellers. They would be faced with intermittent floods associated with storms and continually rebuilding above a transient sea level. Thus we suggest that sea level change may define a low level for global warming that constitutes dangerous change, due to the large concentration of people and infrastructure along global coastlines.
Could the Greenland ice sheet survive if the Arctic were ice-free in summer and fall? It has been argued that not only is ice sheet survival unlikely, but its disintegration would be a wet process that can proceed rapidly (Hansen, 2004, 2005a, b). Thus an ice-free Arctic Ocean, because it may hasten melting of Greenland, may have implications for global sea level, as well as the regional environment, making Arctic climate change centrally relevant to definition of dangerous human interference.
Hansen et al. do have some good news. For example, the threat posed by methane hydrates, frozen submarine chunks of a potent greenhouse gas, may not be as serious as once thought:
With our present lack of understanding, we can perhaps only say with reasonable confidence that the chance of significant methane hydrate feedback is greater with BAU scenarios than with the alternative scenario, and that empirical evidence from prior interglacial periods suggests that large methane hydrate release is unlikely if global warming is kept within the range of recent interglacial periods.
Recall that the current tropospheric CO2 level is now 381 ppm, up 35 percent from pre-industrial levels, and almost no one thinks we have much a chance of reining in our emissions such that we won’t hit 450 ppm. Hansen’s team, writes that
…a CO2 level exceeding 450 ppm is almost surely dangerous, and the ceiling may be even lower.
Have we already passed a “tipping point” such that it is now impossible to avoid “dangerous” climate change (Lovelock, 2006)? [Reference here is to last year's book "The Revenge of Gaia, in which James Lovelock argues it's already too late.] In our estimation, we must be close to such a point, but we may not have passed it yet. It is still feasible to achieve a scenario that keeps additional global warming under 1 C, yielding a degree of climate change that is quantitatively and qualitatively different than under BAU scenarios.
Continued rapid growth of CO2 emissions and infrastructure for another decade may make attainment of the alternative scenario impractical if not impossible. Because widescale use of power plants with CO2 sequestration is at least a decade away, near-term emphasis on energy efficiency and renewable energy is needed to minimize construction of previous-generation pulverized-coal power plants.
A scenario that avoids “dangerous” climate change appears to be still technically feasible.
The principal implication is that avoidance of dangerous climate change requires the bulk of coal and unconventional fossil fuel resources to be exploited only under condition that CO2 emissions are captured and sequestered. A second inference is that remaining gas and oil resources must be husbanded, so that their role in critical functions such as mobile fuels can be stretched until acceptable alternatives are available, thus avoiding a need to squeeze such fuels from unconventional and environmentally damaging sources.
Take that, boss.
[PLUS: I've posted reaction from the scientific community here.]
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