Australian climate scientist Barry Pittock gave a terrific and terrifying talk at the 20th Anniversary of the Climate Insitute last week. He made the case that the U.N.’s Intergovernmental Panel on Climate Change (IPCC), the key international process for determining the “consensus” view on climate, is systematically underestimating the future impacts of climate change. Since Pittock was a major contributor to the IPCC’s Third Assessment Report (2001) and since their Fourth Assessment is due out next year, we should pay attention to what he says.
1. “The climate sensitivity, or global warming after a doubling of the pre-industrial carbon dioxide concentration, is probably in the range of 2º–6°C rather than the 2001 IPCC estimate of 1.5º–4.5ºC. This suggests a more than 50% chance of that global warming by 2100 will be 3ºC or more, a level that many consider dangerous.”
3. “Permafrost melting is widespread,” which “leads to emissions of carbon dioxide and methane,” a dangerous vicious climate cycle that CP has written about.
7. & 8. “Rapid changes in Antarctica” and “Rapid melting and faster outlet glaciers in Greenland,” which combine to threaten far faster and greater sea level rise than climate models have been predicting.
I found his talk very compelling as it matched what I’ve been hearing from a number of climate scientists I interviewed for my book, including James Hansen. Pittock concludes:
The above lines of evidence (supported by well over 100 recent scientific papers), while not definitive and in some cases controversial, suggest that the balance of evidence may be swinging toward a more extreme outcome. While some of the observations may be due merely to natural fluctuations, their conjunction and, in several cases, amplifying effects are causes for concern. They suggest that critical levels of global warming may occur at even lower greenhouse gas concentrations and emissions than was considered justified in the Third Assessment Report of the Intergovernmental Panel on Climate Change report issued in 2001.
In short, the time for inaction has run out.
http://climateprogress.org/2006/09/25/ten-reasons-why-climate-change-may-be-more-severe-than-projected/.........and Dr. A. Barrie Pittock........
Scientific Symposium Presentation Abstracts
September 19
Dr. A. Barrie Pittock: Ten Reasons Why Climate Change May Be More Severe than Projected*
Uncertainties in climate change science are inevitably large, due both to inadequate scientific understanding and to uncertainties in future human behavior. Policies therefore must be based on risk management, that is, on consideration of the probability times the magnitude of any deleterious outcomes for different scenarios of human behavior. In this talk I want to focus on observations and modeling studies in the last year or two in ten areas of concern, which when taken together strongly suggest that the risk of more serious outcomes is greater than was understood previously.
1. The climate sensitivity, or global warming after a doubling of the pre-industrial carbon dioxide concentration, is probably in the range of 2º–6°C rather than the 2001 IPCC estimate of 1.5º–4.5ºC. This suggests a more than 50% chance of that global warming by 2100 will be 3ºC or more, a level that many consider dangerous.
2. Global dimming is large but decreasing. Reductions of sunlight at the Earth’s surface by atmospheric pollution particles are diminishing as particulate emissions are brought more under control, thus decreasing their cooling effect and making the warming effect of greenhouse gases more evident.
3. Permafrost melting is widespread. Observations show rapid melting of permafrost (i.e., frozen ground). This tends to reduce the reflectivity of the surface to sunlight and, as vegetable matter in the soil starts to decay, leads to emissions of carbon dioxide and methane. These changes will enhance global warming.
http://washington_summit.climate.org/abstracts/pittock_tenreasons.html