Hill Heat

NOAA has recently debuted a new website, Arctic Report Card 2007, summarizing the state of environmental changes in the arctic, linking each section with the detailed reports from NOAA researchers. Their summary:

Collectively, the observations indicate that the overall warming of the Arctic system continued in 2007. There are some elements that are stabilizing or returning to climatological norms. These mixed tendencies illustrate the sensitivity and complexity of the Arctic System.

On Wednesday, October 17, 2007, the Investigations and Oversight Subcommittee will hold a hearing on the impacts of global warming on the Arctic. This hearing will provide the Committee with an opportunity to hear from witnesses on three interrelated matters: (1) the current situation in the Arctic, including the situation facing the polar bear, (2) ways in which warming in the Arctic may accelerate global warming, especially through the emission of more greenhouse gases, and (3) interim steps that could be taken to reduce greenhouse gas emissions while the Congress weighs more elaborate carbon trade or tax proposals.

One of the themes that should emerge from this hearing is that, from a layman’s perspective, the models used to project climate change and its ramifications appear to be conservative in their projections. This is because any phenomena that are not understood well enough to be represented in models with confidence are excluded. These other phenomena may accentuate or depress warming trends. In the case of the Arctic, most of the phenomena that have been excluded from the models are believed to accentuate warming and its effects. Few will depress it. The modeling on polar bear survival, for example, uses projections from the IPCC models to estimate future changes in sea ice extent. Since the bears’ condition is very dependent upon both the extent of the sea ice and the duration of ice-free periods, projections of the bear survival are very dependent upon projections of sea ice. This summer the sea ice extent is far less than projected by the models.

The Center for Biological Diversity will appear to provide some advice on steps that can be taken to reduce warming, with particular emphasis on their efficacy in the Arctic. Among the steps they advocate are programs to reduce methane emissions and “black carbon.” Black carbon is soot that, in the Arctic, has a particularly pernicious effect. When it is deposited on snow and ice it decreases its reflectivity and increases its heat absorption leading to greater melting. As the Arctic comes under more and more industrialization with other warming, one could anticipate further production of black carbon. Methane is a powerful greenhouse gas, with an estimated global warming potential 23 times greater than carbon dioxide over a 100-year time frame. Methane is a precursor to tropospheric ozone. In that form, it traps shortwave radiation as it enters the earth’s atmosphere from the sun and then when it is reflected back again by snow and ice. As a consequence, its impact is strongest over the poles. Reducing global methane emissions would provide a particular benefit to the Arctic.

• Dr. Richard Alley, Evan Pugh Professor of Geosciences, Pennsylvania State University, Department of Geosciences
• Dr. Glenn Juday, Professor, University of Alaska at Fairbanks, School of Natural Resources and Agricultural Sciences
• Dr. Sue Haseltine, Associate Director for Biology, U.S. Geological Survey, U.S. Department of Interior
• Kassie R. Siegel, Director, Center for Biological Diversity, Climate, Air and Energy Program

10/17/2007 at 10:00AM