May 24, 2007

Cooling the Permafrost Scare

The global warming story is told over and over, and today every school child in America is aware that burning fossil fuels increases the atmospheric concentration of carbon dioxide, and they have learned that carbon dioxide is a greenhouse gas that will warm the Earth as its concentration increases. Of course, the United States is largely responsible for this mess, and children are given terrific suggestions on how they can get their parents to stop global warming.

Should someone begin to look more into the global warming issue, they will uncover literally hundreds of additional gems in the greenhouse apocalypse – they will rather quickly discover that Arctic region permafrost is melting at an unprecedented rate, and somehow this will lead us to a runaway greenhouse effect that might warm the Earth far more than any of us ever feared. The melting of permafrost is a solid, never-weakening pillar, of the greenhouse – global warming story.

But all is not as it seems (or as Al Gore would have you believe).

There has been a flurry of research recently about the melting permafrost issue, and if you do nothing more that search the internet for “Global Warming and Permafrost”, literally hundreds of thousands of pages will be brought to your attention. You will read repeatedly that permafrost is a sink for carbon dioxide and other greenhouse gases such as methane. Basically, the soils of the high latitudes froze at the beginning of the last ice age of the Pleistocene, and when they froze, they entrapped very large amounts of organic material (carbon rich grasses, animal remains, soil material) in the frozen permafrost. As the permafrost thaws, carbon trapped within the once-frozen soils is released largely as methane, and as this methane is mixed into the global atmosphere, it will cause even more warming worldwide. We know that the warming is predicted to occur the most in the high latitude land areas of the Northern Hemisphere - exactly where the permafrost is found today. With more warming in permafrost regions, more permafrost will melt, more methane will be released, and global warming will speed up.

The entire process is described by many as a time bomb that is going off before our very eyes. The bomb is not just causing the world to warm at a more rapid pace, but the melting permafrost is also routinely connected to the destruction of forests (recall Gore’s drunken forest pictures in “An Inconvenient Truth”), collapse of homes and other structures (e.g., pipelines), erosion of coastal areas and hillsides, disruption of animal habitats, and … well, you name it.

A very interesting article appeared recently in Geophysical Research Letters entitled “Near-surface permafrost degradation: How severe during the 21st century?” by a scientist from Hannover, Germany. Just the fact that we at World Climate Report had not heard anything about this research elevated our interest in the answer to the question raised in the title. The final sentence of the abstract states “Based on paleoclimatic data and in consequence of this study, it is suggested that scenarios calling for massive release of methane in the near future from degrading permafrost are questionable.” No wonder we never heard about this work, and no wonder this piece is doomed to receive zero press coverage.

The sole author (Delisle) acknowledges that warming is occurring in the Arctic regions and that the warming will undoubtedly impact the permafrost of the high latitudes. The author notes, however, that many numerical models used to simulate the impact of warming on permafrost deal only with the upper 10 feet of the earth’s surface. The previously-used models do not take into account the cooling effect of deeper and colder zones that do interact thermodynamically with the active layer near the surface. Delisle also exposes other assumptions of previous models that are “in clear conflict with field evidence.” We have a case here of modelers fighting with modelers, and we pay every time for these pay-per-view events!

Delisle presents “a unidimensional long term permafrost temperature model of general application” “which is capable to fully incorporate all relevant thermal processes within the active layer and the permafrost, and between the permafrost and the non frozen ground below. The model space is made up of 600 layers with a minimum spacing of 10 cm within the active layer and the uppermost ‘‘permafrost zone.” Rather than look at only 10 feet into the surface as was done by previous models, the new model goes 100 yards into the surface, and is deemed as more realistic.

Well, with the improved model, Delisle reports that continuous permafrost in Alaska and Siberia will survive over the next 100 years, even if a significant warming takes place. Further, we learn that “Based on this result and on the presented analysis, it appears that all areas north of 60°N will maintain permafrost at least at depth. North of 70°N, surface temperature values today are in general below -11°C. These areas should maintain their active layer. It appears unlikely that almost all areas with near-surface permafrost today will lose their active layer within the next 100 years” as concluded by others. Delisle claims that the new model is far more consistent with field measurements and far more realistic in terms of including the energy flux component from the deeper and colder core.

Delisle throws in another fast ball regarding methane (CH4) at the end of the article by stating “A second, rarely touched upon question is associated with the apparently limited amount of organic carbon that had been released from permafrost terrain in previous periods of climatic warming such as e.g. the Medieval Warm Period or during the Holocene Climatic Optimum. There appear to be no significant CH4-excursions in ice core records of Antarctica or Greenland during these time periods which otherwise might serve as evidence for a massive release of methane into the atmosphere from degrading permafrost terrains.”

We couldn’t say it better ourselves!

Reference:

Delisle, G. 2007. Near-surface permafrost degradation: How severe during the 21st century? Geophysical Research Letters, 34, L09503, doi:10.1029/2007GL029323.




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