By David L. Brown
We have written here before about the dangers of melting tundra in the north polar regions, pointing out that these frozen lands hold sequestered CO2 and methane — potent greenhouse gases (GHG) that could boost global warming if released through thawing. (See the article “Bad News for Polar Bears … The Big Thaw,” April 28, 2006. Use search field at right to find previous articles.)
Predictions of Arctic thawing are rapidly becoming more ominous. As recently as last October an article in Science magazine estimated it would be as much as 50-100 years before the polar ice cap would completely melt. Star Phoenix Base has estimated it will be much sooner, and more recent scientific findings also move the timeline much closer to the present.
Now more evidence has appeared showing that melting tundra could release far more GHG into the atmosphere than previously believed. In the June 16 issue of Science a trio of researchers from Russia and the U.S. estimate the carbon content of the permafrost (permanently frozen ground) in northern regions surrounding the fast-thawing Arctic Ocean, carbon that is likely to be released into the atmosphere in coming decades as the “Big Thaw” continues. The news is not encouraging.
The “Perspectives” article is titled Permafrost and the Global Carbon Budget.” In it, Sergey A. Zimov, et al., report on their study of frozen windblown loess soils (called “yedoma” in Siberia) which cover more than one million square kilometers of Siberia and Alaska to an average depth of about 25 meters. They reveal that these frozen soils contain two to five percent carbon — ten to thirty times as much as is found in typical non-frozen mineral soils. Earlier assumptions placed the figure far lower, which means that the thawing of frozen Polar wasteland could have a far greater impact on greenhouse warming than previously believed. (Read article here; subscription required.)
There is at present about 730 gigatons (Gt) of carbon gases in the Earth’s atmosphere. What could the thawing yedoma contribute to this carbon load? Calculating from an average of 2.6 percent carbon content and the estimated total volume of yedoma, thawing could release approximately 500 Gt from this source alone.
But that’s not all. Zimov and his associates also estimate that other non-yedoma permafrost contains another 400 Gt, and that frozen peatlands in western Siberia hold another 50 to 70 Gt. That’s a whopping total of nearly 1000 Gt, significantly more than the present carbon load in our atmosphere.
The researchers suggest that earlier freezing or thawing of these carbon “sinks” could explain sudden warming or cooling episodes during the distant past. For example, during the last glacial maxima permafrost extended much farther south, locking up quantities of carbon and helping reduce GHG warming. Similarly, glacial retreat saw the amount of GHG in the atmosphere rise, contributing to a feedback effect that resulted in further warming. As evidence of this, atmospheric carbon levels were only 360 Gt during the last Ice Age and had risen to about 560 Gt in pre-industrial times when the effects of human activity began to contribute significantly to the carbon load in the atmosphere.
What can be done? Well, the authors conclude with this statement:
Factors inducing high-latitude climate warming should be mitigated to minimize the risk of a potentially large carbon release that would further increase climate warming.
Unfortunately, this statement does not contain any useful information about how we might go about “mitigating” those “factors,” and it seems to Star Phoenix Base that this vague and empty statement is an admission of helplessness.
If the truth be known, there is no presently known way to reverse the on-going global warming. Natural forces are at work, just as they were at the end of the Ice Ages, with the impact of industrial activity adding to the momentum. Even if humankind could reduce to zero our emissions of GHG to (which we could achieve only through the selfless expedience of becoming extinct), the trend is going to continue for the foreseeable future.
Perhaps the only possible “solutions” can be found in the realm of science fiction — for example, the deployment of enormous orbiting sunshades to block the solar rays and reverse Arctic melting; weather manipulation on a massive scale; the design and construction of devices that could somehow remove and sequester billions of tons of carbon from the atmosphere. Until imagined solutions such as these can be found and put to use, the Earth will continue to grow warmer and the frozen North will continue inexorably to release its vast store of CO2 and methane.
What effect could this have on global warming? I remind our readers of a statement made recently by Dr. Rajendra Pachauri, the chairman of the official Intergovernmental Panel on Climate Change (IPCC), who reported that global warming has already hit the danger point that international attempts to curb it are designed to avoid.
The danger is that a tipping point is now being reached, one that can plunge the Earth into a hothouse mode with rapidly rising temperatures. Many believe this is possible and that it may require relatively small incremental increases in atmosphere GHG to lead us into an environmental disaster. The news that the frozen North could yield far more CO2 and methane than previously suspected adds grave new weight to these concerns.