Tag Archives: permafrost

Thawing Permafrost Feedback Loop

Within the scientific community there is no argument about global warming. It is real, and it is caused by human activities. Those activities include burning fossil fuels which release carbon dioxide (CO₂.) The carbon dioxide acts as a climatic blanket to retain heat in the atmosphere which would otherwise be radiated out to space.

Other activities which release carbon dioxide to the atmosphere are deforestation. Cutting trees causes the release of CO₂, if the biota is simply burned to clear land as is practiced in the rain forests of the Amazon and southeast Asia. Even if the timber is harvested for construction, there is still a significant portion of the biomass in the form of twigs, branches, roots, and shoots which degrade rapidly to release CO₂.

Carbon dioxide is only one of the so called greenhouse gasses, the major one, but only one just the same. Methane, CH4, is another greenhouse gas. On a per weight basis methane is much more effective at global warming than CO₂, but its contribution is lower as there is a lot less of it. That may be changing – read on.

As stated earlier, global warming is real, the planet is getting warmer and it is to a very large degree caused by humans. A question yet answered is how fast will the planetary temperature rise? That depends on how fast the concentrations of the gasses increase.

If there is one condition that keeps climate scientists up at night, it is a risk of a “runaway” feedback mechanism. If warming itself can cause the release of greenhouse gasses, then a feedback loop causes more heating which causes more gas release which causes more rapid heating which causes more rapid gas release…

Image from thepolicylass.org

Image from thepolicylass.org

Feedback loops exist, but how sensitive are they to what is happening now? A disturbing result was recently published in Nature Climate Change. One of the vagaries of climate change is that it is happening faster at the higher latitudes (nearer the poles) than near the equator. Not only are glaciers melting but areas of exposed permafrost are thawing rapidly. The permafrost is composed of a thick layer of accumulated biomass from the slow growth of moss, lichens, and sedge. There is estimated to be twice as much carbon sequestered in the permafrost as exists in the atmosphere.

The carbon in the permafrost can degrade in two ways depending on environmental conditions. Microbial action can convert the carbon to either CO₂ or methane. If more methane is produced the feedback loop is accelerated even faster than if CO₂ were produced.

This all starts with burning fossil fuels which enrich the atmosphere in carbon dioxide. This causes the climate to warm, which causes the permafrost to thaw which causes the production of even more carbon dioxide or even worse methane.

The only way to stem this cycle is to stop extracting and stop burning coal, oil, and methane. The Environmental Protection Agency has taken some early steps to limit burning coal, the worst of the fossil fuels.