By: Michael Knust
Summary: Organic sources of carbon are naturally stored deep within permafrost. This is because dead plants and animals get frozen in the soil and do not decompose. The reason the organic material freezes before decomposing is due to the glaciers during the last ice age. In the summer plants would grow in the sediment layer left behind by the receding glacier. Then when the glacier spreads southwards in the winter it will cover and freeze these plants as well as some dead animals in its path. When the glacier retreats again, it will cover these frozen organisms with a new sediment layer and the process starts over, adding a new layer every year during the ice age. The frozen organic material is mostly roots and other plant matter, but there are some animals. When permafrost thaws, which is being sped up by climate change, microbes in the soil are able to eat the dead organisms. The decomposition releases large quantities of methane and carbon dioxide into the atmosphere. The microbes produce methane rather than carbon dioxide when there is no oxygen available. Oxygen is not available to microbes in environments such as swamps and wetlands and a large portion of the southern region of the Arctic, where permafrost is melting, consists of wetlands. As global temperatures rise, more permafrost thaws, contributing further to climate change.
Why we should care? Methane is a potent greenhouse gas and is a significant contributor to climate change. Melting permafrost adds more methane to the Earth’s atmosphere and is not accounted for in most climate projections.
This article does a partially good job at concisely explaining the methane released from thawing permafrost. It explains that microbes produce methane rather than mathan and carbon dioxide when there is no oxygen in the soil and that there is little to no free oxygen available in water saturated soil. It also explains that methane is a much more potent greenhouse gas when compared to carbon dioxide (thirty times more devastating to climate change). Greenhouse gas emissions from thawing permafrost will significantly impact the climate budget and previously has not been estimated to have this great of an impact.
Science in Action.
Dr. Katey Walter Anthony is a professor of aquatic ecosystem ecology at University of Alaska Fairbanks.
Dr. Walter Anthony researches the effect of the release of methane and carbon dioxide from melting permafrost. Her research focuses on thermokarst lakes in the arctic. Thermokarst lakes are shallow freshwater lakes that form from ice heaving. These lakes tend to produce sudden large releases of methane and carbon dioxide as these formations trap the greenhouse gases in their ice. Part of Dr. Walter Anthony’s research is estimating the amount of methane that will be released by these lakes as the permafrost melts. She estimates that by the end of the 21st century that melting permafrost will be the second most devastating source of greenhouse gases.