Abrupt thaw of permafrost lakes in the Arctic

10/24/2018 Arctic , carbon , climate change , crisis , feedback , methane , permafrost , tipping points 0 Comments

There's an ongoing debate in the scientific community regarding the threshold value, tipping point, for frozen grounds in the Arctic, permafrost, to start thawing irreversibly. And whether released methane from the permafrost will occur gradually over time or more abruptly. There is more stored carbon in frozens soils than we currently have in the atmosphere.

There are basically two camps, some believe the permafrost to be stable with a threshold value around <3°C while others claim 1,5°C is enough to start thawing large parts of the frozen grounds and lakes in the Arctic. 

For a lay person this is quite confusing, but it simply means that there isn't enough data to know for sure and so some scientists are more or less conservative in their estimates. Then there is the question of using climate models to try and predict potential threshold values or doing actual fieldwork and extrapolating conclusions from that. To my knowledge, climate models have a pretty bad track record of capturing highly non-linear dynamics in the climate system. For example, Arctic sea ice passed a tipping point in 2007 and is now in a death spiral but models had predicted sea ice to remain until the end of this century. Pretty high margin of error if you ask me. Also, we are learning that there seems to be differences in how permafrost soils and lakes thaw. 

According to a recent field research study funded by NASA of thermokarst lakes, formed by thaw of permafrost below the soil, in Alaska and Siberia the potential for abrupt thaw (decades) is now likely and irreversible. As the Arctic warms more of these lakes are appearing and growing in size which expands the thaw below. It has been estimated that they now cover about 20% of northern permafrost regions. This could double the release from terrestrial landscapes by the 2050s. A carbon cycle feedback that is not yet included into climate models.

This is bad news for climate change mitigation efforts. This feedback is significant because methane is about 30 times more potent than carbon dioxide as a heat-trapping gas. And the lakes are expected to thaw even under the lowest IPCC emissions scenario, adding further warming. Since we most likely are already committed, warming yet to come from current emissions, to 1,5-2°C this extra warming from the permafrost reinforcing feedback could take us above the 2C threshold for potentially catastrophic warming. Unless we rapidly decarbonize our economy and try to take out carbon from the atmosphere by for example large-scale reforestation efforts. Time is not on our side. We need a climate emergency plan.