SOURCE: Yale Climate Connections

DATE: February 2, 2018

SNIP: About a fifth of the Northern Hemisphere landmass is permafrost, ground that has been mostly frozen for half a million years or more. Now there are signs of thaw appearing in many places across this vast landscape circling the Arctic, and at accelerated rates.

It is only a matter of time until the incremental thawing of the permafrost reaches a tipping point of no return, a state of accelerated and irreversible change, the side effects of which might well push other parts of the Arctic beyond their own tipping points.

The major side effect of a thawing permafrost is that it will further enhance global warming with the release of large quantities of methane, a potent greenhouse gas.

During the last two million years, the climate has periodically shifted between cold (glacial) and warm (interglacial) states. We are currently in an interglacial that began about 11,000 years ago. Not coincidentally, the beginning of this warm stable period marked the dawn of agrarian societies and complex human civilizations.

The last time there was a large-scale thaw of the permafrost was four interglacials ago. At the time of the thaw, about 450,000 years ago, the climate was about 1.5°C warmer than pre-industrial temperatures. Today, the temperature is nearly as warm – 1°C hotter than in pre-industrial times. Even more worrisome is the rate of the current warming, unprecedented in over 50 million years of geological history.

Is it too late to prevent a regime shift in the Arctic? Possibly. That by no means implies that we might as well sit back and continue with the “business-as-usual” agenda. By acting now, and on a frantic global scale, we just might be able to delay the tipping and the climatic domino effect from taking hold.