One of the major “tipping points” that climate scientists worry about is the melting of the permafrost in the world’s tundra zone. The fear is that a massive release of methane gas will occur, and that, since methane is 20 times more heat-trapping than CO2, an irreversible and catastrophic increase in the rate of global warming will result.
A recent paper in the Journal Science by Anton Baks et. al. has studied the effects of past climate warming on the planet’s permafrost and concluded that a 1.5˚C global rise in temperatures over the long term baseline will create a significant weakening of the permafrost. We’re already halfway there (0.8˚C) and will hit that target by mid-century.
When the permafrost melts, the buried plant matter is exposed to sunlight (UV rays in particular), and the process of bacteria converting that stored carbon to CO2 and methane accelerates, releasing perhaps 40 percent of these greenhouse gases into the atmosphere. That can’t be good, no matter what.
Just how bad it is, however, is still scientifically uncertain, as is the rate of warming up there.
On “just how bad it is,” there are mitigating factors. One, the bacteria convert a lot of the biomass to CO2 which is much less threatening than methane. No one knows what that ration will be, but the scary articles usually assume its all methane. Not so. Two, the process takes time – decades will pass between the arrival of the warming and the actual increase in atmospheric heat trapped as a result. By that time, the total greenhouse gas releases from all the usual suspects may drown out the permafrost contribution.
On the rate of change front, however, there is plenty of reason to worry. Studies by NASA in 2012 indicate that the permafrost is melting much faster than the global average – in fact, they’ve already risen by 2.2-3.9 degrees C (or 4-7 degrees F) over the last century. Another study shows that the actual recorded rises in methane and CO2 over the world’s permafrost is much, much greater than predictions by the IPCC and others. One thing we’ve certainly learned from three decades or so of climate predictions is: the consensus is always low, and often very low, compared to what actually shows up.
We need more study on the permafrost front, certainly. My takeaway is this: it’s one more time bomb ready to go off, and when you add up all the similarly under-studied and under-reported time bombs (melting of the glaciers comes to mind), we need to be very, very worried. Even if the odds are low, it’s the only planet we have and we can’t afford to guess wrong.
Photo caption: Permafrost cracking pattern in the high Arctic.
Photo credit: Brocken Inaglory via Wikimedia Commons