A lot has been said about this lately (and earlier) yet I sense that in spite of that most folks are whistling in the dark. Here is a good place to get schooled on the phenomenon even if you are an armchair expert like me: Permafrost In a Warming World.
Permafrost is permanently frozen soil, and occurs mostly in high latitudes. Permafrost comprises 24% of the land in the Northern Hemisphere, and stores massive amounts of carbon. As a result of climate change, permafrost is at risk of melting, releasing the stored carbon in the form of carbon dioxide and methane, which are powerful heat-trapping gases. In addition, permafrost is structurally important, and its melting has been known to cause erosion, disappearance of lakes, landslides, and ground subsidence. It will also cause changes in plant species composition at high latitudes.For starters that should get anyone's attention. But there is more if you read on.
The Effect of Climate Change on PermafrostThere is little wonder that human minds are having trouble grasping the significance of this. We have enough of our own human activity to drive us up the walls with Gaza, elections, etc. Each of those has the possibility of triggering other forms of nonlinear positive feedback kinds of change. Nor is any one of them isolated from the things discussed above.
The upper layer of permafrost, or the active layer, sometimes thaws in the summer. Recently, the active layer of permafrost has been observed to be getting larger with time, which means more permafrost is melting each summer. This is not unexpected—the high latitudes are expected to warm much more than low latitudes as the atmosphere continues to warm
Climate change is expected to significantly affect above and below-ground climate. Although widespread changes to permafrost usually take centuries, the IPCC estimates that by the mid-21st century, the area of permafrost in the northern hemisphere will decline by 20-35%. Additionally, the United Nations Environmental Programme suggests the depth of thawing could increase by 30-50% by the year 2080.
Recent studies have shown that there has been a decrease in freezing during the cold season in North America's permafrost regions. Coastal areas and eastern Canada have started to see significant increases in warm season thawing of permafrost. This means there has been a decrease in freeze depths and in the amount of permafrost, and an increase in the area of the active layer. The increase in the active layer doesn't mean there's more ground being frozen, it means more permafrost is melting seasonally, losing its distinction as "permanent." Permafrost is not only affected by climate change, but eventually will affect climate change itself by releasing the greenhouse gases it stores.
Recently I wrote about multidimensional "tipping points":Are you ready for this? A multi-dimensional tipping point. Tipping points are places in the trajectory of a system's evolution where nonlinear dynamics leads to a pronounced jump rather than gradual change. The concept of Positive feedback is useful to enhance our understanding of what may happen.
Positive feedback is a process in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system in which the results of a change act to reduce or counteract it has negative feedback.This is, to say it more simply, the idea that the warming releases more gases that increase warming and so on. Even that is too simple for other effects get mixed in due to the interconnectedness of the Earth system. Among them are changes in the oceans, ecosystems, and,not trivially, human behavior.
Mathematically, positive feedback is defined as a positive loop gain around a feedback loop. That is, positive feedback is in phase with the input, in the sense that it adds to make the input larger. Positive feedback tends to cause system instability. When the loop gain is positive and above 1, there will typically be exponential growth, increasing oscillations or divergences from equilibrium. System parameters will typically accelerate towards extreme values, which may damage or destroy the system, or may end with the system latched into a new stable state.
The Disaster ScenarioWe are pretty smart, we humans, to be able to see these things with even this much clarity. But as we say in the blurb to our recent book:
It's not hard to imagine a disaster scenario surrounding permafrost. As the atmosphere warms, permafrost melts, which releases greenhouse gas, which further warms the atmosphere, which speeds up the permafrost melting, and so on. Currently, climate models do not incorporate the effects of methane released from melting permafrost, which means even the most extreme warming scenarios we've come up with might not be extreme enough. A spike in atmospheric methane concentration could set off catastrophic global warming.
David Shindell and Gavin Schmidt (climate scientists of RealClimate) suggest that a real-world disaster scenario would be an instantaneous release of about 10 gigatons carbon-equivalent (gton C) of methane into the atmosphere. Right now, it contains approximately 3.5 gton C of methane.
They don't see any way to get more than 1 gton C as methane into the air emitted at one time, fortunately, but the world has seen a massive release of methane in the past: the Paleocene Eocene Thermal Maximum (PETM). Studies focusing on this time period estimate that several thousand gton C of methane were released into the atmosphere. But, although it's hard to accurately conclude how long it took for this to happen, current estimates are around a thousand years. In other words, it wasn't immediate. But the warming that is occurring due to anthropogenic climate change is unprecedented in its rate—the world is warming ten times faster today that in did in the PETM. For this reason, it's hard to rule out any disaster global warming scenario.
Hence, in the evolution of life most species become extinct. This perspective reveals the limits that complexity places on knowledge and technology, bringing to light our hubristically dysfunctional relationship with the natural world and increasingly tenuous connection to reality.To paraphrase the songster, we really do not need a weatherman to tell us that an ill wind is blowing.
7:54 PM PT: Once again many thanks for putting this on the rec list. I hope it helps.