Abrupt switching
Thresholds, switches, amplifiers, chaos — contemporary geophysics assumes that earth history is inherently revolutionary. This is why many prominent researchers — especially those who study topics like ice-sheet stability and North Atlantic circulation — have always had qualms about the consensus projections of the Intergovernmental Panel on Climate Change (IPCC), the world authority on global warming.
In contrast to Bushite flat-Earthers and shills for the oil industry, their skepticism has been founded on fears that the IPCC models fail to adequately allow for catastrophic nonlinearities like the Younger Dryas. Where other researchers model the late 21st-century climate that our children will live with upon the precedents of the Altithermal (the hottest phase of the current Holocene period, 8000 years ago) or the Eemian (the previous, even warmer interglacial episode, 120,000 years ago), growing numbers of geophysicists toy with the possibilities of runaway warming returning the earth to the torrid chaos of the Paleocene-Eocene Thermal Maximum (PETM: 55 million years ago) when the extreme and rapid heating of the oceans led to massive extinctions.
Dramatic new evidence has emerged recently that we may be headed, if not back to the dread, almost inconceivable PETM, then to a much harder landing than envisioned by the IPCC.
- the full article is here and some commentary is available here
While I think that such dramatic changes are unlikely (currently assigned odo-probability < 5%), I think the possibility of such “switching” reinforces the need for a coherent global warming plan.
Unfortunately the politics of global warming is deadlocked by the Luddites who ask for certainty or just bleat their fall-back line “you can’t know the future.” That is just silly. For all of animal history we have known how to play the odds for our survival. Imagine that we are hunting deer and reach a fork in the trail. One side has deer tracks and the other side has lion tracks. We take the side with deer tracks. This is based on our short-term odds-based prediction of the future. We think we are more likely to meet a deer than a lion, though we certainly would use care, with the expectation that the lion “might” be circling around to get the deer.
This decision about action is as old as history. Global warming is the lion, and we certainly see tracks.