Anders Levermann writes:

I have studied climate tipping points for more than 20 years, and I’m increasingly concerned that scientists have overlooked the most dangerous aspect of these for societies. The potential collapse of major parts of the Earth system — from ice sheets to ocean circulations — will profoundly alter the warming planet and tip it irreversibly into a different state. But the greatest risks might not lie at that endpoint.

How we get there — how the tipping unfolds — is more important, and there is an urgent need to understand the process. This is missing from current analyses because the scales in time and space it occurs on fall between those of climate and weather. Tipping analyses focus on huge climate changes, often globally, over decades. Weather events are fast and local. But look at the interplay between the two and it’s clear that the transition between one climate state and another is not smooth but extremely volatile.

Climate tipping, therefore, will manifest as a period of increasingly dramatic weather volatility, rather than a sharp shift in average conditions. A fluctuating climate will bring swings and crashes in crop yields, flash flooding and erratic storms. It will stress economies by disrupting supply chains and amplifying insurance losses. Societies are unprepared, because weather volatility related to tipping points is absent from risk assessments.

This problem is urgent. Earth subsystems, including oceans, the cryosphere and biosphere, already seem to be destabilizing. The planet is heading for climate free fall. [Continue reading…]