So 2015 will almost certainly set a new global temperature record. In so doing, it will also discredit the last lingering skeptic arguments that the 2010s “pause” in global warming somehow negates thermodynamics and a century of observations.
Which does bring a new sense of relevance and perhaps urgency to Emil Kirkegaard’s recent post on tail effects in climate science.
Most of us here have heard of IQ bell curves. We also know that the effects are most pronounced at the edges of the graphs. For instance, assuming a 15 point S.D, a 100 IQ population will have 50% of its members above the 100 threshold, relative to 16% of an 85 IQ population. A large difference, but ultimately not that cardinal. But move the threshold to 160 – the approximate level of elite scientists – and the difference becomes onehundredfold. Certain intellectual achievements possible in a 100 average IQ society become impossible in an 85 average IQ society.
Being all about bell curves and thresholds it is not surprising that you would see similar dynamics in climate science.
Small changes in general conditions = potentially big changes in the frequency of extreme events (major new scientific discoveries, intense hurricanes and droughts).
Small changes in general conditions = rising probability of entirely unprecedented events (the Scientific Revolution, clathrate gun scenario – both of which, incidentally, were and would be greatly self-sustaining).
Many ecological systems are also highly susceptible to threshold effects. Liebig’s law states that crop growth is limited by the scarcest resource available, not the total sum of resources. Change net climatic conditions, and the most extreme events can create stresses that impinge on some minimum or other (e.g. max temperature, water availability), leading to sweeping dieoffs of organisms that had become adapted to previously stable steady states and are unable to change in time.
Humans are a sapient, highly K-selected species. They can adapt. A lot. This is a good argument against climate change denialism’s opposite, climate alarmism.
Still, there are limits to this too.
One example: There are models that indicate “zones of uninhabilibility” – levels of thermal stress that mammals just can’t withstand in principle – will start to appear past a 7C rise, and encompass half of the world given another 5C rise, and most of the world with another 5C.
Of course the probability of this is really low, according to conventional climate models, and virtually non-existent within the 21st century.
But then again the probability distributions of future temperature increase are themselves subject to the same rules of bell curves and thresholds. And most feasible climate shocks/changes in assumptions would shift those bell curves right, not left, making the formerly impossible, possible, or even likely.
Both effective altruists and more dispassionate strategic planner types would do well to bear this in mind.