Sunday, April 30, 2017

Bret Stephens' Global Warming Disinformation

The New York Times has inexplicably hired Bret Stephens, known for calling climate change an "imaginary enemy," as a new columnist. His first column packed two pieces of disinformation in this one sentence:
"Anyone who has read the 2014 report of the Intergovernmental Panel on Climate Change knows that, while the modest (0.85 degrees Celsius, or about 1.5 degrees Fahrenheit) warming of the Northern Hemisphere since 1880 is indisputable, as is the human influence on that warming, much else that passes as accepted fact is really a matter of probabilities."
First, it is not true that .85 degrees Centigrade is a modest amount of warming. This change  has been enough to cause more frequent extreme weather events, with what used to be hundred year storms occurring as frequently as every ten years, enough to cause melting of ice that makes the arctic ocean navigable during summer, enough to cause species to move north and to higher elevations in order to escape the heat, and enough to cause many other well known effects.

Second, it is not true that the uncertainty of predictions is an excuse for inaction on climate.  Stephens' main point in this column is that people who claim certainty (including climate advocates) are fanatics, but in reality, one of the most powerful arguments for climate action is based on the uncertainty of predictions.

Harvard economist Martin Weitzman points out that predictions of future warming have a fat-tailed distribution curve, as shown in this graph:

The graph shows that it is most likely that doubling CO2 levels from 350 parts per million to 700 parts per million would increase temperatures by less than 3 degrees centigrade, but that there is 10% chance that it will increase temperatures by 6 degrees centigrade or more, and a tiny chance that it will increase temperatures by 10 degrees centigrade.

The potential damage done in the higher ranges is so disastrous, including ocean rise, desertification and famine that would kill or displace billions of people, that Weitzman says it makes sense economically to reduce CO2 emissions as insurance against this worst case.

People spend money on fire insurance even though there is less than a 10% chance of their homes being destroyed by fire, because a fire would wipe them out economically if they did not have insurance. Likewise, Weitzman says, we should spend money reducing emissions as insurance against the worst case, even if there is less than a 10% chance of global warming wiping out billions of people.

Even more than these two false claims, the oddest thing about Stephens' column is that he spends almost half the column arguing that Hillary Clinton's campaign was based on data, and she could have won if she allowed for the possibility that the data underestimated Trump's strength - and he thinks this means that we should doubt and even dismiss the data about global warming.

The lesson is actually just the opposite. Clinton would not have lost if she had admitted that she might have been doing worse than data-predictions. Likewise, humanity will not lose if we admit that global warming might be worse than the most likely data-based prediction.

The point of Stephens' first column is about as rational as saying that uncertainty is a reason for not buying an insurance policy. Nothing can be further from the truth.

See Stephens' column here.