Another Perspective

May 12, 2021

This book was written by Kerry Emanuel, a climatologist at MIT. At less than a 100 pages, it is a primer on climate change and man’s contribution to it. It added an important perspective to my understanding of the issue.

As opposed to Koonin’s book which can be characterized as a book report on alleged errors he found in several reports (such as the 2014 IPCC report), Emanuel focuses on the physics of climate change. He explains why the models will always have uncertainty in their outputs (modeling of a chaotic system). Perhaps the most helpful part of the book (at least to me) is where he identifies those topics where there is general consensus on climate change. Note, “not settled” which is a phrase that no scientist would ever use!

Here’s an excerpt:

Global climate change presents us with unprecedented challenges. Since science can do no more than estimate a broad envelope of possible outcomes, from the benign to the catastrophic, society must treat the problem as one of risk assessment and management. At one extreme, we could elect to do nothing and gamble on a benign outcome. But if we are wrong we will saddle our grandchildren and their descendents with enormous problems. At the other, we could make serious economic and other tangible sacrifices that might prove unnecessary. Unfortunately, waiting much longer to see which way things go is not a viable option since it takes thousands of years for CO2 levels to return to normal once emissions cease. By the time the consequences of climate change become unequivocally clear, it will almost certainly be too late to do much about the larger problem. Scientists, engineers, and economists can do no more than formulate options for dealing with the risks. It is up to society as a whole to decide what combination of options to deploy. This is a terrifically difficult decision because the costs may be high and those paying them are not likely to be serious beneficiaries of their own actions. Indeed, there are few, if any, historical examples of civilizations consciously making sacrifices on behalf of descendents two or more generations removed

One thing I learned from both books that I did not appreciate is that climate change is a function of cumulative CO2 in the atmosphere. I also did not know the following:

The lifetime in the air of CO2, the most significant man-made greenhouse gas, is probably the most difficult to determine, because there are several processes that remove carbon dioxide from the atmosphere. Between 65% and 80% of CO2 released into the air dissolves into the ocean over a period of 20–200 years. The rest is removed by slower processes that take up to several hundreds of thousands of years, including chemical weathering and rock formation. This means that once in the atmosphere, carbon dioxide can continue to affect climate for thousands of years.