Thursday, May 12, 2016

The Discovery of Global Warming by Spencer R. Weart

Spencer Weart takes us on a journey into the past. In The Discovery of Global Warming, Weart provides a history of the science that has now come to be known as Anthropomorphic Global Warming (AGW), or more simply, man-made climate change. In doing so he demonstrates just how robust and voluminous is the scientific case for human induced climate change.

He begins by recounting the early discoveries by such well-known names as Joseph Fourier, Guy Stewart Callendar, John Tyndall, and Svante Arrhenius. Lesser known scientists who also provided significant contributions to the developing science include James Croll, Vladimir Verdansky, Charles Greeley Abbot, Milutin Milankovitch, Gilbert Plass, Hans Suess, David Keeling, and many others.  As he takes us through the years in come names such as Roger Revelle, Wally Broecker, J. Murray Mitchell, Ed Lorenz, and on to names more familiar to us in the modern day like Stephen Schneider, James Hansen, Gavin Schmidt and Michael Mann. In all, Weart reviewed a thousand studies and says that each study has 10 more like it and 10 more beyond that.  

Weart’s narrative gives us a sense of the trials and tribulations of early scientists trying to make sense of myriad observations as they tested hypothesis after hypothesis. Was the Earth warming or cooling? What were the influences of sunspots, volcanoes, aerosols, and particulates? How does one deal with uncertainties and feedback mechanisms? As he describes the process we see how the science developed piece by piece in fits and starts as scientists first worked on the periphery of fields tangential to their own, then eventually grew to understand how the study of climate was inter- and multidisciplinary. All of these questions were addressed as technology advanced from simple hand calculations through early computers to the supercomputers used today. From simple measurements using thermometers to satellites that scan the globe day and night.

As the case for man-made climate change grew there became a need for a way to synthesis the thousands of studies into a cohesive summary of the state-of-the-science. Thus, the IPCC was born. As more data came in and was compiled the conclusions grew more concrete, from “discernible effects” to “unequivocal warming” and “very likely” (90-99% certainty) that warming was being caused by humans. Data since the last report have made the case for a human cause not even more certain, but the rate and magnitude of change is even greater than previously thought.

Anyone interested in global warming/climate change would do well to read this book.  It provides a valuable history of the development of the science, and demonstrates without a doubt the robustness of the scientific consensus that the planet is warming and that human activity is the main contributor.  As Weart himself says:

“the few who contest these facts are either ignorant or so committed to their viewpoint that they will seize on any excuse to deny the risk.” 

The science is unequivocal; whether we act is our choice.  A choice that has major ramifications for our future and the futures of our children and grandchildren.

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