He should have started with chapter 2. In chapter 1, Pearson invokes the IPCC model scenarios and the contention that human carbon dioxide emissions will produce a temperature rise of somewhere between 2-to 11 degrees F, and that will “likely” cause extinction of 20% to 70% of species. There is, however, no physical evidence which shows that human carbon dioxide emissions have a significant effect on global temperatures. That being said, let’s imagine that the world will continue to warm, regardless of cause, and examine what the consequences might be.
In chapters 2 through 5, Pearson takes the reader on expeditions to Madagascar, Costa Rica, the British Isles, North America, and South Africa where he examines how specific species are reacting to global warming. This is mainly a study of range changes pole-ward and to higher elevations for plants and animals. Some species expand their ranges, some ranges contract, while others are not affected. There are winners and losers. Pearson notes that some amphibians are more susceptible to disease as temperatures “converge on a range that is just right to promote disease outbreaks.” He also examines how plants and animals may react to changes in the onset of the seasons (phenology). Pearson notes that there may be some observation bias in these studies and does point out potential problems.
I did detect one error in this section. On page 88, Pearson says “the world’s oceans are gradually turning acidic.” Not true, the oceans are alkaline, and there is a natural cycle of pH variation within the alkaline range (see my rebuttal here).
Chapters 6 through 8 discuss extinction risk modeling and experiments. Pearson fairly points out areas of uncertainty. He also discusses the ability of plants and animals to adapt to changing conditions. Here, too, there are winners and losers. He discusses complicating factors such as habitat loss due to human encroachment. Pearson says, “we cannot really expect to accurately predict how an ecological community will respond to climate change.” And, “climate change has the potential to rearrange species, assembling new communities as plants and animals shift their ranges and adjust their phenology. The consequences of this reshuffling will be alterations to existing interactions between species as well as the creation of novel sets of interactions.”
Chapter 9, entitled, “Cry Wolf?” discusses exaggeration of scientific studies by the press, and whether scientists should or should not be political advocates. Pearson does not mention possible scientific bias in the competition for research grants.
In the final chapter, Pearson, himself, becomes an advocate for more conservation parks, connectivity between reserves, and for reducing our use of fossil fuels.
Pearson’s thesis is that the current warm period is unprecedented due to human emissions of carbon dioxide, and this may cause many adverse effects on plants and animals. He seems unaware that during the last 10,000 years the world experienced several warm-cold cycles. At least three of the warm cycles were warmer than now and warmer than the high range of IPCC predictions. How did species cope with these changes? Except for extinction of megafauna near the end of the last glacial epoch, an extinction that was abetted by an abrupt cooling period (the Younger Dryas), where are the bodies of victims of global warming from these previous cycles? Many studies of the fossil record during times when the temperature quickly rose at least 4 degrees C, found changes as Pearson describes in chapters 6 through 8. But those same studies found very little evidence of broad scale extinctions.
In spite of my criticisms of this book, I found it well-written and a very interesting read.
About the author: Richard Pearson is Director of Biodiversity Informatics Research at the American Museum of Natural History. He has a PhD. (2004) from Oxford University in biogeography, and is a research scientist in the museum’s department of herpetology.