New book says Earth is too cold for maximum development of the biosphere

A new book by Professor of Earth Sciences Toby Tyrell "finds that the Earth is actually too cold for the maximum development of the biosphere." A review of the book published today in Nature Climate Change states, "Using net primary production and biodiversity as metrics, Tyrell finds that the Earth is actually too cold for the maximum development of the biosphere" and "the climate and biogeochemical cycles of the Holocene [the past ~11,000 years] have been unusually stable."

Requiem for a grand theory

• William Schlesinger

Nature Climate Change

 

3,

 

697

 

(2013)

 

doi:10.1038/nclimate1953

Published online

 

26 July 2013

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On Gaia: A Critical Investigation of the Relationship between Life and Earth

Toby Tyrell
PRINCETON UNIV. PRESS: 2013.
311 pp.$35.00

Gaia, the brainchild of James Lovelock, was born in 1972. The historical constancy of Earth's chemical conditions and climate seemed just too much for chance alone. In Gaia it is postulated that the Earth's conditions were determined by the biosphere and regulated for the further benefit of life's persistence and activity. Gaia has motivated a huge number of biogeochemists to think about ecology on the planetary scale, and to examine what causes the movement and transformation of elements in global cycles. The theory has survived withering criticism and numerous international conventions — some to extend its reach and others to bandage a wounded Gaia with modifications and caveats. Even now, when students read Lovelock's first book on Gaia they engage with his insights enthusiastically.

In this book, Toby Tyrell — a professor of Earth science at the University of Southampton — offers a systematic, dispassionate, retrospective examination of Gaia. It will be hard to ignore the flaws in Gaia, illustrated nicely in a table showing the success and failure of Gaia relative to some alternative theories based on the geosciences and coevolution. In the face of data, Gaia fails in its idea that the Earth is held at conditions optimal for life. Using net primary production and biodiversity as metrics, Tyrell finds that the Earth is actually too cold for the maximum development of the biosphere. Gaia also fails in its postulate that the Earth is held at relatively stable conditions. True, the climate and biogeochemical cycles of the Holocene [the past ~11,000 years] have been unusually stable, but over longer periods of time the biosphere has been buffeted by events that have dealt it quite a blow. What is remarkable is that life persisted at all — a statement of the power of evolution to rebuild the biosphere everywhere as long as life has endured somewhere...