The end of Gaia: requiem for Lovelock's hypothesis

One of the most frequent claims made by deniers and critics of the environmental movement is that acceptance of anthropogenic climate change is not based on science but “faith”

Typically they will accuse scientists, activists and writers such as myself as being in the thrall of a semi-mystical belief in a transcendent “Gaia”. 

For those not familiar with the concept, the Gaia hypothesis was put forward by James Lovelock and biologist Lynn Margulis in the 1970s. They proposed the Earth is composed of a myriad of self-regulating systems that seeks to maintain conditions optimal for life.

Lovelock’s hypothesis has always been controversial, and despite what the deniers would have you believe “faith in Gaia” has never been the driving intellectual force behind the work of climate scientists.

I will note it has gained has some currency in popular culture resulting in some very silly writings and abuse of scientific concepts. 

Climate sceptics have conflated (and confused) some of these pop-culture interpretations of the Gaia hypothesis with climate science. The somewhat bonkers website The Green Agenda gives you a good feel for the kind of criticisms sceptics like to level against climate science:

Gaia worship is at the very heart of the Global Green Agenda. Sustainable Development, Agenda 21, the Earth Charter, and the Global Warming theory are all part of the Gaians mission to save “Mother Earth” from her human infestation. Gaians have succeeded in uniting the environmental movement, the new age movement, Eastern religions, the United Nations and even the leaders of many Christian denominations behind this vile new form of paganism.

Obviously this conspiracy infused criticism has little basis in reality.

But what of the Gaia hypothesis itself?

There has been a long running debate within science about its validity, however a recent book reviewed in Nature Climate Change may offer the final word on the issue.

On Gaia: A Critical Investigation of the Relationship between Life and Earth by Toby Tyrrell (Princeton University Press, 2013) will be of interest to anyone who shares a fascination with the philosophy and history of science.

The counter-arguments put forward by Tyrrell are compelling, in particular the idea the Earth is held at stable conditions to support life:

Tyrrell 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 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.

As the review notes, the fact that life exists on Earth is most likely due to pure chance: 

Tyrrell uses the ‘anthropic principle’ to dismiss any theory that suggests causes for the long-term favourability of planet Earth for the persistence of life. Such a theory cannot be falsified, because we have no replicate planets to examine where life has failed. Chance alone — however small — is a better mechanism to explain why we are all here today to have sex, eat at MacDonald’s and discuss the value of such theories.

I do think it is worth noting that Lovelock’s theory has had some utility, in particular prompting scientists to consider both the climate and Earth as an integrated system.

Thus we may regard Lovelock as a contemporary Jean Baptiste Lamarck.

Lamarck was an eighteenth century French naturalist who put forward an evolutionary hypothesis well before Darwin. Known as the theory of inheritance of acquired characteristics, Lamarck argued the more a certain “body part” was used the stronger it got. These characteristics were then passed on to an organisms progeny.

Thus, every time a giraffe stretched its neck to reach the upper most leaves of a tree its neck got “stronger” and more elongated. This trait was then passed down to later generations of giraffes.

While incorrect, Lamarck’s legacy is considerable in putting forward the first fully realized theory of evolution. Lamarck helped point the way with his mistakes. The same could be said for Lovelock.

While the Gaia hypothesis may not have stood up, at the very least Lovelock suggested we think about the planet as an integrated system.

Science can progress by error as much as it does through the collection of evidence and the formulation of new hypotheses.

About these ads