Thursday, December 07, 2006

A modest proposal

A few months ago, Nobel Prize winner Paul Crutzen published an essay in the journal Climatic Change proposing that the world could eject sulphate aerosols into the stratosphere, sort of a gaseous solar shield, could combat global warming.

Sulphate particles, emitted by burning of coal and many other activities, reflect incoming solar radiation. They are though to have offset some of the expected warming over the past century.
The eruption of Mt. Pinatubo in 1992 emitted 10 Tg of sulphate (10 million metric tons) into the stratosphere, and helped cool the planet by 0.5 degrees C the following year. Crutzen's proposal would effectively be creating a small Pinatubo every year.

So, a scientific meeting was held, a talk was given at the UN meeting in Nairobi and now the 'geoengineering' proposal has developed some life in the scientific community and in the media.

I think we should come down out of the stratosphere. This should be seen as a modest proposal, in the tradition of Jonathan Swift, that's all. It demonstrates the type of drastic action that could be necessary if serious action is not taken to slow greenhouse gas emissions. It is a reasonable alternative only in the worst case scenario.

Let’s not forget all those anthropology, paleoclimate or paleoecology classes. Large injections of aerosols or particles into the atmosphere in the past (from volcanic eruptions) had devastating impacts on life, from massive famines to species extinctions. The year after the eruption of Krakatoa – and after Mt Pinatubo – was popularly referred to as the year without a summer.

We'd have to be supremely confident in model results to embark on this scale of planetary experiment. We're not just talking about turning the thermostat down a notch. We're talking about altering stratospheric chemistry, solar radiation, ozone concentrations, and cloudiness, which would together radically alter ecosystem function across the planet.

This is the solution to climate change? Maybe there is a danger in is using the same type of thinking that got you into a problem to get you out the problem.

Most of all, I'm concerned about the effect that discussing these geoengineering proposals on policy. It sends the erroneous message that there is one magical solution to climate change, that if we wait long enough, the scientists will invent some pill the planet should put under its tongue.


Anonymous said...

I am not sure that we believe in a magical solution, so I don't think the issue will send erroneous messages. But it is very important to look for the cause and to prevent future damaging human actions.

It is not the land which determines the fate of the climate. It is the ocean that does it. Multiple naval war from the last century modified the climate so much. Proofs of that: htpp://

Simon Donner said...

The oceans are important, no doubt, that's why climate scientists generally pursue atmospheric and oceanic science degrees. But the author's thesis - that naval wars directly cause climate change - is an example of the difference between correlation and causation. Just because the witner of 1939/1940 in Europe was cold does not mean the growing naval war at the time was the cause.

Anonymous said...

And why would you say it couldn't have been the cause? From what I have read, it sound clear to me, but I am ready to accept I am wrong if I see a better explination.