Geoengineering our way out of trouble?
As
the effects of global warming begin to frighten us, geoengineering will
come to dominate global politics, says Clive Hamilton.
Geoengineering solutions to global warming are being seriously looked at by some scientists (Source: iStockphotos) http://www.abc.net.au/science/articles/2013/04/09/3730522.htm
Geoengineering — deliberate, large-scale intervention in the climate system designed to counter global warming or offset some of its effects — is commonly divided into two broad classes.
Carbon dioxide removal technologies aim to extract excess carbon dioxide from the atmosphere and store it somewhere less dangerous. This approach is a kind of clean-up operation after we have dumped our waste into the sky.
Solar radiation management technologies seek to reduce the amount of sunlight reaching the planet, thereby reducing the amount of energy trapped in the atmosphere of 'greenhouse Earth'. This is not a clean-up but an attempt to mask one of the effects of dumping waste into the sky, a warming globe.
Diligent contributors to Wikipedia have listed some 45 proposed geoengineering schemes or variations on schemes. Eight or ten of them are receiving serious attention. Some are grand in conception, some are prosaic; some are purely speculative, some are all too feasible; yet all of them tell us something interesting about how the Earth system works.
Taken together they reveal a community of scientists who think about the planet on which we live in a way that is alien to the popular understanding. Let me give a few examples.
Climate Fix
It is well known that as the sea-ice in the Arctic melts the Earth loses some of its albedo or reflectivity — white ice is replaced by dark seawater which absorbs more heat. If a large area of the Earth's surface could be whitened then more of the Sun's warmth would be reflected back into space rather than absorbed.A number of schemes have been proposed, including painting roofs white, which is unlikely to make any significant difference globally. What might be helpful would be to cut down all of the forests in Siberia and Canada.
While it is generally believed that more forests are a good thing because trees absorb carbon, boreal (northern) forests have a downside. Compared to the snow-covered forest floor beneath, the trees are dark and absorb more solar radiation. If they were felled the exposed ground would reflect a significantly greater proportion of incoming solar radiation and the Earth would therefore be cooler.
If such a suggestion appears outrageous it is in part because matters are never so simple in the Earth system. Warming would cause the snow on the denuded lands to melt, and the situation would be worse than before the forests were cleared.
More promisingly perhaps, at least at a local scale, is the attempt to rescue Peruvian glaciers, whose disappearance is depriving the adjacent grasslands and their livestock of their water supply. Painting the newly dark mountains with a white slurry of water, sand and lime keeps them cooler and allows ice to form; at least that is the hope. The World Bank is funding research.
Another idea is to create a particle cloud between the Earth and the Sun from dust mined on the moon and scattered in the optimal place. This is reminiscent of the US military's 'black cloud experiment' of 1973, which simulated the effect on the Earth's climate of reducing incoming solar radiation by a few per cent.
Consistent with the long history of military interest in climate control, the study was commissioned by the Defense Advanced Research Projects Agency, the Pentagon's technology research arm, and carried out by the RAND Corporation, the secretive think tank described as 'a key institutional building block of the Cold War American empire'. I summon up the black cloud experiment here to flag the nascent military and strategic interest being stirred by geoengineering.
Another novel scheme to counter global warming was published in the esteemed journal Climatic Change in 1993. The Indian physicist P. C. Jain proposed that the effects of global warming could be countered by increasing the radius of the Earth's orbit around the Sun. An orbital expansion of 1-2 per cent would do it, although one of the side effects would be to add 5.5 days to each year.
Professor Jain then calculated how much energy would be needed to bring about such a shift in the Earth's celestial orbit. The answer is around 1031 joules — more than the amount of energy humans would consume over 100 billion billion years (the age of the universe is around 14 billion years).
This seems like a lot. Perhaps, Professor Jain speculates, nuclear fusion will enable us to harness enough energy to expand the Earth's orbit. He nevertheless counsels caution: "The whole galactic system is naturally and delicately balanced, and any tinkering with it can bring havoc by bringing alterations in orbits of other planets also".
The caution is well taken, although the intricate network of orbital dependence has stimulated another geoengineering suggestion. The thought is to send nuclear-armed rockets to the asteroid belt beyond the planets of our solar system so as to 'nudge' one or more into orbits that would pass closer to the Earth.
Properly calibrated, the sling-shot effect from the asteroid's gravity would shift the Earth orbit out a bit. Of course, if the calibration were a little out, the planet could be sent careening off into a cold, dark universe, or suffer a drastic planet-scale freezing from the dust thrown up by an asteroid strike.
Some of the schemes suggested may seem properly to belong in an H. G. Wells novel or a geeks' discussion group, and too much emphasis on them for the delights of ridicule would give a very unbalanced impression of the research programme into climate engineering now underway.
There is however, serious work being conducted on schemes to regulate the Earth system by changing the chemical composition of the world's oceans, modifying the layer of clouds that covers a large portion of the oceans and installing a 'solar shield', a layer of sulphate particles in the upper atmosphere to reduce the amount of sunlight reaching the planet.
There are some who believe that we will have no choice but to resort to these radical interventions.
How did we get to this point?
The simple answer is that the scientists who understand climate change most deeply have become afraid.
About the authorClive
Hamilton is an Australian author and public intellectual. In June 2008
he was appointed Professor of Public Ethics at Charles Sturt University.
This is an extract from his recent book 'Earthmasters' published by
Allen & Unwin.
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