Climate scientist reveals new plan to mop up carbon

Posted: 9 December 2004

Author: John Rowley

Seventeen years ago, Professor Wallace (Wally) Broecker, the eminent climate scientist and oceanographer, alerted the world to the danger that the ocean's great conveyer, the Gulf Stream, might close down with devastating consequences, if the climate was allowed to go on warming. This week, at a London briefing, he warned that renewable energy from wind power would not be able to prevent a critical rise in greenhouse gases within the time available. Instead, he advocates a revolutionary new technology, which could extract surplus carbon dioxide from the atmosphere.

Wallace Broecker, Newberry Professor of Earth and Environmental Sciences, Columbia University
Wallace Broecker, Newberry Professor of Earth and Environmental Sciences, Columbia University
Writing in 1987, in a seminal paper published in the scientific journal Nature, Professor Broecker, memorably warned, "The inhabitants of Planet Earth are quietly conducting a gigantic environmental experiment" by releasing huge quantities of CO2 and other greenhouse gases into the atmosphere. "We play Russian roulette with climate, hoping that the future will hold no unpleasant surprises."

He said that ice core records showed that climate fluctuations could happen quite suddenly, and explained why the North Atlantic current was a critical actor in this.

Now, with the evidence of melting sea ice and mountain glaciers, and other signs of global warming - and with new research into the Greenland ice cores, ocean currents and sediments - he has refined his views of the future impact of what he calls "the angry beast" that is the earth's climate.

Sea levels

Recalling that in 1880 carbon dioxide in the earth's atmosphere was found at 280 parts per million, he said that today's level was 380ppm and will almost certainly reach 500 ppm within 50 years, as today's developing countries, including China and India, increase their use of fossil fuels, including coal - unless some very special measures are taken. At over 500ppm, the Greenland icecap is likely to melt away, over a period of some 300 years - leading to a catastrophic rise in sea levels of some five metres, and huge ecological damage.

"No one" he said, "has the foggiest idea of what to do to avert this. Conservation and renewable energy is not going to stop the increase in CO2." By 2072, additions to CO2 in the earth's atmosphere have to be down to zero, he said, but the present Kyoto Treaty arrangements would only bring those additions down by around 5 per cent.

Solar energy and nuclear fuels are the only existing alternatives, which could do the trick, he said, "but solar is too expensive and nuclear too dangerous". It would lead to a plutonium economy, with huge quantities of this potentially lethal material whose use could not easily be controlled.

"And if you were to substitute wind power for fossil fuels, each American citizen would require wind turbines which bisect 80 square metres of wind at the usual rates. But if we could capture CO2 from the atmosphere it would require only a 4/10ths of a square metre."

Permanent storage

The idea was not impossible, he said. Klaus Lackner, a brilliant scientist at Columbia University in New York, who was trained in particle physics at Heidelberg, had worked out a way of extracting CO2 from the atmosphere using sodium hydroxide as an absorber. Work on an extractor capable of doing this was started earlier this year, he revealed, with funding from Gary Comer, the successful founder of the Land's End clothing business and the technical expertise of Alan Wright, who helped to create the Biosphere 2 project.

The aim is to produce sodium carbonate, which can then be liquefied for permanent storage. This could be used to flush out oil reservoirs or buried in salty aquifers, said Professor Broecker. Alternatively it could be lodged in the bottom of the ocean (if environmental objections could be overcome) or mineralised with magnesium silicate to make magnesium carbonate, for permanent storage. If the project was taken up by governments it would be very major undertaking, he said, equivalent in size to 10 per cent of the world's energy industry or one per cent of the global economy. But the cost need not be insuperable, he argues. It might be funded, for example, by putting 15-30 US cents on the price of a gallon of petrol. This would be a small price, he said, in view of the magnitude of the problem facing humanity.

One of his greatest fears, said the professor, was not the inverted hurricanes or giant hailstorms seen in the 'very bad' film The Day After Tomorrow which was inspired by his work, but the redistribution of rainfall that was likely to occur as the climate warms.

Drier tropics

Recent research has shown how, in the past, long droughts can occur as the earth warms. The Sahara dried up 400 years ago, though we have no real idea why. Already, data indicates that the tropics will get drier, as the planet heats up, as will the American West. And along with increasing aridity more frequent El Nino pulses seem likely. The impact of such changes on water supplies in a world with growing populations must be a major concern, he said.

As for the great ocean conveyer (which carries 20 times more water than all the earth's rivers combined) Professor Broecker said most models show that if this does shut down, it will do so only slowly. And if CO2 concentrations can be kept between 400-500ppm, the danger of this happening should be small.

Equally, a global temperature rise of between 4 and 6 degrees might close off the current, but this was not likely to result in a repeat of ice age glaciations or the spread of ice across northern waters.

John Rowley is Editor-in-Chief of Planet 21.

Professor Wally Broecker is based at the Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964, USA.

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