Sep 4th 2008
From The Economist print edition
Some scientists think climate change needs a more radical approach. As well as trying to curb greenhouse-gas emissions, they have plans to re-engineer the Earth

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Perhaps the most intriguing idea—which was published last year, though not discussed by the Royal Society—is to eject carbon dioxide from the atmosphere at the Earth’s poles, using the planet’s magnetic field. This may sound absurd, but oxygen already leaks out this way (the phenomenon is the subject of a paper just published by Hans Nilsson of Swedish Institute of Space Physics). Alfred Wong, a researcher at the University of California, Los Angeles, proposes that a system involving powerful lasers and finely tuned radio waves could encourage carbon dioxide to take the same route. His calculations suggested that using lasers to ionise molecules of carbon dioxide, and radio waves to get them to spin at the correct rate, would cause those molecules to spiral away from Earth along the lines of magnetic force until they were lost for ever in space.

Sep 4th 2008
From The Economist print edition

Elsewhere, however, the taboos still rule. Nowhere more so than in geo-engineering, the idea of combating global warming by altering the climate by, say, absorbing carbon dioxide in the oceans, or reflecting sunlight back into space (see article). This involves fantastic sounding schemes, such as fertilising the oceans with iron (to cause a bloom of planktonic algae, thus sucking carbon dioxide out of the atmosphere) or ejecting carbon from the poles using lasers. Scientists and policymakers have been reluctant even to discuss the subject—much less research it, because they worry that it could cause more problems than it solves and that it will give politicians an excuse to avoid curbing carbon emissions.

Both fears are reasonable. The farmer who introduced rabbits into Australia said the bunnies would do “little harm and might provide a touch of home, in addition to a spot of hunting.” The rabbit went on to become a devastating pest. And the world’s politicians, they may well negotiate with less commitment if they feel that they may one day be let off the hook.

But neither reason should stop research as insurance. Some forms of geo-engineering may in fact turn out to be easier and cheaper than widespread global curbs on climate emissions—though they may still be unacceptably risky. Only research can tell. As for the politics, geo-engineering cannot just be put back in its box. And because research creates new information, it is as likely to disabuse those who think they can avoid climate-change agreements as it is to offer them false hope. Just ask the people who have given their lives to the fuel cell.

The solution to climate change will probably involve an array of technologies, from renewables, nuclear, carbon sequestration, public transport to energy conservation. It is too early to say whether geo-engineering or anything else will be part of this mix. Geo-engineering may turn out to be too risky, however much is spent on researching it. Then again, there may come a time when it is needed. The world needs to be ready—and research is the only way to prepare.

Carbon dioxide emissions are rising so fast that some scientists are seriously considering putting Earth on life support as a last resort. But is this cure worse than the disease?

By Alan robock

The large burden of sulfate aerosols injected into the stratosphere by the eruption of Mount Pinatubo in 1991 cooled Earth and enhanced the destruction of polar ozone in the subsequent few years. The continuous injection of sulfur into the stratosphere has been suggested as a “geoengineering” scheme to counteract global warming. We use an empirical relationship between ozone depletion and chlorine activation to estimate how this approach might influence polar ozone. An injection of sulfur large enough to compensate for surface warming caused by the doubling of atmospheric CO2 would strongly increase the extent of Arctic ozone depletion during the present century for cold winters and would cause a considerable delay, between 30 and 70 years, in the expected recovery of the Antarctic ozone hole.

Research is responsibility

Olive Heffernan

Arguably, what should be of greater concern is the prospect that not a single one of the myriad schemes would actually work in reality. To rely on geoengineering as a solution to climate change would be massively irresponsible, akin to using gambling as a way to get out of debt, and with much higher stakes. But it would be equally irresponsible to avoid garnering all the knowledge we can about whether it is a feasible option.

So it would make sense to conduct small, reversible experiments to determine what substances might be put at what altitude to reflect incoming energy, and to include the results in global climate models to ascertain where they would be most effective and benign. Needless to say, this is not a task

THOMAS HOMER-DIXON
From Saturday’s Globe and Mail
December 1, 2007 at 12:00 AM EST

“In light of these two trends, climate scientists are now beginning to discuss a topic that only two years ago many fervently hoped they’d never have to discuss: geoengineering, or the intentional human modification of the planet’s climate to arrest or slow global warming. Geoengineering would involve, for example, putting sulphate aerosols into the atmosphere or putting mirrors into space to try to block a fraction of incoming solar radiation.

An idea no longer at the margins

Today the topic is at the margins of the public-policy dialogue about climate change, but I expect it will be at the centre of public discussion within five years. In 10 years, we will see demands from some segments of the public and many opinion leaders that we carry out geoengineering. And we’ll probably start doing it within 20 years, likely when it becomes apparent that the Greenland ice sheet is starting to collapse.

We will do it, because by then we’ll be experiencing major socio-economic impacts of climate change — for instance, shortfalls in global food supply, as droughts and heat waves affect grain-growing regions. At that point, we will wonder about what kind of world we’ve created for our children and grandchildren. We’ll recognize that we’re facing an emergency unlike anything humankind has ever faced before, and we will demand that our leaders and experts do something, anything, to stop the slide.”

Recently, 50 respected climate, energy, and economics researchers met at Cambridge University to discuss that very question. The process is called “geoengineering” and it basically involves tinkering with the planet’s climate to find alternate ways to prevent the very worst effects of runaway global warming.

In theory, geoengineering is certainly possible. After all, that’s what we’ve unintentionally been doing for decades with gases like carbon dioxide, that cause global warming. And “aerosols” or soot put in the atmosphere from airplanes, ships, factories and other sources has also been shown to affect the climate. Sometimes, these tiny particles in the air absorb heat and hold it closer to the earth, adding to the overall warming trend. Other times, the particles can cause localized cooling by reflecting sunlight back into space. Indian researchers, for example, now say that air pollution in India has reduced the amount of sunlight the country receives by five per cent over the past 20 years.

But geoengineering in this context specifically refers to intentionally tinkering with the atmosphere - in this case to help mask the effects of our other unintentional tinkering. Would it work? Should we even talk about it?

According to those researchers at the Cambridge meeting, the answer to the second question is a qualified “yes.” In an article in the journal Science, they point out that while they worry that the public and politicians might gravitate towards these technical solutions, they feel that global warming is too dangerous to avoid discussing all available options. Even if they are a last resort.

Huge knowledge gaps exist in geoengineering solutions. One idea involves seeding the oceans with iron or phosphate to help stimulate the growth of plankton, which would theoretically help remove carbon from the atmosphere. However, no one knows what else it would do or if it would work. In fact, parties to the London Convention, an international treaty governing ocean pollution, recently agreed that such large-scale ocean seeding is not justified given gaps in scientific knowledge.

Another idea involves spraying sulfur dioxide into the stratosphere, mimicking the effect of large-scale volcanic eruptions. Similar to what is happening in India, the theory is that this layer of pollution high in the atmosphere would reflect some sunlight away from the earth and act as a buffer against the heating effect of increasing carbon dioxide emissions.

For each theory, the conference participants pointed out gaps and concerns - which ranged from the practical (cost and technical ability) to potentially devastating ecological consequences that are, by and large, unpredictable. To experiment with the atmosphere is to experiment with life as we know it. After all, this isn’t a test tube. This is all the known life in the universe - and it includes us.

The fact that some researchers are even willing to discuss such radical and dangerous methods to slow global warming should be a wake-up call to world leaders meeting at the international climate change conference in Bali, Indonesia next month. If serious scientists are actually contemplating such drastic measures, it ought to show just how dire the situation has become.

What is desperately needed, the researchers say, is what we have yet to see - genuine efforts to substantially reduce greenhouse gas emissions on a global scale. That’s why this next climate conference is so important, fresh on the heels of the IPCC co-winning the Nobel Peace Prize. This is an opportunity to look beyond Kyoto to the next level of engagement and agree to the substantial greenhouse gas reduction targets that scientists say we need if we are to avoid the worst of global warming.

Cooperation from the United States and China, as the world’s largest total greenhouse gas emitters, is obviously critical to reducing global greenhouse pollution. But countries like Canada could play an important role if we lead rather than follow and step up, rather than cower behind our big brother. It isn’t good enough to just hope we don’t have to attempt the unthinkable. We have to actually take serious steps to prevent it.

Carbon cycle: Marine manipulations

Kevin R. Arrigo

The effect of increasing levels of atmospheric carbon dioxide on carbon uptake in and export from the upper ocean is one of the big questions in environmental science. But it can be tackled experimentally.