A Quick Fix for Climate Change?

SINGAPORE: Mount Pinatubo in the Philippines exploded in 1991 with terrifying effects. It was the second-largest volcanic eruption of the 20^th century and by far the biggest in a densely populated area.

Advanced warning saved thousands of lives before avalanches of molten ash and mud roared down the flanks of the mountain, filling valleys with volcanic deposits up to 200 meters thick and displacing more than 200,000 people.

The eruption's ash rose 35 kilometers into the air with a menacing cloud, providing a hint into how geoengineering might stem the effects of climate change. Nearly 20 million metric tons of sulfur dioxide gas was injected into the upper atmosphere where it combined with other materials to form sulfuric-acid particles. These sulfate aerosols acted as a giant sunshade, reflecting solar radiation back into space, thus cooling earth’s surface.

Dispersal of the aerosols around the world in the jet stream caused global temperatures to drop temporarily by 0.5 degrees Celsius for about two years, a level not far short of the increase at that time in the average land and sea surface temperature since the start of the Industrial Revolution.

International climate-change negotiations are intended to prevent ever-larger amounts of greenhouse gas emissions, mainly from burning fossil fuels and clearing forests for agriculture, from spewing into the atmosphere and raising the mean global temperature to 2 degrees C, a threshold for dangerous climate change adopted by the abortive United Nations conference in Copenhagen last December. But in subsequent negotiations there's been little progress on a binding agreement to take the costly steps needed to reduce global warming gases by preserving forests and deploying low-carbon energy sources, such as nuclear, hydro, wind and solar power, on a wide scale. 

The scientific panel advising the UN has warned that without such cuts, the temperature could rise by as much as another 4 degrees C by the end of the century, increasing the risk of dangerous, even catastrophic climate change because of the long-lasting effects of carbon dioxide, the main global warming gas from human activity, once it reaches the atmosphere.

With an effective accord on cutting greenhouse gases unlikely any time soon, an increasing number of scientists and officials call for research into Plan G – geoengineering – to cool the planet. One of the latest signs of growing interest in controversial techniques to make large-scale alterations to the atmosphere, land or oceans to counter the effects of global warming was a September meeting of climate scientists in Washington to debate “Geoengineering: The Horrifying Idea Whose Time has Come?”

The Royal Society, Britain’s national academy of science, added impetus to moves for further funding and study of geoengineering, with a 2009 report that suggests, unless future efforts to slow greenhouse gas emission are more successful, additional action is necessary. The report cautions about uncertainties in the effectiveness, costs and environmental impacts of geoengineering technologies.

The technologies fall into two main categories: One would reflect sunlight back into space, an approach known as solar-radiation management. This mimics the global dimming and cooling associated with major volcanic eruptions. Another would remove carbon dioxide from the atmosphere on a scale far greater than anything attempted so far.

Solar-radiation management includes using high-flying aircraft or projectiles to spread chemicals to make sulfate aerosols in the stratosphere. Aircraft can also inject seawater droplets or other cloud-condensation material into clouds over the ocean to whiten them, thereby reducing incoming solar radiation warming the ocean.

Among the most feasible of the carbon-dioxide removal methods is to add iron, nitrogen or phosphate to selected regions of the ocean to increase phytoplankton growth and remove more carbon from air. These microscopic organisms already soak up huge quantities of carbon dioxide from the atmosphere.

A duststorm from inland Australia that swept across the states of New South Wales and southern Queensland in September 2009, deposited thousands of tons of nitrogen and phosphate in the Tasman Sea between Australia and New Zealand, stimulating phytoplankton growth. By one estimate, 8 million tons of carbon dioxide was captured by an extra 2 million tons of phytoplankton.

Of course, geoengineering raises thorny environmental, geopolitical and governance issues. Would it work as planned without dangerous side-effects? Who would decide if and when to deploy geoengineering techniques? Should the decision be in government or private hands? 

The debate is set to intensify. On October 29, the US Congress received two reports on geoeningeering, both calling for more coordinated research. At about the same time in Nagoya, Japan, an intergovernmental conference to protect global biodiversity proposed a moratorium on large-scale geoengineering experiments “until there is an adequate scientific basis on which to justify such activities and appropriate consideration of the associated risks.” Meanwhile, the European Union has funded a German research group to study the physics, ethics and geopolitical aspects of manipulating the climate system.

The US space agency, NASA, has said that geoengineering could provide a way to slow global warming until carbon emissions can be reduced enough to prevent catastrophic climate change. Some companies have drawn up ocean-seeding plans to sequester carbon dioxide and generate valuable carbon credits.

Critics worry about the side-effects. Fertilizing the seas could cause dead zones and toxic blooms that harm aquatic life. Adding large amounts of sulphate aerosols to the upper atmosphere could cool the planet, stop melting polar ice and slow sea-level rise.

However, interventions might also reduce Asian monsoon rainfall, deplete earth’s protective ozone layer and reduce sunlight for solar power. In addition, it would blur the skies, erode incentives to cut greenhouse gas emissions and do nothing to stop ocean acidification that threatens sealife.

Geoengineering carries costs. At the lower end of the spectrum, a 2009 study by Rutgers University environmental scientists estimated it would cost US$225 million to put 1 million tons of sulfur gas per year into the atmosphere using nine US Air Force KC-10 tankers making three flights a day. European nations have aircraft that could perform a similar task, as do Russia and China.

Other scientists predict the cumulative cost of removing about 855 billion tons of carbon from the atmosphere and storing it by the end of the century would be around US$86 trillion. Global GDP in 2009 amounted to approximately US$70 trillion. Carbon-removal costs, if accurate, would correspond to less than 1 percent of projected global GDP for the remainder of the century.

The 2006 climate change report for the British government compiled by Sir Nicholas Stern, former chief economist of the World Bank, called for international action to cut global warming emissions from human activity. The report warned that unless emissions stabilize in 20 years and fell after that, the overall costs and risks of climate change would be equivalent to losing at least 5 percent of world GDP each year.

But it said that the costs of action – including increased energy efficiency and use of renewable and low-carbon technologies – could be had by shaving the annual growth rate of world GDP from 2.5 to 2.49 percent, around 1 percent.

Recent studies show that although the average global temperature could be lowered by seeding the stratosphere, it might leave some regions too warm and others too cool. Pete Irvine, climate scientist at Bristol University and lead author of a study on geoengineering impacts, warns of likely disagreements between countries and regions over any future schemes. He concludes, “Some may be better off without any geoengineering while others may do better with a large amount.”

Apportioning the burden of cutting greenhouse gases still causes acrimonious debate among governments after years of negotiation. Putting Plan G into effect is also likely to be fraught with contention.