Is Earth’s methane a time bomb?

by Michael Richardson

SINGAPORE — Developed and developing countries continue to haggle over terms of a new pact to limit global warming gases. With only 15 full negotiating days scheduled before a climate change summit convenes in Copenhagen at the end of the year, the next round of negotiations in Bangkok (Sept. 28-Oct. 9) looms as a make-or-break effort.

On two key issues, the parties are poles apart. The panel of scientists and officials advising the United Nations on climate change says industrialized countries need to take the lead by agreeing to cut their greenhouse-gas emissions by as much as 40 percent by 2020. But so far, pledges from Japan and other advanced economies are below these levels.

Meanwhile, their offers of money and technology to help developing countries reduce greenhouse-gas emissions and adapt to climate change are a long way short of the U.N. target. Two recent findings underscore the need for action.

In 2007, the U.N. advisory panel known as the Intergovernmental Panel on Climate Change (IPCC) put the global cost of adapting to climate change at $40 billion to $170 billion a year. In a report Aug. 27, a group of scientists concluded that the real cost was likely to be two to three times greater, and would be even higher when the full range of climate impacts from human activities was considered.

Their report warns that current estimates being used as a basis for the U.N.-sponsored climate negotiations do not include key economic sectors such as energy, manufacturing, retailing, mining, tourism and ecosystems.

These scientists should know. Among them is professor Martin Parry, now at the Grantham Institute for Climate Change at Imperial College in London, which published the report with the International Institute for Environment and Development. Until last year, Parry co-chaired the IPCC’s working group responsible for assessing climate change impacts, vulnerability and adaptation.

If the cost of adapting to a warmer world and more extreme weather is much greater than initially thought, it will only make contentious negotiations more difficult. Finance is a key to an effective deal in Copenhagen. But with industrialized economies anxious about the burden of rising debt and slow recovery from recession, they are unlikely to be in a generous mood.

Much attention has been given to ways of curbing carbon dioxide levels, which are boosted by burning fossil fuels and clearing forests. It is the main greenhouse gas. Less attention has been given to methane, even though it is 25 times more potent.

The climate change negotiators should consider the implications of what may happen to the vast stores of methane in frozen deposits on land and under the seabed as the planet heats up.

After remaining stable for a decade, atmospheric levels of methane started rising two years ago. It is not clear where the gas came from, or whether it is part of a sustained upward trend as is evidently the case with carbon dioxide. However, some scientists have cautioned that continued increases in sea and land temperatures could unleash the huge stores of methane frozen beneath the sea floor and in the Arctic permafrost soil layer, starting at the shallowest levels.

Signs of methane instability have been reported in the relatively shallow waters of the Siberian Shelf, where there is estimated to be 1,400 billion tons of the gas in icelike hydrates, and on land in the permafrost regions of the Northern Hemisphere.

According to research by a multinational team of scientists published last September, the amount of frozen organic carbon material from dead plant and animal matter in the Arctic is double the previous estimate. They said the 1,672 billion tons of carbon stored in the permafrost is over twice the 780 billion tons in the atmosphere today that is blamed for global warming.

Scientists worry that if the methane deposits were to thaw, it could trigger abrupt climate change as more methane releases caused further warming. There is evidence this happened in the distant past. Some refer to the methane store as a potential climate change time bomb.

The permafrost contains carbon dioxide as well as methane. Burning fossil fuels (coal, oil and natural gas) adds about 8.5 billion tons of carbon dioxide to the atmosphere each year. Deforestation adds around 1.5 billion tons per year.

How much permafrost will add depends on how fast it thaws, but the work of the multinational research team suggests that the figure could be as much as 1.1 billion tons annually — with no more than one-ninth of it likely to be absorbed by shrubs and trees expected to grow on what used to be tundra as surface temperatures rise and the permafrost thaws.

Meanwhile, scientists are closely watching seabed methane. In research published in August, a British-German team found over 250 plumes of methane bubbles rising from the seabed off West Spitsbergen, a Norwegian island in the Arctic Ocean, a region of the world where temperatures have been rising the fastest and where sea ice has been thinning and retreating in recent years.

Using sonar technology, the researchers discovered the methane seeps at depths of between 150 to 400 meters. The gas is released from methane hydrate. At present, it is stable at water depths greater than 400 meters in the ocean off Spitsbergen. However, 30 years ago it was stable at water depths as shallow as 360 meters.

Some scientists have predicted that as ocean temperatures rise as a result of global warming, methane hydrates will begin to dissolve at greater depths. But the fact that the process has already begun surprises the team.

“Our survey was designed to work out how much methane might be released by future ocean warming,” said professor Tim Minshull, head of the University of Southampton’s School of Ocean and Earth Science. “We did not expect to discover such strong evidence that this process has already started.”

Michael Richardson is a visiting senior research fellow at the Institute of South East Asian Studies in Singapore.