Methane controls before risky geoengineering, please
WHEN the UN Framework Convention on Climate Change came into force in 1994, climate change's impacts seemed distant. Not any more. With daily reports of changes to glaciers, ice sheets, oceans and ecological systems, climate change seems upon us.
As a result, the debate over what to do is changing. Geoengineering schemes, once considered nearly science fiction, are now discussed seriously. Most attention, though, has focused on reducing emissions of carbon dioxide.
There is no question that to stop climate change in the long run requires a substantial reduction in CO2 emissions. However, significant opportunities exist to slow warming over the next few decades by reducing emissions of other greenhouse gases.
Only about half the warming that has occurred up to now is due to CO2. The rest is caused by other greenhouse gases, particularly methane (Proceedings of the National Academy of Sciences, vol 97, p 9875). Similarly, less than half of the total warming expected over the next 20 years will be caused by CO2. Methane, along with other gases such as carbon monoxide, volatile organic compounds (VOCs) and black carbon particles, will cause most of the changes.