Climate security

Geoengineering is one way to fight climate change and cool the planet

In 2006, James Hansen, noted climate activist and at the time director of the Goddard Institute for Space Studies, made a dire prediction. “We have at most 10 years, not 10 years to decide upon action, but 10 years to alter fundamentally the trajectory of global greenhouse emissions,” he wrote. If we fail to do so, he added, “Climate disasters will become unavoidable.”

It is now more than a decade later, and the trajectory of greenhouse gas emissions has not been fundamentally altered. Yet, we should not be too quick to laugh Hansen out of court. His claim was not that the earth would cease to exist in 10 years and that one day only dangerous levels of global warming would become unavoidable if emissions were not cut, although on the latter point he was right. Under any realistic scenario, humanity has already committed to pump enough greenhouse gas into the atmosphere to raise global temperatures to levels not seen for thousands of years.

But this is not the end of the story. As the prospects for limiting global warming solely through emissions cuts have dwindled, scientists are giving more attention to technology that could counteract this, either by sucking carbon dioxide out of the air or by using heat blocking particles to cancel the warming from trapped heat. Known as geoengineering, these techniques are likely to be the subject of a major report by the United Nations panel on climate change. Despite its potential importance, however, geoengineering has yet to enter the popular consciousness.