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Cautionary “Words of warming” as the world heats up

By A Guest Commentator | August 14, 2008 |

In her periodic newsletter and update, Goddard College Professor Catherine Lowther circulates these “Words of warming”. With her permission, we pass this item to our readers.

James Hansen, director of Nasa's Goddard Institute

As the world hots up, so does the market for books about climate change. Tim Flannery, author of The Weather Makers, looks at the latest works on the crisis, and sizes up their solutions, from nuclear energy to genetically engineered trees.

(August 9) — Most of those interested in climate science nowadays access information online, and one of the most significant of such contributions was recently posted by James Hansen, director of NASA’s Goddard Institute, and his colleagues, who have provided a partial explanation for these changes. They revisited a key piece of science underpinning the IPCC’s work - the findings about how much warming a given amount of atmospheric CO2 pollution would produce - and discovered that, when viewed over the longer term, Earth’s climate system is about twice as sensitive to CO2 pollution as is illustrated in the panel’s century-long projections.

One conclusion they drew is that there is already enough greenhouse gas pollution in the atmosphere to cause 2°C of warming - bringing about conditions not seen on Earth for 2m to 3m years, and constituting, according to the authors, “a degree of warming that would surely yield ‘dangerous’ climate impacts”.

Hansen and his colleagues pointed to a new understanding of how long it takes for the full warming consequences of a given amount of greenhouse gas to be felt. They concluded that we could expect to feel a third of any warming in the first few years. As Hansen and his colleagues put it: “Sea-level changes of several metres per century occur in the palaeoclimate record, in response to forcings slower and weaker than the present human-made forcing. This indicates that the ice may disintegrate and melt faster than previously assumed, and that the warming may be delayed less by the ice than assumed.”

They also make a useful discrimination between climatic “tipping points” and “the point of no return”. A tipping point is that at which the greenhouse gas concentration reaches a level sufficient to cause catastrophic climate change, while a point of no return is reached when that concentration of greenhouse gas has been in place sufficiently long to begin an irreversible process. Humanity is currently suspended between a tipping point and a point of no return, and the point of no return is likely to be reached within two decades.

Oliver Tickell’s just-published book Kyoto2 (Zed Books), provides a big-picture approach to the prevention of climatic catastrophe. In essence, Tickell provides a blueprint for a global climate treaty. He documents the failings of the Kyoto protocol, then goes on to summarise the latest climate science, including the work of Hansen and his colleagues. The replacement to the Kyoto protocol, Tickell writes, must work effectively to achieve a level of atmospheric CO2 below 350ppm. At the heart of the proposal is a global trade in carbon with a series of reducing caps sufficiently rigorous to bring about such an outcome.

For more information, refer to guardian.co.uk