Are We Facing a Point of No Return on Climate Change?

With the publication of a front page story in The Sunday January 29 Washington Post headlined "Debate on Climate Change Shifts to Issue of Irreparable Change," many residents of the US national capital area may have first become aware of a debate that has been simmering in the climate research community for at least the past two years. Are we passing or approaching a point of no return where irreparable damage for climate change will be inevitable no matter how stringent future measures may be to limit global greenhouse gas concentrations? Is the warming already underway likely to produce positive feedbacks that will amplify the rate of future warming and cause irreversible impacts both to humanity and ecosystems?

The Arctic Climate Impact Assessment released in November 2004 indicated that rapid warming was already underway in the Arctic with a likely disappearance of all or most of Arctic sea ice in the summer months by the end of this century. Besides imperiling polar bears and indigenous peoples, the disappearance of much of the Arctic ice pack will change albedo (reflectivity), adding to the warming underway in the Arctic and globally. Already there is evidence that an area of permafrost in Siberia of about a million square kilometers (about the land area of Germany and France combined) may be melting and releasing sizable quantities of methane that could amplify the warming resulting from human industrial and agricultural activities. In addition, New Scientist reports evidence of unexpectedly large methane releases from plants.

Perhaps as great a concern as a spiraling warming is the possibility of an irreversible ocean acidification, a process that might be irreversible for tens of thousands of years.

The possibility that we may be on the verge of abrupt and irreversible climate change has started to creep into policy discussions. In April 2004 Sir Crispin Tickell convened a number of top British policy planners and scientists at Green College, Oxford University to look at contingency plans for such change. An International Climate Change Task Force Co-chaired by US Senator Olympia Snowe, a Maine Republican, and Stephen Byers, a Labour MP, issued a report calling for vigorous international action to limit climate change and citing the possibility of “tipping points” that might make damage irreversible. A Pentagon study of potentially catastrophic impacts of climate change has attracted considerable attention, although it has not seemed to budge US policy on limiting greenhouse emissions.

Exeter UK Feb 2005 symposium

UK Report on tipping points