Climate change is set to hit the tropics as badly as the polar regions, according to a seris of new studies unveiled at the American Geophysical Union’s (AGU) annual conference in San Francisco.

Researchers there have unveiled a series of studies showing how rising levels of CO2 in the air threaten to disrupt some of the world’s largest river systems, as well as making the oceans so acid that most coral reefs could die.

The AGU also saw Jim Hansen, a senior NASA scientist launch a scathing attack on Gordon Brown, the British prime minister, over the latter’s plans to permit a new generation of coal-fired power stations.

Release of the new research follows the end of the Bali climate change conference which closed on Saturday with a pledge by more than 180 countries to make deep cuts in greenhouse gas emissions. The deal has, however, generated widespread skepticism because it lacks any numerical targets for reducing such emissions.

Background

• UN chief to return to Bali climate talks

• Al Gore: free of diplomatic niceties

• Al Gore lambasts US climate obstructions

• Scorching decade claims eight hottest years

2007: worst year for the environment

As UN climate talks go down to the wire, scientists across the world says 2007 was a 'year of worsts' for the planet

• This decade breaks records in table of world's hottest years

Background

• US rejects Bali climate change guidelines

• UN chief: act now on climate or face oblivion

• Al Gore calls for climate ‘mobilisation’

• Carbon emissions are 'higher than claimed'

• A convenient £50m for green Gore

Multimedia

• Video: protests in Bali

• Video: Going green with God

• The environment - 2007 in pictures

Background

• Carbon stand-off puts climate talks at risk

• US 'must change lifestyle' for planet's sake

• Woodman, spare that high-carbon tree

• Act now or prepare for disaster

US laws will sap Europe’s energy

There is a serious danger that the politics of the American cornfield are again threatening trade and development

Background

• Water shortages 'likely trigger for wars'

• Global crisis reveals big cracks in policies

• UN climate circus rolls in on CO2 cloud

• Carbon Trust not meeting the challenge

We’re not doomed yet

Should we really be listening to the views of one man just because they are eye-catchingly more dramatic than the consensus?

Background

• Brown’s bid to seal fate of carrier bags

• Opec ponders wealth of alternatives

• Climate change panel verdict: the future is bleak

• A global warning for UN chief

At the AGU conference, held in San Francisco, researchers explained some of the likely consequences for the earth’s tropical regions if greenhouse gas emissions continue to rise.

Peter Webster, a professor at the School of Earth and Atmospheric Sciences at Georgia Institute of Technology, used computer models to predict that one effect will be massive and uncontrollable flooding around some of the world’s largest rivers such as the Ganges, Brahmaputra, and Yangtze.

He found that as the tropical oceans get warmer so far more water will evaporate from them – all of which will eventually fall back to earth as rain.

By his calculations, these rivers will, on average, carry about 30 per cent more water – and the day-to-day volume will become increasingly variable.

"There's one thing about global warming," he said: "River banks don't increase their size, while the amount of water flowing through does."

Last month, a separate study in the journal Nature Geoscience found that the tropics, defined as a region of constant warmth and low seasonal fluctuation in temperature, are expanding northwards and southwards by about 13 miles per year, and could create new deserts in South Africa, the Southwestern U.S., South America, and around the Mediterranean.

There is also a possibility that the new temperature regimes would disrupt the weather patterns that provide agricultural and drinking water for much of Europe and North America.

However, warming isn't the only problem caused by emissions of CO2. Each year about 40% of the CO2 in the air gets absorbed into the oceans. It is this effect that has saved the world from warming far faster than is currently the case.

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