By Emma Graham-Harrison

BEIJING, April 27 (Reuters) - Drought-hit Australia may offer a warning of how climate change threatens core human needs, as the continent's food bowl faces the prospect of having irrigation cut off, Britain's climate change ambassador said.

Canberra has said it will halt irrigation to an area that usually grows over a third of the country's farm produce, if heavy rain does not fall in the next few weeks.

"If that happens, that is not just an economic blow to Australia, it will do significant damage beyond Australia because of its effect on world food prices," John Ashton told Reuters during a visit to the Chinese capital.

"That is a current threat which almost certainly, or at least very probably, arises from human-induced climate change."

Australia faced an "unprecedentedly dangerous" drought, Australian Prime Minister John Howard said last week. Parts of the country have been stricken for a decade.

Ashton, Britain's Special Representative on Climate Change, said growing worries about global warming should not translate into tight short-term emissions caps for developing nations.

Rich countries responsible for most of the global warming gases currently in the atmosphere should instead channel more funds to poor nations to curb emissions growth, he added.

"It's right that we should lead the effort," he said. "Most of the excess burden of emissions which is in the atmosphere at the moment is the result of (industrial nations') development."

"Furthermore, we have more of the capital, more of the innovative capacity, more of the capacity to shield ourselves from some of the worst consequences of climate change," he added, echoing Beijing's position that it should not be penalised for other countries' past industrialisation.

The Kyoto Protocol, which sets emissions caps for many wealthy signatory countries while setting none for poorer ones such as China, will expire in 2012. Australia has refused to sign the protocol, saying it is ineffective and economically wasteful.

Ashton said the successor to Kyoto should massively expand the Clean Development Mechanism, a system that allows developed world polluters to fund emissions cuts in poorer countries and put them towards their own quotas, he added.

RISING PRESSURE

Beijing could become the world's biggest emitter of greenhouse gasses as early as this year, upping international pressure for action.

It has rejected caps on emissions for decades to come, saying they may hurt growth, but the United States is unlikely to sign up for a post-Kyoto regime that does not have targets for China.

Ashton said he was not in Beijing to try to get commitments on emissions, however, prefering to push a restructuring of the country's dirty energy infrastructure and more carbon trading.

"I think a much more productive conversation with China is how we can help them build an alignment between energy security and climate security," he told Reuters.

Although prickly about rising global attention on Chinese emissions, officials are increasingly worried about temperatures that have risen faster in China than global averages and may threaten food and water supplies, Ashton said.

"Even since last year...it is on the agenda of a much wider range of people including people in leadership positions who until pretty recently would have been pretty difficult to engage on climate change," Ashton said.

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