HONG KONG (Reuters) - The risks of inaction over climate change far outweigh the turmoil of the global financial crisis, a leading climate change expert said on Monday, while calling for new fiscal spending tailored to low carbon growth.

Climate change economist Nicholas Stern walks past the Toronto Stock Exchange ticker showing a quote for oil producer Husky Energy after a news conference at the Toronto Stock Exchange in Toronto, February 19, 2007. REUTERS/J.P. Moczulski

“The risk consequences of ignoring climate change will be very much bigger than the consequences of ignoring risks in the financial system,” said Nicholas Stern, a former British Treasury economist, who released a seminal report in 2006 that said inaction on emissions blamed for global warming could cause economic pain equal to the Great Depression.

“That’s a very important lesson, tackle risk early,” Stern told a climate and carbon conference in Hong Kong.

As countries around the world move from deploying monetary and financial stabilization measures, to boosting fiscal spending to mend real economies, Stern said the opportunity was there to bring about a new, greener, carbon-reducing world order.

“The lesson that we can draw out from this recession, is that you can boost demand in the best way possible by focusing on low carbon growth in future,” Stern said, including greater public spending on mass public transport, energy and green technologies.

Stern’s warning comes on the heels of last week’s Asia-Europe or ASEM meeting in Beijing, where China indicated in talks it was committed to seeking a climate change pact in vital end-game talks in Copenhagen at the end of next year.

Leaders at the summit also urged countries not to use global economic upheaval as a reason for delaying a deal. Partly as a result of the darkening global economic outlook, Italian Prime Minister Silvio Berlusconi recently warned that 10 other EU nations backed his efforts to block an EU climate plan, prompting further doubts over European action on global warming.

Yet Stern remained optimistic, saying while talks would be “very tense” the likelihood of a deal in Copenhagen to reduce carbon emissions by 50 percent by 2050 remained “very high.”

Any deal would have to iron out differences between the United States, historically the largest greenhouse gas emitter, and rapidly developing countries like China, which by some accounts has surpassed the United States on emissions.

China, with its bulging output of carbon dioxide, the main greenhouse gas behind global warming, was singled out by Stern along with the U.S. as pivotal in the talks, with the next U.S. president likely to be much more proactive than George W. Bush.

“The U.S. and China will be the key leaders for a global deal. Either one of them could kill it, and I don’t think either one of them will kill it.”

Fresh from a trip to China, Stern said China’s next national economic blueprint or five-year plan would acknowledge its key role to stave off a big rise in global temperatures, the melting of ice-caps and destructive rises in sea levels the world over.

“I think we’ll see the 12th five-year plan focus on low carbon growth,” he said.