American reports urge a price on carbon emissions

In blunt language at odds with the unwieldy climate change debate in the US Congress, the academy said: "A carbon-pricing system is the most cost-effective way to reduce emissions. Either cap-and-trade, a system of taxing emissions, or a combination of the two could provide the needed incentives." The best way to curb global warming is to put a price on climate-warming carbon dioxide emissions, according to a trio of reports from the US National Academy of Sciences.

In one report on the science of climate change, academy experts discounted doubts about climate warming after revelation of embarrassing e-mails by scientists provided fodder for critics.

"Climate change is occurring, is caused largely by human activities, and poses significant risks for -- and in many cases is already affecting -- a broad range of human and natural systems," the reports concluded.

Senator John Kerry, co-author of new US legislation to curb planet-warming emissions, said the reports which were requested by congressional committees, were "yet another wake-up call on the threats of global climate change."

"These studies clearly demonstrate the urgency for Senate action on the American Power Act," Mr Kerry said in a statement.

The academy, which advises the government on science and technology, drew praise from the Pew Center on Global Climate Change, the Union of Concerned Scientists and other environmental groups.

Emissions "Budget"

A second report, which focused on limiting climate change, said strong US actions would encourage other countries to join in a global response.

"The US should establish a greenhouse gas emissions 'budget' that sets a limit on total domestic emissions over a set period of time and provides a clear, directly measurable goal," the report said.

Legislation aimed at curbing global warming was unveiled last week in the U.S. Senate. Despite support from President Barack Obama, its chances of becoming law this year are slim. The bill would cut domestic greenhouse emissions by 17 percent in the next decade.

The academy's report did not recommend a specific emissions reduction target, but suggested a range of emissions that are roughly in line with the legislation.

Even getting to the high end of that range will require a departure from business as usual, the report said.

Carbon pricing alone will not do the job, the scientists said.

Other policies are needed to ensure progress on energy efficiency, renewable energy, new-generation nuclear power, carbon capture and storage, and fixing or replacing emissions-intensive energy infrastructure, the report said.

A third report said that even with these moves, steps must be taken to ease the most damaging effects of climate change, including rising sea levels, disappearing sea ice and more frequent and intense extreme weather events like heavy precipitation and heat waves.