MELISSA BLOCK, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.
ROBERT SIEGEL, host:
And I'm Robert Siegel.
Today, at the meeting of G8 world leaders, the U.S. agreed to an important benchmark to limit climate change. It joined some other industrialized countries by agreeing that the globe should not warm up more than two degrees Celsius; that's 3.6 degrees Fahrenheit.
As NPR's Richard Harris reports, it's also an extremely ambitious goal.
RICHARD HARRIS: Scientists assembled by the United Nations in 2007 said the world could face significant dangers if we warmed it up by more than two degrees Celsius. Europe is attempting to limit its emissions to prevent the Earth from heating up more than that. But until today, there was not a broader international consensus to limit global warming to two degrees.
Mr. KIM CARSTENSEN (Leader, World Wildlife Fund Global Climate Initiative): This is something that we haven't seen the U.S. say before. It's also something we haven't seen Canada, Russia and Japan say before. So, in that sense, it is a step forward for the G8.
HARRIS: Kim Carstensen from the World Wildlife Fund is at the G8 talks in Italy, and he was pleased to see that step forward even though the goal is an aspiration not legally binding, and words are easier than action.
Mr. CARSTENSEN: What we need to see is what will this translate into in the shorter term.
HARRIS: Countries are willing to agree to long-range goals over the coming decades, but it's much harder to get promises for short-term action to start moving in the right direction. Worse, China and India are expected to produce the lion's share of carbon dioxide in the coming decades, so Carstensen says they have to limit their emissions, too.
Mr. CARSTENSEN: If you really take the level of ambition that is needed for the world, you need to have action in China and India also, and we need to see that action start pretty soon.
HARRIS: But at the meeting in Italy, China and India have bluntly refused to cut their emissions. They want to see more, much more from the richer nations first.
Now, the limit of two degrees Celsius arose out of a scientific consensus process. But David Archer at the University of Chicago says it's not a hard and fast danger point, more of a judgment call.
Professor DAVID ARCHER (Department of the Geophysical Sciences, University of Chicago): Two degrees would make the Earth warmer than it's been in millions of years, and you know, that just seems kind of dangerous.
HARRIS: That kind of warming could, for example, plunge the Southwestern United States and parts of Australia into permanent drought. In fact, the world's climate has already heated up by three-quarters of a degree since the start of the Industrial Revolution, and we're rapidly headed above one degree Celsius.
Prof. ARCHER: I am frightened for the impact of one degree, so I don't want to be cavalier about staying within two. But certainly, limiting it to two is better than business as usual.
HARRIS: And moving away from business as usual will demand a level of ambition far beyond what anyone has achieved so far.
Richard Harris, NPR News.