Fred Pearce has an excellent overview of the framing issues for next steps after Kyoto here:
"David Warrilow from the UK’s department of the environment said time was tight to stave off dangerous and irreversible climate change. Climate systems would not wait for political processes.
To stand a good chance of preventing mass extinctions, droughts, runaway melting of icecaps and the Gulf Stream turning off, we have to keep temperature rise below 2°C from pre-industrial times, he said.
To do that probably requires limiting total cumulative manmade emissions of carbon dioxide between the years 1900 and 2100 to 900 billion tonnes. The world has so far emitted around 300 billion tonnes, he said. But on current trends, 700 billion tonnes will be emitted by 2030 and 2400 billion tonnes by 2100".