Monday, October 18, 1999 Published at 10:32 GMT 11:32 UK
Carbon cuts only buy time
Stabilising carbon emissions would help, but it would be immensely difficult
By Environment Correspondent Alex Kirby
British climatologists say massive reductions in emissions of carbon dioxide (CO2) will have a fairly modest effect in slowing climate change.
In a report, scientists at the Hadley Centre for Climate Prediction and Research, part of the United Kingdom Meteorological Office, assess the global impacts of stabilising atmospheric CO2 at different levels.
The report investigates what would happen with emissions reduced so that CO2 concentrations stabilised at 550 parts per million or 750 ppm.
Carbon dioxide is the main global warming gas produced by human activities: concentrations now are about 360 ppm, the highest for 160,000 years. But this will inexorably increase as emissions continue to build up in the atmosphere.
Global temperatures, for instance, would rise more slowly, sea level rise would be more gradual, and tropical forests would not be so severely affected.
The snag is that achieving the sort of stabilisation the report suggests is far beyond the bounds of what appears to be politically possible.
Massive cuts needed
The international agreement on tackling climate change, the Kyoto Protocol, commits signatories to a global reduction of greenhouse gas emissions of about 5% over the next decade.
To stabilise CO2 concentrations at their present level - where many scientists say the early signs of climate change are already discernible - would require immediate emission cuts more than ten times as large.
They would need to come down by 50-70%, with further reductions later.
"If stabilisation at below 550 ppm were to be aimed for, the annual mean per capita CO2 emission for the whole world would need to be approximately five tonnes during the next century, and below three tonnes by 2100.
"Current levels are about four tonnes/capita as a world average, with a maximum emission of nearly 20 tonnes/capita in North America and a minimum of less than one tonne/capita in many parts of Africa."
The UNEP report comments: "Meeting all the targets agreed at Kyoto will have an insignificant effect on the stabilisation levels of CO2."
So achieving the stabilisation levels investigated by the Hadley Centre scientists might buy the world 50 years' respite, or even a century. But, on present trends, that looks to be impossible.