The rate at which global warming gases are accumulating in the atmosphere has taken a sharp leap upwards, leading to fears that the devastating effects of climate change may hit the world even sooner than has been predicted.
Atmospheric levels of carbon dioxide (CO2 ), the principal greenhouse gas, have made a sudden jump that cannot be explained by any corresponding jump in terrestrial emissions of CO2 from power stations and motor vehicles - because there has been none.
Some scientists think instead that the abrupt speed-up may be evidence of the long-feared climate change "feedback" mechanism, by which global warming causes alterations to the earth's natural systems and then, in turn, causes the warming to increase even more rapidly than before.
Such a development would mean the worldwide droughts, agricultural failure, sea-level rise, increased weather turbulence and flooding all predicted as consequences of climate change would arrive on much shorter time-scales than present scenarios suggest, and the world would have much less time to co-ordinate its response.
Only last month, Tony Blair expressed anxiety that global warming's dire effects would arrive not just in his children's lifetime, but in his own, and would "radically alter human existence".