Scientists will this week issue their starkest warning yet about the mounting dangers of global warming.
In a report to be handed to political leaders in Stockholm tonight, they will say that the burning of fossil fuels and deforestation have led to a warming of the globe, including land surfaces, oceans and the atmosphere.
Extreme weather events, including heatwaves and storms, have increased in many regions while ice sheets are dwindling at an alarming rate. Sea levels are rising while the oceans are being acidified - a development that could see the planet's coral reefs disappearing before the end of the century.
Economist and climate change expert Lord Stern yesterday called on governments to start working to create a global low-carbon economy to curtail global warming. Governments, he states, must decide what "kind of world we want to present to our children".
The fifth assessment report on the physical science of climate change by the Intergovernmental Panel on Climate Change (IPCC) warns that humanity is on course over the next few decades to raise global temperatures by more than 2C compared with pre-industrial levels.
Such a rise could trigger the release of plumes of the greenhouse gas methane from the thawing Arctic tundra, while the polar ice caps, which reflect solar radiation back into space, could disappear.
Although the report does not say so, Earth would probably then be facing a runaway greenhouse effect.
The warning - the most comprehensive and convincing yet produced by climate scientists - comes at a time when growing numbers of people are doubting the reality of global warming. Last week, the UK Energy Research Centre published a survey showing the proportion of British people who do not think the world's climate is changing has almost quadrupled since 2005.
But as the IPCC report underlines, scientists are becoming more and more certain that climate change poses a real danger to the planet.
Many believe the disconnection between popular belief and scientific analysis has been engineered by "deniers" explicitly opposed to the lifestyle changes - including restrictions on fossil fuel burning - that might be introduced in the near future. "There are attempts by some politicians and lobbyists to confuse and mislead the public about the scientific evidence that human activities are driving climate change and creating huge risks," said Stern.
"But the public should be wary of those who claim they know for certain that unmanaged climate change would not be dangerous. For they are not only denying 200 years of strong scientific evidence - the overwhelming view of the world's scientific academies and over 95 per cent of scientific papers on the subject - but they are often harbouring vested interests or rigid ideologies as well."
The report will be discussed this week by political leaders meeting in Stockholm. The study - the work of more than 200 scientists - outlines the physical changes that are likely to affect Earth's climate this century.
Future reports will cover the social impact of these changes and the efforts required to offset the damage caused by global warming. A UN meeting in Paris in 2015 will then debate what actions are needed to mitigate climate change.
Most measures proposed for tackling global warming rely on curtailing the burning of fossil fuels and these will form the focus of the Paris meeting. But other measures have been suggested. In particular, many scientists have backed geo-engineering projects that would involve either spraying particles into the atmosphere to reflect solar radiation back into space or extracting carbon dioxide from the atmosphere in order to bury it.
Both suggestions get short shrift in the new report. One author said: "We have to face up to the prospect of weaning ourselves off our addiction to oil and coal."