Experts from two of the world's leading academic institutions have joined forces to explain the "clear evidence" of human-caused climate change.

Britain's Royal Society and its American counterpart, the US National Academy of Sciences, published the report for policymakers, teachers and ordinary citizens in an attempt to dispel global warming myths.

Climate Change: Evidence and Causes spells out which aspects of climate change are well understood and which are still uncertain and need further research.

It maintains there is unequivocal evidence that soaring levels of the greenhouse gas carbon dioxide (CO2) in the atmosphere are chiefly the result of burning fossil fuels.

Carbon dioxide is now at its highest level for at least 800,000 years, and records dating back to the mid-19th century show a clear long-term warming trend.

One of the main clues to the origin of the CO2 is its atomic fingerprint, say the scientists. Measurements of different isotopes - or atomic "strains" - of carbon show that most of the increase is human-generated.

On the other hand, there is much less certainty about the extent to which sea levels are likely to rise, and what effect increasing acidity of the oceans will have on marine life.

"Our aim with this new resource is to provide people with easy access to the latest scientific evidence on climate change, including where scientists agree and where uncertainty still remains," said Royal Society president Sir Paul Nurse.

"We have enough evidence to warrant action being taken on climate change; it is now time for the public debate to move forward to discuss what we can do to limit the impact on our lives and those of future generations."

American colleague Professor Ralph J Cicerone, president of the National Academy of Sciences, said: "As two of the world's leading scientific bodies, we feel a responsibility to evaluate and explain what is known about climate change, at least the physical side of it, to concerned citizens, educators, decision makers and leaders, and to advance public dialogue about how to respond to the threats of climate change."