A draft UN report has concluded that man-made climate change has boosted the frequency or intensity of heat waves, wildfires, floods and cyclones and that such disasters are likely to increase in the future.

The document, which was three years in the making, says that the severity of the climate impacts vary, and some regions are more vulnerable than others.

The AFP, having obtained a copy of the draft report's 20-page Summary for Policymakers, reports that hundreds of scientists working under the Intergovernmental Panel for Climate Change (IPCC) will vet the "phonebook-sized draft" at a meeting in Uganda of the 194-nation body later this month.

"This is the largest effort that has ever been made to assess how extremes are changing," said Neville Nicholls, a professor at Monash University in Melbourne and a coordinating lead author of one of the review's key chapters.

The AFP reports the new report's main conclusions as follows:

– An increase in the frequency and magnitude of warm daily temperature extremes over the 21st century on a global scale is "virtually certain" (99-100 per cent);

– An increase in length, frequency and/or intensity of warm spells, including heat waves, will continue over most land areas is "very likely" (90-100 per cent certainty);

– An increase in peak temperatures – compared to the late 20th century – of up to 3 degrees Celsius by 2050, and 5 degrees C by 2100 is "likely" (66-100 per cent);

– An increase in heavy rain and snowfall over the next century over many regions, especially in the tropics and at high latitudes (likely);

- Droughts will likely intensify in other areas, notably the Mediterranean region, central Europe, North America, northeastern Brazil and southern Africa.