Climate change is likely to cause more storms, floods, droughts, heatwaves and other extreme weather events, according to the most authoritative review yet of the effects of global warming.
The Intergovernmental Panel on Climate Change will publish on Friday its first special report on extreme weather, and its relationship to rising greenhouse gas emissions.
The final details are being fought over by governments, as the "summary for policymakers" of the report has to be agreed in full by every nation that chooses to be involved. But the conclusions are expected to be that emissions from human activities are increasing the frequency of extreme weather events. In particular, there are likely to be many more heatwaves, droughts and changes in rainfall patterns.
Jake Schmidt of the US-based Natural Resources Defense Council said: "This report should be a wake-up call to those that believe that climate change is some distant issue that might impact someone else. The report documents that extreme weather is happening now and that global warming will bring very dangerous events in the future. From the report you can see that extreme weather will impact everyone in one way or another. This is a window into the future if our political response doesn't change quickly."
This special report - one of only two that the IPCC is publishing before its 2014 comprehensive assessment of the state of climate change science - is particularly controversial as it deals with the relationship between man-made climate change and damaging events such as storms, floods and droughts. Some climate change sceptics and scientists cast doubt on whether the observed increase in extreme weather events can be attributed directly to human actions, or whether much of it is due to natural variability in the weather.
The IPCC, a body of the world's leading climate scientists convened by the United Nations, is likely to conclude that extreme weather can be linked to man-made climate change, but that individual weather events can at present only rarely be linked directly to global warming.
The Red Cross warned that disaster agencies were already dealing with the effects of climate change in vulnerable countries across the world. "The findings of this report certainly tally with what the Red Cross Movement is seeing, which is a rise in the number of weather-related emergencies around the world," said Maarten van Aalst, director of the Red Cross / Red Crescent Climate Centre and coordinating lead author of the IPCC report. "We are committed to responding to disasters whenever and wherever they happen, but we have to recognise that if the number of disasters continues to increase, the current model we have for responding to them is simply impossible to sustain."
Insurers are also worried. Mark Way, of the insurance giant Swiss Re, told the Guardian that the massive increase in insurance claims was causing serious concern. He said that between 1970 and 1989, the insurance industry globally had paid out an average of $5bn a year in weather-related claims, but that this had increased enormously to $27bn a year. Although not all of this was attributable to climate change - increasing population, urbanisation and prosperity also play a major part - he said insurers wanted governments to get to grips with the effects of climate change in order to prepare for likely damage and tackle the causes of global warming.
Mike Hulme at the Tyndall Centre said it would be dangerous for governments to use this report in order to justify directing overseas aid only to those countries that could be proved to be suffering from climate change, rather than other problems. In that scenario, he said: "Funding will no longer go to those who are most at risk from climate-impacts and with low adaptive capacity, but will go to those who are lucky enough to live in regions of the world where weather extremes happen to be most attributable by climate models to human agency. These regions tend to be in mid-to-high latitudes, with lots of good weather data and well calibrated models. So, goodbye Africa."