Record extremes of weather throughout the world this year are vividly documented in the latest report from the World Meteorological Organisation. Heavy rainfall and flooding, cyclones, wind storms, heat waves and rare snowfall are "outside historical norms" in Europe, Asia, Africa and Latin America.
Many of these reports have made the headlines, but this authoritative account brings them together in telling detail and identifies definite trends which make overall sense of them.
While no one particular extreme event can necessarily be blamed directly on changing weather patterns, the report says research by its associate, the Intergovernmental Panel on Climate Change (IPCC), shows human-induced global warming through the burning of fossil fuels is now unequivocal. This year's events are utterly consistent with that pattern. The global linear warming trend over the last 50 years is nearly twice that for the last 100 years, and the rate of change is increasing. Projections indicate it is "very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent".
This means there will be more heavy monsoon depressions like those which have devastated India, Pakistan and Bangladesh - killing at least 500 people, displacing 10 million and destroying vast areas of croplands, livestock and property. The first recorded cyclone in the Arabian Sea which affected 20,000 people and caused 50 deaths in Oman is likely to be repeated. So is the wettest summer to have hit England since records began in 1766 - although it could strike neighbouring Ireland next time. And the heat waves affecting south-eastern Europe over the last two months in which dozens have died and huge stretches of forest have been destroyed by wildfire will also recur. Put differently, the IPCC reports that 11 of the last 12 years are the warmest since reliable records began in 1850. As William Reville points out today in his weekly science column "the odds of such warm sequential years happening by chance are minuscule".
So we now know the association between global warming caused by human activity and changing weather patterns is scientifically established to the highest levels of credibility possible. The time has come to take urgent action to correct it. Humanity has about a decade to halt and then reverse carbon gas emissions before fundamental and irreversible environmental change occurs which would overwhelm us.
The IPCC will report next month on what can best be done, whether by precise targeting of reductions, taxation, radical changes in lifestyle, technological innovation or trading schemes. An international summit in Bali next December will make strategic decisions on how to proceed. We must hope this year's extreme weather events will reinforce the determination to tackle the issue with the radicalism and imagination required, rather than to postpone or fudge painful decisions. Public debate and pressure are essential to ensure this is so.