We waited a long time for summer this year, but we may have to wait a lot longer.
Weather scientists came together for an unprecedented gathering at the Met Office last week.
They predicted that a cycle of bad weather that began in 2007 has at least another five to ten years to run. Already we’ve seen widespread floods and ruined, waterlogged harvests.
Tory environment secretary Owen Paterson has played up the scary weather in the run-up to the government’s spending review. But he puts it down to natural changes.
In the face of overwhelming evidence—and to the exasperation of his junior minister Ed Vaizey—Paterson remains a “sceptic” about climate change.
There has always been massive variability from one year to the next. And these annual variations can occur within longer cycles of ten or 20 years.
That happened in the 1880s and 1950s, and since 2007 it is happening again.
This is to do with the way heat moves around the Earth. Both water and air flow from hot regions to cold ones, but air does it much faster.
The weather systems that hit Britain are carried here by a very fast river of air very high in the atmosphere, called the jet stream.
Its route changes each year depending on the temperature differences between different regions.
It takes years for heat to seep from warm seas to cooler ones, driving the longer cycles.
So we can’t blame any given storm, flood or drought directly on climate change any more than the Daily Express can say they “prove” that the whole thing is made up.
But looking at long term average temperatures makes it clear that the world is getting hotter.
This is because carbon dioxide and other greenhouse gases emitted by human activity mean that less heat escapes into space.
We can’t predict exactly what this means for any given year.
Average temperatures have gone up since the unprecendented heat wave of 2003, but we’ve yet to see another summer like it. More than 20,000 people died in France alone due to a lack of preparations.
But if emissions continue to rise then by 2023 a year like 2003 would be considered average. By 2043 it would seem positively chilly.
Global average temperatures have only risen slightly so far. But the rise is not evenly distributed. Some regions are warming up faster than others, the Arctic fastest of all.
So the temperature difference between polar and tropical regions is shrinking—and that’s slowly sending the jet stream haywire.
A bit like a rope that’s allowed to go slack, it can wriggle about more when it isn’t being pulled by large temperature differences.
That can “block” the movement of weather systems. The jet stream can bypass some regions for weeks or months without bringing clouds their way.
At the same time other regions get no respite from rain.
Paterson has used this to lobby for slashing more money from welfare to spend on flood defences and weather-proof genetically modified crops.
But flood defences are a sticking plaster at best. Tory attacks on poor people and public services will put millions at much greater risk from extreme weather.
And their insistence that society should be run according to the needs of profit stands in the way of cutting emissions and stopping runaway global warming before it’s too late.