Stefan Rahmstorf writes:

We’ve all become increasingly used to reports of extreme weather over the past few years. But this summer’s raft of dramatic weather events is significant: Not only does it show what warming can do, it points to the potential large-scale trouble that lurks in the disruption of the planet’s winds and ocean currents.

In the past few months alone, we’ve seen extreme heat in Western Europe, Canada, Alaska, the western United States, Texas, Japan and Algeria, which set a new temperature record for Africa. Greece, Scandinavia, California and Siberia all suffered through drought and wildfires, while Japan, the U.S., Europe and India were hit with devastating floods. The human toll and harvest losses are still being tallied.

That global warming leads to more heat extremes is not rocket science and has been confirmed by global data analysis. We’re seeing five times more monthly heat records — such as “hottest July on record in California” — now than we would in a stable climate.

As part of this pattern, we can expect more heat drying out soils and causing more drought and wildfires. We also expect to see more extreme rain, given that a warmer atmosphere can take up and then release more moisture. A global increase in rainfall records has also been documented in weather station data.

But there is something more interesting going on here too.

It’s not just that the weather is doing what it always does, except at a higher temperature level. Rather, there is growing evidence that the dynamics of weather itself are changing. [Continue reading…]