There are no comparisons to be made. This is not like war or plague or a stock market crash. We are ill-equipped, historically and psychologically, to understand it, which is one of the reasons why so many refuse to accept that it is happening.
What we are seeing, here and now, is the transformation of the atmospheric physics of this planet. Three weeks before the likely minimum, the melting of Arctic sea ice has already broken the record set in 2007. The daily rate of loss is now 50 percent higher than it was that year. The daily sense of loss — of the world we loved and knew — cannot be quantified so easily.
The Arctic has been warming roughly twice as quickly as the rest of the northern hemisphere. This is partly because climate breakdown there is self-perpetuating. As the ice melts, for example, exposing the darker sea beneath, heat that would previously have been reflected back into space is absorbed.
This great dissolution, of ice and certainties, is happening so much faster than most climate scientists predicted that one of them reported: “It feels as if everything I’ve learned has become obsolete.”
In its last assessment, published in 2007, the Intergovernmental Panel on Climate Change (IPCC) noted that “in some projections, Arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century.”
These were the most extreme forecasts in the panel’s range. Some scientists now forecast that the disappearance of Arctic sea-ice in late summer could occur in this decade or the next.
As I have warned repeatedly, but to little effect, the IPCC’s assessments tend to be conservative. This is unsurprising when you see how many people have to approve them before they are published.
There have been a few occasions — such as its estimate of the speed at which glaciers would be lost in the Himalayas — on which the panel has overstated the case. However, it looks as if these will be greatly outnumbered by the occasions on which the panel has understated it.
The melting disperses another belief — that the temperate parts of the world, where most of the rich nations are located, will be hit last and least, while poorer nations will be hit first and worst. New knowledge of the way in which the destruction of the Arctic sea ice affects northern Europe and North America suggests that this is no longer true. A paper published earlier this year in Geophysical Research Letters shows that Arctic warming is likely to be responsible for the extremes now hammering once-temperate nations.
The north polar jet stream is an air current several hundred kilometers wide, traveling eastwards around the hemisphere. The current functions as a barrier, separating the cold, wet weather to the north from the warmer, drier weather to the south. Many of the variations in weather in the temperate zone are caused by great traveling meanders — Rossby waves — in the jet stream.
Arctic heating, the paper shows, both slows the Rossby waves, and makes them steeper and wider. Instead of moving on rapidly, the weather gets stuck.
Regions to the south of the stalled meander wait for weeks or months for rain — regions to the north (or underneath it) wait for weeks or months for a break from the rain. Instead of a benign succession of sunshine and showers, droughts or floods.
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