Hot hot hot

I can't remember the last time it was 40 (or 41?) degrees in the part of the Brisbane where I live.  But yesterday it was hot, still, and the temperature dropped to 27 degrees overnight, making for a very unpleasant weekend.  I don't know how the people of Western Sydney, who have had a much worse run of heatwave weather than Brisbane, have been able to put up with it.  It certainly makes one disinclined to go out, at least if the airconditioning is working at home...

And heat is in the news globally.   Last week it was in the news that the Arctic has had 3 bursts of sudden winter temperature rises this northern winter, and the Washington Post analysed it this way:

Scientists believe that a number of different factors are feeding into these warming events, including the steady march of climate change and interactions between the air and Arctic sea ice, which global warming is melting a little more each year. And a good low-pressure system, like the one that barreled through this week, can help to jump-start these kinds of sudden warming events by carrying a large amount of warm air up to the North Pole all at once.

The presence of the storm itself isn’t exactly unusual, according to atmospheric physics expert Kent Moore of the University of Toronto. Each year, there are some storms that roll through the northern Atlantic. What’s uncommon is just how far north some of them have been making it lately.

“There’s these extratropical cyclones that appear to be tracking farther north than they usually do, and these low-pressure systems are bringing the heat up into the polar region,” he said. It’s unclear why this happens, he added. But when it does, temperatures can vault up above zero degrees, or in extreme cases, sometimes even above freezing.

In a recent paper published in December, Moore notes that these types of anomalous warming events have been recorded since the 1950s — but they usually only occur once or twice a decade. Scientists believe that factors related to climate change may now be making it easier for weather systems like this week’s storm to carry warm air into the Arctic.

Changes in Arctic sea ice extent are one major issue. As a result of global warming, temperatures in the Arctic are rising at about twice the global average rate, and one of the consequences is a reduction in Arctic sea ice. These changes are most obvious in the warm summer months, when sea ice is at a minimum anyway — but lately, scientists have been observing record lows for the frozen winter months as well, a time of year when the ice is actually expanding. But where it is missing, those parts of the ocean become warmer.
“As that sea ice moves northward, there’s a huge reservoir of heat over the north Atlantic,” Moore said. “As we lose the sea ice, it allows essentially this reservoir of warmth to move closer to the pole.”

I think it's fair to say that it seems that the energy from global warming is acting to stir up the atmosphere so that warm air and cold air masses are being distributed to places they normally wouldn't be.  Or wouldn't be so often...