Monday, April 18, 2016

Odd Greenland Heat Wave Breaks April Records, Worries Scientists

A freak weather pattern caused this unprecedented
melting in Greenland in 2012. Are we setting up
for more extreme melting this year? We'll find out,
but a bit of melting has already started two
months earlier than normal.  
That cold wave we had here in Vermont in early April is fast fading from memory (we hope!), especially after the gorgeous 70 degree weather Sunday.

But during our nasty April cold spell a couple weeks back,  a corresponding, unprecedented heat wave in Greenland won't be forgotten by climate scientists soon.

That's because these scientists are downright scared by what happened.

A few places in southern, coastal Greenland do get above freezing fairly often in April. But most of the frozen ice capped island stays well below freezing into late May or June. Some places in the middle, high elevation part of Greenland rarely get above freezing at all.

The heat in Greenland last week was something else, though.

About 12 percent of Greenland's ice sheet had some melting during this early heat wave. That doesn't sound like much, but in April, none of it melts. Until now.

Thule, on Greenland's northwest coast, experienced southerly winds gusting to 75 mph which brought temperatures that hit 34 degrees. That's more than 30 degrees above normal for this time of year.

Nuuk, Greenland hit 46 degrees and a spot on the southwestern coast of the island spiked up to 61 degrees, compared to an average high of 25 degrees there this time of year.

There's a spot in the middle of Greenland that hit 21 degrees above zero. Below freezing, yes, but still 41 degrees above normal.

That's the equivalent of it hitting 96 degrees here in northern Vermont in the middle of April. And that 21 degrees is roughly 10 degrees warmer than the average high temperature for what passes for normal summer "heat" in the middle of July up there.

The reason why scientists care about this Greenland heat wave, and why you should to, is it started the summer melt season in Greenland two months ahead of schedule.

Ice has been melting off the Greenland ice fields with increasing vigor over the past several decades, under the influence of global warming.

The more ice melts off Greenland, the more sea levels globally could rise.

The early April heat in Greenland does not guarantee that the summer melt season will be much worse than normal up there. It could stay colder than normal there this summer for all I know.

But signs are not pointing toward such a cool summer.

I brought up the cold New England weather in early April and the Greenland heat together at the top of this post for a reason. There was a relationship between the two events.

You might remember in previous posts that I brought up the weird jet stream gyrations that seem to be bringing more extreme weather events to different parts of the world, including here in the Good Ole USA, including Vermont.

The jet stream during early April was consistent with what scientists have been saying would probably happen with increasing frequency.

The upper level air flow plunged from far northern Canada all the way down to New England.

Then it recurved north, far much north than usual, taking warm air fro the subtropic Atlantic and delivering it to Greenland. Normally the jet stream wouldn't bulge as far north as Greenland to bring that much warm air, but this time it did.

As climate and environmental blogger Robert Scribner wrote:

"An extraordinary polar amplification of this kind -- one that includes Equator-to-Pole heat transfers -- risks hitting or increasing the intensity of a number of harmful climate tipping points. These include the amplifiying feedbacks of increasing rates of sea ice melt and Arctic carbon store response. 

In addition, extreme warmth over Greenland risks further glacial destabilizaion, increasing rates of se level rise and increasing weather instability in the North Atlantic."

In other words, weird jet stream gyriations like this one would set off more melting, which would make these weird jet stream twists and turns even more extreme, and worse for us.

Of course, not every climate scientist and watcher paints as dire a picture as Scribner. But most are worried about events like the April Greenland heat wave. Mostly because these Arctic heat waves have been happening more and more frequently.

And another early season Greenland hot spell might be in the offing.

A weather pattern similar to the one in early April seems to be setting up for this coming weekend.

The core of the coldest air in North America this weekend will stay well up into central and northern Quebec and Ontario. It's going to turn chilly in New England Saturday and Sunday,  but it won't be extreme like early in the month. Colder than normal, yes, but not something utterly weird.

But another surge of extremely warm air with this pattern wants to make a beeline toward Greenland. That could cause a little more unwelcome ice melt.

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