|This winter's maximum extent of winter|
ice in the Arctic was on the lame
side, says NASA
As dawn broke, it was just 12 degrees outside my window.
But, as I noted the other day, it's warm pretty much everywhere else. We got new evidence of that yesterday, when we learned the ice in the Arctic sure ain't what it used to be.
In late February, the size of the Arctic ice cap surrounding the North Pole reached its smallest winter peak on record, says NASA.
The ice in the Arctic waxes and wanes greatly with the seasons, obviously reaching its greatest extent in the late winter.
It appears that this year, the ice cap reached its greatest size on February 25 and then began to retreat and melt a bit after that.
The ice at its peak this year covered 5.61 million square miles, said the NASA-supported National Snow and Ice Data Center.
That's about 50,000 square miles less than the previous record smallest winter peak, set in 2011.
The start of this year's melt was a good two weeks earlier than normal. There's still a chance that there could be another good freeze up and the peak could come later, but NASA says that's pretty doubtful.
The ice will keep melting like it does every spring and summer and reach a minimum extent for the year somewhere around September.
The trend toward less and less ice in the Arctic has been continuing for a few decades now, but the seasonal minimum in September has been getting smaller at a faster rate.
That this year's maximum was a record low doesn't necessarily mean the ice extent will hit a record low when it hits its annual minimum in September.
It all depends upon temperatures, wind patterns and currents between now and September.
"'The winter maximum gives you a head start, but the minimum is so much more dependent on what happens in the summer that it seems to wash out anything that happens in the winter,' said Walt Meier, a sea ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
'It the summer is cool, the melt rate will slow down. And the opposite is true, even if you start from a fairly high point, warm summer conditions make the ice melt faster. This was highlighted by 2012, when we had one of the later maximums on record and extent was near normal early in the melt season, but still the 2012 minimum was by far the lowest minimu we've seen."
A very low September minimum is more important, scientifically, than a low late winter maximum.
A lot of the ice up there now is stuff that just formed over this past winter. That ice is pretty thin and will melt fairly easily. It the September minimum is really low, that means some of the permanent ice that formed years ago and got thicker and harder is melting.
That would be a sign of climate change.
Also, declining ice expanses up in the Arctic could worsen global warming. Ice is pretty white, and much of sun's light hitting the ice is reflected off of it back into space, and doesn't warm things up much.
But if the sun hits open water, a lot of ole Sol's heat is absorbed into the ocean, and acts as what scientists call a positive feedback that accentuates and accelerates the Earth's rate of warming.
The bottom line: It's fine for us up here in New England to hope for months and months of warm spring, summer and autumn weather as a salve for this winter's bitter cold and snow.
But we also want to hope that the Arctic stays on the chilly side this summer, and the rate of melting slows.