Simple fact: the maximal extent of the Arctic ice pack is mid-March, and the minimum is in mid-September.
Until recent years, the maximum has been about 15 million square miles, the minimum about half of that, that is, between 7 and 8 million SQ M.
In September 2007 the usual time for the annual minimum, the ice pack shrank to only 4.3 million SQ. M., or about half of the usual minimum. This was a record for recorded history.
In recent Septembers it has been somewhat larger, that is, 2007 retains that record. But these last few years have included the second third and fourth lowest extents. in other words, the lowest four coverages ever recorded have all been notched within the last six years.
Don't want to believe that? It's from The New Yorker, and for all I know you might consider that a dubious source. Still, nations and commercial interests are both acting as if a critical change is underway, and it would be churlish to act as if they're all crazy.
Also, since about 2005, Denmark and Canada have gotten cranky with one another over claims of sovereignty to Hans Island, which is between Greenland and Canada, and is pictured above. Back in the day, before this development we might as well for convenience call "climate change" had reached this point, Hans Island wasn't worth arguing about.
Climate has changed suffciently to make prospecting possible there.
So: the institutions with money at stake act as if climate change is a fact. Here is another example of that. My own take then: it is a fact.
This leaves a lot of open questions: what are the causes of these changes, how valuable and/or calamitous they will all turn out to be on balance, and if negative on balance, what can or should be done about it -- feel free to argue. Whether it is underway? Don't bother.
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