One of the oldest and best-established ideas about global warming is that it will hit the Arctic the hardest. The concept, which goes back to papers published decades ago, is called “Arctic amplification,” and the basic idea is that there’s a key feedback in this system that makes everything worse.

It basically works like this: Warmer air melts more of the sea ice cover that sits atop the Arctic ocean, especially during summer, which is, of course, ice melt season. That means the ocean is able to absorb more solar radiation than before, when it was covered with ice that reflected this sunlight away. That means there’s more heat retained in the system — and so on, and so on.

So Arctic amplification has long been known — and, confirming the theory, the Arctic has already been warming much faster than the more temperate latitudes. Even in this context, though, scientists have been noting that there seems to be something especially stark about what’s happening atop the world this year, which has seen overall temperatures soar to new highs.