Last week we learned from the National Oceanic and Atmospheric Administration that the first eight months of 2015 were the hottest such stretch yet recorded for the globe’s surface land and oceans, based on temperature records going back to 1880. It’s just the latest evidence that we are, indeed, on course for a record-breaking warm year in 2015.
Yet, if you look closely, there’s one part of the planet that is bucking the trend. In the North Atlantic Ocean south of Greenland and Iceland, the ocean surface has seen very cold temperatures for the past eight months:
What’s up with that?
First of all, it’s no error. I checked with Deke Arndt, chief of the climate monitoring branch at NOAA’s National Centers for Environmental Information, who confirmed what the map above suggests — some parts of the North Atlantic Ocean saw record cold in the past eight months…
And there’s not much reason to doubt the measurements — the region is very well sampled. “It’s pretty densely populated by buoys, and at least parts of that region are really active shipping lanes, so there’s quite a lot of observations in the area,” Arndt said. “So I think it’s pretty robust analysis.”
Thus, the record seems to be a meaningful one — and there is a much larger surrounding area that, although not absolutely the coldest it has been on record, is also unusually cold.
At this point, it’s time to ask what the heck is going on here. And while there may not yet be any scientific consensus on the matter, at least some scientists suspect that the cooling seen in these maps is no fluke but, rather, part of a process that has been long feared by climate researchers — the slowing of Atlantic Ocean circulation…
The fact that a record-hot planet Earth coincides with a record-cold northern Atlantic is quite stunning. There is strong evidence — not just from our study — that this is a consequence of the long-term decline of the Gulf Stream System, i.e. the Atlantic ocean’s overturning circulation AMOC, in response to global warming.
The short term variations will at some point also go the other way again, so I don’t expect the subpolar Atlantic to remain at record cold permanently. But I do expect the AMOC to decline further in the coming decades. The accelerated melting of the Greenland ice sheet will continue to contribute to this decline by diluting the ocean waters.
This won’t lead to anything remotely like The Day After Tomorrow (which was indeed based — quite loosely — on precisely this climate scenario). But if the trend continues, there could be many consequences, including rising seas for the U.S. East Coast and, possibly, a difference in temperature overall in the North Atlantic and Europe.
A good time to go back and watch at least the first portion of Day After Tomorrow. The movie does a good job of explaining the slowing of Atlantic Ocean circulation and what potentially can happen. There are climate scientists who agree – and some who disagree. A localized effect can become a regional effect and vice versa.
What is fairly likely is that if the circulation is interrupted by what has long been a predictable feature of global warming, folks in NW Europe and the UK who’ve been getting used to a generally warmer year-round batch of seasons better get out their woolies. The Gulf Stream circulation brings a fair chunk of warmth to what should feel like Poland or even Belarus. And may, soon.