It is an extremely warm year for our planet.

Last week we learnt 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 to 1880.

It's just the latest evidence that we are, indeed, on course for a record-breaking warm year in 2015.
Land and ocean temperature percentiles from January to August 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 had very cold temperatures for the past eight months. What's up with that?

First of all, it's no error. Deke Arndt, chief of the climate monitoring branch at NOAA's National Centres for Environmental Information, confirmed what the map above suggests - some parts of the North Atlantic Ocean had record cold in the past eight months.
As Arndt said in an email: "For the grid boxes in darkest blue, they had their coldest Jan-Aug on record, and in order for a grid box to be 'eligible' for that map, it needs at least 80 years of Jan-Aug values on the record."

Those grid boxes encompass the region from "20W to 40W and from 55N to 60N", Arndt said.

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," Dr Arndt said. "So I think it's pretty robust analysis."

So, 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.

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 long been feared by climate researchers - the slowing of Atlantic Ocean circulation.

In March, several top climate scientists, including Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research and Michael Mann of Penn State, published a paper in Nature Climate Change suggesting that the gigantic ocean current known as the Atlantic Meridional Overturning Circulation, or AMOC, is weakening. It is sometimes confused with the "Gulf Stream" but, in fact, that is just a southern branch of it.

The current is driven by differences in the temperature and salinity of ocean water. In essence, cold salty water in the North Atlantic sinks because it is denser, and warmer water from further south moves northward to take its place, carrying tremendous heat energy along the way. But a large injection of cold, fresh water can, theoretically, mess it all up - preventing the sinking that would otherwise occur and, thus, weakening the circulation.

In the Nature Climate Change paper, the researchers suggested that this source of fresh water is the melting of Greenland, which is now losing more than a hundred billion tonnes of ice each year.

"I was formerly somewhat sceptical about the notion that the ocean 'conveyor belt' circulation pattern could weaken abruptly in response to global warming. Yet this now appears to be under way, as we showed in a recent article, and as we now appear to be witnessing before our very eyes in the form of an anomalous blob of cold water in the subpolar North Atlantic," Mann said via email.

Rahmstorf also commented via email: "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."

Chimp_Logic wrote on Sep 28^th, 2015 at 11:15pm:


According to the satellite data a the past 18 years hasn't warmed at all. How can it be warming. As far as I knew the global warming catch cry was dropped and we moved on to climate change because that was a safe bet as the climate is always changing.

I always call it AGW. Wasn’t it Dubya called it CC to hide what was happening?

What do you think will happen if the Gulf Stream disappears due to Greenland melts?

http://www.smh.com.au/content/dam/images/g/j/w/6/h/i/image.related.articleLeadwi...

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Read more: http://www.smh.com.au/environment/climate-change/scientists-worried-about-cold-b...l


If the Gulf Stream stops even in part a lot of North and West Europe will freeze—it is on same sort of latitude as Anchorage, Alaska.

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Re the suggestion the sun entering a quiet phase will trigger an ice age, the suns cycle is 11 years, the last low spot of the sun cycle coincided with record high temperatures.