The ‘cold blob’ is also known as the ‘warming hole (Picture: Nasa Scientific Visualization Studio/Goddard Space Flight Center)
The science of climate change is complex,but the overall effect is pretty simple – the planet is getting warmer.
Except,however,for a cool ‘blob’ just southeast of Greenland that no one has ever been able to properly explain.
The blob,also called the ‘warming hole’,is a large patch of the North Atlantic that has cooled by as much as 1°C over the last few decades.
Now scientists think they know what’s behind the blob: the Atlantic Meridional Overturning Circulation (AMOC),a tangle of currents.
AMOC (pronounced: AY-mock) carries warm,salty surface waters from the tropics into the North Atlantic,where they cool and sink into the ocean.
This oceanic conveyor belt has a massive influence on the weather as the currents transfer heat around the planet,so any changes in it would have cascading effects for large parts of the planet.
Unlike most of the planet,this strange patch is getting colder (Picture: Kai-Yuan Li/UCR)
And quite a big change is happening now,according to a study published in Geophysical Research Letters: AMOC is weakening.
AMOC’s slowing isn’t a discovery,but scientists have never been able to agree on why it’s happening.
As Atlantic currents are powered by wind,salinity and heat,some suggest that the blob is created by strong winds that could be forcing more evaporation,sucking heat from the ocean.
With more water in the air,more clouds are forming above,blocking out the sun above the oceans below Greenland.
But University of California Riverside climate scientist Wei Liu,who led the study,found that the cold blob is 1,000 metres deep,suggesting the ocean is the biggest factor.
‘People have been asking why this cold spot exists. We found the most likely answer is a weakening AMOC,’ she said.
Her team only had about 20 years of data to work with but managed to dive further back by looking over weather observations made by boats and satellites,called a climate reanalysis.
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If AMOC collapses,winters could become colder and longer,a climate expert warned (Picture: Getty Images Europe)Her team found that heat loss from the ocean surface has decreased in the blob since 1955.Stefan Rahmstorf at the Potsdam Institute for Climate Impact Research in Germany,who was also involved in the study,said wind and clouds only explain a ‘modest fraction of the warming hole’.
Meltwater from Greenland is diluting the tropical water,mucking up AMOC (Picture: Pedersen/NurPhoto/Shutterstock)‘It’s not happened as yet,but it is one of the major consequences of anthropogenic global warming.’By ‘anthropogenic’,Dale means the view widely accepted by scientists that climate change is the result of humans burning fossil fuels.Outside of Europe,scientists predict the loss of AMOC could cause the sea level to rise rapidly in North America,while the Sahel in Africa and the monsoon regions of Asia would most likely get less rain.Researchers admit that the data isn’t conclusive,so alternative explanations can’t be ruled out.AMOC might not even be weakening,with some suggesting that the system’s Norwegian current may be strengthening and hoovering up heat.Agreeing with the findings,Dale added that the cold blob has long ‘stood out like a sore thumb’ compared to the rest of the world.‘It’s almost certainly caused by melting ice [freshwater] off the Greenland ice sheet,seeping into the ocean,’ he said.‘The colder temperatures create what is known as an Atmospheric Loop with less evaporation taking place at the surface; it simply gets colder still over time.’Get in touch with our news team by emailing us at .For more stories like this,check our news page.
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