Scientists used state-of-the-art technology to determine whether or not an event similar to what is seen in the disaster movie "The Day After Tomorrow" could occur in the future.
In the 2004 film, global warming triggers a devastating collapse of the Atlantic meridional overturning circulation (AMOC), causing catastrophes that flood major cities such as Los Angeles and New York and freezing the entire Northern Hemisphere. Climate scientists have generally criticized the credibility of the film, but the events had never been looked at using a state-of-the-art climate model, the University of Southampton reported.
To make these new findings, a team of researchers used the German climate model ECHAM at the Max-Planck Institute in Hamburg. The results suggested that if global warming and a collapse of the AMOC occur at the same time, the world will go through a cooling period lasting about two decades.
"The planet earth recovers from the AMOC collapse in about 40 years when global warming continues at present-day rates, but near the eastern boundary of the North Atlantic (including the British Isles) it takes more than a century before temperature is back to normal," said professor Sybren Drijfhout from Ocean and Earth Science at the University of Southampton.
The researchers found the effect of atmospheric cooling from an AMOC collapse is linked the flow of heat from the atmosphere into the ocean, and this phenomenon has been witnessed during the climate "hiatus" believed to have taken place over the past 15 years.
"When a similar cooling or reduced heating is caused by volcanic eruptions or decreasing greenhouse emissions the heat flow is reversed, from the ocean into the atmosphere. A similar reversal of energy flow is also visible at the top of the atmosphere. These very different fingerprints in energy flow between atmospheric radiative forcing and internal ocean circulation processes make it possible to attribute the cause of a climate hiatus period," Drijfhout said.
The researchers noted the climate hiatus cannot be attributed to one specific factor, but is likely linked to a combination of things such as El Niño.
"It can be excluded, however, that this hiatus period was solely caused by changes in atmospheric forcing, either due to volcanic eruptions, more aerosols emissions in Asia, or reduced greenhouse gas emissions. Changes in ocean circulation must have played an important role. Natural variations have counteracted the greenhouse effect for a decade or so, but I expect this period is over now," Drijfhout concluded.
The findings were published in a recent edition of the journal Nature Scientific Reports.
