Ice and snow cover New York City in a future ice age brought on by catastropic climate events, in the 2004 film The Day After Tomorrow.
In the film, climate warming caused an abrupt collapse of the Atlantic meridional overturning circulation (AMOC). This led to catastrophic events such as New York being flooded, the northern hemisphere freezing and tornadoes destroying Los Angeles. While the abrupt collapse of the AMOC in the movie has long been criticized, researchers believe it could happen, acording to a new study.
For their study, researchers used the German climate model ECHAM at the Max-Planck Institute in Hamburg. They discovered that if global warming and a collapse of the AMOC occur simultaneously, the Earth will cool for a period of 20 years, according to a news release. After this time, global warming continues as if the AMOC never collapsed, and the global average temperature would offset about 0.8 degrees Celsius.
"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," Professor Sybren Drijfhout, from Ocean and Earth Science Department at the University of Southampton, said in the release.
A collapse of the AMOC is associated with atmospheric cooling and heat flow from the atmosphere into the ocean, according to the recent study. This climate "hiatus" has been witnessed over the course of the last 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," Professor Drijfhout exaplained in the release. "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."
The researchers noted that the recent period of very weak warming cannot be attributed to one single cause, but instead a combination of factors including large-scale shifting westerlies in the Southern Ocean, which were brought on by El Niño patterns.
"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," Professor Drijfhout said in a statement. "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.
Their study was recently published in the journal Scientific Reports.
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