It often happens to be a doomsday fiction or an exaggerated movie plot that seeks to project climate change dooming a major ocean current.
However, that is not a far-fetched reality. A study conducted at research centers including Scripps Institution of Oceanography shows that the possibility may be underestimated by climate models.
The new study makes assumptions that climate change will indeed collapse a key ocean current in Atlantic and dispels the assumptions of its stability.
Departing from the conventional climate models that reiterated the stability of the current, the Yale study says the Atlantic Meridional Overturning Circulation (AMOC) is vulnerable to a collapse in the long run. The AMOC system has critical significance as a major player in regional climate change among the Atlantic rim countries, especially the European nations.
The findings of the study have been published in the journal Science Advances.
The study led by Wei Liu, a former Scripps researcher and now with Yale University, was done in conjunction with Shang-Ping Xie and other colleagues and breaks the mold of stability about the major Atlantic current.
"The significance of our study is to point out a systematic bias in current climate models that hinders a correct climate projection," said Liu.
Many recent reports on climate change by the Intergovernmental Panel had affirmed that the AMOC is quite stable and ruled out any collapse despite accepting that some weakening induced by climate changes is possible.
Realistic Stability Regime
As mentioned, the study departs from the long-held positions on AMOC as very stable after running a number of simulations to develop a model, which argues breakdown of the AMOC circulation at some point in the future is possible and can trigger large-scale cooling in the North Atlantic.
The consequences of such a collapse of AMOC would include hindering the flow of warm surface water to Greenland and bringing back cold water toward the equator near the seafloor.
In enumerating the future changes of AMOC, the study has pursued a scenario of doubling of carbon dioxide in the atmosphere in the course of climate change.
The simulation convinced the researchers that the scope of circulation breaking down after 300 years is a possibility when the carbon dioxide concentration becomes two-fold, beyond the 1990 levels of 355 parts per million.
More Validation Awaited
However, the researchers have noted that their new model needs more validation from data on water salinity, ocean temperature, and ice melting of many decades to substantiate the accuracy of AMOC models.
Co-author Zhengyu Liu calls the model a very "provocative idea". He is a professor of atmospheric and oceanic sciences, at the University of Wisconsin who adds that their AMOC model has taken an 180-degree turn.
Regarding the effects, Liu's model predicts that collapse of the AMOC would step up cooling in the Northern Atlantic ocean and expand Arctic sea ice, besides pushing the tropical Atlantic rain belts farther south.
