A new study found in the journal Science Advances proposes that intense climate change can have a different impact on the world than it has been predicted so far. If atmospheric concentrations of carbon dioxide double in the future, the ocean current that regulates climate and weather patterns could collapse.
AMOC (The Atlantic Meridional Overturning Circulation) is an oceanic conveyor belt. Warm water from the Atlantic is transported to the North, towards the Arctic. This explains the mild climate from Western Europe, for example. In the Northern Atlantic, the flowing surface water cools and sinks down to the bottom of the ocean. It has to complete the cycle and is transported southwards. This circulating system is part of a much larger system of overturning currents that circulate all around the world.
But scientists started worrying that the AMOC is not accurately represented in the climate models. These models portray the currents as way more stable than real-life observations have proven to be. These observations proved that the AMOC is weakening, but there are still debates over the cause: human interaction or natural phenomena. Nevertheless, the stable portrayal of AMOC in the current climate models might affect the predictions we make on the future changes of climate.
Researchers at the University of South California in San Diego and University of Wisconsin corrected the stability bias in a commonly used climate model and then ran an experiment to see how future climate predictions would change with the more accurate data introduced. They doubled the atmospheric concentrations of carbon dioxide in both the corrected and uncorrected model and let them run simulations for a few hundred years.
The results were striking. The uncorrected model shows AMOC weakening for a while but eventually recovering. The corrected model shows AMOC weakening continuously until it collapses altogether in about 300 years.
This does not mean that everything that has been known about climate is wrong. Most climate models are usually run only for a few decades and, in about 50 years, both the corrected and the uncorrected model would produce more or less the same results. Only after that, under extreme global warming, the currents can shift.
Also, certain aspects of the changing model are not entirely realistic. For example, the instantaneous doubling of the carbon dioxide concentration. Efforts are being kept that such thing should not happen, but even if it did happen, the transformation would take place gradually and not all of a sudden. Therefore, a more realistic climate change model would have provided different results.
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