麻豆淫院

The Atlantic Meridional Overturning Circulation (AMOC) is an enormous loop of ocean current in the Atlantic Ocean that carries warmer waters north and colder waters south, helping to regulate the climate in many regions. The collapse of this critical circulation system has the potential to cause drastic global and regional climate impacts, like droughts and colder winters, especially in Northwestern Europe.

Previous has already indicated a weakening in the AMOC, but there has been uncertainty about when the AMOC will collapse under future climate change or whether it will collapse at all. But , now published in the Journal of Geophysical Research: Oceans, indicates that collapse of the AMOC is likely and that it might begin sooner rather than later.

Using a new physics-based indicator and the Community Earth System Model (CESM), the study authors have produced new simulations of the AMOC collapse under various conditions.

The researchers believe the new indicator better represents the water circulation compared to previously used parameters, such as the ocean's surface temperature. Instead, it represents a tipping point indicated by a sign change in surface buoyancy flux (Bflux) over a key part of the North Atlantic Ocean from 40掳N to 65掳N. They also compared their results to historical observations and data.

Their simulations tested out 25 different climate models. They say that the AMOC was fairly stable until about 2020, but since then, there have been signs of weakening. Future modeling shows that, in high-emission scenarios, the AMOC collapse tipping point began as early as 2023 and as late as 2076, with a median tipping point at 2055. Under more intermediate scenarios, the tipping point was placed between 2026 and 2095, with a median of 2063.

The study authors note, "If the AMOC starts to collapse, it takes more than 100 years to reach a substantially weaker state. During that transition, the Northwestern European climate would change drastically and is expected to see colder winters, less rainfall, and more severe winter storms."

The study authors also note that many prior simulations only ran until around 2100, but letting simulations go further into the future might provide more accurate results. They say, "Given these risks of AMOC tipping under climate change, we encourage modeling groups to simulate to at least the year 2200."

There were some limitations in this research; for example, most models did not include enhanced Greenland ice melt, which could actually accelerate AMOC weakening. In some cases, background circulation can balance surface buoyancy gain. In these cases, the proposed indicator can also give false positives, but this is rare.

There is still time for societies to limit the impact of eventual AMOC collapse or to develop adaptation strategies, but the study authors offer a stark warning, saying, "To limit the risk of AMOC weakening and a potential collapse in the foreseeable future, global society needs to be on track of a low鈥恊mission scenario and urgent climate action is needed to guarantee this."

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