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Climate change under the microscope: The mysterious dynamics of the AMOC!
Find out more about the effects of the Atlantic Meridional Overturning Movement on the climate and current research results from Heidelberg University.
Climate change under the microscope: The mysterious dynamics of the AMOC!
In connection with the dramatic changes in the climate system over the last millennia, the Atlantic Meridional Overturning Current (AMOC) has proven to be a central element in global climate events. The University of Heidelberg states that the AMOC flow force was reconstructed from geochemical measurements of thorium and protactinium in North Atlantic sediments. These measurements span a period of 12,000 years and provide valuable insights into environmental conditions since the end of the last Ice Age.
The reconstruction shows a marked weakening of the AMOC between 9,200 and 8,000 years ago, which correlates with meltwater pulses in the North Atlantic. Scientists suspect that these changes were triggered by the retreat of the North American ice sheet. The flow began to stabilize around 6,500 years ago, and the AMOC reached its current strength of around 18 Sverdrup, which corresponds to a volume flow of one billion liters per second.
Importance of the AMOC for the climate
How GEOMAR explains, the ocean currents in the Atlantic Ocean are crucial for the climate. Cold, salty water is sinking off Greenland while warm water flows north from the tropics. This overturning movement is known as AMOC and plays an essential role in regulating temperatures in different regions.
For example, the Gulf Stream, as part of the AMOC, transports heat to Europe. The studies show that at the latitudes where the AMOC is active, almost twenty times more water is moved per second than through all the world's rivers combined. A new study in Nature Reviews Earth & Environment highlights that the strength of the AMOC varies within natural rhythms, but this is even more important in the context of the current climate crisis.
Current challenges and research results
Uncertainties remain regarding a possible long-term weakening of the AMOC caused by climate change. In fact, the simulation results from the VIKING20X computer model support the idea that the flow has both weakened and strengthened in recent decades - suggesting that this variability may be part of the AMOC's natural dynamics. Scisimple further states that changes in the AMOC can cause abrupt climate change behavior associated with extreme weather events and global climate patterns.
An important aspect is that climate change and human activities, such as burning fossil fuels, can increase the concentration of greenhouse gases and thus disrupt the balance of the AMOC. The influx of fresh water from melting ice also has the potential to change the salinity of ocean water and destabilize currents.
Research on the AMOC is considered crucial to better predict future climate scenarios and reduce the impact of abrupt changes. In this context, it is essential to collect new measurements of currents and hydrography in the Atlantic in order to improve model simulations and fully understand the influence of the AMOC on our climate.