The Atlantic Meridional Overturning Circulation (AMOC) is a complex system of oceanic currents, of which the Gulf Stream is an integral component. The AMOC carries warm water from the Gulf of Mexico to Europe, playing a crucial role in maintaining a mild climate. However, recent research has revealed that the strength of the AMOC is influenced by various factors, including the sinking processes in the Labrador Sea southwest of Greenland.
In a groundbreaking study conducted by scientists from the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany, it was found that fluctuations in the Labrador Sea can have a significant impact on the strength of sinking processes east of Greenland. The Labrador Sea, situated between Canada and Greenland, experiences intense winter storms that cool the ocean temperatures, causing the surface water to become heavier than the water below. This leads to the mixing of the water column during winter, resulting in the formation of dense Labrador Sea water.
Using advanced computer simulations, the researchers examined the Labrador Sea’s influence on sinking processes in the deep-sea basin between Greenland and Iceland over the past 60 years. The simulations highlighted the years 1990 to 1994, during which the Labrador Sea experienced exceptionally strong cooling. The volume and density of the resulting Labrador Sea water were significantly higher during this period, leading to increased sinking between Greenland and Iceland. As a result, the simulations predicted a substantial increase in Atlantic overturning transport, peaking in the late 1990s.
The study’s findings shed light on the observed weakening of the Atlantic circulation in the North Atlantic since 2004. The measurements of the circulation during this period coincided with the decay phase of the simulated transport maximum, confirming the impact of the Labrador Sea on the AMOC. However, it is important to note that the observed weakening may be attributed, at least partially, to the extreme Labrador Sea winters of the 1990s.
While the study provides valuable insights into the past and present state of the AMOC, it also serves as a warning for the future. Climate models indicate that human-induced climate change will likely lead to a long-term weakening of the overturning circulation. Therefore, ongoing observing programs and the continued development of simulations are crucial in understanding the key climate-relevant processes and projecting the future of the Gulf Stream system under climate change.
The Labrador Sea and its intense winter storms play a crucial role in the strength of sinking processes in the Atlantic Meridional Overturning Circulation. The findings of the study conducted by the GEOMAR Helmholtz Centre for Ocean Research highlight the impact of the Labrador Sea on the transport of dense Labrador Sea water between Greenland and Iceland. The study’s results not only explain the observed weakening of the Atlantic circulation but also emphasize the need for further research and monitoring to better understand the implications of climate change on the Gulf Stream system. With continued efforts in studying the AMOC, scientists aim to improve future projections and develop effective strategies to mitigate the potential consequences of a weakened overturning circulation.