January Arctic Ocean’s natural archive unlocks secrets of climate change

 The scientists studied how tiny polar foraminifera plankton record ocean acidity (pH) in their shells. When these organisms die and sink to the ocean floor, their shells form part of the ocean’s natural climate archive, which can be studied when collecting sediment cores from the seabed.   

 In both hemispheres, Polar seas are areas of strong deep-water formation which play a major role in the storage of CO2 and the Atlantic Meridional Overturning Circulation (AMOC) - the conveyor belt of marine currents that keep Northern Europe, in particular Ireland and Britain, relatively mild in winter.  

 The new findings now allow scientists to go back in time to test whether the rate at which CO2 is removed from the atmosphere is reduced when the AMOC slows down. 

 The research has been published in the scientific journal Biogeosciences and is available here https://cp.copernicus.org/articles/19/2493/2023/cp-19-2493-2023.pdf. 

 These and other findings and policy issues will be discussed at the third Annual Irish Atlantic Meridional Overturning Circulation (AMOC) Meeting taking place from today at University of Galway.   

 Dr Audrey Morley, senior researcher on the project, said: “Our analysis of the tiny polar foraminifera has opened a door to answer questions about climate change which was previously unavailable. We can use our new method to look at the acidity of the polar surface ocean and how it changed over time. That also gives us a deeper understanding of how the Atlantic Meridional Overturning Circulation controls our climate.”  

 Scientists warn that Atlantic Meridional Overturning Circulation (AMOC) is at risk of being disrupted due to rapid global warming. The ultimate threat is that a weakening or collapse of the AMOC triggers extreme weather events and disruptive changes in seasonality across Europe. 

 Dr Morley said: “Today, 25-30% of the anthropogenic (human-caused) CO2 emitted into the atmosphere is absorbed by the ocean, effectively mitigating the impact of anthropogenic greenhouse gas emissions on climate change. Whether or not, or how, the rate at which CO2 is removed from the atmosphere changes in response to global warming, or a weakening or collapse of the AMOC, is a critical question that remains to be determined. 

 “There is a risk if the AMOC slows down and deep-water formation slows down then the cold-water areas of the Polar Oceans won’t remove as much CO2 from the atmosphere and store it away in the deep ocean as they do now.  

 “The analysis of past warm climates can help us shed light on these important feedback processes. Closing this knowledge gap is crucial if we want to fully understand and quantify the risks of future global warming.” 

 The third Annual Irish Atlantic Meridional Overturning Circulation (AMOC) Meeting is hosted by the Ryan Institute at University of Galway and is proudly co-organised with Maynooth University and Met Éireann. It brings together leading researchers, state agencies and policymakers to discuss latest research findings and future priorities for AMOC research in Ireland. 

 Ends