For a moment, forget rainforest wildfires and 40C London summers. Two of the most profound climate change symptoms may be quietly unfolding below the waterline.
There’s a ‘cold blob’ in the North Atlantic. The jury is out on what this phenomena says about a global climate system that’s shifting faster than we can model the potential outcomes. But a growing number of voices are warning this could mark the beginning of the end for the planet as we have known it for millennia.
The ‘warming hole’, as some people term it, is a patch of very cold water in the sub-polar North Atlantic. Just south of Greenland, this area is unique: it’s the only place on Earth to have experienced significant cooling since the 19th Century, with temperatures now around 1C below 1900 levels.
At the most hopeful — kind of — this mystery could be explained by more heat from the ocean passing into the atmosphere in this particular location. In contrast, it could be an early sign that the collapse of the Atlantic Meridional Overturning Circulation (AMOC) is now underway.
If that is happening, the impact on weather systems and thermometers with be huge. Initially, extreme summer heatwave patterns will continue as the aquatic ‘blob’ triggers a change in other natural processes, including the atmospheric jetstream, leading to heat dumps and sudden cold snaps in countries like the UK. Longer term, the outlook reverses as less warm water and air passes through Europe.
‘You can compare the weather and climate in other regions at the same latitude as us. To the west there are these notoriously cold regions of Canada, right?,’ Dr Dafydd Gwyn Evans, a senior research scientist in physical oceanography at the National Oceanography Centre, told The Independent. ‘The idea is that the reason we have such a mild climate here is because of all this warm water that’s transported north by the AMOC. And, in the absence of that warm water and a cooling of the subpolar North Atlantic, we might expect that our weather could become more like eastern Canada.’
Thousands of miles south, tidal patterns around the last land mass before the Antarctic are also puzzling scientists. Academics working on the Convex Seascape Survey have ‘reconstructed’ ancient tides across the Patagonian shelf, and concluded the flow of water is now stronger than it has been for around 21,000 years. Although this contrasts the AMOC collapse theory, which, if true, would mean currents are weakening up north, both are caused by the same thing — melting ice caps and sheets.
Although the impacts of tidal changes in South America are not overtly clear, those working on the project say the study is significant as it shows that even with relatively minor sea level rise there can be an important shift in the shape and pattern of tides. The effect on habitats and ecosystems, including fisheries, will be profound, and could reduce the innate capacity to store carbon emissions and produce food sources.
‘Continental shelf seas are dynamic systems, and tides are one of the key forces shaping them,’ said Dr Sophie Ward, lead author of the study and a physical oceanographer at Bangor University. ‘By reconstructing how tides changed across the Patagonian Shelf over thousands of years, we can see that sea-level change can reorganise tidal energy in complex and sometimes abrupt ways. This matters because tides influence sediment transport, habitats, coastal evolution and the processes that help lock organic carbon away in the seabed.’
Image: Joe Dudeck / Unsplash
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