Breaching the Paris Agreement's temperature goal of two degrees Celsius could significantly melt the Filchner Ronne Ice Shelf in Antarctica, the second largest ice sheet on Earth, and could substantially contribute to raising global sea levels, according to new research.
The water temperature within the trough is regulated by the Antarctic Coastal Current, which causes a seasonally varying amount of warm deep water to flow into the Filchner Trough lying under the eastern portion of the ice shelf, which covers the southern part of the Weddell Sea bordering Antarctica.
Through modelling, researchers at the Alfred Wegener Institute for Polar and Marine Research in Germany have found that pulses of warm deep water -- distinct periods of time when increased volumes of this water flow into the Filchner Trough -- have been linked with an increased melting of the base of the ice shelf above.
The authors warned that continued warming of the water in the trough could lead to increased melting and subsequent rise in global sea levels. Their study is published in the journal Communications Earth & Environment.
For the study, the researchers modelled how the amount of warm deep water entering the Filchner Trough, which is up to 1,600 metres deep in places, changed between 2015 and 2100 under four different climate scenarios, based on the Intergovernmental Panel on Climate Change's (IPCC's) Shared Socioeconomic Pathways (SSPs).
They found that under the best scenario of meeting the Paris Agreement of not exceeding two degrees Celsius of global warming compared to the pre-industrial period, these warm water pulses became more frequent and by 2100, the average temperature in the trough rose 0.5 degrees Celsius above that between 1850-2014.
However, they also observed that between these pulses, the temperature in the trough returned to closer to the 1850-2014 mean, thereby limiting the melting of the ice shelf, although they were not clear exactly when and how often these pulses occur.
Under other scenarios involving greater average global temperature increases, the researchers found that the pulses of warm water became frequent enough for the trough to remain mostly filled with warm deep water year round. They thus warned that increasing average global temperatures could lead to increased melting and rising sea levels.
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