Melting Sea Ice Freshens the Water, Reducing Nutrient Supply to Marine Life
Melting Antarctic ice is having a profound impact on deep ocean water circulation, which plays an important role in carbon sequestration and the maintenance of marine life. A study has suggested that deep ocean water flows from the Antarctic could decline by up to 40% by 2050 due to melting Antarctic ice, potentially ending an ocean system that has sustained life for thousands of years. The implications of this slowdown could have disastrous consequences for global climate and marine food chains.
According to the study, a slowdown in deep ocean water circulation is considered vital for the health of the sea, as it plays a role in sequestering carbon absorbed from the atmosphere. The process of sinking water in the Southern Ocean helps to transport CO2 out of the atmosphere and into the deep ocean. However, melting sea ice “freshens” the water around Antarctica, diluting its saltiness and raising its temperature. This means that it sinks to the bottom of the ocean less efficiently, reducing nutrient supply to sea life.
Slowing Deep Ocean Water Circulation Could Lead to Feedback for Further Ocean Warming
The report’s authors warn that slowing down of the Antarctic ocean overturning has other knock-on effects for the planet. It could lead to feedback for further ocean warming at the base of ice shelves around Antarctica, reinforcing the original change. This would cause warm water intrusions in the western Antarctic ice shelf to increase, leaving more CO2 in the atmosphere and potentially having a disastrous impact on global climate.
Moreover, a slowdown in deep ocean water circulation could stagnate the deep ocean, starving it of oxygen and affecting production of phytoplankton – which forms part of marine food chains – leading to a cascade of impacts including sea level rise, altered weather patterns and the widespread starvation of marine life.
The modeling presented in major UN climate reports did not capture how meltwater influenced the deep ocean, which means a ‘longstanding and major shortcoming’. While it is possible to slow down the decline by lowering greenhouse gas emissions, immediate and deep changes to carbon pollution are required to prevent the world from heading towards increasingly dangerous and irreversible consequences of climate change.
Slowing Down Deep Ocean Water Circulation Has Implications for Climate Change and Marine Life
Melting ice around Antarctica is affecting a major global deep ocean current that transports heat, carbon, oxygen, and vital nutrients around the world. Greenhouse gas emissions at current levels could cause a 40% slowdown of the current in the deepest parts of the ocean in just three decades – leading to a cascade of impacts including sea level rise, altered weather patterns, and starvation of marine life.
Moreover, without immediate action on reducing greenhouse gas emissions, it may lead to a disastrous feedback loop where more melting causes accelerated slowing of the current, more heating, more ice sheet melt, and even further global warming. The slowdown would “profoundly alter the ocean overturning of heat, fresh water, oxygen, carbon and nutrients with impacts felt throughout the global ocean for centuries to come,” according to the study.
In conclusion, melting Antarctic ice is having significant impact on deep ocean water circulation that flushes nutrients from the sea floor to fish near the surface. This has implications for sustaining long-established marine food chains and mitigating global warming. Timely action such as reducing carbon emissions is important to prevent this situation from deteriorating further.
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