Effects of Earth’s Slowing Circulatory System By Peter Gaughan
The increased global temperature has led to dramatic shifts in climate and weather phenomena. A recent study in Nature has found new evidence supporting a predicted side effect of climate change that will have a significant global impact.
The increased global temperature resulting from human-caused global warming is making the Atlantic meridional overturning circulation (AMOC) system to slow. The AMOC is the cycle of cooling and heating that occurs in the ocean. This is where water heats up and rises to the top of the ocean, where it then cools off and falls to the bottom of the ocean. This creates what sometimes is referred to as a conveyor belt responsible for ocean currents, weather patterns, precipitation, and seasonal weather shifts.
The AMOC has slowed from 15 percent according to publications in Nature and from Yale. Warmer global temperatures are melting ice caps and glaciers meaning the ocean water at these integral “churning points” has more freshwater mixed in. This decreases salinity, and with that decreases the density of the water, which in turn decreases its sinking ability.
The rising global temperature has also led to increased ocean temperature. This means less ocean water cools enough to become dense enough to sink and then turnover inhibiting the cycle.
Another result of climate change that is exacerbating AMOC stagnation is increased precipitation in the North. Modeling by researchers at the University of Groningen anticipates up to a 4 percent increase in precipitation in the Arctic and an extension to its rainy season. This will be freshwater that will mix in with ocean water and further decrease the density of the salt water decreasing its ability to sink and cycle.
Another harm to the AMOC comes as a result of weakening wind currents. The AMOC is in part reliant on wind patterns to aid in its flow and current, without which the cycle stops. But the same concerns about ocean water’s inability to sink and rise due to increased temperatures and decreased density applies to the atmosphere as well. Increased temperatures create less dense air which makes it less able to sink and therefore it turns over less.
Politically, this means a few things. It may affect weather phenomena like monsoons in Southeast Asia, extreme weather in North America, temperatures in the Northern Hemisphere, and sea life. It will also affect the international economy.
In certain regions, monsoons may essentially dry up because they are so fueled by the constant turnover of the sea. This will hurt agriculture and access to freshwater in India and many nations on the coast in Southeast Asia that rely on the rainy season to flood rice fields, provide nutrient inputs to agricultural land for products like tea, and fill water sources. Dairy farms in India would, in particular, be affected, as most need monsoons to keep cows fed and healthy.
A decrease in monsoons could create a humanitarian concern at the international level with water and food shortages throughout the region. India and Southeast Asia could also experience an energy crisis as they rely on monsoon season to produce hydroelectric power. An energy crisis this extreme would affect hospitals, homes, and businesses. This would not only create political problems, it could decimate local economies and dent the global one.
North American storms will become more dramatic because of the lack of turnover. Communities in New Orleans and Puerto Rico still haven’t recovered from extreme weather phenomena and have both cost the country economically, politically, and emotionally in ways, it is not prepared for should their intensity and occurrence increase.
The stagnation of AMOC can also cool temperatures in the Northern Hemisphere. Cooler temperatures may mean decreased agricultural yields and shorter growing seasons because frosts and winter weather would last longer into the year, while the warm months struggle to get warm enough for agriculture to thrive. It would also lead to more extreme winter weather conditions and temperatures that could be dangerous.
Ocean cycling is also integral to the survival of plankton, sea creatures that cannot swim against ocean currents, who use ocean currents as transportation. Many planktons are small, but core to the ocean's food chain. Many of the fish we enjoy eat plankton or other fish that in turn eat plankton as their primary food source. Without plankton the ocean ecosystem risks collapse, hurting biodiversity and the human food chain.
This will also hurt trade by increasing the cost of shipping across the ocean. Ocean liners and cargo ships take advantage of currents and trade winds even now to reduce drag and offer natural propulsion so as to cut down fuel consumption and speed up travel times. The use of fuel goes up in still water, so travel becomes more expensive. That extra cost will be added stress to the economy and inevitably the consumer.
Peter J. Gaughan V is a research assistant at The Utica College Center of Public Affairs and Election Research and student of government and geoscience.