GLOBAL OCEAN CONVEYOR BELT: Changes due to Global Warming

Sea water along the equatorial area gets heated by the sun, and the warmed water forms a stratification layer above the colder lower water. Eastern Trade Winds caused by Earth’s rotation and atmospheric temperatures push this water layer, creating the Global Ocean Conveyor Belt (GOCB). 

Part of this GOCB is The Gulf Stream.

The warm water reaches the North Atlantic and Labrador areas, where heat is lost to the atmosphere, mixes with cold water, and sinks. These actions form the North Atlantic Gyre, also known as the Sargasso Sea. As the cooled water sinks, warmer water replaces it, enhancing the GOCB and the Gulf Stream current. The cooled water forms a deep-water channel flowing south, under the Gulf Stream, along the eastern South American and Antarctic coasts, to the Indian and Pacific Oceans. Other gyres in the major oceans are also formed and act to further energize the GOCB by the current created by the flowing warm-to-cold water actions.  

The GOCB facilitates heat transfer among the ocean’s seas and atmosphere, thus modulating global warming. 

Increased global carbon levels, through various actions, are causing global warming. Also increasing are the depths of various heat-stratification layers, lessening the heat transfer efficiencies among these layers; the GOCB warm layer is one of these layers. 

The heat of the atmosphere is increasing, lessening the amount of heat transferrable from the oceans to the air. This causes the upper warm ocean layer to both get warmer and get thicker. The lowered water-to-air heat transfer effectively slows the water cooling, slowing the decent of cool water to the deep water current of the GOCB, thus slowing the Gulf Stream. 

The slowed current allows the trade winds to push the Gulf Stream closer to the North American continental shelf and its shallow water, lessening the cooling effects from the cool, deeper water layer. The water thus gets warmer, the warmer water expands, and sea levels rise along the coastline. Due to the Gulf of Maine’s configuration and placement, ocean warming and sea level rise is especially egregious in New England and Maine.     

Adding to this is the fresh water from increased river flowage from increasingly severe storms and the melting of polar caps, ice sheets and glaciers. Fresh water is less dense than sea water so tends to stay at the surface, further increasing the depth of the upper stratified layer of warm water, further decreasing heat transfer actions.

Recent research indicates that the GOCB has been reduced by 15-20% since the mid-1800…the surge of the Industrial Revolution, fossil-fuel burning, and its carbon-releasing effects. Evidence from research of ancient ice cores also suggests that the GOCB is at its weakest point in the past 1600 years. 

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