According to one new study carried out by a team of Irish, British and German scientists and published in the journal Nature Geoscience (Caesar et. at the., February 25, 2021), human-induced climate change has resulted in a substantial reduction in the flow of the Gulf Stream. In addition, the researchers predict that if the trend continues, which is likely under current conditions, the degradation of the Gulf Stream will reach a “tipping point” beyond which the change will become irreversible, producing major negative impacts on human resources. weather patterns along the coasts of the North Atlantic in Europe and North America. The results of this study corroborate previous modeling that predicted the now documented slowdown.
The North Atlantic Gulf Stream, also known as the Atlantic Meridional Reversing Circulation (AMOC), originates near Florida, flows north along America’s east coast north, then moves east towards Europe, before diverging into several distinct currents. It is one of the major ocean currents in the world having a major influence on the global climate. In particular, the Gulf Stream exerts a moderating influence on the climatic regimes of eastern North America and western Europe. Without it, the weather conditions in these regions would be more extreme, with a greater amplitude of temperatures and precipitation, and a marked increase in severe storms, or even a deviation of the trajectories of winter storms over Europe. It would also accelerate sea level rise in these two regions.
The moderating effect of the Gulf Stream on weather patterns along the Atlantic coasts of the northern hemisphere is due to the enormous amount of hot water – over 20 million cubic meters per second – that it pumps into the North Atlantic, offsetting the cooler water of the arctic region to the north.
Researchers predict that the tipping point could be reached by 2100, after which the Gulf Stream would either degrade significantly or come to a complete stop. Once that happens, the change is likely to be irreversible, no matter how hard we try to moderate climate change.
Although the recording of precise measurements did not begin until 2004, researchers were able to use 11 proxy indicators to reconstruct the main characteristics of the Gulf Stream over approximately 2,000 years. These include records of atmospheric temperature, data on Atlantic silt from underwater sediment cores, records of populations of deep-sea corals, tree rings and carrots. of ice. These data made it possible to estimate the temperature of the water and the flow of the Gulf Stream. For example, different species of coral prefer specific temperature environments. Changes in coral populations therefore indicate changes in water temperature over time. And the greater the flow of water, the larger the sediment particles that can be moved by the current. The data collected, which comes from a variety of sources and dispersed locations, nevertheless presents a generally consistent pattern.
Similar research has been carried out for years. A work on the impact of climate change on the Gulf Stream was published in 2007, when Zickfield et. at the. noted that if current warming trends continue, there would be a 40% chance that the ocean current will “collapse” by 2100.
The sensitivity of the Gulf Stream flow to global warming is indicated by two changes identified in the study. The first is a slight reduction brought about by the end of the Little Ice Age, a period of natural cooling of the planet that lasted from around 1300 to 1850. The second is much more important. From the middle of the 20th century, with the acceleration of anthropogenic (man-made) global warming, the flow began to drop precipitously, which is now 15% less than the previous level. It is now at its lowest level in over a millennium.
The historical pattern of the Gulf Stream flow is determined by what is called deep convection. Hot, salty water moves from south to north where it cools and therefore becomes more dense. When it is dense enough, the water sinks into the deeper ocean layers and heads south again. Global warming is disrupting this mechanism: increased precipitation and increased melting of the Greenland ice sheet add fresh water to the surface ocean. This reduces the salinity and therefore the density of the water, which prevents sinking and therefore weakens the flow of the Gulf Stream.
A warmer climate increases precipitation and accelerates the rate of melting glaciers, the most important in this case being the Greenland ice sheet. Separate research has shown that the melting of the Greenland ice sheet is 14% faster today than it was between 1985 and 1999.
Researchers predict that at the current rate, assuming there is no significant reduction in the rate of global warming, the Gulf Stream could slow another 45% by the end of the century, reaching or approaching a point criticism of no return.
The consequences of the disruption of the Gulf Stream are yet another indication of the truly catastrophic effects of unchecked climate change. So far, meager efforts to slow the rate of global warming have been woefully inadequate, amounting to empty talk.
As in the case of the lack of an effective response to the COVID-19 pandemic, this criminal pattern is a direct result of capitalism’s manic and myopic desire to maximize profits, whatever the cost, even if it means making the earth unlivable. One only needs to look at our close neighbor, the planet Venus, an extreme and unlivable greenhouse, to see what lies ahead if the working class does not take power and quickly implement the necessary measures to stop climate change.
(Article published in English on May 4, 2021)
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