Paris (AFP)
U.S. Government scientists reported Monday that the Arctic Ocean’s ice cover has reached its second-lowest level since satellite records began in 1979.
So far this month, the Earth’s stationary skull cap has covered less than four million square kilometers (1.5 million square miles) only once in the last 42 years.
The trend is clear: the sea ice limit has decreased by 14 percent per decade during that period. Researchers reported last month in Nature Climate Change that Arctic could see the first summer of 2035.
But all that melting ice and ice does not directly raise sea levels more than a cube of melted ice, which overflows a glass of water, giving rise to a strange question: who cares?
Granted, this would be bad news for the polar bear, which is already on a glide path towards extinction, according to a recent study.
And yes, that would certainly mean a profound shift in the marine ecosystems of the region from phytoplankton to whales.
But if our main concern is the impact on humanity, then someone legitimately asks, “So what?”.
As it turns out, there are many reasons to worry about the consequences of declining Arctic sea ice.
– Feedback Loops –
Scientists say that perhaps the most basic point to make is that the shrinking ice cap is not only a feature of global warming, but also a driver.
Marco Tedesco, a geologist at Columbia University’s Earth Institute, told AFP that removing sea ice exposes the Dark Sea, creating a powerful response system.
Fresh ice reflects about 100 percent of the sun’s radioactive energy back into space.
But when that mirror-like surface is replaced by deep blue water, an equal percentage of earth-thermal energy is absorbed instead.
And we’re not talking about a postage stamp area here: the difference between the minimum average snow cap from 1979 to 1990 and the low point recorded today – more than 3 million km – is twice the size of France, Germany and Spain combined.
The oceans have already reversed the heat generated by man-made greenhouse gases by about 0 percent, but at a terrible cost, including altered chemistry, massive marine heatwaves, and dying coral reefs.
And at times, scientists warn, the liquid heat sponge can only be saturated.
– Changes in ocean currents –
Earth’s complex climate system consists of interconnected ocean currents known as wind, tide, and thermohline circulation, driven by changes in temperature (“thermo”) and salt concentrations (“helen”).
Even small changes in this great ocean conveyor belt – which revolves between the poles and in the three main seas – can have a destructive atmosphere.
For example, about 13,000 years ago, as the Earth was transitioning from the Ice Age to the International Period, allowing our species to evolve, global temperatures suddenly plummeted to several degrees Celsius. They jumped back after about 1000 years.
Geological evidence suggests a partial slowdown in thermoholin circulation due to the vast and rapid flow of cold, fresh water from the Arctic region. Was to blame.
“Melting sea ice and freshwater from groundwater in the Greenland’s Girland, and weakening Gulf currents,” said Xavier Fatvey, a research associate at the University of Liege in Belgium.
“This is what allows for a temperate climate in Western Europe compared to the same latitudes in North America.”
The huge ice sheet over Greenland’s land mass caused a net loss of more than half a trillion tons last year, all of which flowed into the ocean.
Unlike sea ice, which does not rise to sea level when melted, flows flowing from Greenland.
That significant amount was due to the degree of air temperature, which has doubled as fast as the entire planet in the Arctic.
But it was also due to a change in weather patterns, especially on an increase in sunny summer days.
“Some studies suggest that this increase in anticyclonic conditions in the Arctic in the summer results from a minimum fraction of sea ice.”
– Bear on thin ice –
According to the July study of Nature, the current pace of climate change and the arrival of ice-free summers – defined by the UN’s IPCC Climate Science Panel under one million km2 – according to the July study of Nature, polar bears will starve to death by the end of the century.
“Human-caused global warming means that polar bears have less sea ice in the summer months,” Stephen Amstrup, lead author of the study and chief scientist at Polar Bear International, told AFP.
“The final path of the polar bear has disappeared with uncontrolled greenhouse gas emissions.”
20 2020 AFP
