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Home / Science / The melting Arctic ice will not increase sea levels. But it still affects us

The melting Arctic ice will not increase sea levels. But it still affects us



US government scientists reported on Monday that since the start of satellite records in 1979, the coverage of ice floes in the Arctic Ocean has shrunk to the second lowest level.

As of this month, in the past 42 years, the Earth’s frozen skull cap has covered less than 4 million square kilometers (1.5 million square miles).

The trend line is clear: During this period, the area of ​​sea ice decreased by 14% every ten years.

Researchers report that the Arctic may see its first summer as early as 2035. Natural climate change last month.

However, everything that the melted ice and snow brings does not directly raise the level of the sea level, and the melted ice will overflow a glass of water, which raises an embarrassing question: who cares?

Of course, this is bad news for polar bears. According to a recent study, polar bears are already on the orbit of extinction.

Yes, this must mean that the marine ecosystem in the area has undergone a profound transformation from phytoplankton to whales.

However, if we are most concerned about the impact on humans, we can reasonably ask: “So what?”

;.

Facts have proved that there are many reasons to worry that the reduction of Arctic sea ice will have a ripple effect.

Feedback loop

Scientists say that perhaps the most basic point is that shrinking ice sheets is not only a symptom of global warming, but also a driving force.

Marco Tedesco, a geophysicist at Columbia University’s Earth Institute, told AFP: “Clearing sea ice will expose the dark ocean and form a powerful feedback mechanism.

The newly fallen snow reflects 80% of the solar radiation back to space.

But when the mirror-like surface is replaced by dark blue water, it will absorb approximately the same proportion of geothermal energy.

And we are not talking about the area of ​​stamps here: the difference between the lowest ice sheet average from 1979 to 1990 and the lowest point reported today (over 3 million square kilometers) is twice that of France, Germany and Spain combined.

The ocean has absorbed 90% of the excess heat produced by man-made greenhouse gases, but at a high price, including chemical changes, huge ocean heat waves and dying coral reefs.

Scientists warn that at some point, the liquid sponge may become saturated.

Change ocean currents

The Earth’s complex climate system includes interlocking ocean currents driven by wind, tides, and so-called thermohaline circulations, which are themselves driven by changes in temperature (“heat”) and salt concentration (“salt”).

Very small changes in the ocean conveyor belt (moving between the poles and across all three major oceans) can have devastating effects on the climate.

For example, nearly 13,000 years ago, the Earth was transitioning from an ice age to an interglacial period, allowing our species to thrive, and the global temperature suddenly dropped a few degrees Celsius.

About a thousand years later, they jumped up again.

Geological evidence shows that this is partly due to the slowing of the hot salt circulation caused by the large and fast influx of cold fresh water in the Arctic.

Xavier Fettweis, a research assistant at the University of Liege in Belgium, said: “The freshwater from the melting of sea ice and ground ice from Greenland disturbs and weakens the Gulf Stream,” said part of the conveyor belt flowing through the Atlantic Ocean.

“Compared with the same latitude in North America, this gives Western Europe a milder climate.”

The huge ice sheet on the land of Greenland lost a net loss of more than five trillion tons last year, all flowing to the sea.

Unlike sea ice that does not increase sea level when it melts, Greenland’s runoff will melt.

The record number is partly due to rising temperatures, which are rising at twice the rate of the entire planet in the Arctic.

But this is also caused by changes in weather patterns, especially on sunny summer days.

Fetweis told AFP: “Some studies have shown that the increase in Arctic anticyclone conditions in summer is partly due to the smallest extent of sea ice.”

Bear on thin ice

According to the UN IPCC Climate Science Group definition, the current trajectory of climate change and the arrival of an ice-free summer (according to the UN IPCC Climatology Group definition, less than one million square kilometers) will indeed starve polar bears to death until the end of the century. nature.

The lead author of the study and the chief scientist of Polar Bear International, Steven Amstrup, said: “Man-made global warming means that polar bears eat less and less sea ice during the summer months.”

The final trajectory of polar bears’ greenhouse gas emissions is to disappear.

©AFP


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