The mystery of the growing “dark zone” GreenlandThe melting ice sheet is resolved.
Researchers have found that Phosphorus– Dust blown on ice can be the key to the event.
Greenland’s ice sheet is the second largest in the world. It covers about 656,000 square miles (1.71 million square kilometers), three times the size of Texas. According to the National Snow and Ice Data Center (NSIDC). However, the ice sheet is now in a state of permanent isolation, losing 500 gigatonnes (500 billion tons) of ice each year. Living science previously reported.
That’s why Dark zone So worrying. During the summer months, the western part of the ice sheet shifts from bright white to dark gray as the moss thrives on the entire surface. Since 2000, these blooms have grown, expanding the Dark Zone A statement by researchers.
The darker color of the ice reduces its albedo – the amount of sunlight it reflects back into space – and causes the ice sheet to absorb more heat. However, so far, what has turned this algal peacock into a mystery remains a mystery.
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“We see a lot of variation in the peacocks on the surface of the ice sheet,” said Janine McCachchen, a microbiologist at the University of Waterloo in Ontario and lead author of the new study describing the findings. “We want to better understand what is causing their growth,” he told LiveScience.
Understanding algal blooms
During the sunless winter months of the Arctic, ice is composed mainly of moss – Ansilonema nordenskyoldii And species in Mesothenium Genus – dormant inside ice. During the spring, as the snow melts, the algae slowly migrate to the surface. When they reach the surface, Arctic summers provide 24-hour sunlight for photosynthesis and growth. Algae are usually green, but when exposed to constant sunlight, they form dark sunscreens to protect themselves from harmful ultraviolet rays. This is what makes the ice darker and, ironically, causes it to absorb more sunlight.
But the reason for the extended blooms seen by sunlight researchers alone does not seem to be enough.
“After researchers analyzed samples collected from the surface, it became clear that algae were the most important nutrient,” Jim Qued, a climate scientist at the University of Leeds in England, told living science. “Then we found out that it is locally produced.”
In Greenland, phosphorus comes from hydroxylapetite – a mineral containing phosphate Calcium, Oxygen And Hydrogen – which is blown to this side of the ice like dust from an open scattered crop.
“As the atmosphere warms due to climate change, the exposed stone dries out and the wind becomes stronger.” “This means more dust is carried to the ice.”
More hydroxylipatite-rich rocks are also found in the area than melted ice, thus increasing the available phosphorus. Algal blooms are therefore part of the positive feedback loop: increasing melting of ice leads to higher phosphorus input, which accelerates algal growth, in turn, increasing the melting of ice.
“This kind of thing will continue to happen in the future; I have no doubt in my mind,” McQuide said, referring to the dynamic melting.
However, now that scientists have fully understood the phenomenon of the dark zone, they can more accurately predict how quickly Greenland’s ice sheet will melt.
“If we can measure the amount of phosphorus in the environment, it is possible to simulate it by predicting algal growth and allowing us to better monitor the rate of melting of ice,” McCashes said.
The study was published January 25 in the journal Nature Communications.
Published on Original Living Science.
