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lakes & # 39; skating on thin ice & # 39; freeze as heating limits

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Thousands of lakes in the northern hemisphere lose winter ice as global temperatures rise, saying scientists will lose over 35,000 lakes to their winter cover.

Researchers say that the disappearance will have a significant impact on millions of people living near these waters.

It could also pose a threat to drinking water supplies and fish species Lakes in Canada, the US and northern Europe experience intermittent ice cover during the winter months. This means that they freeze in the colder winds, but stay free of ice during warmer winters.

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Traditional activities such as outdoor skating may become more difficult as the world warms

This already poses problems for the communities living in these regions, who stand on ice paths, crossing lakes, providing food and social connections.

Sea ice is also regarded by scientists as an important long-term indicator of climate change and one of the world's most threatened by rising temperatures.

According to the researchers, the most comprehensive analysis of lake ice loss is the case, researchers say many more lakes are ice-free in winter.

If the world manages to keep the rise in global temperatures at 2 ° C, the study suggests that the number of lakes with intermittent ice will rise to over 35,000. This can affect 394 million people living off their shores within an hour.

"It's not about the lakes getting warmer, we're talking about the ice disappearing in the winter," Dr. Catherine O & # 39; Reilly, co-author of the study at Illinois State University. [1

9659005] "Our children and grandchildren would not take something for granted."

In a worst case, when the world had warmed by 8 ° C at the end of this century, 230,400 lakes were affected. [19659005] The authors emphasize that this melting is no longer a long-term prediction of the future effects of warming.

"It will not take so much warming to feel these effects," said lead author Dr. Sapna Sharma from York University in Toronto, Canada.

"It just happens – Lake Superior, for example, is no longer frozen every winter – the Great Lakes are experiencing it – we have examples from all over the world of lakes undergoing this great change, and we predict that this will happen in many The loss of sea ice promises to put an end to cultural and recreational activities such as outdoor skating and ice fishing.

This also endangers the environmental impact. Lakes that do not freeze are more susceptible to loss of water due to evaporation.

Ice Disappear – A Case Study

From Alaska to Canada, from Germany to Japan, the report highlights similar trends in the disappearance of ice.

Suwa Lake in Japan has been gathering ice data since the 14th century. Legend has it that the back of the foot of the ice is formed by the feet of the Shinto gods as they cross the lake.

Priests have recorded the date on which this icy ridge has appeared since 1443. In the first 250 years of the record, the lake not only froze three times. Between 2005 and 2016 there were seven winters when the lake was frozen.

In the spring, the lakes get warmer faster, possibly causing harmful algal blooms and reducing the oxygen content in the water.

"From an ecological point of view, it is not good to have ice on these lakes as the ecosystem will react," Dr. Sharma.

"The rapid warming of lakes has an impact on the potential to compromise water quality and the development of algal blooms earlier in the open water season, and the levels of dissolved oxygen may decrease earlier in the summer season, leaving more fish at risk die, due to an impaired habitat. "

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The danger of ice melting may limit ice fishing in the future

The most important element in limiting the ice is the air temperature. However, there were other factors, including the shape of the lake, with more circular shorelines receiving more wind shear over their surfaces that can prevent the formation of ice.

The water depth is also very important.

"The deeper the lake is, the more heat it has and the colder it gets until the lake reaches a temperature where it could freeze," said Professor John Magnuson, a co-author of the University of Wisconsin. Madison.

The study was published in the journal Nature Climate Change.

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