divendres, 27 de setembre del 2019

Sweden's tallest mountain has shrunk, thanks to climate change

View from the summit of Kebnekaise

The south summit of Kebnekaise mountain, the highest peak in Sweden, is iconic.
Several thousand climb or hike to the top every year, Ninis Rosqvist, director of Tarfala Research Station, which measures the summit annually, told USA TODAY.
But the reason for its notoriety has begun to shrink, literally.
Kebnekaise, the highest mountain in Sweden

Researchers at Stockholm University's Tarfala Research Station have found that the highest peak in the country, is the lowest it's been in recorded history. And the new height dethrones the peak from its status of tallest summit in Sweden. Scientists began recording the mountain's height in 1880, Rosqvist said.
Over the last 50 years, the height of Kebnekaise's southern peak has decreased by almost 78 feettotal.
They found that the southern peak of the mountain now stands at 6,875 feet,  nearly 4 feet shorter than the northern peak, which measured in at 6,879 feet, according to the report.
Last year, Rosqvist said that the elevation of the two peaks was the same.
The height of the southern summit varies around 10 feet between summer and winter, according to the report. The highest measurement is in May with the lowest in September.
At some point, the northern peak will become Sweden's highest point year-round. 
The top of mount Kebnekaise
The reason: Climate change.
Because a glacier covers the south peak, its height has decreased due to temperature increase.
"The melting of glaciers is mainly forced by higher summer temperatures," said Rosqvist. "If winters are snow rich and summers cool then glaciers can gain mass, but that does not occur very often anymore."
Now, a warm summer means winter snow melts away in addition to some of the glacier ice, resulting in a net loss of ice mass on the peak.

Sweden, Lapland, Snowy ridge and peak of Kebnekaise mountain

Glaciers have changed over the centuries. They grew larger from the 17th to the 19th centuries in Europe and elsewhere because the weather was colder. And in the early 20th century, the climate warmed. That kind of shift is considered natural, Rosqvist said.
"It is not possible to separate out what is ‘natural’ and human-induced climate change, but the relationship between the global temperature and the level of greenhouse gases in the atmosphere is very clear over the past 50 years," she continued.
Rosqvist said that, in her opinion, the warming over the past decade can be attributed to human activity.
The Arctic is warming at almost twice the global average with sea ice disappearing from the ecosystem. While this has made the waters more navigable through the Northwest Passage, it is also contributing to a rise in global sea level.
Click through to see other places affected by climate change.

The north summit's height remains consistent because it is composed of bedrock and isn't covered by ice, Rosqvist explained.
But it's more difficult and more dangerous to get to the new highest peak. To reach the summit, climbers have to cross a thin strip of snow surrounded by a free fall.
"The climate scenarios do not look very good, summers will continue to warm, ," Rosqvist said. "Also the winters are warming, and sometimes it rains instead of snows and that is not good of course either."

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