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New Satellite Data Reveals Dramatic Shrinkage of Arctic Ice Cap

Climate

An ice cap in the high Arctic has lost what British scientists say is a significant amount of ice in an unusually short time.

Ice caps and glaciers such as this one in Svalbard account for about a third of recent global sea level rise.

Photo credit: Woodwalker via Wikimedia Commons

It has thinned by more than 50 metres since 2012—about one sixth of its original thickness—and the ice flow is now 25 times faster, accelerating to speeds of several kilometers per year.

Over the last two decades, thinning of the Austfonna ice cap in the Svalbard archipelago—roughly half way between Norway and the North Pole—has spread more than 50km inland, to within 10km of the summit.

A team led by the scientists from the UK Centre for Polar Observation and Modelling (CPOM) at the University of Leeds combined observations from eight satellite missions, including Sentinel-1A and CryoSat, with results from regional climate models, to understand what was happening.

Sea level rise

The study’s lead author, geophysicist Dr. Mal McMillan, a member of the CPOM team, said: “These results provide a clear example of just how quickly ice caps can evolve, and highlight the challenges associated with making projections of their future contribution to sea level rise.”

The study, published in Geophysical Research Letters, is the first to make use of measurements from the European Space Agency’s latest Earth observation satellite, Sentinel-1A.

Dr. McMillan said: “New satellites, such as the Sentinel-1A and CryoSat missions, are essential for enabling us to systematically monitor ice caps and ice sheets, and to better understand these remote polar environments.”

Melting ice caps and glaciers account for about a third of recent global sea level rise. Although scientists predict that they will continue to lose ice in the future, determining the exact amount is difficult, because of a lack of observations and the complex nature of how they interact with the climate around them.

The 20 years of satellite data that the scientists have amassed show some fairly small changes at the start of the study period, but these have since increased.

“Glacier surges, similar to what we have observed, are a well-known phenomenon,” said Professor Andrew Shepherd, the director of CPOM. “What we see here is unusual because it has developed over such a long period of time, and appears to have started when ice began to thin and accelerate at the coast.”

There is evidence that the surrounding ocean temperature has increased in recent years, which may have been the original trigger for the ice cap thinning.

Flow models

Prof. Shepherd said: “Whether or not the warmer ocean water and ice cap behaviour are directly linked remains an unanswered question. Feeding the results into existing ice flow models may help us to shed light on the cause, and also improve predictions of global ice loss and sea level rise in the future.”

The team says long-term observations by satellites are the key to monitoring such climate-related phenomena.

Dr. McMillan told Climate News Network he did not think what was happening in Austfonna suggested any sort of tipping point in the Arctic, which scientists say is warming more than twice as fast as anywhere else on Earth.

He said: “What I take from this work is that we don’t understand well enough what’s caused this sort of behavior—natural variability, ocean temperatures or atmospheric temperatures. It reinforces the complexities and the challenges of the future.”

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Aerial view of Ruropolis, Para state, northen Brazil, on Sept. 6, 2019. Tthe world's biggest rainforest is under threat from wildfires and rampant deforestation. JOHANNES MYBURGH / AFP via Getty Images

By Kate Martyr

Deforestation in Brazil's Amazon rainforest last month jumped to the highest level since records began in 2015, according to government data.

A total of 563 square kilometers (217.38 square miles) of the world's largest rainforest was destroyed in November, 103% more than in the same month last year, according to Brazil's space research agency.

From January to November this year an area almost the size of the Caribbean island of Puerto Rico was destroyed — an 83% overall increase in destruction when compared with the same period last year.

The figures were released on Friday by the National Institute for Space Research (INPE), and collected through the DETER database, which uses satellite images to monitor forest fires, forest destruction and other developments affecting the rainforest.

What's Behind the Rise?

Overall, deforestation in 2019 has jumped 30% compared to last year — 9,762 square kilometers (approximately 3769 square miles) have been destroyed, despite deforestation usually slowing during November and December.

Environmental groups, researchers and activists blamed the policies of Brazil's president Jair Bolsonaro for the increase.

They say that Bolosonaro's calls for the Amazon to be developed and his weakening support for Ibama, the government's environmental agency, have led to loggers and ranchers feeling safer and braver in destroying the expansive rainforest.

His government hit back at these claims, pointing out that previous governments also cut budgets to environment agencies such as Ibama.

The report comes as Brazil came to loggerheads with the Association of Small Island States (AOSIS) over climate goals during the UN climate conference in Madrid.

AOSIS blasted Brazil, among other nations, for "a lack of ambition that also undermines ours."

Last month, a group of Brazilian lawyers called for Bolsonaro to be investigated by the International Criminal Court over his environmental policies.

Reposted with permission from DW.

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