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Rain Is Melting Greenland’s Ice, Even in Winter

Climate
Meltwater on the Greenland ice sheet. Ashley Cooper / Corbis Documentary / Getty Images

Greenland is getting rainier, even in winter, a new study has found, and that has major implications for sea level rise.

The Greenland ice sheet loses about 270 billion tons of ice each year to climate change, raising global sea levels by 7.5 millimeters (approximately 0.3 inches) between 1992 and 2011, Science Magazine explained. About half of that was due to the calving of icebergs, but recent satellite observations have revealed that 70 percent of Greenland's contribution to global sea level rise in recent years has come from meltwater running off into the ocean. Scientists wanted to understand what was driving the meltwater.


The results of one investigation, published in The Cryosphere Wednesday, show that a third of the runoff observed by the research team between 1979 and 2012 was caused by rainfall, Columbia University's Earth Institute reported. Over that same period, rain-caused melt doubled during summer and tripled during winter. Total precipitation over Greenland did not change, but the balance of snow to rain shifted.

"We were surprised that there was rain in the winter," lead study author Dr. Marilena Oltmanns of the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany told BBC News. "It does make sense because we're seeing flows of warm air coming up from the South, but it's still surprising to see that associated with rainfall."

In order to reach their conclusions, the researchers used satellite data to determine when melting was taking place as well as automated readings from 20 weather stations to determine when rainfall occurred. They pinpointed 313 incidents over the study period when rainfall triggered melting, according to Science.

Rain can lead to more melting even if it falls in winter and refreezes right away, study author Marco Tedesco explained to BBC News. That's because it leaves the ice both darker and smoother. Darker ice absorbs more heat from the sun, leading to more melt, and smooth ice enables that melt to flow faster over its surface.

"The potential impact of changes taking place in the winter and spring on what happens in summer needs to be understood," Tedesco said.

Professor Jason Box, a Geological Survey of Denmark and Greenland glaciologist not involved with this study, told BBC News he had observed first-hand during a research trip how rain could transform the ice sheet:

"After weeks of sunshine, it started raining on us and it completely transformed the surface—it got darker.

"And I became convinced—only by being there and seeing it with my own eyes—that rain is just as important as strong sunny days in melting the Greenland ice sheet."

The winter rain usually falls in lower elevations in Greenland's south and southwest, where it is carried on warm, wet winds from the south that may be getting more common as climate change shifts the jet stream, The Earth Institute explained.

"This is what climate change looks like, it's the 'Atlantification' of the Arctic," climate scientist Ruth Mottram of the Danish Meteorological Institute in Copenhagen, who did not participate in the study, told Science Magazine. "This paper identifies a really important mechanism and we need to figure out how it plays into our predictions of sea level rise."

If all the ice in Greenland melted, it would raise global sea levels by 7 meters (approximately 23 feet). Most projections say that sea levels will rise two to four feet by 2100, The Earth Institute said, but more research is needed to determine how much Greenland and Antarctica will contribute.

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A volcano erupts on New Zealand's Whakaari/White Island on Dec. 9, 2019. Michael Schade / Twitter

A powerful volcano on Monday rocked an uninhabited island frequented by tourists about 30 miles off New Zealand's coast. Authorities have confirmed that five people died. They expect that number to rise as some are missing and police officials issued a statement that flights around the islands revealed "no signs of life had been seen at any point,", as The Guardian reported.

"Based on the information we have, we do not believe there are any survivors on the island," the police said in their official statement. "Police is working urgently to confirm the exact number of those who have died, further to the five confirmed deceased already."

The eruption happened on New Zealand's Whakaari/White Island, an islet jutting out of the Bay of Plenty, off the country's North Island. The island is privately owned and is typically visited for day-trips by thousands of tourists every year, according to The New York Times.

Michael Schade / Twitter

At the time of the eruption on Monday, about 50 passengers from the Ovation of Seas were on the island, including more than 30 who were part of a Royal Caribbean cruise trip, according to CNN. Twenty-three people, including the five dead, were evacuated from the island.

The eruption occurred at 2:11 pm local time on Monday, as footage from a crater camera owned and operated by GeoNet, New Zealand's geological hazards agency, shows. The camera also shows dozens of people walking near the rim as white smoke billows just before the eruption, according to Reuters.

Police were unable to reach the island because searing white ash posed imminent danger to rescue workers, said John Tims, New Zealand's deputy police commissioner, as he stood next to Prime Minister Jacinda Ardern in a press conference, as The New York Times reported. Tims said rescue workers would assess the safety of approaching the island on Tuesday morning. "We know the urgency to go back to the island," he told reporters.

"The physical environment is unsafe for us to return to the island," Tims added, as CNN reported. "It's important that we consider the health and safety of rescuers, so we're taking advice from experts going forward."

Authorities have had no communication with anyone on the island. They are frantically working to identify how many people remain and who they are, according to CNN.

Geologists said the eruption is not unexpected and some questioned why the island is open to tourism.

"The volcano has been restless for a few weeks, resulting in the raising of the alert level, so that this eruption is not really a surprise," said Bill McGuire, emeritus professor of geophysical and climate hazards at University College London, as The Guardian reported.

"White Island has been a disaster waiting to happen for many years," said Raymond Cas, emeritus professor at Monash University's school of earth, atmosphere and environment, as The Guardian reported. "Having visited it twice, I have always felt that it was too dangerous to allow the daily tour groups that visit the uninhabited island volcano by boat and helicopter."

The prime minister arrived Monday night in Whakatane, the town closest to the eruption, where day boats visiting the island are docked. Whakatane has a large Maori population.

Ardern met with local council leaders on Monday. She is scheduled to meet with search and rescue teams and will speak to the media at 7 a.m. local time (1 p.m. EST), after drones survey the island, as CNN reported.