Night clouds may play an important part in melting Greenland’s ice sheet, because they act like a blanket that keeps the warm air in place and prevents it from escaping, according to scientists.
In a new study – published January 14 in the journal Nature Communications – scientist from the University of Leuven in Belgium found that thirty percent of the ice sheet’s melting was caused by clouds. The temperature of the Greenland Ice Sheet also increased by three degrees due to clouds, the team of scientists said.
Kristof Van Tricht, lead author of the study and a graduate of the University of Leuven, said that a better understanding of how clouds impact the climate is necessary, especially nowadays when global warming and the potential consequences of a global sea level rise are a huge problem.
When it comes to heat, clouds can act two different ways, the scientists said. They either reflect the sunlight back into space, alleviating the warm temperatures, or they trap the sunlight, intensifying the temperatures. According to scientists, the clouds over Greenland typically trigger a cloud greenhouse effect, so they fall in the latter category.
Tristan L’Ecuyer, co-author of the study and a professor in the Department of Atmospheric and Oceanic Sciences at the University of Wisconsin-Madison, said that over the past ten years, the National Aeronautics and Space Administration (NASA) launched two satellites that have altered scientists’ views of what clouds look like around Earth.
Researchers at the Space Science and Engineering Center (SSEC) of the University of Wisconsin–Madison (UW-Madison) have developed advanced satellite meteorology. Knowing how clouds look like helps scientists better understand how much heat they are going to trap and how much they are going to reflect, L’Ecuyer said.
CALIPSO – a joint NASA and CNES (Centre national d’études spatiales) environmental satellite – and CloudSat – a NASA Earth observation satellite – provide data about clouds above Greenland, to help scientists figure out whether they actually contribute to climate change, rather than mitigate it.
From 2007 to 2010, L’Ecuyer took X-ray images of clouds above Greenland. Then, the team of scientists from Belgium combined that data with one of their ground-based research. They found that night clouds contributed to increased levels of ice loss, because they prevented the ice that melted during the day from refreezing overnight.
The authors wrote in their study that the refreezing of molten water drops from 58 percent in clear-sky conditions, to 45 percent when clouds are present. The thirteen percent decrease is substantial, and it could grow even further.
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