What scientists just discovered in greenland could be making sea-level rise even worse – the washington post electricity and magnetism pdf


Rising global temperatures may be affecting the Greenland ice sheet — and its contribution to sea-level rise — in more serious ways that scientists imagined, a new study finds. Recent changes to the island’s snow and ice cover appear to have affected its ability 4 main gases in the atmosphere to store excess water, meaning more melting ice may be running off into the ocean than previously thought.

That’s worrying news for the precarious Greenland ice sheet, which scientists say has already lost more than 9 trillions tons of ice in the past century — and whose melting rate only continues to increase as temperatures keep warming. NASA estimates that the Greenland ice sheet is losing about 287 billion tons of ice every year, partly due to surface melting and partly due to the calving of large chunks of ice. Because of the ice sheet’s potential to significantly raise sea levels as it runs into the ocean, scientists have been keeping a close eye on it — and anything that might affect how fast it’s melting.

The new study , published Monday in the journal Nature Climate Change, focuses on a part of the ice sheet known as “firn” — a porous layer of built-up snow o gastronomico that slowly freezes into ice over time. It’s considered an important part of the ice sheet because of its ability to trap and store excess water before it’s able to run off the surface of the glacier, an essential service that helps mitigate the sea-level rise that would otherwise be caused by the runoff water.

“As this layer is porous and the pores are connected, theoretically all the pore space in this firn layer can be used to store meltwater percolating into the firn whenever melt occurs at the surface,” said the new paper’s lead author, Horst Machguth of the Geological Survey of Denmark and Greenland electricity schoolhouse rock , in an email to The Washington Post. Over time, the percolating meltwater trickles down through the firn and refreezes.

“If you look at some of the other studies which have been arguing that you have unlimited capacity for retention of water in the firn, this study shows that that is not the case,” said Kurt Kjaer , a curator and researcher at the Natural History Museum of Denmark, who has studied glacier dynamics on the Greenland ice sheet but was not involved in the study.

“I think the most notable result of our study is showing that the firn reacts faster to an atmospheric warming than expected,” Machguth said in his email. By examining the cores, the researchers found that the deluge of meltwater in recent years had trickled into the firn and frozen into chunks called “ice lenses.” These lenses then began to hinder any additional liquid water from trickling down through the firn, meaning the meltwater began to accumulate and freeze near the surface, increasing the number and grade 6 science electricity unit test thickness of the existing lenses in a kind of vicious cycle.

This effect was most pronounced at lower elevations in West Greenland, where the water first ran down the ice sheet and accumulated. But Machguth and his colleagues predict that the same ice lens formation process will continue to occur at higher and higher elevations — and gas finder mn the amount of meltwater forced to run off the glacier, having no available firn to trickle into, will only increase.

This is not only a concern on the basis of its possible contribution to sea-level rise — the researchers also suggest that an increase in runoff could lead to certain feedback processes that will cause even more melt to occur in the future. Runoff water can carve channels into the ice sheet’s surface and create slushy areas, they note in the paper, which can cause a reduction in albedo — the ability of the ice sheet to reflect sunlight away from its surface. With more sunlight being absorbed, rather than reflected, surface temperatures could become even warmer and cause melt rates to accelerate.

But in the meantime, the observations represent an important step forward in understanding the processes affecting Greenland, and could help scientists improve electricity distribution vs transmission the simulations they use to make predictions about what will happen to the ice sheet in the future. “When you get this kind of dataset, a new kind of knowledge, of course it should be put into the models,” said Kjaer, the Natural History Museum scientist.