New research from Colgate University alters our understanding of seasonal thawing in parts of Antarctica, revealing that summer thawing occurs nearly a month earlier and lasts nearly two months longer than previously thought.
Antarctic summer thaw starts earlier and ends later than previously believed
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The study, "Timing and duration of ephemeral Antarctic water tracks and wetlands in the McMurdo Dry Valleys using high temporal-resolution satellite imagery, high spatial-resolution satellite imagery, and ground-based sensors," was published today in Arctic, Antarctic, and Alpine Research,as per ScienceDaily.
The researchers used Planet's newly available satellite imaging, which can scan the Earth's surface daily or even multiple times per day.
The new data stream is having a significant impact, as researchers previously had to rely on far fewer satellite images, or travel to Antarctica to conduct soil measurements in person.
Scientists discovered that when you can scan coastal Antarctica almost every day, not just a couple of times a summer, the ground is actually thawing and turning into icy swamps a full month earlier than we used to think, and it stays wet and thawed a full two months later, even into March, said Levy.
What's more intriguing is that this ground is thawing and staying thawed at temperatures below freezing, indicating that salts must be assisting in melting and keeping it muddy, similar to salting a road during a snowstorm, he said.
According to Levy, the extended melt is beneficial to organisms that require meltwater to survive in the harsh climate, but it is detrimental to the permafrost's long-term stability.
Antarctic thaw quickens, trillions of tonnes of ice raise sea levels
An accelerating thaw of Antarctica has raised global sea levels by nearly a centimeter since the early 1990s, posing a risk to coasts from the Pacific islands to Florida, according to an international team of scientists, as per Reuters.
If all of Antarctica's ice melted, it would raise sea levels by 58 meters (190 feet), dwarfing frozen stores from Greenland to the Himalayas and creating the greatest uncertainty in understanding global warming and ocean levels.
Between 1992 and 2017, the frozen continent lost nearly three trillion tonnes of ice, according to 84 scientists in what they called the most comprehensive overview of Antarctic ice to date.
The thaw, as measured by satellite data and other methods, has contributed 0.76 cm to sea level rise since 1992, the researchers report in the journal Nature.
Since 2012, ice losses have increased to 219 billion tonnes per year, up from 76 billion previously.
"The sudden increase is a big surprise," University of Leeds professor Andrew Shepherd, who led the report, told Reuters.
According to the study, the majority of the ice is being lost from West Antarctica and the Antarctic Peninsula, where warmer ocean water is melting floating ice shelves at the ends of glaciers, allowing ice that has accumulated on land to slide faster toward the sea.
A single millimeter of global sea level rise is equivalent to 360 billion tonnes of melted ice, or an imaginary seven-kilometer-long ice cube.
Overall, global sea levels have risen by about 20 cm over the last century, owing primarily to the natural expansion of water already in the oceans as it warms, as well as the thawing of glaciers from the Andes to the Alps.
And significant U.N. According to a 2014 assessment, sea levels could rise by 30 cm to nearly a meter this century.
According to Shepherd, Antarctica alone is now on track to raise global sea levels by about 15 cm by 2100, exceeding most previous estimates.
Such a rise, while minor, would exacerbate coastal floods during storms at high tides, he said.
Cities from New York to Shanghai, as well as low-lying nations from the Pacific Ocean to the Netherlands, are all threatened by sea level rise.
"We're keeping a close eye on these reports," said Michiel van den Broeke, professor of Polar Meteorology at Utrecht University in the Netherlands, adding that they would serve as a guide for defending the Dutch coast.
To limit global warming, nearly 200 governments agreed in Paris in 2015 to phase out fossil fuels by the end of the century.
U.S. President Donald Trump intends to withdraw from the agreement, focusing instead on American jobs and coal.
