Antarctic summer thaw lasts longer than previously thought

A new study led by Colgate University has found that summer thaw in Antarctica occurs nearly a month earlier, and lasts for a full two months longer than previously thought. These findings change our scientific understanding of seasonal thawing in parts of the Antarctic continent, raising alarms regarding the negative impact of global warming on our planet.

“Antarctic water tracks and ephemeral wetlands are a primary location for biogeochemical soil processes driving cold desert soil formation. Though the spatial extent of water tracks and wetted soils has been mapped in the McMurdo Dry Valleys (MDV) on the basis of mapping darkened pixels in high-resolution commercial satellite imagery, the timescale over which water tracks and wetlands form and the duration of these biogeochemically active environments remain unknown,” the study authors explained.

By using a combination of in situ soil sensors and data from two complementary remote imagining platforms (Planet and WorldView) – which can scan the surface of the Earth daily or even multiple times per day – the scientists determined the start and end dates, together with the duration of wetted soils at ten sites located across the MDV. Their analyses revealed that Antarctic summer thawing is much more extended temporally than previously thought.

“What we found was that when you can scan coastal Antarctica almost every day, not just a couple of times a summer, we see that the ground is actually thawing and turning into icy swamps a full month earlier than we used to think, and it’s staying wet and thawed a full two months later, even into March,” said study co-author Joseph Levy, a geomorphologist and planetary scientist at Colgate.

“What’s even more fascinating is that this ground is thawing and staying thawed at temperatures below freezing, so we know salts must be helping it to melt and keeping it muddy, like salting a road during a snowstorm.”

According to the researchers, while this extended melt is beneficial for organisms that need meltwater to survive in Antarctica’s harsh climate, it is quite bad news for the long-term stability of the permafrost and for ecosystems that thrive in freezing conditions.

“This extended hydroperiod has intriguing implications for biogeochemical processes such as long-term soil development in the Antarctic, biological functioning in long-lived soil waters and droplets, and the thermal evolution of Antarctic permafrost. Our observations can serve as a baseline for detecting future change in the duration and extent of water track and wetland processes in the terrestrial Antarctic in response to future climate change,” the authors concluded.

The study is published in the journal Arctic, Antarctic, and Alpine Research.  

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By Andrei Ionescu, Earth.com Staff Writer