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Abstract Continuous permafrost is present across the McMurdo Dry Valleys of southern Victoria Land, Antarctica. While summer active-layer thaw is common in the low-elevation portions of the Dry Valleys, active layers have not significantly thickened over time. However, in some locations, coastal Antarctic permafrost has begun to warm. Here, based on soil and meteorological measurements from 1993 to 2023, we show that wintertime soil temperatures have increased across multiple sites in the Dry Valleys, at rates exceeding the pace of summer soil warming. Linear warming trends over time are significant (P< 0.05) at six of seven soil monitoring sites. Winter warming is strongly correlated with increased numbers of down-valley wind events (Foehn/katabatics), but it may also be driven by increased incident longwave radiation at some stations (although winter longwave increase is not significant over time). While down-valley wind events increase winter warming, when down-valley wind events are excluded from the record, winter soil warming remains persistent and significant, suggesting that Antarctic soils are experiencing less cold winters over time in response to regional warming. Together, these observations suggest that some Antarctic permafrost may be approaching a transition to discontinuous permafrost in some regions as winter freezing intensity is reduced over time.
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Response of a Terrestrial Polar Ecosystem to the March 2022 Antarctic Weather Anomaly
Abstract Record high temperatures were documented in the McMurdo Dry Valleys, Antarctica, on 18 March 2022, exceeding average temperatures for that day by nearly 30°C. Satellite imagery and stream gage measurements indicate that surface wetting coincided with this warming more than 2 months after peak summer thaw and likely exceeded thresholds for rehydration and activation of resident organisms that typically survive the cold and dry conditions of the polar fall in a freeze‐dried state. This weather event is notable in both the timing and magnitude of the warming and wetting when temperatures exceeded 0°C at a time when biological communities and streams have typically entered a persistent frozen state. Such events may be a harbinger of future climate conditions characterized by warmer temperatures and greater thaw in this region of Antarctica, which could influence the distribution, activity, and abundance of sentinel taxa. Here we describe the ecosystem responses to this weather anomaly reporting on meteorological and hydrological measurements across the region and on later biological observations from Canada Stream, one of the most diverse and productive ecosystems within the McMurdo Dry Valleys.
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- PAR ID:
- 10537628
- Publisher / Repository:
- Wiley Online Library
- Date Published:
- Journal Name:
- Earth's Future
- Volume:
- 12
- Issue:
- 8
- ISSN:
- 2328-4277
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1029/2023EF004306
