02022nas a2200217   4500008004100000022001400041245004800055210004800103260001200151300000900163520139500172653001501567653001501582653001901597653002401616653001701640653001501657100001801672700002101690856009301711       2025                        eng d  a0954-102000aWinter warming of McMurdo Dry Valleys soils0 aWinter warming of McMurdo Dry Valleys soils  c01/2025  a1-183 a<p>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 &lt; 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.</p>10aAntarctica10aFoehn wind10akatabatic wind10aMcMurdo Dry Valleys10amicroclimate10apermafrost1 aFowler, Gavin1 aLevy, Joseph, S.  uhttps://www.cambridge.org/core/product/identifier/S0954102024000488/type/journal_article