A paradox of cooling winter soil surface temperatures in a warming northeastern United States

Climate model projections indicate that wintertime temperatures will warm and change snowfall patterns in the northeastern U.S. Snow provides insulation for soils from air temperature fluctuations. Therefore, these snowfall changes will have consequences, particularly for soil surface temperatures. Changes in minimum soil surface temperatures were investigated using a heat flow soil temperature model, driven using daily average air temperature and snow depth data. Two scenarios of three coupled atmosphere-ocean circulation models were used to run the soil temperature model. Modeled projections of minimum soil surface temperatures in the northeastern U.S. indicate that warming will occur over the majority of the region over the 2000–2099 period. In contrast, soil surface temperature projections in the northernmost and snowiest regions of the Northeast indicate minimum soil surface temperatures will be colder. In these northern regions, the coldest soil surface temperatures are also projected to occur later in winter, but show little change in other regions. Most trends throughout the Northeast are enhanced using the higher emission scenario A1fi. Changes to snow depth drive the changes in the minimum soil surface temperatures where snow persists during winter, whereas average air temperatures drive changes in the rest of the northeastern U.S.

► Coldest minimum soil surface temperatures will warm in the future.
► Northern snowy areas show soils cooling, and coldest temperatures occurring later.
► The timing of the coldest soil surface temperatures show little change.
► Changes in snow depth affect soil surface temperatures in the north.
► Average air temperatures drive changes in the rest of the northeastern U.S.