Soil temperature in Canada during the twentieth century: Complex responses to atmospheric climate change

Abstract

[1] Most climate records and climate change scenarios projected by general circulation models are for atmospheric conditions. However, permafrost distribution as well as ecological and biogeochemical processes at high latitudes is mainly controlled by soil thermal conditions, which may be affected by atmospheric climate change. In this paper, the changes in soil temperature during the twentieth century in Canada were simulated at 0.5°latitude/longitude spatial resolution using a process-based model. The results show that the mean annual soil temperature differed from the mean annual air temperature by À2°to 7°C, with a national average of 2.5°C. Soil temperature generally responded to the forcing of air temperature but in complex ways. The changes in annual mean soil temperature during the twentieth century differed from that of air temperature by À3°to 3°C from place to place, and the difference was more significant in winter and spring. On average, for the whole of Canada the annual mean soil temperature at 20 cm depth increased by 0.6°C, while the annual mean air temperature increased by 1.0°C. Three mechanisms were investigated to explain this differentiation: air temperature change, which altered the thickness and duration of snow cover, thereby altering the response of soil temperature; seasonal differences in changes of air temperature; and changes in precipitation. The first two mechanisms generally buffer the response of soil temperature to changes in air temperature, while the effect of precipitation is significant and varies with time and space. This complex response of soil temperature to changes in air temperature and precipitation would have significant implications for the impacts of climate change.

Borehole climatology: a discussion based on contributions from climate modeling

“…As discussed in Sect. 3 the soil thermal and hydrological states are shaped by surface conditions (surface temperature, precipitation, snow cover, vegetation, land use, etc., Lewis and Wang, 1998;Hu and Feng, 2003;Zhang, 2005;Zhang et al, 2005;Davin et al, 2007). However, the thermal and hydrological conditions in the subsurface have also the potential to influence surface climate by modulating turbulent latent and sensible heat fluxes (e. g. Peters-Lidard et al, 1998;Sokratov and Barry, 2002;Schaefer et al, 2007) that feed back to regional climate (e.g.…”

Assessing effects of permafrost thaw on C fluxes based on multiyear modeling across a permafrost thaw gradient at Stordalen, Sweden

“…In NEST, soil temperature and the permafrost thermal regime are calculated by solving the heat conduction equation, with the upper boundary condition determined by surface energy balance and the lower boundary condition being defined as the geothermal heat flux. The effects of climate, vegetation, snow pack, ground features, and hydrological conditions on the soil thermal regime are incorporated into the model on the basis of energy and water exchanges within soil-vegetation-atmosphere system (Zhang et al, 2003(Zhang et al, , 2005. To ensure that DNDC simulates permafrost environmental factors and biogeochemistry in synchrony, NEST's functions, which describe soil thermal and hydrologic regimes, were embedded into the framework of DNDC at the model code level.…”

Observed groundwater temperature response to recent climate change

“…Such studies are often based on the assumption that long-term trends in GST will track long-term trends in surface air temperature (SAT), although this has been a matter of considerable debate (e.g., Mann and Schmidt, 2003;Chapman et al, 2004;Schmidt and Mann, 2004). For example, decreases in the duration of thickness of the insulating winter snowpack due to rising SAT can paradoxically lead to decreased winter GST (Smerdon et al, 2004;Zhang et al, 2005;Mellander et al, 2007;Mann et al, 2009;, and thus cause a decoupling of mean annual SAT and GST trends.…”