Statistical Forecasting of Current and Future Circum‐Arctic Ground Temperatures and Active Layer Thickness

Abstract

Mean annual ground temperature (MAGT) and active layer thickness (ALT) are key to understanding the evolution of the ground thermal state across the Arctic under climate change. Here a statistical modeling approach is presented to forecast current and future circum‐Arctic MAGT and ALT in relation to climatic and local environmental factors, at spatial scales unreachable with contemporary transient modeling. After deploying an ensemble of multiple statistical techniques, distance‐blocked cross validation between observations and predictions suggested excellent and reasonable transferability of the MAGT and ALT models, respectively. The MAGT forecasts indicated currently suitable conditions for permafrost to prevail over an area of 15.1 ± 2.8 × 106 km2. This extent is likely to dramatically contract in the future, as the results showed consistent, but region‐specific, changes in ground thermal regime due to climate change. The forecasts provide new opportunities to assess future Arctic changes in ground thermal state and biogeochemical feedback.

Toward the Detection of Permafrost Using Land-Surface Temperature Mapping

“…Among the TIR imagers on these satellites, only MODIS provides daily measurements of LST. Numerical modeling studies based on the empirical relationship between the ground temperature and air temperature have taken advantage of the MODIS LST products (e.g., [27][28][29]) to derive static maps of the spatial distribution of permafrost. Recently, a numerical modeling study has combined the MODIS LST products with gridded air temperature data to derive time-series maps of permafrost extent [5].…”

Identifying multidisciplinary research gaps across Arctic terrestrial gradients

“…Mean annual ground temperatures, which impact permafrost distribution, are also changing (Biskaborn et al 2019) in under-sampled regions. Aalto et al (2018b) showed that the highest increases in mean annual ground temperatures by 2080 would occur in Taimyr and east of Taimyr and in a few areas in the Canadian Arctic. Major declines in permafrost extent are expected to occur in the areas surrounding the Taimyr region, northeastern Siberia and in West Greenland (Aalto et al 2018b).…”

“…Aalto et al (2018b) showed that the highest increases in mean annual ground temperatures by 2080 would occur in Taimyr and east of Taimyr and in a few areas in the Canadian Arctic. Major declines in permafrost extent are expected to occur in the areas surrounding the Taimyr region, northeastern Siberia and in West Greenland (Aalto et al 2018b). Permafrost soils store large SOC stocks that are high in the under-sampled regions in western Canada and some parts of the Canadian archipelago (Hugelius et al 2014, Hengl et al 2017, though permafrost extent is not predicted to decrease in these areas as rapidly as for example in the Taimyr region (Aalto et al 2018b).…”

“…Major declines in permafrost extent are expected to occur in the areas surrounding the Taimyr region, northeastern Siberia and in West Greenland (Aalto et al 2018b). Permafrost soils store large SOC stocks that are high in the under-sampled regions in western Canada and some parts of the Canadian archipelago (Hugelius et al 2014, Hengl et al 2017, though permafrost extent is not predicted to decrease in these areas as rapidly as for example in the Taimyr region (Aalto et al 2018b). More observations are needed from permafrost areas with MAGT ranging between −4°C and −1°C with high SOC stocks (2000-4000 t ha −1 ) as these conditions could represent the tipping point of permafrost thaw driving a positive carbon cycle feedback.…”

“…Although we focus on under-sampled areas, we want to highlight that well-sampled regions are also undergoing rapid changes in the future (e.g. changes in permafrost extent in northern Fennoscandia, the advancement of trees in Alaska as shown in Pearson et al 2013, Aalto et al 2018b. Sampling locations within these regions has been, and will continue to be, extremely important to gain deeper insight of how Arctic environments are changing.…”