Permafrost is ground that remains at or below 0°C for at least two consecutive years and usually appears in the areas at high latitudes such as Alaska, Siberia or Northern Scandinavia, or at high altitudes like the Andes, Himalayas or the Alps.
About 50% of the world’s underground organic carbon is found in northern permafrost regions. This is more than double the amount of carbon currently in the atmosphere in the form of the greenhouse gases carbon dioxide and methane.
The effects of climate change are most severe and rapid in the Arctic, causing the permafrost to thaw. When permafrost thaws, it releases greenhouse gases into the atmosphere, exacerbating the effects of climate change.
Although permafrost cannot be directly measured with remotely sensed data, many parameters which influence the ground thermal regime and surface indicators – such as surface temperature, land cover and snow parameters, soil moisture and terrain changes – can be captured by satellites.
Within ESA’s Permafrost project, a wide range of Earth observation datasets are investigated and integrated to create an information system for the permafrost research community.
The information system comprises of Circum-Arctic, regional and local scale investigations, utilising data from ESA’s Envisat satellite, along with other Earth-observing satellites and field measurements.
“Combining fields measurements with remote sensing and climate models can advance our understanding of the complex processes in the permafrost region and improve projections of the future climate,” said Dr Hans-Wolfgang Hubberten, head of the Alfred Wegner Institute Research Unit (Germany) and President of the International Permafrost Association.
Last month, more than 60 permafrost scientists and Earth observation specialists came together for the 3rd Permafrost User Workshop at the Alfred Wegener Institute in Potsdam, Germany, to discuss their latest findings.
"The already available Permafrost products provide researchers with valuable datasets which can be used additionally to other observational data for climate and hydrological modelling,” said Dr Leonid Bobylev, the director of the Nansen Centre in St. Petersburg.
“However, for climate change studies – and in particular for evaluation of the climate models’ performance – it is essential to get a longer time series of satellite observational data.
“Therefore, the Permafrost related measurements should be continued in the future and extended consistently in the past.”
ESA will continue to monitor the permafrost region with its Envisat satellite and the upcoming Sentinel satellite series for Europe’s Global Monitoring for Environment and Security (GMES) programme.
Caption: Land surface status
Long caption: Seasonal freezing patterns on land surfaces in the northern hemisphere have
varied over the past years. This animation was created using data from the scatterometer aboard the weather-monitoring satellite, MetOp.
Credits: Vienna University of Technology
Caption: Surface temperature
Long caption: Mean annual surface temperature based on data from Envisat’s Advanced Along Track Scanning Radiometer from 2006 to 2009. The rate at which permafrost evolves can be determined by studying its thermal regime, which is dependent on surface temperature. Surface temperature is a key parameter as it governs the surface energy budget and the thickness of the permafrost active layer.
Credits: University of Waterloo
Caption: Alaska subsidence
Long caption: Seasonal subsidence due to active layer dynamics on top of permafrost on the North Slope, Alaska. The animation was created using data from German satellite TerraSAR-X during the summers of 2010 and 2011.
Credits: Gamma Remote Sensing
DUE Permafrost http://www.ipf.tuwien.ac.at/permafrost/
AWI Potsdam http://www.awi.de/en/institute/sites/potsdam/