We are heading out today (August 18) to a site about 20 km north of Inuvik. We are excited to be finally in the field. Our two trucks are fully packed with instruments and our rucksacks, some hot tea and snacks. For our first outing, we picked an easily accessible site, meaning not far walking distance to the road but within the flight line of the DLR (German Aerospace Center) campaign. Our goal is to detect rapid thaw permafrost thaw on land and from the air, i.e., to combine our observations on the ground with aerial images and airborne measurements. The thawing of permafrost can potentially tap into the carbon frozen in the ground and result in additional release of green house gases – a process that we would like to detect with our MOSES infrastructure.
Grizzly bears inhabit this area; we had already seen a couple on our road trip – safely from the car. You never know when one of those impressive creatures might just walk up to you in the tundra. So, before any field work can start, Bill gives us all an outdoor lecture on bear safety and on how to use the bear spray and bear bangers! Luckily, no bear came in sight that day.
Into the ground
Our two teams, “team aquatic” and “team terrestrial” work together to test the instrumentation on the lake and on the tundra. It is so windy though that we have to stop the sampling on the lake with the canoe after a short time. But the wind does not stop us to do mobile climate and albedo measurements and to drill into the frozen soil. First, we shovel away, removing the upper 60 cm of the soil that is thawed. Then we drill down into the frozen soil for about one meter. A first look at the frozen cores confirms that the permafrost here contains a high amount of ice, which makes this area very sensitive to permafrost degradation – once the ice thaws, the ground starts to sink – a process also called thermokarst. All samples are packed and will be taken back to Germany for ice content quantification as well as soil physical, chemical and microbiological analysis.
Good to know: Thermokarst shapes Arctic landscapes
“Thermokarst” describes both a process and resulting characteristic landforms. When permafrost thaws, ice in the ground melts. The volume change from ice to water causes the permafrost to slump, subside or fall as it deflates or settles out. In ice-rich soils this process can lead to drastic and massive changes of the land surface. Typical Arctic thermokarst landforms include thermokarst lakes, collapsed pingos, sinkholes, and pits.
Edited by: Sina Muster