Globally, the temperature of permafrost on Earth has risen 0.3 degrees Celsius in the last decade; and the temperature keeps rising, shows the first comprehensive study of temperature changes in permafrost at a global scale that has recently been published in Nature Communications.
When we talk about the consequences of rising temperatures in the Arctic, the focus is often on melting ice caps. Another less visible consequence happens underground - ice is melting in the permafrost which affects the foundations of houses and infrastructure in Greenland and the rest of the Arctic.
Permafrost is soil or rock in a permanently frozen state. More precisely, permafrost is defined as areas where soil (or rocks) is below zero degrees Celsius for more than two consecutive years.
A new study recently published in the journal Nature Communication under the title “Permafrost is warming at a global scale” shows that the temperature in permafrost globally has risen with 0.3 degrees Celsius on average from 2007-2016.
Associate Professor Thomas Ingeman-Nielsen from DTU Civil Engineering is co-author of the article, which is the first comprehensive study of temperature changes in permafrost globally. More than 100 boreholes distributed across a large part of the world have been examined and compared.
“The study is interesting because for the first time we have the opportunity to say something qualified about temperature changes measured in permafrost at a global scale. Our study also describes the regional differences and shows the link to changes in climatic parameters such as air temperature and snow cover. Among other things, the study shows that temperature is rising more slowly in areas where the permafrost is relatively warm (temperatures close to 0 degrees Celsius), because a larger part of the energy that is supplied to the area is used to melt the ice in the ground instead of raising the temperature,” explains Thomas Ingeman-Nielsen.
Thawing permafrost has consequences for local communities
Together with a number of Arctic Technology students, Thomas Ingeman-Nielsen and his colleague Soňa Tomaškovičová have studied the permafrost in several West Greenland towns as part of the EU-funded research project Nunataryuk, which examines the consequences of the thawing permafrost for the Arctic coastal communities.
Changes in the permafrost has great consequences for Arctic communities. When the permafrost thaws and the ice in the ground melts, the mechanical properties of the soil will change.
“Changes in the permafrost create issues with the stability of buildings and important infrastructure such as roads and airports. In certain cases, the thawing can lead to land or rock slides that can endanger both humans and the built environment. It’s therefore important to have updated knowledge of the permafrost when planning construction projects,” says Thomas Ingeman-Nielsen.
The temperature in the 124 bore holes that are part of the study have been measured yearly in connection with fieldwork. Temperature was measured either by lowering a calibrated thermistor into a borehole, or recorded using permanently installed multi-sensor cables.
Data from the 124 bore holes have been harvested from the database Global Terrestrial Network for Permafrost (GTN-P). The results are available here.