How plants, insects and soil influence Arctic climate change
Biogenic volatile organic compounds (BVOCs) are gaseous molecules released primarily by vegetation. “There are thousands of different BVOCs,” explains TUVOLU project principal investigator Riikka Rinnan from the University of Copenhagen in Denmark. “These are not greenhouse gases, but rather gases that react quickly with other components in the air.” Scientists are discovering that these reactions can have consequences for our climate. They can increase the production of ozone, a greenhouse gas, and increase the lifetime of methane, another greenhouse gas. BVOC interactions can also produce aerosol particles, which can seed clouds.
Vegetation changes, insect outbreaks and permafrost
The TUVOLU project, supported by the European Research Council, looked at how BVOC emissions might be changing in Arctic ecosystems. This is a critical area of study, as the Arctic region is warming faster than the global average. “This warming is causing large vegetation changes in the Arctic,” notes Rinnan. “We wanted to find out how this might be affecting BVOC levels, and whether permafrost thaw might be relevant.” The project also looked at the role of insect outbreaks in the Arctic region. As temperatures increase, insect survival rates may also increase. Many plants produce and release certain BVOCs to protect against insect attacks. A key element of the project involved fieldwork in Greenland, Norway and Sweden. “We used helicopters to transport really expensive equipment, such as mass spectrometers, into really difficult and challenging conditions,” adds Rinnan. This equipment was used to measure vegetation temperatures and BVOC gases, and to take samples back to the lab. “Permafrost samples for example were collected in the Arctic, shipped back frozen and melted in the lab,” says Rinnan. “This enabled us to measure what was happening when permafrost thaws. We also carried out computer-based modelling to get a picture of the whole Arctic region.”
Temperature sensitivity and BVOC production
The project successfully linked temperature sensitivity to BVOC production. “By combining thermal imaging of leaves with the BVOC data we gathered, we were able to show that vegetation in the Arctic tundra is very sensitive to temperature,” notes Rinnan. “We could see that BVOC emissions increase steeply in line with temperature increases.” One surprising discovery was just how strong an impact insects can have on the release of BVOCs. “Many BVOCs are designed to deter insects, and are only released when under attack,” explains Rinnan. “We found that severe insect outbreaks, often encouraged by warmer weather, can have a significant impact on BVOC levels.” The team is still working on gleaning insights from the permafrost samples. Rinnan adds that current BVOC models tend not to take account of either insects or soils – something that the TUVOLU project has shown needs to be addressed.
Modelling Arctic climate change
Indeed, the project has helped to underline just how complex modelling Arctic climate change is and opened new avenues of research. “There are still lots of questions,” says Rinnan. “For example, how do CO2-level increases impact BVOC emissions?” Another important avenue of research is the role of soils. “It seems that soils tend to take up BVOCs, rather than produce them,” remarks Rinnan. “This is something of a hot topic, and something that we are continuing to work on. These are all questions that we first need to find answers to, in order to start on the road towards mitigation.”
Keywords
TUVOLU, plants, insects, Arctic, climate change, vegetation, permafrost
