As befitting a researcher who has received an ERC Starting Grant, talented earth scientist Jorien Vonk has ambitious plans. She will form a multidisciplinary team with which, over the coming years, she will study the thawing of permafrost in the Arctic Circle. At times, this is a gradual process and at others, it occurs quite suddenly. When the underlying permafrost disintegrates, large tracts of frozen land and ice are swept away. The partially thawed sediments seep through groundwater towards pools, rivers and the sea and release greenhouse gases into the atmosphere. Vonk plans to analyse these extra emissions in the water, through quantitative measurements recorded around the North Pole. The research could have major implications for current climate models and the predictions based upon them.
Text: Youetta Visser
"So far, the IPCC climate models have mostly been based on the thawing at surface level. But we are increasingly observing that the deeper layers of soil are also thawing. If 50 to 80% of this permafrost is made up of wedges of ice, it thaws so suddenly that large parts of the landscape collapse and disappear. The landscape is then transformed into something resembling a gigantic piece of Swiss cheese. The chunks of thawed permafrost are seeping into the groundwater or glide away below the surface through small streams and rivers, finally flowing into the sea. There are many types of bacteria that need water to become active, which then start decomposing the permafrost during transport. Once it reaches the sea, the organic material from the permafrost sinks to the bottom. What is more, carbon dioxide and methane are also emitted as a result of the decomposition. My plan is to chart this process, estimate the volume of emissions as well as the burial at the sea bottom, and model the impact on the climate." To do this, Vonk will use a range of hydrological and biochemical research methods and a new incubation method, among other techniques. "It always starts with an idea. I observed that the permafrost in Siberia was thawing rapidly and was curious about the impact of this. This dynamic was confirmed via satellite images. Subsequently, I began seeking a way to demonstrate this in a scientifically sound manner." For the research, in addition to her own fieldwork and samples, Vonk can also use samples taken by researchers whom she has worked with previously. "In this way, I can chart the course of this dynamic over a period of ten to 15 years. They can also re-use my data again later."
As yet, very little is known about how greenhouse gases are emitted via water. The research team will therefore carry out their investigations at different places surrounding the Arctic Ocean. "We are studying a number of major Arctic rivers, such as the Mackenzie River in Canada, and taking measurements at the coast, including in a location in Northern Siberia where I have performed research before. We are also taking measurements in the Yukon area in Alaska." To properly understand the dynamics of this process, Vonk will take measurements during the seasonal thaw as well as during winter.
When putting together her research team, Vonk will focus on more than just her researchers' area of expertise. "Both when travelling and out in the field, we often work in very harsh conditions. It is freezing cold and when drilling through ice on a river, the elements have free reign. In contrast, it can get quite warm in the summer and then the air and the tundra are swarming with mosquitoes. The measurement stations are often no more than an empty room, a bed and a freezer for samples. We incubate samples onsite as far as possible, because we can only transport a small amount in dried form back to the Netherlands for further research. So I look for tough, sturdy researchers, who can work well together." The team will follow Vonk to VU University Amsterdam, where she is now based. "Of course, I will continue working with the researchers at Utrecht University; it's a small world in our field."
Dissolved organic carbon
Vonk does not shy away from large projects. "Others are doing research on the small residues in water, namely dissolved organic carbon or DOC. I am now, for the first time, examining the larger pieces of thawed permafrost, that is, particulate organic carbon or POC. This is much more diverse, which is why we must apply our techniques with great precision." After years of solo research, Vonk is happy that she now has the funds to set up her own research group, with whose help she can contribute to the field of Arctic research. "This research could have a significant impact. The most recent estimates of the influence of thawed permafrost on the future climate are that this will amount to as much as 25% of our greenhouse gas emissions."