Enhanced Nitrous Oxide Emissions Found in Field Warming Experiment in the Arctic

As anthropogenic climate change continues seemingly unabated, research continues into the impact of our warming climate on a variety of habitats. IET Editor Rachael Simpson recently spoke to Carolina Voigt, lead author of the paper “Warming of subarctic tundra increases emissions of all three important greenhouse gases - carbon dioxide, methane and nitrous oxide”, about her work monitoring greenhouse emissions on the Russian tundra, and the interesting results she has seen.

1.    So Carolina, could you give us a bit on your background – your qualifications, where your interest on this subject stems from for example. 

I am a PhD student and I’m writing my doctoral thesis at the moment at the University of Eastern Finland with the Biogeochemistry research group. I did my masters in Germany on a similar topic, studying greenhouse gas cycling from peatlands which is where I became interested in this topic. I then applied for a PhD position here in Finland, with the opportunity of studying greenhouse gas fluxes from permafrost soils in the Arctic. I’ve been here in Finland for the past 5 years. 

2. You mention similar research you’d undertaken in Germany – was this study in the Arctic a follow-on from your previous work? 

Fluxes of carbon dioxide, methane, and nitrous oxide from Arctic soils is generally a topic that interests me, and in particular the fieldwork connected to it. Taking measurements during Arctic field expeditions and living in remote conditions with an international research team for several months in a row – that’s what interested me in the first place. And then of course in terms of the topic itself, there is huge potential for new findings and some very interesting subjects for a PhD thesis work in this field. 

3. Can you give an explanation of the methods, research techniques and equipment used in this study? 

What we are using is a quite basic method called the chamber method that is used to measure fluxes of greenhouse gases produced (or consumed) in the soil. We just place a chamber, any kind of chamber from simple to very sophisticated, on pre-installed collars in the soil and then leave the chamber in place for a certain period of time. Within this time frame there is an accumulation of gases within the chamber headspace and that is what we actually measure. From that concentration change in the chamber headspace we can calculate the flux of greenhouse gases that are emitted or taken up by the soil and vegetation. 

We also have a warming experiment going on alongside, where we are measuring fluxes from control surfaces next to surfaces that are artificially warmed. We use Plexiglass chambers (so-called open-top chambers, OTCs) which are open on top so they don’t limit air exchange much but are still warming the soil surface and the air close to it by a few degrees, which is what is predicted for the near future in climate change scenarios.

These are the core measurement methods that we are using. Of course, we are also using all kinds of surrounding supportive measurements, for example a weather station logging the meteorological conditions at the site. We are collecting water samples to determine the concentration of nutrients and carbon in the soil pore water, and we are also measuring soil temperature, moisture and other surrounding parameters that help us to put the flux data into context later on and help us to explain the patterns we are observing. 

4. Do you face any challenges whilst working in the Arctic conditions that make this research difficult?  

In the field we are living without running water or electricity so the conditions are very basic. I have to say, I was worried when I was first going out there to be living under these conditions, but I was really surprised by how quickly one can adapt to living like that, even within just a couple of days. I can’t say that I missed much other than certain kinds of food! Otherwise it was fairly easy to adapt.

You do have to be physically fit, the work involves lots of walking. The tundra landscape has no roads or paths so there is a lot of walking with quite heavy backpacks. Other than that I found living out there quite easy.

It’s quite amazing to be living in nature with the feeling of freedom that you get from being so far away from everything. On top of that we were working in the North of Russia, which I think was an additional factor in the feeling of being in the wild, even feeling like an outlaw in a way! 

5. What where the results of this study? 

We have measured over two years, two summer growing seasons that we have been in the Arctic, mainly during July and August as this is the main growing period. We measured fluxes of carbon dioxide, methane and nitrous oxide. 

What we saw was that warming of only a few degrees centigrade increased fluxes of all three greenhouse gases, not just carbon dioxide and methane but also nitrous oxide which was quite surprising - to our knowledge this is the first study that has found this warming-induced increase in nitrous oxide emissions from Arctic tundra. 

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