Ancient carbon beneath frozen Arctic lakes... by Mark Stevenson

These images weren't taken while location scouting for Disney's Frozen but during a science expedition to find ancient carbon in West Greenland. In the first blog of 2015 Mark describes his icy expedition and why it's important to understand how much carbon is stored in  the thousands of lakes along the ice free coastal plain. He asks if these lakes will act as a good store of carbon or whether with future climate warming they will start to release more CO2 into the atmosphere...

Let it snow... an ice covered Lake Disko (Photo by E.Pearson)
Disko island lake number 2 (of many thousands), I am on the right and my field assistant Joe Bailey on the left.
During my PhD research I had the opportunity to visit the remote and beautiful island of Qeqertarsuaq (Greenlandic) or Disko Island as it is more widely known. The visit involved taking cores of sediment that had accumulated at the bottom of the lakes (over the last 10,000 years) for various geochemical analysis of the carbon in the sediments.

As we visited Disko Island in spring the lakes were still frozen so we had to core through the surface  ice into the sediments underneath. We also surveyed the areas around the lakes to look at the soils and plants that subsequently might get washed in and then have their carbon stored on the lake bed. Access to the lakes was by snowmobile which was an amazing experience, with lots of helpful logistical support provided by the University of Copenhagen’s Arctic Station.

Me placing the samples into a mass spectrometer
for isotope analysis at the BGS (Photo Jonathan Dean).
Back in the UK I have spent the last year doing laboratory work (at Nottingham, Newcastle and the BGS) focusing for the moment on just three lakes with different catchment (the area immediately around the lake) types. I can tell where the carbon in the lake sediments has come from using carbon isotope, pigment, and lipid biomarker analysis.  These types of analyses are complicated and take a lot of time, but worthwhile as I can unpick the source of the carbon (soils, rocks, plants within the lake etc.) which is really important. From initial data I have shown that the lakes with small catchments have less soil carbon in-washed, whereas much larger lakes have greater soil carbon washed in during the spring thaw, and this relationship has changed over the last 10,000 years. Another important finding is that some lakes, mostly those at higher altitudes in the landscape, with smaller catchments have algal communities that are different today compared to the past. 

So what have I found out and how do these lakes’ influence the global carbon cycle?

It’s complicated! The thousands of Arctic lakes contain a lot of carbon which is effectively being stored in the sediments, preventing more CO2 from entering the atmosphere (carbon from soils often reverts into CO2 through bacterial action). At the moment the larger lakes are storing more carbon than is being released as CO2 back into the atmosphere. What I now need to investigate is if this was the case in the past when conditions were warmer, for example the Medieval Warm Period (AD950 to 1100) or early Holocene (c. 8,000-6,000 years ago) warm period. When I have figured this out I can estimate how much additional CO2 will go into the atmosphere from Arctic lakes during a warmer world. Release of this store of Arctic carbon will further exasperate global warming.

I am very pleased with the progress of my project so far and am looking forward to new data in the New Year which will help to make my initial interpretations more robust. The collaborations in my project have really helped ‘add value’ to my project and training and I am very grateful to everyone who has been involved. Big thanks especially to Suzanne McGowan and George Swann (Nottingham), Emma Person (Newcastle) and Melanie Leng (BGS).

Happy New Year, I will look forward to updating you later in the year!


Mark is doing his PhD research at the University of Nottingham in the School of Geography, he has recently started a new aspect of his project within the Centre for Environmental Geochemistry at the BGS.


John Hopper said…
This work is so vital we need to have hard geo info asap. Look forward to reading the results of his research.