Arctic Rivers to Spill Their Climate Change Secrets

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A team of scientists from France, Russia and the US is analysing Arctic river water to understand the impact of thawing soil on the carbon cycle. Results from the EU-funded project will help researchers better model the long-term effects of climate change.

Every spring in Igarka, residents of the isolated Siberian timber town, located some 160km north of the Arctic Circle, sweep snow into neat piles in front of their apartment blocks. Though green shoots can be seen in the trees, the long winter is far from over. The ground is thick with snow; the river still iced over.

In April 2014, the town’s 6 000 residents received a rare visit: a group of scientists from the Functional Ecology and Environment Laboratory (EcoLab) in Toulouse, France, were in town to take water samples from Igarka’s vast Yenisei River, which stretches 5 539km from Mongolia to the Kara Sea. The scientists planned to return for several years so they could better understand what effect dissolved and particulate organic carbon in the river could have on global warming.

Credit: © alekseynikiforov – fotolia.com

Organic carbon is found in all living matter: your skin, the lettuce in your sandwich, the wood of your table. It is also stored in permafrost – ground that is kept perennially below zero for at least two consecutive years. Permafrost covers around a quarter of the Earth’s surface, including Siberia, and stores half the world’s soil organic carbon. But as climate change warms the Arctic soil, its frozen layer is becoming thinner. Bacteria feed on the thawing carbon, turning it into CO2. The CO2 released into the atmosphere contributes to global warming, which thaws the soil further.

“It’s as if you left your freezer unplugged for two weeks,” explains Roman Teisserenc, leader of the TOMCAR-Permafrost project. “The food would go mouldy and start to produce lots of liquid. Everything would decay.”

Breaking the ice

Teisserenc and his team focus their efforts on the water that flows from the thawing watersheds of Siberian permafrost and into the river. It is a dangerous operation, especially during springtime when the ice on the river is fragile, and the water beneath flows fast. Thankfully, his Russian colleagues have an intimate knowledge of Igarka’s weather and snow conditions.

The scientists extract thousands of litres of water from beneath the river’s icy surface. They reduce this to a concentrate, from which they obtain just a few grams of powder: all the solid material that has dissolved in the river. They use this powder to analyse the quality of the organic carbon. During each day of sampling they are able to analyse more than 200 variables, including mercury.

“The mercury we’re recording helps us calculate the mercury budget in the Arctic Ocean,” explains Teisserenc. “Fish and birds there are contaminated, even though we are quite remote from anthropogenic pollution.”

It is currently too early to accurately describe the effect of carbon transfer from soils to rivers on climate change. However, the TOMCAR team has made its data publically available, and is producing a number of publications that should help climate scientists refine their carbon-cycle models.

A personal journey

Teisserenc says his repeated trips to Igarka have affected him deeply: “One of the big motivations of doing this research is sharing these moments with people who are kind and welcoming and protective. You imagine the people you meet will be very different to you, because they live in a totally different country and culture. But after a while, you realise you have a lot of common experiences and shared values,” he notes.

He is also optimistic that the results of the research project, supported by the Marie Curie Programme, will not only shed light on what is happening on the ground in this remote part of Russia but also play a future role in better understanding the wider ‘horizontal’ impacts of climate change.

Teisserenc says the TOMCAR project has given his career and research a huge boost.

“The project changed my life! Thanks to the funding I received, I was able to get a permanent position and develop several related projects internationally. TOMCAR helped me to develop a new network of colleagues in Europe, after 10 years spent in Canada. It launched what’s been a dynamic and exciting scientific career, where I’m given a lot of independence in my research.”