Finnish researcher looks for climate answers in cold water

When you’re an academic researcher and assistant professor in water engineering at Finland’s Aalto University, as Eliisa Lotsari is, it helps to have a passion for cold water.

You research the impact of climate change on water systems, and you specialise in rivers, from the Finnish far north to the south. Can you tell us a bit about that?

Water systems have always been a presence in my life. I spent my childhood on a farm in Pukkila, southern Finland, and I liked to keep watch on the nearby tributary of Porvoo River. So I started observing nature and the environment almost by chance.

While doing my PhD, I was struck by how little was known about water systems in winter – for example, what happens to sediment transport when a river freezes? Such issues hadn’t been considered in modelling the impact of climate change, because there was hardly any data.

Your research team performs a lot of aerial and underwater photography. Has anything particularly surprising shown up in the pictures?

You do sometimes see elk, reindeer or even a fox [in the aerial images]. And it was great to see a salmon in the underwater photos. But the most impressive thing was when we happened to schedule an autumn shoot at the very moment frazil ice was forming. [Frazil ice refers to tiny ice crystals that can form and accumulate in moving water.] We were able to see how the ice started to form at the bottom of the river. It’s rare to be able to observe and measure a phenomenon in that brief moment.

You like to study cold water – but do you like to go ice swimming?

Before Aalto, I worked at the University of Eastern Finland, in Joensuu, where they have one of the largest ice-swimming clubs in Finland. I used to frequent it quite often.