“Sea ice and snow act like a protective shield”

8 June is World Oceans Day. The SLF is also conducting research in the ocean, namely on sea ice. In a short interview Ruzica Dadic, head of the research unit Snow and Atmosphere at the SLF, talks about the motivation for and the goals of these studies.
Sunset over the sea ice in Antarctica. (Photo: Mario Hoppmann / AWI / MOSAiC)

Ms Dadic, why does an institute for snow and avalanche research conduct research on the world's oceans?

Strictly speaking, we study ice on the sea and the snow on this sea ice. We are primarily interested in how snow influences the Earth's energy balance, i.e., the heat or energy that the world's oceans absorb. Especially in times of climate change, it is important to consider all processes that can influence sea ice, including snow.

In what way?

Snow and ice act like a protective shield on the surface of the sea. Similar to the sun shields for parked cars that reflect the sunlight so that it doesn't get too hot inside the vehicle. It's similar with snow, which reflects sunlight back into Space. The Earth then absorbs less solar radiation, so it heats up less. If the sea surface covered with sea ice and snow decreases due to global warming, much less energy is reflected. As a result, the warming intensifies even more. Studies show that the decrease in Arctic ice alone between 1979 and 2011 had the same effect on global energy inflow as a quarter of global CO2 emissions in the same period, which is really not negligible. We therefore want to better understand snow processes on the sea ice so that we can improve climate models on the one hand and increase the accuracy of satellite measurements on the other.

How does the SLF conduct research at sea?

First, we are making high-resolution snow measurements on the sea ice to understand how the snow differs from our alpine snow. This allows us to improve model runs so that they also take this "new" snow into account. In cooperation with the Finnish Meteorological Institute, we also use drones that are specially made to measure albedo. Of course, we can only do that on site. We also work with scientists who process satellite data to improve the interpretation of this data in relation to snow. 

Does snow affect sea ice in other ways?

Snow insulates. The more of it there is on the ice, the less ice melts in the warm season. Even biology draws on our findings. Because the amount of snow on the ice also influences how much light penetrates through the ice into the water below. And that in turn affects algae and other creatures in the sea. Our colleagues at WSL are also investigating which processes influence the stability of the large Antarctic ice shelf. Ice shelf is ice that floats on the ocean but is still connected to the ice on the mainland and can be hundreds of metres thick. It also affects the stability of the West Antarctic Ice Sheet. If this huge mass of ice becomes unstable, it can lead to a rapid rise in sea level.