Ice thickening field experiments via artificial flooding of snow-covered sea ice in Vallunden Lagoon, Svalbard

Ice thickening via flooding offers an intervention to combat the rapid decline in Arctic summer sea ice. To investigate this climate engineering technique, field experiments were conducted in Vallunden Lagoon in Van Mijenfjorden, Spitsbergen between March and June 2024, whereby first-year snow-covered sea ice was artificially flooded with an ice road pump. SIMBA thermistor chain systems and net radiometers were installed to actively monitor the snow and ice thicknesses and the incoming and outgoing shortwave and longwave radiation at specific sites. Additionally, ice cores were collected during and for several days immediately following the flooding for the ice thickness, salinity, and density measurements. It was found that flooding the snow resulted in thicker ice (snow ice on top of congelation ice) which melted at a similar rate as a nearby reference site of unaltered ice cover. The thickened site was measurably colder during the melt season than the reference site. During a particular week in the melt season with clear skies, the thickened site demonstrated a higher surface albedo than the reference site, which may be attributed to higher freeboard and less melt pond coverage, and more visible whiteness of snow ice compared to congelation ice. Several topics remain to be addressed in upcoming field experiments. The effect of size of the thickened area on longevity, the effect of timing of the flooding in the ice season on congelation ice growth, and the effect of flooding on sea ice biota require further investigation.