We are exploring different ways by which we could possibly not only reduce the rate of loss of ice from the Arctic but start to refreeze it. The first approach involves increasing the amount of the incoming radiation from the sun which is reflected back into space. There are a number of potential concepts which might work, but the one we are focusing on is Marine Cloud Brightening. The fundamental concept is based on the fact that for a given moisture content in a cloud, if the moisture is contained in more smaller droplets rather than fewer larger ones, the cloud is whiter and hence will reflect more sunlight. The key question is then how we might provide more cloud condensation nuclei of the right size in order to make the clouds which form brighter.
Condensation nuclei for clouds which form over the ocean are provided by salt crystals emanating from evaporated droplets of sea spray; when the wind blows over the ocean it generates sea spray, and once these droplets evaporate they are carried upwards naturally by convection currents. We are therefore looking at ways in which we might generate more sea spray, and where and when this activity should take place.
The second area of research we have commenced involves exploring whether it might be possible to create more freezing during the Arctic winter. When sea ice forms, it does so from the bottom of the previously formed ice because ice is less dense than water. As a result of this feature, the rate at which ice forms decreases with thickness of the ice; ultimately the latent heat of freezing is lost by transfer to the Arctic air and radiation to space, but thicker ice acts a better insulator than thinner ice. We are therefore looking at whether it might be possible to pump sea water on top of the previously formed sea ice. This work currently involves laboratory experiments and mathematical modelling.