Q1. Will the latent heat produced during ice generation cause increased localised ice melt or significant warming of the region?
A. The latent heat released during ice formation will not cause significant local warming for several reasons, including the fact that the re-icing process affects a very small geographic area at any given time and occurs at a rate comparable to natural ice growth.
This slow, distributed approach means the released heat has time to dissipate widely through the atmosphere via winds and into the ocean, without causing any major shocks in the immediate area. In addition, re-icing is carried out during the coldest part of winter, when ambient temperatures are far below freezing, so any local temperature effects are negligible.
Additional latent heat inputs are also rebalanced during the summer months when extra ice melting (due to the creation of extra ice in winter) works in reverse to absorb latent heat, resulting in the same localised temperature change experienced in the direction of cooling.
The whole process aims to restore a natural balance between winter ice formation and summer melt, reverting from the current scenario experienced, where melting is more prominent than sea ice growth.
Finally, the enhanced albedo from additional sea ice has a longer-term planetary cooling impact that is of greater significance than the transient effect of latent heat.
Q2. What are the implications for ocean biogeochemistry from sea ice thickening?
A. During sea ice growth, brine is rejected from the ice column as seawater freezes, which enhances the salinity and density stratification of the underlying water.
Whilst the brine rejection process naturally encourages further sea ice formation, it also has other biogeochemical implications. The sinking of dense, salty water during brine rejection is fundamental to the formation of deep bottom waters at high latitudes, which feed into the global thermohaline circulation.
Brine is rich in dissolved inorganic carbon, and so the mixing of descending brine columns influences the vertical distribution of carbon in the upper-ocean and therefore carbon, and other gases, exchange between the air and ocean.
During sea ice formation, dissolved organic matter, nutrients, and microorganisms become highly concentrated within the remaining brine pockets and channels in the sea ice structure, creating an extreme habitat for tolerant organisms.
We acknowledge that biogeochemical implications are a current knowledge gap in ice-thickening research.