There’s been quite a lot of discussion, in various places, about the increase in Antarctic sea ice extent. I think it’s been increasing at around about 1% per decade. This is still quite a bit slower than the about 3% per decade rate at which Arctic sea ice extent is declining. However, in terms of energetics, this doesn’t tell the whole story as what is important is the amount of sea ice, not the extent.
For example, if we consider the figure below (which is PIOMAS data and is from Neven’s sea ice blog) the volume/mass of Arctic sea ice is dropping exponentially. Just the average change since 1979, is 10-20% per decade (unless I’ve done my sums wrong). This is quite remarkable and it would seem unlikely that the thickness of the new Antractic sea ice would be such as to mean that the rate of increase in Antarctic sea ice volume would be even close to the rate of decrease of Arctic sea ice volume.
I had, however, never been able to find any information about the rate at which Antarctic sea ice volume is increasing. Today, however, Oliver Bothe tweeted a link to a recent paper called Modelled trends in Antarctic sea ice volume (by Holland et al.) that seems to be an attempt to determine this. The abstract says
The model suggests that overall Antarctic sea ice volume has increased by approximately 30km3/y (0.4%/y) as an equal result of areal expansion (20×103km2/y, or 0.2%/y) and thickening (1.5mm/y, or 0.2%/y). This ice volume increase is an order of magnitude smaller than the Arctic decrease, and about half the size of the increased freshwater supply from the Antarctic Ice Sheet.
I appreciate that this is the first source that I’ve been able to find that has presented evidence for the rate of increase of Antarctic sea ice volume, so one should be careful about making too much of a single study. However, it does seem to be suggesting, quite strongly, that the rate of increase of Antarctic sea ice volume is about an order of magnitude smaller than the rate of decrease of Arctic sea ice volume. I don’t know about the rest of you, but in my world that means one is quite a bit faster than the other.