Once again reports of the imminent death of Arctic sea ice have been greatly exaggerated. As even the pro-alarmist BBC has conceded, ‘to understand Arctic sea ice requires measurement of both area and thickness’, and it turns out that sea ice volume is well above the lowest recorded level for the time of year.
BBC: Although Arctic sea ice set a record this year for its lowest ever winter extent – that was not the case for its volume, new data reveals.
Europe’s Cryosat spacecraft routinely monitors the thickness of floes in the far north.
The thinnest winter ice it has ever seen was in 2013. This February, in contrast, the Arctic floes were about 25cm (17%) thicker on average.
The long-term trend is, however, still downwards, the Cryosat team cautions.
“Year to year, the numbers will jump about, and it just so happens that we’ve seen relatively high levels of Arctic sea ice thickness and volume in recent years,” said Rachel Tilling from the UK’s Nerc Centre for Polar Observation and Modelling (CPOM).
“But sea ice volume is definitely the number people should watch, because it is the most reliable measure of how much ice is left. It’s also what we need to understand the processes that have caused the Arctic climate to change which, in turn, will help us to build more accurate models of what may happen to sea ice in the future,” the University College London researcher told BBC News. [bold added]
The maximum extent of winter sea ice this year was called for 25 February at some 14.54 million sq km. That is the smallest winter maximum in the satellite record. It is, though, a two-dimensional view of the Arctic, and just considering extent can hide the fact that winds will sometimes spread out the floes and sometimes pile them up.
Full BBC report here.
Of course whether the long-term trend is ‘downwards’ largely depends on the start date of the period being measured. Start high and there’s a very good chance of a downward trend somewhere along the line.