I reported recently that the extent of Arctic sea ice in 2013 was greater than its extent in the previous few years and how some of the media have reported this as evidence that the planet is not warming. Of course nature and climate is far too complex to be able to regard one fact as conclusive of any climate change theory; matters are complex beyond our present understanding; we can get glimmers and hints of the truth but always have to look at as many different sources as we can find.
Let us look at how this works with Arctic sea ice. There are two ways of measuring ice at the Polar Regions. The extent of ice cover measures the area, but that in itself is not enough; we must also look at the volume of sea ice as well as its extent, because it is perfectly possible to have a large area of thin ice or a small area of thick ice.
For the past three years the European Space Agency Cyrosat mission has found that Arctic sea ice in terms of its volume is shrinking. During April and May it recorded a volume of Arctic ice of just less than 15,000 cubic kilometres, which is half the volume of ice estimated to have existed thirty years ago.
That fact in itself is not proof of anthropogenic climate change; it is simply another fact that will make us all feel less comfortable for the futures of our descendants.