Spring is springing into life in Teddington, and lifting my spirits.
Meanwhile, further north, the winter growth of sea-ice in the Arctic is slowing, and about to reach its maximum extent.
As the graph at the head of page shows, it looks like this years ‘sea-ice maximum’ (blue line on graph) will not cover the same extent as previous maxima.
In fact, it could prove to be a minimum maximum.
The graph above shows the trend in February monthly-averaged sea-ice extent since 1979.
The downward trend is pretty clear: typically 1.5 million square kilometres of sea-ice that used to form in 1979 no longer forms.
But there is also the variability – typically ± 0.3 million square kilometres of sea-ice either forms or doesn’t because of the weather: the arctic too can have ‘mild’ and ‘harsh’ winters.
There is still time for a little more sea-ice growth before the summer melt commences. So this might not be an minimum maximum, but it will be close.
Will a minimum maximum lead to a minimum minimum?
One might think that a smaller extent of sea-ice would automatically lead – after a summer of melting – to a minimum sea ice extent this September.
This is a possibility, but the data suggests there is not a direct link.
For example, in summer 2012, the sea-ice extent ‘collapsed’ to a new record minimum. However, the March before that ‘collapse’, the winter maximum in the sea-ice extent had been ‘on the high side’ of the recent trend.
You can review the data yourself over at the US National Snow and Ice Data Centre.
They have a clever ‘Charctic’ tool for plotting the data year by year. Enjoy 🙂