Fortunately it appears there are ways of estimating it in the past. Also decent records have been kept since the 1950s and partial records have been kept since the 1700s which apparently give a reasonable picture of the pattern of arctic ice melt.
I was wondering when we were all desperate for a summer a few weeks back what the displaced the jet stream might mean. A severe winter doesn't sound so good. Let's hope the local authorities are stocking up on grit.
I hope it's not too bad as high heating bills are the last thing a lot of us need at the moment. Fingers crossed it's not as bad as they think it might be.
A record low summer sea ice cover has been recorded this year and by a substantial margin. Causes can be debated, but whatever the cause this is worrying and could have a profound impact on our climate. Some have theorised that the displaced jet stream this summer has been caused by the temperature differential between the pole and the equator changing.
One of the problem with the sea ice melting is that it is a self accelerating process, the more it melts, the less reflective that part of the globe is and the more it warms.
There are also concerns that not only does it effect the jet stream but it could also affect the oceans currents, thus further impacting on weather systems.
Some Canadian scientists have predicted that the record melt this year will create a severe winter for Europe according to the guardian. I've yet to find the source for that information.