The UK’s position about half way between the north pole and the equator, and bathed by the relatively warm waters of the Atlantic, means that while we do get a few winter days when the temperature drops below freezing it rarely lasts long.

Even though the ground may be frozen for a day or two we know the ice will soon melt and we’ll shortly be back to normal because the superficial freezing is only close to the surface.

However this isn’t the case in much of the land area to the north of us, in Canada, Norway, Sweden, Finland and Russia – they often have vast areas permanently frozen solid in a condition well summed up by the word ‘permafrost’. Such areas cover about one quarter of the northern hemisphere.

There the ground can be frozen to great depths and it’s only the top metre or so that’ll melt each summer. However it’s just long enough to allow minute organisms to become active and consume organic matter resulting in high levels of carbon dioxide and methane.

This is all helped by the fact that the rate of Arctic temperature increase is around three times that closer to the equator. The melting of the frozen ground is especially active under lakes, and because of the surface melting there are thousands of them resulting in a steady increase in CO2 emissions.

The slight increase in temperature makes it more likely that snow cover will be deeper and this in turn reduces the amount of freezing and encourages more melting, in some cases staying unfrozen throughout the year.

It will be close to the end of the century before much of the permafrost melts but because it contains twice the amount of carbon trapped in the atmosphere just a fifth of it melting would be catastrophic. The result would be vigorously rising sea levels, temperatures well over 50 degrees and destructive rainfall.

It’s vital that we keep the permafrost and ice frozen if our grandchildren are to live, so drive less, have smaller cars, and think more than twice about flying anywhere.