The politics of harsh winters

In the past, extreme weather and disastrous harvests have proved socially divisive. We have been warned, say climate researchers

In the winter of 1432-33 people in Scotland "had to use fire to melt the wine before drinking it" ran a line in the research about the coldest decade of winters in the last 1,000 years.

Short of real temperature readings, descriptions of such incidents and records of rivers and lakes freezing over for months at a time, tree rings and ice cores are what climate scientists have to use to trace weather extremes of the past.