Prefering warmth to cold.......................

      A modest understanding of the dynamics of climactic change in past societies could well prove useful in the event that climates continue to fluctuate.  If you know that a drop of one degree Centigrade on average reduces the growing season by three to four weeks and shaves five hundred feet off of the maximum elevation that crops can be grown, then you know something about the boundary conditions that will confine people's actions in the future.  You can use this knowledge to forecast changes in everything from grain prices to land values.  You may even be able to draw informed conclusions about the likely impact of falling temperatures on real income and political stability.  In the past, governments have been overthrown when crop failures over several years raised food prices and shrank disposable incomes.

     For example, it is no coincidence that the seventeenth century, the coldest in the modern period, was also a period of revolution worldwide.  A hidden megapolitical cause of this unhappiness was sharply colder weather.  It was so cold, in fact, that wine froze on the "Sun King's" table at Versailles.  Shortened growing season produced crop failures and undermined real income.  Because of the colder weather, prosperity began to wind down into a long global depression that began around 1620.  It proved drastically destabilizing.  The economic crisis of the seventeenth century led to the world being overwhelmed by rebellions, many clustering in 1648, exactly two hundred years before another and more famous cycle of rebellions.  Between 1640 and 1650, there were rebellions in Ireland, Scotland, England, Portugal, Catalonia, France, Moscow, Naples, Sicily, Brazil, Bohemia, Ukraine, Austria, Poland, Sweden, the Netherlands, and Turkey.  Even China and Japan were swept by unrest.

-James Dale Davidson and Lord William Rees-Mogg, The Sovereign Individual: Mastering the Transition to the Information Age