Free Cold by Bill Streever Page A

shortened growing seasons translated quickly into hardship, but at the same time, certain fish species moved south. “The
     herrings,” wrote British geographer William Camden in 1588, “which in the times of our grandfathers swarmed only about Norway,
     now in our times… swim in great shoals round our coasts every year.” In 1610, John Taylor of central Scotland wrote, “The
     oldest man alive never saw but snow on the tops of divers of these hills, both in summer as well as in winter.” The Thames
     froze repeatedly, providing an icy thoroughfare through central London. Diarist John Evelyn, in an entry dated January 24,
     1684, wrote, “Frost… more & more severe, the Thames before London was planted with bothes [booths] in formal streets, as in
     a Citty… the trees not onely splitting as if lightning-strock, but Men & Cattel perishing in divers places, and the very seas
     so locked up with yce, that no vessells could stirr out, or come in.” In 1692, a French official wrote, “The poor people are
     obliged to use their oats to make bread. This winter they will have to live on oats, barley, peas, and other vegetables.”
     Between 1695 and 1728, Eskimo kayakers, apparently hunting along the southern edge of the polar ice and then perhaps blown
     off course or intentionally exploring south of their normal hunting grounds, were spotted off Scotland’s Orkney Islands. In
     at least one case, kayaks were seen as far south as the River Don near Aberdeen.
    This was all part of what has come to be called the Little Ice Age. François Matthes, a glacial geologist, first used the
     phrase “little ice age” in 1939: “We are living in an epoch of renewed but moderate glaciation — a ‘little ice age’ that already
     has lasted about 4,000 years.” Later, the Medieval Warm Period was recognized, separating a cold snap that had started around
     2000 b.c. from the cold snap that started sometime around the fourteenth century. But it is not right to think of these periods
     as cold snaps. They were, on average, colder than earlier times, but only by a couple of degrees. Summers could be quite hot,
     but winters were colder and longer than at other times, bringing the average down.
    Dust from volcanoes played a role, but only well after cooling had started. A disruption in warm ocean currents may have played
     a role, too, but then one would have to ask what disrupted the currents themselves. It is known that changes in the sun of
     only a few tenths of a percent can change the earth’s climate. In 1711, the English astronomer William Derham commented on
     “great intervals” with no sunspots between 1660 and 1684, at a time when stargazing was increasingly popular: “Spots could
     hardly escape the sight of so many Observers of the Sun, as were then perpetually peeping upon him with their Telescopes…
     all the world over.” Although much has been made of this, no one has explained why sunspot activity decreased or exactly how
     this might explain climate change.
    Snow played a role in the making of the Little Ice Age. Snow is an almost perfect reflector, sending heat and light back into
     space with remarkable efficiency. When snow covers the ground, the earth does not warm as quickly as it does when the snow
     is gone. A snow-covered planet is a cold planet. But this leaves the question of cause unanswered, since the cold would have
     had to come before the snow, at least initially.
    Whatever the cause of the Little Ice Age, and as significant as it may have been to the people it iced, it was nothing compared
     to what is normally thought of as the Pleistocene Ice Age, the series of cold snaps that led to massive glaciation. Despite
     its name, the Pleistocene Ice Age started during the late Pliocene, some two and a half million years ago, with the spread
     of ice sheets in the Northern Hemisphere. For two and a half million years, it waxed and waned in intensity. The ice sheets
     advanced and retreated,