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The lessons of climate change -- be ready to adapt rather than deny it is happening The history of climate change is more complex than often presented in the popular press. But it does tell us that those civilizations and communities that failed to prepare or adapt perished by HENRY HENGEVELD Last January, I spoke to a gathering of farmers in Guelph about the vagaries of past and future weather in Canada. As might be expected, part of the presentation touched on the prospects for warmer climates in the decades to come. Afterwards, a member of the audience came forward to argue, in a rather earthy sort of way, that predictions for a warmer world and claims that such is already taking place were a bunch of rubbish. After all, he asked, wasn't there good evidence that, a thousand years ago, farmers thrived on Greenland and the Brits grew grapes? Wasn't that proof that the world has been getting colder, not warmer? Climatologists digging into historical records, tree rings and other indicators of past climates have indeed discovered that Europe, Greenland and eastern North America were warm during the medieval days when the Vikings roamed the Atlantic and the Normans occupied jolly old England. While farmers in Greenland hardly "thrived," there is archaeological evidence to suggest that two colonies of some 5,000 Vikings, perched on the south and west shores of Greenland, managed to grow hay and even tried cultivating grain crops at the time, although their success in these endeavours is somewhat questionable. Their main means of sustenance, however, appears to have been fishing. This was also a time when Europe enjoyed a remarkably benign period of warm climates. I recall the late Hubert Lamb, a noted British historical climatologist, suggesting to me a few decades ago that, in his opinion, the European climate during this "Medieval Warm Period" was perhaps a touch warmer than that of the 1980s. Then the climate in these regions began to change. By 1400 AD, a major cold period (referred to as the Little Ice Age) began to engulf them, staying in place for the next few centuries. Not until the mid-1800s did the climate begin to slowly return to warmer conditions. During this time, both of the Greenland colonies disappeared completely. Historians suggest that the more northern colony assimilated with the indigenous Skraeling people of Greenland, while the southern colony was gradually extinguished by the failure of the community to adapt to the changes and the conflicts that arose with Skraelings pushed southward by the cold climates. Similarly, in Europe, many villages were abandoned because of repeated crop failures due to the wet, cold conditions. Some researchers suggest that the political unrest that caused the French revolution may, in fact, have been triggered in part by the hunger, homelessness and social unrest caused by bad climates. During the past decade or so, however, analyses of new evidence from tree rings, soil sediments and ice cores indicate that past climate conditions in other parts of the Northern Hemisphere followed a significantly different pattern from that in the regions surrounding the North Atlantic. In fact, while Europe and Greenland were warm, other regions were cold, and vice versa. When these climate conditions were averaged around the Northern Hemisphere, experts found that, at this larger scale, the Medieval Warm Period virtually disappeared and the Little Ice Age, while still evident, was of much shorter duration and much less pronounced. They concluded that the changes in Europe and Greenland were caused by periodic shifts in the North Atlantic currents, particularly the tropical Gulf Stream that keeps the lands around the North Atlantic uncharacteristically warm, given their high latitudes. Furthermore, with the continued warming in Europe and elsewhere during the 1990s, even Hubert Lamb would have to concede that the European temperatures today must be at least as warm as they were during the Medieval period. There are some lessons to be learned in this. First, we need to be cautious about what we read about climate and its variability in the popular press. Invariably, the information provided is entertaining but incomplete. We need to put such information into context with "the rest of the story." That is true with almost any information we receive, whether economic, political or scientific. Second, the demise of the Greenland colonies and the fate of the European villages in response to a relatively small change in regional climates (less than one degree) underscore the need for societies to be adaptable to change. These are not the only such examples of the collapse of societies in the wake of a shift in climate. Other similar stories emerge in the study of, for example, the collapse of Mesopotamian cultures (the cradle of civilization) about four thousand years ago, and of the Mayan civilization in the Yucatan Peninsula (now part of Mexico) a little over a thousand years ago. For these civilizations, the cause was not changes in temperature, but the onset of extended periods of drought. These disasters serve as an important reminder that, with the prospect of hotter, drier summer climates in Ontario in the decades to come, preparing for and quick response to such changes may go a long way towards coping. Such anticipatory measures can help take advantage of the related benefits (like longer, warmer growing seasons) and avoid some of the more negative consequences. Now if only we could predict the changes with greater confidence! BF Henry Hengeveld is Emeritus Associate, Science Assessment and Integration Branch/ACSD/MSC, Environment Canada © copyright 2005 AgMedia Inc.. top back