Adaptation of water resources management to climate change

Chapter 1Waking Up to Climate Change“The evidence shows that climate change is occurring …and we cannot wait any longer totake action,” declared UN Secretary-General Kofi Annan in a speech to American college studentsback in May 2001. Almost every day, it seems that we hear further evidence that the Earth's climateis changing. The 1990s was the warmest decade in the last hundred years, and 1998 was thewarmest year on record. During the past century, global temperatures climbed by about 0.5°C –the largest increase in at least one thousand years. 1 As a result, snow cover is decreasing, glaciersare retreating, lakes and rivers are warming, rainfall patterns are changing and El Niño episodesare occurring more often. Extreme weather, including thunderstorms, flash floods, and droughts,are becoming more frequent and severe in many areas of the world. The diminishing Arctic seaiceand rising sea levels further contribute to global distress. These changes are causing biologicalsystems to alter, affecting the range, distribution and population density of a multitude of plantsand animals around the globe. Whether the topic is polar bears or poplar trees, there is nowcompelling evidence of a world that is starting to warm up.For many water professionals, however, the onset of a warming world is not considered a realproblem. Many of the public debates on climate change have left the impression that the scienceis unclear and that the causes and effects of climate change are still in doubt. In addition, therehave been few serious attempts to inform water experts about the links between climate changeand the water sector. Under such circumstances, it is hardly surprising that the water sector hasso far paid little attention to climate change, preferring for the most part to focus on other issuesthat must seem far more pressing. Although quite understandable, continuing to ignore orunderestimate climate change and its impact on the water sector would be a mistake.In the first place, the science of climate change is now anything but unclear about whatdirection we are heading. While models might differ in projecting the rate and magnitude ofwarming, all of them project a warming of the Earth's climate, and all forecast significant changesin water quantity and quality and in the ecological character of ecosystems around the world.Though there are still some processes such as the role of clouds and water vapour that vex climateexperts, the last fifteen years of research and modelling has revealed a great deal about how theclimate system operates and the key factors that drive it to change. The original trickle of evidencehas now become a flood. Further, though a small number of scientists contest the conclusions ofclimate change research, the vast majority agree that the Earth's climate is changing and thatmuch of the change can be attributed to human activities 2,1 .“THE ORIGINAL TRICKLE OF EVIDENCE HAS NOWBECOME A FLOOD.”“So climate change is a problem, but it is probably not an urgent one” might be the reply ofa sceptical water professional. He/she would point out, quite correctly, that the most dramatic1