BIODIVERSITY AND CLIMATE CHANGE ISSUE PAPER No. 3 FRESHWATER AND CLIMATE CHANGE: DEALING WITH TOO MUCH, TOO LITTLE AND BOTH

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Source; Millennium Ecosystem Assessment. Ecosystems and Human Well-being; Ocean acidification
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.371.2131; http://www.cbd.int/doc/publications/unep-cbd-issue-papers/unep-cbd-issue-papers-03-en.pdf

Climate change affects ecosystems and people mainly by affecting the availability of water. In most areas, there will be more or less water and increasing frequency and extremes of drought and flood. Water security, already the world’s most important natural resource issue, will be significantly worsened by climate change. The role of ecosystems in sustaining the availability of water and reducing water-related risks is central to climate change adaptation. The economic case for working with nature, instead of against it, is strong. Impact of climate change on water The science may be complicated but the conclusion is simple: the impacts of climate change occur mainly through freshwater (box 1). Ocean acidification (issue paper No. 7) is the major exception. Water moves through the Earth’s ecosystems through the water cycle (figure 1). Global warming affects the Earth by changing this cycle at the global, regional and local levels. Changing weather patterns are characterized by shifts in temperature, wind and water — water being the basis of atmospheric humidity, cloud cover and precipitation of rain and snow. Although extreme temperatures (e.g., heat stress) and excessive wind can be a problem for both people and nature, it is what happens to water that matters most. Water causes the main damage from storms through flooding, and its absence is responsible for prolonged drought and desertification. The impact of climate change will vary from region to region, and often locally, but most