ADB_book_18 April.qxp - Himalayan Document Centre - icimod

Climate ChangeA region’s climate is a summary of the past weatherevents that have occurred at that location. Climate istypically described by the statistics of a set ofatmospheric and surface variables, such astemperature, precipitation, wind, humidity,cloudiness, soil moisture, sea surface temperature,and the concentration and thickness of sea ice.Statistics may be in terms of the long-term averagesor other measures such as daily minimumtemperature, length of the growing season, orfrequency of floods. Weather, on the other hand,refers to the temperature, precipitation (rain andsnow), humidity, sunshine, and wind that occur at aparticular time at a specific location.Climatologists say that our planet is gettingwarmer overall and that this is leading to climatechange (IPCC 2001). The mean global surfacetemperature has increased by about 0.3 to 0.6°Csince the late 19th century and by about 0.2 to 0.3°Cover the last 40 years, which is the period with themost reliable data (UNEP undated). This build-up isattributed to the result of human activities, especiallyour use of fossil fuels in, for example, automobilesand power plants. In other words, air pollutants in thebroadest sense are considered to be the main causeof climate change. The impacts of thisunprecedented warming—increased floods anddrought, rising sea levels, spread of deadly diseasessuch as malaria and dengue fever, increasingnumbers of violent storms—threaten to be moresevere and imminent than previously believed.Impacts are already being felt in the Arctic,where the average annual temperature hasincreased approximately four times as much asaverage annual temperatures around the rest of theglobe (CIEL 2004). Rising temperatures have causedoutbreaks of insect pests such as the spruce barkbeetle, which is reproducing at twice its normal ratein today’s warmer climate (Anchorage Daily News2005). Similarly, observable changes have also beenfelt in Nepal. Some particular aspects of climatechange as they relate to Nepal are discussed below.Climate Change in NepalTemperature ChangeIn Nepal, the elevation generally increases fromsouth to north and is accompanied by decreasingtemperatures. Temperature observations in Nepalfrom 1977–1994 showed a general warming trend(Shrestha et al. 1999) with significantly greaterwarming at higher elevations in the northern part ofthe country than at lower elevations in the south.This finding is reinforced by observations by Liu andChen in 2000 on the other side of the Himalayas onthe Tibetan Plateau. Significant glacier retreat as wellas significant expansion of several glacial lakes hasalso been documented in recent decades, with anextremely high likelihood that such impacts arelinked to rising temperatures. The results of atemperature trend analysis for the period 1981 to1998 based upon data from 80 stations are shown inFigure 7.13. Except for small pockets in the easternFigure 7.13: Observed Mean Annual Temperature Trend (°C) per Decade for the Period [1981-1998]Source: MOPE and UNEP (2004)92 Environment Assessment of Nepal : Emerging Issues and Challenges