IPCC Report.pdf - Adam Curry

Changes in Climate Extremes and their Impacts on the Natural Physical EnvironmentChapter 3Europe and the Mediterranean region, central Europe, central North America, Central America and Mexico, northeastBrazil, and southern Africa. Definitional issues, lack of observational data, and the inability of models to include all thefactors that influence droughts preclude stronger confidence than medium in the projections. Elsewhere there is overalllow confidence because of inconsistent projections of drought changes (dependent both on model and dryness index).There is low confidence in projected future changes in dust storms although an increase could be expected wherearidity increases. [3.5.1, 3.5.8; Box 3-3; Table 3-3; Figure 3-10]There is high confidence that changes in heat waves, glacial retreat, and/or permafrost degradation willaffect high-mountain phenomena such as slope instabilities, mass movements, and glacial lake outburstfloods. There is also high confidence that changes in heavy precipitation will affect landslides in someregions. There is low confidence regarding future locations and timing of large rock avalanches, as these depend onlocal geological conditions and other non-climatic factors. There is low confidence in projections of an anthropogeniceffect on phenomena such as shallow landslides in temperate and tropical regions, because these are stronglyinfluenced by human activities such as land use practices, deforestation, and overgrazing. [3.5.6, 3.5.7]The small land area and often low elevation of small island states make them particularly vulnerable torising sea levels and impacts such as inundation, shoreline change, and saltwater intrusion intounderground aquifers. Short record lengths and the inadequate resolution of current climate models to representsmall island states limit the assessment of changes in extremes. There is insufficient evidence to assess observedtrends and future projections in rainfall across the small island regions considered here. There is medium confidence inprojected temperature increases across the Caribbean. The very likely contribution of mean sea level rise to increasedextreme coastal high water levels, coupled with the likely increase in tropical cyclone maximum wind speed, is aspecific issue for tropical small island states. [3.4.4, 3.5.3; Box 3-4]This chapter does not provide assessments of projected changes in extremes at spatial scales smaller thanfor large regions. These large-region projections provide a wider context for national or local projections,where these exist, and where they do not exist, a first indication of expected changes, their associateduncertainties, and the evidence available. [3.2.3.1]114