IPCC Report.pdf - Adam Curry

Chapter 3Changes in Climate Extremes and their Impacts on the Natural Physical EnvironmentTable 3-2 (continued)C. AfricaRegions TmaxTmin Heat Waves / Warm SpellsHeavy Precipitation DrynessAll AfricaW. Africa(WAF, 15)E. Africa(EAF, 16)S. Africa(SAF, 17)Sahara(SAH, 14)Low confidence to medium confidence: Lowconfidence due to insufficient evidence (lack ofliterature) in many regions. Medium confidencein increase in frequency of WD and decrease infrequency of CD in southern part of continent(Alexander et al., 2006). See also regionalassessments.Medium confidence: Significant increase intemperature of warmest day and coldest day,significant increase in frequency of WD, andsignificant decrease in frequency of CD inwestern central Africa, Guinea Conakry, Nigeria,and Gambia (New et al., 2006; Aguilar et al.,2009).Low confidence: Lack of literature in other partsof the region.Low confidence: Lack of evidence due to lack ofliterature and spatially non-uniform trends. Overtime period 1939–1992 spatially non-uniformtrends in daytime temperature, some areas withcooling (King’uyu et al., 2000). In southern tip ofdomain increases in WD, decreases in CD(Alexander et al., 2006).Medium confidence: Increases in WD, decreasesin CD (Alexander et al., 2006).Low confidence to medium confidencedepending on region: Low confidence due toinsufficient evidence (lack of literature) inmany regions. Medium confidence inincrease in frequency of WN in northern andsouthern part of continent (Alexander et al.,2006). Medium confidence in decrease infrequency of CN in southern part ofcontinent (Alexander et al., 2006). See alsoregional assessments.Medium confidence: Decreases in frequencyof CN in western central Africa, Nigeria, andGambia; insignificant decreases in frequencyof CN in Guinea Conakry (New et al., 2006;Aguilar et al., 2009).Low confidence: Lack of literature onchanges in CN in other parts of the region.Medium confidence: Increases in frequencyof WN (Alexander et al., 2006; New et al.,2006; Aguilar et al., 2009).Medium confidence: Over time period 1939–1992, spatially non-uniform trends, rise ofnighttime temperature at several locations,but with many coastal areas and stationsnear large water bodies showing asignificant decrease (King’uyu et al., 2000).In southern tip of domain, decreases in CN,increases in WN (Alexander et al., 2006).Medium confidence: Decreases in CN,increases in WN (King’uyu et al., 2000;Alexander et al., 2006).Low confidence: Lack of literature. Medium confidence: Increases in WN(Alexander et al., 2006).Low confidence: Lack of literature on trendsin CN.Low confidence: Insufficient evidence(lack of literature). Some analyses forlocalized regions (see regionalassessments).Low confidence: Insufficient evidence(lack of literature) for most of theregion; increases in WSDI in Nigeria andGambia (New et al., 2006).Low confidence: Insufficient evidence(lack of literature) for most of region;increase in WSDI in southern tip ofdomain (New et al., 2006).Medium confidence: Increase in WSDI(New et al., 2006).Low confidence: Insufficient evidence(lack of literature).Low confidence: Partial lack of data andliterature and inconsistent patterns inexisting studies (New et al., 2006; Aguilaret al., 2009). See also regional assessments.Medium confidence: Precipitation fromheavy events has decreased (westerncentral Africa, Guinea Conakry) but lowspatial coherence (Aguilar et al., 2009),rainfall intensity increased (New et al.,2006).Low confidence: Insufficient evidence (lackof literature) to assess trends.Low confidence: No spatially coherentpatterns of trends in precipitation extremes(Kruger, 2006; New et al., 2006; Trenberthet al., 2007).Medium confidence: Overall increase indryness (SMA, PDSI); regional variability,1970s prolonged Sahel drought dominates(Sheffield and Wood, 2008a; Dai, 2011). Noapparent continent-wide trends in changein rainfall over the 20th century, althoughthere was a continent-wide drought in1983 and 1984 (Hulme et al., 2001). Wetseason arrives 9–21 days later, large interannualvariability of wet season start, localscalegeographical variability (Kniveton etal., 2009).Medium confidence: 1970s prolongedSahel drought dominates, conditions arestill drier (SMA, PDSI, precipitationanomalies) than during the humid 1950s(L'Hôte et al., 2002; Dai et al., 2004;Sheffield and Wood, 2008a; Dai, 2011). Dryspell duration (CDD) overall increased from1961 to 2000 (New et al., 2006). Recentyears characterized by a greaterinterannual variability than previous 40years, western Sahel remaining dry and theeastern Sahel returning to wetterconditions (Ali and Lebel, 2009).Low confidence: Spatially varying trends indryness (SMA, PDSI) (Sheffield and Wood,2008a; Dai, 2011).Medium confidence: Slight dry spellduration increase (Alexander et al., 2006;Kruger, 2006; New et al., 2006). Generalincrease in dryness (SMA, PDSI) (Sheffieldand Wood, 2008a; Dai, 2011).Low confidence: Insufficient evidence. Low confidence: Limited data, spatialvariation in the trends (Dai, 2011).Continued next page193