The 21st Century climate challenge

2Climate shocks: risk and vulnerability in an unequal worldMap 2.1Source: Met Office 2006.Drying out: Africa’s drought area is expandingDrought severity under IPCC scenario A2 (change relative to 2000 by 2090)Palmer DroughtSeverity Index–5–3–10135Note: The boundaries shown and the designations used on this map do not imply official endorsement or acceptance by theUnited Nations.IPCC scenarios describe plausible future patterns of population growth, economic growth, technological change andassociated CO 2emissions. The A1 scenarios assume rapid economic and population growth combined with reliance on fossilfuels (A1FI ), non-fossil energy (A1T ) or a combination (A1B ). The A2 scenario, used here, assumes lower economic growth,less globalization and continued high population growth. A negative change in the Palmer Drought Severity Index, calculatedbased on precipitation and evaporation projections, implies more severe droughts.sub-Saharan Africa of a 2.9°C increase intemperature, coupled with a 4 percent reductionin rainfall by 2060. The result: a reduction inrevenue per hectare of about 25 percent by 2060.In 2003 prices, overall revenue losses wouldrepresent around US$26 billion in 2060 54 —afigure in excess of bilateral aid to the region in2005. More broadly, the danger is that extremefood insecurity episodes, such as those that havefrequently affected countries like Malawi, willbecome more common (box 2.7).Cash crop production in many countriescould be compromised by climate change. Withan increase of 2°C in average temperatures, it isprojected that the land area available for growingcoffee in Uganda will shrink. 55 This is a sectorthat accounts for a large share of cash incomein rural areas and figures prominently in exportearnings. In some cases, modelling exercisesproduce optimistic results that mask pessimisticprocesses. For example, in Kenya it would bepossible to maintain tea production—but notin current locations. Production on MountKenya would have to move up to higher slopescurrently occupied by forests, suggesting thatenvironmental damage could be a corollary ofsustained production. 56Climate change on the scale projected forsub-Saharan Africa will have consequencesthat extend far beyond agriculture. In somecountries, there are very real dangers thatchanged climate patterns will become driversfor conflict. For example, climate models forNorthern Kordofan in Sudan indicate thattemperatures will rise by 1.5°C between 2030and 2060, with rainfall declining by 5 percent.Possible impacts on agriculture includea 70 percent drop in yields of sorghum. Thisis against the backdrop of a long-term declinein rainfall that, coupled with overgrazing, hasseen deserts encroach in some regions of Sudanby 100 kilometres over the past 40 years. Theinteraction of climate change with ongoingenvironmental degradation has the potentialto exacerbate a wide range of conflicts, underminingefforts to build a basis for long-termpeace and human security. 57The wider threatsThese extreme threats facing sub-SaharanAfrica should not distract from wider risks forhuman development. Climate change will haveimportant but uncertain consequences for rainfallpatterns across the developing world.Large uncertainties surround the El Niño/Southern Oscillation (ENSO)—an ocean–atmospherecycle that spans a third of the globe.In broad terms, El Niño increases the risk ofdrought across southern Africa and large areasof South and East Asia, while increasing hurricaneactivity in the Atlantic. Research in Indiahas found evidence of links between El Niñoand the timing of the monsoon, on which the viabilityof entire agricultural systems depends. 58Even small changes in monsoon intensity andvariability could have dramatic consequencesfor food security in South Asia.Global projections of climate change canobscure important local effects. Considerthe case of India. Some projections point to92 HUMAN DEVELOPMENT REPORT 2007/2008