Executive Summary 78422 Turn Down Heat the Climate Extremes, Regional Impacts, and the Case for Resilience Executive Summary Turn Down Heat the Climate Extremes, Regional Impacts, and the Case for Resilience June 2013 A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics © 2013 International Bank for Reconstruction and Development / The World Bank 1818 H Street NW Washington DC 20433 Telephone: 202-473-1000 Internet: www.worldbank.org This report was prepared for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this commissioned work. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on the part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Rights and Permissions The material in this work is subject to copyright. Because the World Bank encourages dissemination of its knowledge, this work may be reproduced, in whole or in part, for noncommercial purposes as long as full attribution to this work is given. Any queries on rights and licenses, including subsidiary rights, should be addressed to the Office of the Publisher, The World Bank, 1818 H Street NW, Washington, DC 20433, USA; fax: 202-522-2422; e-mail: pubrights@worldbank.org. Contents Acknowledgments v Foreword vii Executive Summary 1 Abbreviations 17 Glossary 19 Figures 1. Projected sea-level rise and northern-hemisphere summer heat events over land in a 2°C World (upper panel) and a 4°C World (lower panel) 2 2. Projected impact of climate change on the annual Aridity Index in Sub-Saharan Africa 5 3. Projected impact of climate change on coral systems in South East Asia 7 4. Projected impact of climate change on annual, wet and dry season rainfall in South Asia 9 Tables 1. Climate Impacts in Sub-Saharan Africa 12 2. Climate Impacts in South East Asia 13 3. Climate Impacts in South Asia 14 Boxes 1. Regional Tipping Points, Cascading Impacts, and Development Implications 10 2. New Clusters of Vulnerability—Urban Areas 11 iii Acknowledgments The report Turn Down the Heat: Climate Extremes, Regional Impacts, and the Case for Resilience is a result of contributions from a wide range of experts from across the globe. The report follows Turn Down the Heat: Why a 4°C Warmer World Must be Avoided, released in November 2012. We thank everyone who contributed to its richness and multidisciplinary outlook. The report has been written by a team from the Potsdam Institute for Climate Impact Research and Climate Analytics, including Hans Joachim Schellnhuber, Bill Hare, Olivia Serdeczny, Michiel Schaeffer, Sophie Adams, Florent Baarsch, Susanne Schwan, Dim Coumou, Alexander Robinson, Marion Vieweg, Franziska Piontek, Reik Donner, Jakob Runge, Kira Rehfeld, Joeri Rogelj, Mahé Perette, Arathy Menon, Carl-Friedrich Schleussner, Alberte Bondeau, Anastasia Svirejeva-Hopkins, Jacob Schewe, Katja Frieler, Lila Warszawski and Marcia Rocha. The ISI-MIP projections were undertaken by modeling groups at the following institutions: ORCHIDEE1 (Institut Pierre Simon Laplace, France); JULES (Centre for Ecology and Hydrology, UK; Met Office Hadley Centre, UK; University of Exeter, UK); VIC (Norwegian Water Resources and Energy Directorate, Norway; Wageningen University, Netherlands); H08 (Institute for Environmental Studies, Japan); WaterGAP (Kassel University, Germany; Universität Frankfurt, Germany); MacPDM (University of Reading, UK; University of Nottingham, UK); WBM (City University of New York, USA); MPI-HM (Max Planck Institute for Meteorology, Germany); PCR-GLOBWB (Utrecht University, Netherlands); DBH (Chinese Academy of Sciences, China); MATSIRO (University of Tokyo, Japan); Hybrid (University of Cambridge, UK); Sheffield DGVM (Univer- sity of Sheffield, UK; University of Bristol, UK); JeDi (Max Planck Institut für Biogeochemie, Germany); ANTHRO-BGC (Humboldt University of Berlin, Germany; Leibniz Centre for Agricultural Landscape Research, Germany); VISIT (National Institute for Environmental Studies, Japan); GEPIC (Eawag, Switzerland); EPIC (University of Natural Resources and Life Sciences, Vienna, Austria); pDSSAT (University of Chicago, USA); DAYCENT (Colorado State University, USA); IMAGE (PBL Netherlands Environmental Assessment Agency, Netherlands); PEGASUS (Tyndall Centre, University of East Anglia, UK); LPJ-GUESS (Lunds Universitet, Sweden); MAgPIE (Potsdam Institute, Germany); GLOBIOM (International Institute for Applied Systems Analysis, Austria); IMPACT (International Food Policy Research Institute, USA; International Livestock Research Institute, Kenya); DIVA (Global Climate Forum, Germany); MARA (London School of Hygiene and Tropical Medicine, UK); WHO CCRA Malaria (Umea University, Sweden); LMM 205 (The University of Liverpool, UK); MIASMA (Maastricht University, Netherlands); and VECTRI (Abdus Salam International Centre for Theoretical Physics, Italy). 1 A full list of ISI-MIP modeling groups is given in Appendix 2 of the Main Report v Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce The report was commissioned by the World Bank’s Global Expert Team for Climate Change Adaptation and the Climate Policy and Finance Department. The Bank team, led by Kanta Kumari Rigaud and Erick Fernandes under the supervision of Jane Ebinger, worked closely with the Potsdam Institute for Climate Impact Research and Climate Analytics. The team comprised Raffaello Cervigni, Nancy Chaarani Meza, Charles Joseph Cormier, Christophe Crepin, Richard Damania, Ian Lloyd, Muthukumara Mani, and Alan Miller. Robert Bisset, Jayna Desai, and Venkat Gopalakrishnan led outreach efforts to partners, the scientific community, and the media. Patricia Braxton and Perpetual Boateng provided valuable support to the team. Scientific oversight was provided throughout by Rosina Bierbaum (University of Michigan) and Michael MacCracken (Climate Institute, Washington DC). The report benefited greatly from scientific peer reviewers. We would like to thank Pramod Aggarwal, Seleshi Bekele, Qamar uz Zaman Chaudhry, Brahma Chellaney, Robert Correll, Jan Dell, Christopher Field, Andrew Friend, Dieter Gerten, Felina Lansigan, Thomas Lovejoy, Anthony McMichael, Danielle Nierenberg, Ian Noble, Rajendra Kumar Pachauri, Anand Patwardhan, Mark Pelling, Thomas Peterson, Mark Tadross, Kevin Trenberth, Tran Thuc, Abdrahmane Wane, and Robert Watson. Valuable guidance and oversight was provided by Rachel Kyte, Mary Barton-Dock, Fionna Douglas, John Roome, Jamal Saghir, and John Stein, and further supported by Zoubida Allaoua, Magdolna Lovei, Iain Shuker, Bernice Van Bronkhorst, and Juergen Voegele. We are grateful to colleagues from the World Bank for their input: Herbert Acquay, Kazi Ahmed, Sameer Akbar, Asad Alam, Preeti Arora, Rachid Benmessaoud, Sofia Bettencourt, Anthony Bigio, Patricia Bliss- Guest, Ademola Braimoh, Henrike Brecht, Haleh Bridi, Adam Broadfoot, Penelope Brook, Timothy Brown, Ana Bucher, Guang Chen, Constantine Chikosi, Kenneth Chomitz, Christopher Delgado, Ousmane Diagana, Ousmane Dione, Inguna Dobraja, Philippe Dongier, Franz Dress-Gross, Julia Fraser, Kathryn Funk, Habiba Gitay, Olivier Godron, Gloria Grandolini, Poonam Gupta, Stephane Hallegatte, Valerie Hickey, Tomoko Hirata, Waraporn Hirunwatsiri, Bert Hofman, Kathryn Hollifield, Andras Horvai, Ross Hughes, Steven Jaffee, Denis Jordy, Christina Leb, Jeffrey Lecksell, Mark Lundell, Henriette von Kaltenborn-Stachau, Isabelle Celine Kane, Stefan Koeberle, Jolanta Kryspin-Watson, Sergiy Kulyk, Andrea Kutter, Victoria Kwakwa, Marie-Francoise Marie-Nelly, Kevin McCall, Lasse Melgaard, Juan Carlos Mendoza, Deepak Mishra, John Nash, Moustapha Ndiave, Dzung Huy Nguyen, Iretomiwa Olatunji, Eustache Ouayoro, Doina Petrescu, Christoph Pusch, Madhu Raghunath, Robert Reid, Paola Ridolfi, Onno Ruhl, Michal Rutkowski, Jason Russ, Maria Sarraf, Robert Saum, Tahseen Sayed, Jordan Schwartz, Animesh Shrivastava, Stefanie Sieber, Benedikt Signer, Alanna Simpson, Joop Stoutjesdijk, Madani Tall, Mike Toman, David Olivier Treguer, Ivan Velev, Catherine Vidar, Debbie Wetzel, Gregory Wlosinski, Johannes Woelcke, Gregor Wolf, and Winston Yu. We acknowledge with gratitude the Climate and Development Knowledge Network (CDKN), the Global Facility for Disaster Reduction and Recovery (GFDRR), the Climate Investment Funds (CIF), and Connect4Climate (C4C) for their contributions to the production of this report and associated outreach materials. vi Foreword The work of the World Bank Group is to end extreme poverty and build shared prosperity. Today, we have every reason to believe that it is within our grasp to end extreme poverty by 2030. But we will not meet this goal without tackling the problem of climate change. Our first Turn Down the Heat report, released late last year, concluded the world would warm by 4°C by the end of this century if we did not take concerted action now. This new report outlines an alarming scenario for the days and years ahead—what we could face in our lifetime. The scientists tell us that if the world warms by 2°C—warming which may be reached in 20 to 30 years—that will cause widespread food shortages, unprecedented heat-waves, and more intense cyclones. In the near-term, climate change, which is already unfolding, could batter the slums even more and greatly harm the lives and the hopes of individuals and families who have had little hand in raising the Earth’s temperature. Today, our world is 0.8°C above pre-industrial levels of the 18th century. We could see a 2°C world in the space of one generation. The first Turn Down the Heat report was a wake-up call. This second scientific analysis gives us a more detailed look at how the negative impacts of climate change already in motion could create devastating conditions especially for those least able to adapt. The poorest could increasingly be hit the hardest. For this report, we turned again to the scientists at the Potsdam Institute for Climate Impact Research and Climate Analytics. This time, we asked them to take a closer look at the tropics and prepare a climate forecast based on the best available evidence and supplemented with advanced computer simulations. With a focus on Sub-Saharan Africa, South East Asia and South Asia, the report examines in greater detail the likely impacts for affected populations of present day, 2°C and 4°C warming on critical areas like agricultural production, water resources, coastal ecosystems and cities. The result is a dramatic picture of a world of climate and weather extremes causing devastation and human suffering. In many cases, multiple threats of increasing extreme heat waves, sea-level rise, more severe storms, droughts and floods will have severe negative implications for the poorest and most vulnerable. In Sub-Saharan Africa, significant crop yield reductions with 2°C warming are expected to have strong repercussions on food security, while rising temperatures could cause major loss of savanna grasslands threatening pastoral livelihoods. In South Asia, projected changes to the monsoon system and rising peak temperatures put water and food resources at severe risk. Energy security is threatened, too. While, across South East Asia, rural livelihoods are faced with mounting pressures as sea-level rises, tropical cyclones increase in intensity and important marine ecosystem services are lost as warming approaches 4°C. Across all regions, the likely movement of impacted communities into urban areas could lead to ever higher numbers of people in informal settlements being exposed to heat waves, flooding, and diseases. vii Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce The case for resilience has never been stronger. This report demands action. It reinforces the fact that climate change is a fundamental threat to eco- nomic development and the fight against poverty. At the World Bank Group, we are concerned that unless the world takes bold action now, a disastrously warming planet threatens to put prosperity out of reach of millions and roll back decades of development. In response we are stepping up our mitigation, adaptation, and disaster risk management work, and will increasingly look at all our business through a “climate lens.” But we know that our work alone is not enough. We need to support action by others to deliver bold ideas that will make the biggest difference. I do not believe the poor are condemned to the future scientists envision in this report. In fact, I am convinced we can reduce poverty even in a world severely challenged by climate change. We can help cities grow clean and climate resilient, develop climate smart agriculture practices, and find innovative ways to improve both energy efficiency and the performance of renewable energies. We can work with countries to roll back harmful fossil fuel subsidies and help put the policies in place that will eventually lead to a stable price on carbon. We are determined to work with countries to find solutions. But the science is clear. There can be no substitute for aggressive national emissions reduction targets. Today, the burden of emissions reductions lies with a few large economies. Not all are clients of the World Bank Group, but all share a commitment to ending poverty. I hope this report will help convince everyone that the benefits of strong, early action on climate change far outweigh the costs. We face a future that is precarious because of our warming planet. We must meet these challenges with political will, intelligence, and innovation. If we do, I see a future that eases the hardships of others, allows the poor to climb out of poverty, and provides young and old alike with the possibilities of a better life. Join us in our fight to make that future a reality. Our successes and failures in this fight will define our generation. Dr. Jim Yong Kim President, World Bank Group viii Executive Summary Executive Summary This report focuses on the risks of climate change to development in Sub-Saharan Africa, South East Asia and South Asia. Build- ing on the 2012 report, Turn Down the Heat: Why a 4°C Warmer World Must be Avoided1, this new scientific analysis examines the likely impacts of present day, 2°C and 4°C warming on agricultural production, water resources, and coastal vulnerability for affected populations. It finds many significant climate and development impacts are already being felt in some regions, and in some cases multiple threats of increasing extreme heat waves, sea-level rise, more severe storms, droughts and floods are expected to have further severe negative implications for the poorest. Climate-related extreme events could push households below the poverty trap threshold. High temperature extremes appear likely to affect yields of rice, wheat, maize and other important crops, adversely affecting food security. Promoting economic growth and the eradication of poverty and inequal- ity will thus be an increasingly challenging task under future climate change. Immediate steps are needed to help countries adapt to the risks already locked in at current levels of 0.8°C warming, but with ambitious global action to drastically reduce greenhouse gas emissions, many of the worst projected climate impacts could still be avoided by holding warming below 2°C. Scope of the Report The Global Picture The first Turn Down the Heat report found that projections of Scientific reviews published since the first Turn Down the Heat global warming, sea-level rise, tropical cyclone intensity, arid- report indicate that recent greenhouse gas emissions and future ity and drought are expected to be felt disproportionately in the emissions trends imply higher 21st century emission levels than developing countries around the equatorial regions relative to the previously projected. As a consequence, the likelihood of 4°C countries at higher latitudes. This report extends this previous warming being reached or exceeded this century has increased, analysis by focusing on the risks of climate change to development in the absence of near-term actions and further commitments to in three critical regions of the world: Sub-Saharan Africa, South reduce emissions. This report reaffirms the International Energy East Asia and South Asia. Agency’s 2012 assessment that in the absence of further mitiga- While covering a range of sectors, this report focuses on how tion action there is a 40 percent chance of warming exceeding climate change impacts on agricultural production, water resources, 4°C by 2100 and a 10 percent chance of it exceeding 5°C in the coastal zone fisheries, and coastal safety are likely to increase, often same period. significantly, as global warming climbs from present levels of 0.8°C The 4°C scenario does not suggest that global mean tempera- up to 1.5°C, 2°C and 4°C above pre-industrial levels. This report tures would stabilize at this level; rather, emissions scenarios leading illustrates the range of impacts that much of the developing world to such warming would very likely lead to further increases in both is already experiencing, and would be further exposed to, and it temperature and sea-level during the 22nd century. Furthermore, indicates how these risks and disruptions could be felt differently in other parts of the world. Figure 1 shows projections of temperature 1 Turn Down the Heat: Why a 4°C Warmer World Must be Avoided, launched by and sea-level rise impacts at 2°C and 4°C global warming. the World Bank in November 2012. 1 Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce even at present warming of 0.8°C above pre-industrial levels, the of varying complexity, including the state of the art Coupled observed climate change impacts are serious and indicate how Model Intercomparison Project Phase 5 (CMIP5), semi-empirical dramatically human activity can alter the natural environment modeling, the “Simple Climate Model” (SCM), the Model for upon which human life depends. the Assessment of Greenhouse Gas Induced Climate Change The projected climate changes and impacts are derived (MAGICC; see Appendix 1 of the Main Report) and a synthesis from a combined approach involving a range of climate models of peer reviewed literature. Figure 1 Projected sea-level rise and northern-hemisphere summer heat events over land in a 2°C World (upper panel) and a 4°C World (lower panel) * ** Upper panel: In a 2°C world, sea-level rise is projected to be less than 70 cm (yellow over oceans) and the likelihood that a summer month’s heat is unprecedented is less than 30 percent (blue/purple colors over land) Lower panel: In a 4°C world, sea-level rise is projected to be more than 100 cm (orange over oceans) and the likelihood that a summer month’s heat is unprecedented is greater than 60 percent (orange/red colors over land) *RCP2.6, IPCC AR5 scenario aiming to limit the increase of global mean temperature to 2°C above the pre- industrial period. **RCP8.5, IPCC AR5 scenario with no-climate-policy baseline and comparatively high greenhouse gas emissions. In this report, this scenario is referred to as a 4°C World above the pre-industrial period. 2 Execu tiv e Sum m ary Key Findings Across the Regions 4. Terrestrial ecosystems: Increased warming could bring about ecosystem shifts, fundamentally altering species compositions Among the key issues highlighted in this report are the early and even leading to the extinction of some species. onset of climate impacts, uneven regional distribution of climate • By the 2030s (with 1.2–1.3°C warming), some ecosys- impacts, and interaction among impacts which accentuates cascade tems in Africa, for example, are projected to experience effects. For example: maximum extreme temperatures well beyond their present range, with all African eco-regions exceeding this range 1. Unusual and unprecedented heat extremes2: Expected by 2070 (2.1–2.7°C warming). to occur far more frequently and cover much greater land • The distribution of species within savanna ecosystems are areas, both globally and in the three regions examined. For projected to shift from grasses to woody plants, as CO2 example, heat extremes in South East Asia are projected fertilization favors the latter, although high temperatures to increase substantially in the near term, and would have and precipitation deficits might counter this effect. This significant and adverse effects on humans and ecosystems shift will reduce available forage for livestock and stress under 2°C and 4°C warming. pastoral systems and livelihoods. 2. Rainfall regime changes and water availability: Even without 5. Sea-level rise: Has been occurring more rapidly than previ- any climate change, population growth alone is expected to ously projected and a rise of as much as 50 cm by the 2050s put pressure on water resources in many regions in the future. may be unavoidable as a result of past emissions: limiting With projected climate change, however, pressure on water warming to 2°C may limit global sea-level rise to about 70 resources is expected to increase significantly. cm by 2100. • Declines of 20 percent in water availability are projected • As much as 100 cm sea-level rise may occur if emission for many regions under a 2°C warming and of 50 percent increases continue and raise the global average tempera- for some regions under 4°C warming. Limiting warming ture to 4°C by 2100 and higher levels thereafter. While to 2°C would reduce the global population exposed to the unexpectedly rapid rise over recent decades can declining water availability to 20 percent. now be explained by the accelerated loss of ice from the • South Asian populations are likely to be increasingly vul- Greenland and Antarctic ice sheets, significant uncertainty nerable to the greater variability of precipitation changes, remains as to the rate and scale of future sea-level rise. in addition to the disturbances in the monsoon system • The sea-level nearer to the equator is projected to be and rising peak temperatures that could put water and higher than the global mean of 100 cm at the end of the food resources at severe risk. century. In South East Asia for example, sea-level rise is projected to be 10–15 percent higher than the global 3. Agricultural yields and nutritional quality: Crop production mean. Coupled with storm surges and tropical cyclones, systems will be under increasing pressure to meet growing this increase is projected to have devastating impacts on global demand in the future. Significant crop yield impacts coastal systems. are already being felt at 0.8°C warming. • While projections vary and are uncertain, clear risks 6. Marine ecosystems: The combined effects of warming and emerge as yield reducing temperature thresholds for ocean acidification are projected to cause major damages to important crops have been observed, and crop yield coral reef systems and lead to losses in fish production, at improvements appear to have been offset or limited by least regionally. observed warming (0.8°C) in many regions. There is also • Substantial losses of coral reefs are projected by the time some empirical evidence that higher atmospheric levels warming reaches 1.5–2°C from both heat and ocean of carbon dioxide (CO2) could result in lower protein levels of some grain crops. 2 In this report, “unusual” and “unprecedented” heat extremes are defined by • For the regions studied in this report, global warming using thresholds based on the historical variability of the current local climate. The absolute level of the threshold thus depends on the natural year-to-year variability in above 1.5°C to 2°C increases the risk of reduced crop the base period (1951–1980), which is captured by the standard deviation (sigma). yields and production losses in Sub-Saharan Africa, Unusual heat extremes are defined as 3-sigma events. For a normal distribution, South East Asia and South Asia. These impacts would 3-sigma events have a return time of 740 years. The 2012 US heat wave and the 2010 Russian heat wave classify as 3-sigma events. Unprecedented heat extremes have strong repercussions on food security and are likely are defined as 5-sigma events. They have a return time of several million years. to negatively influence economic growth and poverty These events which have almost certainly never occurred to date are projected for reduction in the impacted regions. the coming decades. See also Chapter 2 (Box 2.2). 3 Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce acidification effects, with a majority of coral systems no is projected to lead to an overall increase in the risk of longer viable at current locations. Most coral reefs appear drought in southern Africa. unlikely to survive by the time 4°C warming is reached. • Strong warming and an ambiguous precipitation signal • Since the beginning of the Industrial Revolution, the pH over central Africa is projected to increase drought risk of surface ocean waters has fallen by 0.1 pH units. Since there. the pH scale, like the Richter scale, is logarithmic, this • In the Horn of Africa and northern part of east Africa change represents approximately a 30 percent increase substantial disagreements exists between high-resolution in acidity. Future predictions indicate that ocean acidity regional and global climate models. Rainfall is projected will further increase as oceans continue to absorb carbon by many global climate models to increase in the Horn dioxide. Estimates of future carbon dioxide levels, based of Africa and the northern part of east Africa, making on business as usual emission scenarios, indicate that by these areas somewhat less dry. The increases are pro- the end of this century the surface waters of the ocean jected to occur during higher intensity rainfall periods, could be nearly 150 percent more acidic, resulting in pH rather than evenly during the year, which increases levels that the oceans have not experienced for more the risk of floods. In contrast, high-resolution regional than 20 million years. climate models project an increasing tendency towards drier conditions. Recent research showed that the 2011 Horn of Africa drought, particularly severe in Kenya and Sub-Saharan Africa: Food Production Somalia, is consistent with an increased probability of at Risk long-rains failure under the influence of anthropogenic climate change. Sub-Saharan Africa is a rapidly developing region of over 800 mil- • Projected aridity trends: Aridity is projected to spread due lion people, with 49 countries, and great ecological, climatic and to changes in temperature and precipitation, most notably in cultural diversity. Its population for 2050 is projected to approach southern Africa (Figure 2). In a 4°C world, total hyper-arid 1.5 billion people. and arid areas are projected to expand by 10 percent compared The region is confronted with a range of climate risks that could to the 1986–2005 period. Where aridity increases, crop yields have far-reaching repercussions for Sub-Saharan Africa´s societies are likely to decline as the growing season shortens. and economies in future. Even if warming is limited below 2°C, there are very substantial risks and projected damages, and as warming Sector Based and Thematic Impacts increases these are only expected to grow further. Sub-Saharan Africa is particularly dependent on agriculture for food, income, • Agricultural production is expected to be affected in the and employment, almost all of it rain-fed. Under 2°C warming, near-term, as warming shifts the climatic conditions that large regional risks to food production emerge; these risks would are conducive to current agricultural production. The annual become stronger if adaptation measures are inadequate and the average temperature is already above optimal values for wheat CO2 fertilization effect is weak. Unprecedented heat extremes are during the growing season over much of the Sub-Saharan projected over an increasing percentage of land area as warming Africa region and non-linear reductions in maize yield above goes from 2 to 4°C, resulting in significant changes in vegetative certain temperature thresholds have been reported. Significant cover and species at risk of extinction. Heat and drought would impacts are expected well before mid-century even for relatively also result in severe losses of livestock and associated impacts low levels of warming. For example, a 1.5°C warming by the on rural communities. 2030s could lead to about 40 percent of present maize cropping areas being no longer suitable for current cultivars. In addi- Likely Physical and Biophysical Impacts as a Function of Pro- tion, under 1.5°C warming, significant negative impacts on jected Climate Change sorghum suitability in the western Sahel and southern Africa are projected. Under warming of less than 2°C by the 2050s, • Water availability: Under 2°C warming the existing differ- total crop production could be reduced by 10 percent. For ences in water availability across the region could become higher levels of warming there are indications that yields may more pronounced. decrease by around 15–20 percent across all crops and regions. • In southern Africa, annual precipitation is projected to • Crop diversification strategies will be increasingly important: decrease by up to 30 percent under 4°C warming, and The study indicates that sequential cropping is the preferable parts of southern and west Africa may see decreases option over single cropping systems under changing climatic in groundwater recharge rates of 50–70 percent. This conditions. Such crop diversification strategies have long been 4 Execu tiv e Sum m ary Figure 2 Projected impact of climate change on the annual Aridity Index in Sub-Saharan Africa Multi-model mean of the percentage change in the annual Aridity Index in a 2°C world (left) and a 4°C world (right) for Sub-Saharan Africa by 2071–2099 relative to 1951–1980. In non-hatched areas, at least 4/5 (80 percent) of models agree. In hatched areas, 2/5 (40 percent) of the models disagree. Note that a negative change corresponds to a shift to more arid conditions. Particular uncertainty remains for east Africa, where regional climate model projections tend to show an increase in precipitation, which would be associated with a decrease in the Aridity Index. A decrease in aridity does not necessarily imply more favorable conditions for agriculture or livestock, as it may be associated with increased flood risks. practiced in Africa, providing a robust knowledge base and • Health is expected to be significantly affected by climate opportunity for scaled up approaches in this area. change. Rates of undernourishment are already high, rang- ing between 15–65 percent, depending on sub-region. With • Diversification options for agro-pastoral systems are likely warming of 1.2–1.9°C by 2050, the proportion of the popula- to decline (e.g. switching to silvopastoral systems, irrigated tion undernourished is projected to increase by 25–90 percent forage production, and mixed crop-livestock systems) as climate compared to the present. Other impacts expected to accompany change reduces the carrying capacity of the land and livestock climate change include mortality and morbidity due to extreme productivity. For example, pastoralists in southern Ethiopia events such as extreme heat and flooding. lost nearly 50 percent of their cattle and about 40 percent of their sheep and goats to droughts between 1995 and 1997. • Climate change could exacerbate the existing develop- • Regime shifts in African ecosystems are projected and could ment challenge of ensuring that the educational needs of result in the extent of savanna grasslands being reduced. By the all children are met. Several factors that are expected to time 3°C global warming is reached, savannas are projected worsen with climate change, including undernourishment, to decrease to approximately one-seventh of total current land childhood stunting, malaria and other diseases, can under- area, reducing the availability of forage for grazing animals. mine childhood educational performance. The projected Projections indicate that species composition of local ecosystems increase in extreme monthly temperatures within the next might shift, and negatively impact the livelihood strategies of few decades may also have an adverse effect on learning communities dependent on them. conditions. 5 Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce South East Asia: Coastal Zones and the Mahaka River region in Indonesia for a 100 cm sea-level Productivity at Risk rise by 2100, the land area affected by saltwater intrusion is expected to increase by 7–12 percent under 4°C warming. South East Asia has seen strong economic growth and urbanization trends, but poverty and inequality remain significant challenges Sector Based and Thematic Impacts in the region. Its population for 2050 is projected to approach 759 • River deltas are expected to be impacted by projected sea- million people with 65 percent of the population living in urban level rise and increases in tropical cyclone intensity, along areas. In 2010, the population was 593 million people with 44 with land subsidence caused by human activities. These fac- percent of the population living in urban areas. tors will increase the vulnerability of both rural and urban South East Asia has a high and increasing exposure to slow populations to risks including flooding, saltwater intrusion onset impacts associated with rising sea-level, ocean warming and coastal erosion. The three river deltas of the Mekong, and increasing acidification combined with sudden-onset impacts Irrawaddy and Chao Phraya, all with significant land areas less associated with tropical cyclones and rapidly increasingly heat than 2 m above sea-level, are particularly at risk. Aquaculture, extremes. When these impacts combine they are likely to have agriculture, marine capture fisheries and tourism are the most adverse effects on several sectors simultaneously, ultimately exposed sectors to climate change impacts in these deltas. undermining coastal livelihoods in the region. The deltaic areas of South East Asia that have relatively high coastal population • Fisheries would be affected as primary productivity in the densities are particularly vulnerable to sea-level rise and the pro- world´s oceans is projected to decrease by up to 20 percent by jected increase in tropical cyclones intensity. 2100 relative to pre-industrial conditions. Fish in the Java Sea and the Gulf of Thailand are projected to be severely affected Likely Physical and Biophysical Impacts as a Function of Pro- by increased water temperature and decreased oxygen levels, jected Climate Change with very large reductions in average maximum body size by 2050. It is also projected that maximum catch potential in • Heat extremes: The South East Asian region is projected to see the southern Philippines could decrease by about 50 percent. a strong increase in the near term in monthly heat extremes. Under 2°C global warming, heat extremes that are virtually • Aquaculture farms may be affected by several climate absent at present will cover nearly 60–70 percent of total change stressors. Increasing tropical cyclone intensity, salinity land area in summer, and unprecedented heat extremes up to intrusion and rising temperatures may exceed the tolerance 30–40 percent of land area in northern-hemisphere summer. thresholds of regionally important farmed species. Aquaculture With 4°C global warming, summer months that in today´s is a rapidly growing sector in South East Asia, which accounts climate would be termed unprecedented, would be the new for about 5 percent of Vietnam’s GDP. As nearly 40 percent of normal, affecting nearly 90 percent of the land area during dietary animal protein intake in South East Asia comes from the northern-hemisphere summer months. fish, this sector also significantly contributes to food security in the region. • Sea-level rise: For the South East Asian coastlines, projec- tions of sea-level rise by the end of the 21st century relative to • Coral reef loss and degradation would have severe impacts 1986–2005 are generally 10–15 percent higher than the global for marine fisheries and tourism. Increasing sea surface tem- mean. The analysis for Manila, Jakarta, Ho Chi Minh City, and peratures have already led to major, damaging coral bleaching Bangkok indicates that regional sea-level rise is likely to exceed events in the last few decades.3 Under 1.5°C warming and 50 cm above current levels by about 2060, and 100 cm by 2090. increasing ocean acidification, there is a high risk (50 percent probability) of annual bleaching events occurring as early as • Tropical cyclones: The intensity and maximum wind speed 2030 in the region (Figure 3). Projections indicate that all coral of tropical cyclones making landfall is projected to increase reefs in the South East Asia region are very likely to experience significantly for South East Asia; however, the total number severe thermal stress by the year 2050, as well as chemical of land-falling cyclones may reduce significantly. Damages stress due to ocean acidification. may still rise as the greatest impacts are caused by the most intense storms. Extreme rainfall associated with tropical cyclones is expected to increase by up to a third reaching 3 Coral bleaching can be expected when a regional warm season maximum 50–80 mm per hour, indicating a higher level of flood risk in temperature is exceeded by 1°C for more than four weeks and bleaching becomes susceptible regions. progressively worse at higher temperatures and/or longer periods over which the regional threshold temperature is exceeded. Whilst corals can survive a bleaching • Saltwater intrusion: A considerable increase of salinity intru- event they are subject to high mortality and take several years to recover. When sion is projected in coastal areas. For example, in the case of bleaching events become too frequent or extreme coral reefs can fail to recover. 6 Execu tiv e Sum m ary Figure 3 Projected impact of climate change on coral systems in South East Asia Probability of a severe bleaching event (DHW>8) occurring during a given year under scenario RCP2.6 (approximately 2°C, left) and RCP8.5 (ap- proximately 4°C, right). Source: Meissner et al. (2012). Reprinted from Springer; Coral Reefs, 31(2), 2012, 309–319, Large-scale stress factors affecting coral reefs:open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years, Meissner et al., Figure 3, with kind permission from Springer Science and Business Media B.V. Further permission required for reuse. • Agricultural production, particularly for rice in the Mekong could occur by the 2030s), to about 70 percent under an Delta, is vulnerable to sea-level rise. The Mekong Delta 88cm sea-level rise scenario (which could occur by the 2080s produces around 50 percent of Vietnam’s total agricultural under 4°C warming). Further, the effects of heat extremes are production and contributes significantly to the country’s rice particularly pronounced in urban areas due to the urban heat exports. It has been estimated that a sea-level rise of 30 cm, island effect and could result in high human mortality and which could occur as early as 2040, could result in the loss morbidity rates in cities. High levels of growth of both urban of about 12 percent of crop production due to inundation and populations and GDP further increase financial exposure to salinity intrusion relative to current levels. climate change impacts in these areas. The urban poor are particularly vulnerable to excessive heat and humidity stresses. • Coastal cities concentrate increasingly large populations and In 2005, 41 percent of the urban population of Vietnam and assets exposed to climate change risks including increased 44 percent of that of the Philippines lived in informal settle- tropical storm intensity, long-term sea-level rise and sudden- ments. Floods associated with sea-level rise and storm surges onset coastal flooding. Without adaptation, the area of Bangkok carry significant risks in informal settlements, where lack of projected to be inundated due to flooding linked to extreme drainage and damages to sanitation and water facilities are rainfall events and sea-level rise increases from around 40 accompanied by health threats. percent under 15 cm sea-level rise above present (which 7 Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce South Asia: Extremes of Water Scarcity with precipitation increasing during the monsoon season for and Excess currently wet areas (south, northeast) and precipitation decreas- ing for currently dry months and areas (north, northwest), South Asia is home to a growing population of about 1.6 billion with larger uncertainties for those regions in other seasons. people, which is projected to rise to over 2.2 billion people by • Monsoon: Significant increases in inter-annual and intra- 2050. It has seen robust economic growth in recent years, yet seasonal variability of monsoon rainfall are to be expected. poverty remains widespread, with the world’s largest concentra- With global mean warming approaching 4°C, an increase tion of poor people residing in the region. The timely arrival of in intra-seasonal variability in the Indian summer monsoon the summer monsoon, and its regularity, are critical for the rural precipitation of approximately 10 percent is projected. Large economy and agriculture in South Asia. uncertainty, however, remains about the fundamental behavior In South Asia, climate change shocks to food production and of the Indian summer monsoon under global warming. seasonal water availability appear likely to confront populations with ongoing and multiple challenges to secure access to safe • Drought: The projected increase in the seasonality of precipita- drinking water, sufficient water for irrigation and hydropower tion is associated with an increase in the number of dry days, production, and adequate cooling capacity for thermal power leading to droughts that are amplified by continued warming, production. Potential impact hotspots such as Bangladesh are with adverse consequences for human lives. Droughts are projected to be confronted by increasing challenges from extreme expected to pose an increasing risk in parts of the region. river floods, more intense tropical cyclones, rising sea-level and Although drought projections are made difficult by uncertain very high temperatures. While the vulnerability of South Asia’s precipitation projections and differing drought indicators, some large and poor populations can be expected to be reduced in the regions emerge to be at particularly high risk. These include future by economic development and growth, climate projections north-western India, Pakistan and Afghanistan. Over southern indicate that high levels of local vulnerability are likely to remain India, increasing wetness is projected with broad agreement and persist. between climate models. Many of the climate change impacts in the region, which • Glacial loss, snow cover reductions and river flow: Over appear quite severe with relatively modest warming of 1.5–2°C, the past century, most of the Himalayan glaciers have been pose a significant challenge to development. Major investments retreating. Melting glaciers and loss of snow cover pose a in infrastructure, flood defense, development of high temperature significant risk to stable and reliable water resources. Major and drought resistant crop cultivars, and major improvements in rivers, such as the Ganges, Indus and Brahmaputra, depend sustainability practices, for example in relation to groundwater significantly on snow and glacial melt water, which makes extraction would be needed to cope with the projected impacts them highly susceptible to climate change-induced glacier under this level of warming. melt and reductions in snowfall. Well before 2°C warming, a rapid increase in the frequency of low snow years is projected Likely Physical and Biophysical Impacts as a Function of Pro- with a consequent shift towards high winter and spring runoff jected Climate Change with increased flooding risks, and substantial reductions in dry season flow, threatening agriculture. These risks are projected • Heat extremes: Irrespective of future emission paths, in the to become extreme by the time 4°C warming is reached. next twenty years a several-fold increase in the frequency of unusually hot and extreme summer months is projected. A • Sea-level rise: With South Asian coastlines located close to substantial increase in mortality is expected to be associated the equator, projections of local sea-level rise show a stronger with such heat extremes and has been observed in the past. increase compared to higher latitudes. Sea-level rise is pro- jected to be approximately 100–115 cm in a 4°C world and • Precipitation: Climate change will impact precipitation with 60–80 cm in a 2°C world by the end of the 21st century relative variations across spatial and temporal scales. Annual precipi- to 1986–2005, with the highest values expected for the Maldives. tation is projected to increase by up to 30 percent in a 4°C world, however projections also indicate that dry areas such Sector Based and Thematic Impacts as in the north west, a major food producing region, would get drier and presently wet areas, get wetter. The seasonal • Crop yields are vulnerable to a host of climate-related distribution of precipitation is expected to become amplified, factors in the region, including seasonal water scarcity, ris- with a decrease of up to 30 percent during the dry season and ing temperatures and salinity intrusion due to sea-level rise. a 30 percent increase during the wet season under a 4°C world Projections indicate an increasingly large and likely negative (Figure 4). The projections show large sub-regional variations, impact on crop yields with rising temperatures. The projected 8 Execu tiv e Sum m ary CO2 fertilization effect could help to offset some of the yield Figure 4 Projected impact of climate change on annual, wet and reduction due to temperature effects, but recent data shows dry season rainfall in South Asia that the protein content of grains may be reduced. For warm- ing greater than 2°C, yield levels are projected to drop even with CO2 fertilization. • Total crop production and per-capita calorie availability is projected to decrease significantly with climate change. Without climate change, total crop production is projected to increase significantly by 60 percent in the region. Under a 2°C warming, by the 2050s, more than twice the imports might be required to meet per capita calorie demand when compared to a case without climate change. Decreasing food availability is related to significant health problems for affected populations, including childhood stunting, which is projected to increase by 35 percent compared to a scenario without climate change by 2050, with likely long-term consequences for populations in the region. • Water resources are already at risk in the densely popu- lated countries of South Asia, according to most methods for assessing this risk. For global mean warming approaching 4°C, a 10 percent increase in annual-mean monsoon intensity and a 15 percent increase in year-to-year variability of Indian summer monsoon precipitation is projected compared to normal levels during the first half of the 20th century. Taken together, these changes imply that an extreme wet monsoon Multi-model mean of the percentage change in annual (top), dry- that currently has a chance of occurring only once in 100 years season (DJF, middle) and wet-season (JJA, bottom) precipitation for is projected to occur every 10 years by the end of the century. RCP2.6 (left) and RCP8.5 (right) for South Asia by 2071–2099 relative to 1951–1980. Hatched areas indicate uncertainty regions, with 2 out • Deltaic regions and coastal cities are particularly exposed of 5 models disagreeing on the direction of change compared to the to compounding climate risks resulting from the interacting remaining 3 models. effects of increased temperature, growing risks of river flooding, rising sea-level and increasingly intense tropical cyclones, posing a high risk to areas with the largest shares of poor populations. Under 2°C warming, Bangladesh emerges as an impact hotspot with sea-level rise causing threats to food production, liveli- Tipping Points, Cascading Impacts and hoods, urban areas and infrastructure. Increased river flooding Consequences for Human Development combined with tropical cyclone surges also present significant risks. Human activity (building of irrigation dams, barrages, This report shows that the three highly diverse regions of Sub- river embankments and diversions in the inland basins of rivers) Saharan Africa, South East Asia, and South Asia that were analyzed can seriously exacerbate the risk of flooding downstream from are exposed to the adverse effects of climate change (Tables 1-3). extreme rainfall events higher up in river catchments. Most of the impacts materialize at relatively low levels of warming, well before warming of 4°C above pre-industrial levels is reached. • Energy security is expected to come under increasing Each of the regions is projected to experience a rising inci- pressure from climate-related impacts to water resources. dence of unprecedented heat extremes in the summer months The two dominant forms of power generation in the region by the mid-2020s, well before a warming of even 1.5°C. In fact, are hydropower and thermal power generation (e.g., fossil with temperatures at 0.8°C above pre-industrial levels, the last fuel, nuclear and concentrated solar power), both of which decade has seen extreme events taking high death tolls across can be undermined by inadequate water supply. Thermal all regions and causing wide-ranging damage to assets and agri- power generation may also be affected through pressure cultural production. As warming approaches 4°C, the severity placed on cooling systems due to increases in air and water of impacts is expected to grow with regions being affected dif- temperatures. ferently (see Box 1). 9 Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce Box 1: Regional Tipping Points, identified as a potential tipping element of the Earth system. Physi- cally plausible mechanisms for an abrupt change in the Indian Cascading Impacts, and monsoon towards a drier, lower rainfall state could precipitate a Development Implications major crisis in the South Asian region. Climate impacts can create a domino-effect and thereby ulti- • Sub-Saharan Africa’s food production systems are increas- mately affect human development. For example, decreased yields ingly at risk from the impacts of climate change. Significant and lower nutritional value of crops could cascade throughout yield reductions already evident under 2°C warming are expected to have strong repercussions on food security and society by increasing the level of malnutrition and childhood stunt- may negatively influence economic growth and poverty re- ing, causing adverse impacts on educational performance. These duction in the region. Significant shifts in species composition effects can persist into adulthood with long-term consequences and existing ecosystem boundaries could negatively impact for human capital that could substantially increase future devel- pastoral livelihoods and the productivity of cropping systems opment challenges. Most of the impacts presented in the regional and food security. analyses are not unique to these regions. For example, global • South East Asian rural livelihoods are faced with mounting warming impacts on coral reefs worldwide could have cascading pressures as sea-level rises and important marine ecosystem impacts on local livelihoods, and tourism. services are expected to be lost as warming approaches 4°C. Coral systems are threatened with extinction and their Multi-Sectoral Hotspots loss would increase the vulnerability of coastlines to sea-level Under 4°C warming, most of the world’s population is likely rise and storms. The displacement of impacted rural and to be affected by impacts occurring simultaneously in multiple coastal communities resulting from the loss of livelihood into sectors. Furthermore, these cascading impacts will likely not be urban areas could lead to ever higher numbers of people confined to one region only; rather they are expected to have far- in informal settlements being exposed to multiple climate reaching repercussions across the globe. For example, impacts in impacts, including heat waves, flooding, and disease. the agricultural sector are expected to affect the global trade of • South Asian populations in large parts depend on the stabili- food commodities, so that production shocks in one region can ty of the monsoon, which provides water resources for most of have wide-ranging consequences for populations in others. Thus, the agricultural production in the region. Disturbances to the vulnerability could be greater than suggested by the sectoral monsoon system and rising peak temperatures put water and analysis of the assessed regions due to the global interdependence, food resources at severe risk. Particularly in deltaic areas, and impacts on populations are by no means limited to those that populations are exposed to the multiple threats of increasing tropical cyclone intensity, sea-level rise, heat extremes and form the focus of this report. Many of the climatic risk factors are extreme precipitation. Such multiple impacts can have severe concentrated in the tropics. However, no region is immune to the negative implications for poverty eradication in the region. impacts of climate change. In fact, under 4°C warming, most of the world´s population is likely to be affected by impacts occur- ring simultaneously in multiple sectors. Results from the recent Inter-Sectoral Impact Model Intercom- Tipping Points and Cascading Impacts parison Project (ISI-MIP) were used to assess ‘hotspots’ where considerable impacts in one location occur concurrently in more As temperatures continue to rise, there is an increased risk of than one sector (agriculture, water resources, ecosystems and critical thresholds being breached. At such “tipping points”, health (malaria)). The proportion of the global population affected elements of human or natural systems—such as crop yields, dry contemporaneously by multiple impacts increases significantly season irrigation systems, coral reefs, and savanna grasslands— under higher levels of warming. Assuming fixed year-2000 popu- are pushed beyond critical thresholds, leading to abrupt system lation levels and distribution, the proportion of people exposed changes and negative impacts on the goods and services they to multiple stressors across these sectors would increase by 20 provide. Within the agricultural sector, observed high temperature percent under 2°C warming to more than 80 percent under 4°C sensitivity in some crops (e.g., maize), where substantial yield warming above pre-industrial levels. This novel analysis4 finds reductions occur when critical temperatures are exceeded, points exposure hotspots to be the southern Amazon Basin, southern to a plausible threshold risk in food production regionally. In a Europe, east Africa and the north of South Asia. The Amazon and global context, warming induced pressure on food supplies could have far-reaching consequences. 4 Based on the first inter-sectoral climate model intercomparison, the first round Some major risks cannot yet be quantified adequately: For of which was concluded in early 2013. Papers are in revision at the time of writing example, while large uncertainty remains, the monsoon has been this report. 10 Execu tiv e Sum m ary Box 2: New Clusters of the East African highlands are particularly notable due to their exposure to three overlapping sectors. Small regions in Central America and West Africa are also affected. Vulnerability—Urban Areas One of the common features that emerge from the regional analy- Consequences for Development ses is of new clusters of vulnerability appearing in urban areas. Climate change is already undermining progress and prospects for development and threatens to deepen vulnerabilities and Urbanization rates are high in developing regions. For example, erode hard-won gains. Consequences are already being felt on by 2050, it is projected that up to 56 percent of Sub-Saharan Af- every continent and in every sector. Species are being lost, lands rica’s population will live in urban areas compared to 36 percent in 2010. Although the urbanization trend is driven by a host of are being inundated, and livelihoods are being threatened. More factors, climate change is becoming an increasingly significant droughts, more floods, more strong storms, and more forest fires driver as it places rural and coastal livelihoods under mounting are taxing individuals, businesses and governments. Climate- pressure. related extreme events can push households below the poverty trap threshold, which could lead to greater rural-urban migration While rural residents are expected to be exposed to a variety of (see Box 2). Promoting economic growth and the eradication of climatic risk factors in each region, a number of factors define poverty and inequality will thus be an increasingly challenging the particular vulnerability of urban dwellers, especially the urban task under future climate change. poor, to climate change impacts. For example: Actions must be taken to mitigate the pace of climate change • Extreme heat is felt more acutely in cities where the built-up and to adapt to the impacts already felt today. It will be impos- environments amplify temperatures. sible to lift the poorest on the planet out of poverty if climate • As many cities are located in coastal areas, they are often change proceeds unchecked. Strong and decisive action must be exposed to flooding and storm surges. taken to avoid a 4°C world—one that is unmanageable and laden with unprecedented heat waves and increased human suffering. • Informal settlements concentrate large populations and often It is not too late to hold warming near 2°C, and build resilience lack basic services, such as electricity, sanitation, health, infrastructure and durable housing. In such areas, people are to temperatures and other climate impacts that are expected to highly exposed to extreme weather events, such as storms still pose significant risks to agriculture, water resources, coastal and flooding. For example, this situation is the case in Metro infrastructure, and human health. A new momentum is needed. Manila in the Philippines, or Kolkata in India, where poor Dramatic technological change, steadfast and visionary political households are located in low-lying areas or wetlands that are will, and international cooperation are required to change the particularly vulnerable to tidal and storm surges. trajectory of climate change and to protect people and ecosystems. • Informal settlements often provide conditions particularly The window for holding warming below 2°C and avoiding a 4°C conducive to the transmission of vector and water borne world is closing rapidly, and the time to act is now. diseases, such as cholera and malaria that are projected to become more prevalent with climate change. • The urban poor have been identified as the group most vulnerable to increases in food prices following production shocks and declines that are projected under future climate change. Climate change poses a particular threat to urban residents and at the same time is expected to further drive urbanization, ultimately placing more people at risk to the clusters of impacts outlined above. Urban planning and enhanced social protec- tion measures, however, provide the opportunity to build more resilient communities in the face of climate change. 11 Table 1: Climate Impacts in Sub-Saharan Africa 0.8°C WARMING 2°C WARMING 4°C WARMING Risk/Impact (Observed) (2040s)1 (2080s) Unusual heat Virtually absent About 45 percent of land in austral sum- >85 percent of land in austral extremes mer months (DJF) summer months (DJF) Unprecedented Absent About 15 percent of land in austral sum- >55 percent of land in austral Heat extremes heat extremes mer months (DJF) summer months (DJF) Increasing drought trends ob- Likely risk of severe drought in southern Likely risk of extreme drought served since 1950 and central Africa, increased risk in in southern Africa and severe west Africa, possible decrease in east drought in central Africa, Africa but west and east African projec- increased risk in west Africa, tions are uncertain2 possible decrease in east Africa, but west and east Afri- Drought can projections are uncertain3 Increased drying4 Area of hyper-arid and arid regions Area of hyper-arid and arid Aridity grows by 3 percent regions grows by 10 percent 70cm (60–80cm) by 2080–2100 105 (85–125cm) by Sea-level rise 2080–2100 10–15 percent Sub-Saharan species at risk of extinction (assuming warming too Ecosystem shifts rapid to allow migration of species) 5 50–70 percent decrease in recharge Increase in blue water avail- rates in western southern Africa and ability in east Africa and parts southern west Africa; 30 percent in- of west Africa7; decrease in Water availability crease in recharge rate in some parts of green water availability in (Run-off / Ground- eastern southern Africa and east Africa6 most of Africa, except parts water recharge) of east Africa Crop growing Projected climate over less than 15 Reduced length of grow- areas percent of maize, millet and sorghum ing period by more than 20 areas overlaps with present-day climate percent of crop-growing areas Crop Baseline of approximately 81 mil- Without climate change, a large pro- production lion tonnes in 2000, about 121 kg/ jected increase of total production to capita 192 million tonnes that fails to keep up with population growth, hence decrease Crop yields, to 111 kg/capita. With climate change areas and food smaller increase to 176 million tonnes production and further decrease to 101 kg/capita8 All crops Increased crop losses and damages (maize, sorghum, wheat, millet, ground- Yields nut, cassava)9 Severe drought impacts on live- 10 percent increase in yields stock10 of B. decumbens (pasture species) in east and southern Africa; 4 percent and 6 per- cent decrease in central and Livestock west Africa11 Significant reduction in available protein; economic and job losses Marine fisheries projected12 Approximately 18 million people flooded per year Coastal areas without adaptation13 Undernourishment is expected to in- crease significantly, and those affected by moderate and severe stunting is Health and poverty expected to increase14 12 Execu tiv e Sum m ary Table 2: Climate Impacts in South East Asia 0.8°C WARMING 2°C WARMING 4°C WARMING Risk/Impact (Observed) (2040s)1 (2080s) Unusual heat Virtually absent About 60–70 percent of land in boreal >90 percent of land in boreal extremes summer months (JJA) summer months (JJA) Unprecedented Absent 30–40 percent of land area during >80 percent of land area heat extremes boreal summer months (JJA)15 during boreal summer Heat extremes months (JJA) Overall decrease in tropical cyclone fre- Decreased number of tropical quency 16,17; global increase in tropical cyclones making landfall, cyclone rainfall; increasing frequency of but maximum wind velocity category 5 storms18 at the coast is projected to increase by about 6 percent for mainland South East Asia and about 9 percent for the Tropical cyclones Philippines 75cm (65–85cm) by 2080–2100 110 cm (85–130 cm) by 2080–2100, lower around Sea-level rise Bangkok by 5 cm Coastal erosion For the south Hai Thinh commune Mekong delta significant (loss of land) in the Vietnamese Red River delta, increase in coastal erosion20 about 34 percent (12 percent) of the increase of erosion rate between 1965 and 1995 (1995 and 2005) has been attributed to the direct effect of sea-level rise19 Population 20 million people in South East 8.5 million people more than exposure Asian cities exposed to coastal at present are projected to be flooding in 200521 exposed to coastal flooding by 2100 for global sea-level rise of 1 m22 City exposure Ho Chi Minh City—up to 60 percent of the built-up area Sea-level rise projected to be exposed23 to impacts 1 m sea-level rise Mekong River delta (2005): Long Mahakam river region in Indo- An province’s sugar cane produc- nesia, increase in land area tion diminished by 5–10 percent; affected by 7–12 percent25 and significant rice in Duc Hoa Salinity intrusion district was destroyed24 Nearly all coral reefs experience severe Coral reefs subject to severe Ecosystem im- thermal stress under warming levels of bleaching events annually pacts (Coral reefs / 1.5–2°C and coastal wetland area coastal wetlands) decrease26 Estimations of the costs of adapting27 aquaculture in South East Asia range from US$130–190 million per year from Aquaculture 2010–2050 Decrease in maximum catch potential Markedly negative trend in Marine fisheries around the Philippines and Vietnam28 bigeye tuna29 The relative risk of diarrhoea is ex- Health and poverty pected to increase30 Thailand, Indonesia, the Philippines, Myanmar and Cambodia among the Tourism most vulnerable tourism destinations31 13 Table 3: Climate Impacts in South Asia 0.8°C WARMING 2°C WARMING 4°C WARMING Risk/Impact (Observed) (2040s)1 (2080s) Unusual heat Virtually absent About 20 percent of land in boreal sum- >70 percent of land in boreal extremes mer months (JJA) summer months (DJF) Unprecedented Absent <5 percent of land in boreal summer >40 percent of land in boreal heat extremes months (JJA), except for the south- summer months (DJF) ernmost tip of India and Sri Lanka with 20-30 percent of summer months Heat extremes experiencing unprecedented heat Increased drought over northwestern India, Pakistan, and Afghanistan32. Increased length of dry spells in eastern Drought India and Bangladesh33 70cm (60–80cm) by 2080–210034 105 cm (85–125cm) by 2080–2100, higher by 5–10 Sea-level rise cm around Maldives, Kolkata Increasingly severe tropical cyclone Tropical cyclones impacts35 Increasingly severe flooding36 By 2070 approximately 1.5 million people are projected to be affected by coastal floods in the coastal cities of Flooding Bangladesh37 Indus Mean flow increase of about 65 per- cent38 Ganges 20 percent increase in run-off39 50 percent increase in run-off Brahmaputra Very substantial reductions in late River run-off spring and summer flow40 Overall In India, gross per capita water Food water requirements in India availability is projected to decline projected to exceed green water due to population growth41 availability42, 43. Around 3°C, it is very likely that per capita water availability in South Asia will decrease by more than 10 percent44 Groundwater Groundwater resources already Climate change is projected to further Water availability recharge under stress45 aggravate groundwater stress Overall crop production is projected to increase by only 12 percent above 2000 levels (instead of a 60 percent increase without climate change), leading to a one third decline in per capita crop Crop production production46 All crops Reduced rice yields, especially in Crop yield decreases regardless of Yields rain-fed areas potentially positive effects Malnutrition With climate change percentages and childhood increase to 14.6 percent and about 5 stunting percent respectively47 Malaria Relative risk of malaria projected to increase by 5 percent in 205048 Diarrheal Relative risk of diarrheal disease disease increase by 1.4 percent compared to 2010 baseline by 2050 Heat waves New Delhi exhibits a 4 percent in- Most South Asian countries are likely to vulnerability crease in heat-related mortality per experience a very substantial increase 1°C above the local heat threshold in excess mortality due to heat stress by Health and poverty of 20°C49 the 2090s50 14 Execu tiv e Sum m ary Endnotes 1 Years indicate the decade during which warming levels are exceeded in a business-as-usual scenario, not in mitigation scenarios limiting warming to these levels, or below, since in that case the year of exceeding would always be 2100, or not at all. 2 This is the general picture from CMIP5 global climate models; however, significant uncertainty appears to remain. Observed drought trends (Lyon and DeWitt 2012) and attribution of the 2011 drought in part to human influence (Lott et al. 2013) leaves significant uncertainty as to whether the projected increased precipitation and reduced drought are robust (Tierney, Smerdon, Anchukaitis, and Seager 2013). 3 Dai (2012). CMIP5 models under RCP4.5 for drought changes 2050–99, warming of about 2.6°C above pre-industrial levels. 4 see Endnote 2. 5 Parry et al. (2007). 6 Temperature increase of 2.3°C and 2.1°C for the period 2041–2079 under SRES A2 and B2 (Döll, 2009). 7 Gerten et al. (2011). 8 Nelson et al. (2010). 9 Schlenker and Lobell (2010). 10 FAO (2008). 11 Thornton et al. (2011). 12 Lam, Cheung, Swartz, & Sumaila (2012). Applying the same method and scenario as (Cheung et al., 2010). 13 Hinkel et al. (2011) high SLR scenario 126 cm by 2100. In the no sea-level rise scenario, only accounting for delta subsidence and increased population, up to 9 million people would be affected. 14 Lloyd, Kovats, and Chalabi (2011) estimate the impact of climate-change-induced changes to crop productivity on undernourished and stunted children under five years of age by 2050 and find that the proportion of undernourished children is projected to increase by 52 percent, 116 percent, 82 percent, and 142 percent in central, east, south, and west Sub-Saharan Africa, respectively. The proportion of stunting among children is projected to increase by 1 percent (for moderate stunting) or 30 percent (for severe stunting); 9 percent or 55 percent; 23 percent or 55 percent; and 9 percent or 36 percent for central, east, south, and west Sub-Saharan Africa. 15 Beyond 5-sigma under 2°C warming by 2071–2099. 16 Held and Zhao (2011). 17 Murakami, Wang, et al. (2012). 18 Murakami, Wang, et al. (2012). Future (2075–99) projections SRES A1B scenario. 19 Duc, Nhuan, & Ngoi (2012). 20 1m sea-level rise by 2100 (Mackay and Russell, 2011). 21 Hanson et al. (2011). 22 Brecht et al. (2012). In this study, urban population fraction is held constant over the 21st century. 23 Storch & Downes (2011). In the absence of adaptation, the planned urban development for the year 2025 contributes to increase Ho Chi Minh City exposure to sea-level rise by 17 percent. 24 MoNRE (2010) states “Sea-level rise, impacts of high tide and low discharge in dry season contribute to deeper salinity intrusion. In 2005, deep intrusion (and more early than normal), high salinity and long-lasting salinization occurred frequently in Mekong Delta provinces.” 25 Under 4°C warming and 1 m sea-level rise by 2100 (Mcleod, Hinkel et al., 2010). 26 Meissner, Lippmann, & Sen Gupta (2012). 27 US$190.7 million per year for the period 2010–2020 (Kam, Badjeck, Teh, Teh, & Tran, 2012); US$130 million per year for the period 2010–2050 (World Bank, 2010). 28 Maximum catch potential (Cheung et al., 2010). 29 Lehodey et al. (2010). In a 4°C world, conditions for larval spawning in the western Pacific are projected to have deteriorated due to increasing temperatures. Overall adult mortality is projected to increase, leading to a markedly negative trend in biomass by 2100. 30 Kolstad & Johansson (2011) derived a relationship between diarrhoea and warming based on earlier studies. (Scenario A1B). 31 Perch-Nielsen (2009). Assessment allows for adaptive capacity, exposure and sensitivity in a 2°C warming and 50cm SLR scenario for the period 2041–2070. 32 Dai (2012). 33 Sillmann & Kharin (2013). 34 For a scenario in which warming peaks above 1.5°C around the 2050s and drops below 1.5°C by 2100. Due to slow response of oceans and ice sheets the sea-level response is similar to a 2°C scenario during the 21st century, but deviates from it after 2100. 35 World Bank (2010a). Based on the assumption that landfall occurs during high-tide and that wind speed increases by 10 percent compared to cyclone Sidr. 36 Mirza (2010). 37 Brecht et al. (2012). In this study, urban population fraction is held constant over the 21st century. 38 Van Vliet et al. (2013), for warming of 2.3°C and of 3.2°C. 39 Fung, Lopez, & New (2011) SRES A1B warming of about 2.7°C above pre-industrial levels. 40 For the 2045 to 2065 period (global-mean warming of 2.3°C above pre-industrial) (Immerzeel, Van Beek, & Bierkens, 2010). 41 Bates, Kundzewicz, Wu, & Palutikof (2008); Gupta & Deshpande (2004). 42 When taking a total availability of water below 1300m3 per capita per year as a benchmark for water amount required for a balanced diet. 43 Gornall et al. (2010). Consistent with increased precipitation during the wet season for the 2050s, with significantly higher flows in July, August and September than in 2000. Increase in overall mean annual soil moisture content is expected for 2050 with respect to 1970–2000, but the soil is also subject to drought conditions for an increased length of time. 44 Gerten et al. (2011). For a global warming of approximately 3°C above pre-industrial and the SRES A2 population scenario for 2080. 45 Rodell, Velicogna, & Famiglietti (2009). (Döll, 2009; Green et al., 2011). 46 Nelson et al. (2010). 47 Lloyd et al. (2011). South Asia by 2050 for a warming of approximately 2°C above pre-industrial (SRES A2). 48 Pandey (2010). 116,000 additional incidents, 1.8°C increase in SRES A2 scenario. 49 McMichael et al. (2008). 50 Takahashi, Honda, & Emori (2007), global mean warming for the 2090s of about 3.3°C above pre-industrial under the SRES A1B scenario and estimated an increase in the daily maximum temperature change over South Asia in the range of 2 to 3°C. 15 Abbreviations °C degrees Celsius IEA International Energy Agency 3-sigma events Events that are three standard deviations IPCC Intergovernmental Panel on Climate Change outside the historical mean ISI-MIP Inter-Sectoral Impact Model Intercomparison 5-sigma events Events that are five standard deviations out- Project side the historical mean JJA June July August AI Aridity Index MAGICC Model for the Assessment of Greenhouse-gas ANN Annual Induced Climate Change AOGCM Atmosphere-Ocean General Circulation Model MGIC Mountain Glaciers and Ice Caps AR4 Fourth Assessment Report of the Inter­ NH Northern Hemisphere governmental Panel on Climate Change OECD Organisation for Economic Cooperation and AR5 Fifth Assessment Report of the Inter­ Development governmental Panel on Climate Change PDSI Palmer Drought Severity Index BAU Business as Usual ppm parts per million CaCO3 Calcium Carbonate RCP Representative Concentration Pathway CAT Climate Action Tracker SCM Simple Climate Model CMIP5 Coupled Model Intercomparison Project SLR Sea-level Rise Phase 5 SRES IPCC Special Report on Emissions Scenarios CO2 Carbon Dioxide SREX IPCC Special Report on Managing the Risks DIVA Dynamic Interactive Vulnerability of Extreme Events and Disasters to Advance Assessment Climate Change Adaptation DJF December January February SSA Sub-Saharan Africa ECS Equilibrium Climate Sensitivity UNEP United Nations Environment Programme GCM General Circulation Model UNFCCC United Nations Framework Convention on GDP Gross Domestic Product Climate Change FPU Food Productivity Units UNRCO United Nations Resident Coordinator’s Office GFDRR Global Facility for Disaster Reduction and USAID United States Agency for International Recovery Development IAM Integrated Assessment Model WBG World Bank Group 17 Glossary Aridity Index The Aridity Index (AI) is an indicator designed for a scenario additionally incorporating reductions currently identifying structurally “arid” regions, that is, regions with a pledged internationally by countries. long-term average precipitation deficit. AI is defined as total annual precipitation divided by potential evapotranspiration, CMIP5 The Coupled Model Intercomparison Project Phase 5 with the latter a measure of the amount of water a representative (CMIP5) brought together 20 state-of-the-art GCM groups, crop type would need as a function of local conditions such as which generated a large set of comparable climate-projections temperature, incoming radiation and wind speed, over a year data. The project provided a framework for coordinated climate to grow, which is a standardized measure of water demand. change experiments and includes simulations for assessment in the IPCC´s AR5. Biome A biome is a large geographical area of distinct plant and animal groups, one of a limited set of major habitats, classified CO2 fertilization The CO2 fertilization effect may increase the rate by climatic and predominant vegetative types. Biomes include, of photosynthesis mainly in C3 plants and increase water use for example, grasslands, deserts, evergreen or deciduous efficiency, thereby producing increases in agricultural C3 crops forests, and tundra. Many different ecosystems exist within in grain mass and/or number. This effect may to some extent each broadly defined biome, which all share the limited range offset the negative impacts of climate change, although grain of climatic and environmental conditions within that biome. protein content may decline. Long-term effects are uncertain as they heavily depend on a potential physiological long-term C3/C4 plants refers to two types of photosynthetic biochemical acclimation to elevated CO2, as well as on other limiting factors “pathways”. C3 plants include more than 85 percent of plants including soil nutrients, water and light. on Earth (e.g. most trees, wheat, rice, yams and potatoes) and respond well to moist conditions and to additional carbon GCM A General Circulation Model is the most advanced type dioxide in the atmosphere. C4 plants (for example savanna of climate model used for projecting changes in climate due grasses, maize, sorghum, millet, sugarcane) are more efficient to increasing greenhouse-gas concentrations, aerosols and in water and energy use and outperform C3 plants in hot and external forcings like changes in solar activity and volcanic dry conditions. eruptions. These models contain numerical representations of physical processes in the atmosphere, ocean, cryosphere CAT The Climate Action Tracker (CAT) is an independent science- and land surface on a global three-dimensional grid, with based assessment, which tracks the emission commitments the current generation of GCMs having a typical horizontal and actions by individual countries. The estimates of future resolution of 100 to 300 km. emissions deducted from this assessment serve to analyse warming scenarios that would result from current policy: GDP (Gross Domestic Product) is the sum of the gross value (a) CAT Reference BAU: a lower reference ‘business-as-usual’ added by all resident producers in the economy plus any (BAU) scenario that includes existing climate policies, but not product taxes and minus any subsidies not included in the pledged emission reductions; and (b) CAT Current Pledges: value of the products. It is calculated without deductions for 19 Tur n Do wn t he H e at: C l imat e E x t r eme s , Region a l Impa cts, a n d th e C a se for Resi li e nce depreciation of fabricated assets or for depletion and degrada- representative of present-day warming. Fitting a linear trend over tion of natural resources. the period 1901 to 2010 gives a warming of 0.8°C since “early industrialization.” Global-mean near-surface air temperatures GDP (PPP) per capita is GDP on a purchasing power parity basis in the instrumental records of surface-air temperature have divided by population. Please note: Whereas PPP estimates for been assembled dating back to about 1850. The number of OECD countries are quite reliable, PPP estimates for develop- measurement stations in the early years is small and increases ing countries are often rough approximations. rapidly with time. Industrialization was well on its way by 1850 and 1900, which implies using 1851–1879 as a base Hyper-aridity Land areas with very low Aridity Index (AI), gener- period, or 1901 as a start for linear trend analysis might lead ally coinciding with the great deserts. There is no universally to an underestimate of current and future warming, but global standardized value for hyper-aridity, and values between 0 and greenhouse-gas emissions at the end of the 19th century were 0.05 are classified in this report as hyper-arid. still small and uncertainties in temperature reconstructions before this time are considerably larger. IPCC AR4, AR5 The Intergovernmental Panel on Climate Change (IPCC) is the leading body of global climate change assess- RCP Representative Concentration Pathways (RCPs) are based on ments. It comprises hundreds of leading scientists worldwide carefully selected scenarios for work on integrated assessment and on a regular basis publishes assessment reports which modeling, climate modeling, and modeling and analysis of give a comprehensive overview over the most recent scientific, impacts. Nearly a decade of new economic data, information technical and socio-economic information on climate change about emerging technologies, and observations of environmental and its implications. The Fourth Assessment Report (AR4) was factors, such as land use and land cover change, are reflected in published in 2007. The upcoming Fifth Assessment Report this work. Rather than starting with detailed socioeconomic sto- (AR5) will be completed in 2013/2014. rylines to generate emissions scenarios, the RCPs are consistent sets of projections of only the components of radiative forcing ISI-MIP The first Inter-Sectoral Impact Model Intercomparison (the change in the balance between incoming and outgoing Project (ISI-MIP) is a community-driven modeling effort which radiation to the atmosphere caused primarily by changes in provides cross-sectoral global impact assessments, based on atmospheric composition) that are meant to serve as input for the newly developed climate [Representative Concentration climate modeling. These radiative forcing trajectories are not Pathways (RCPs)] and socio-economic scenarios. More than associated with unique socioeconomic or emissions scenarios, 30 models across five sectors (agriculture, water resources, and instead can result from different combinations of economic, biomes, health and infrastructure) participated in this model- technological, demographic, policy, and institutional futures. ing exercise. RCP2.6 RCP2.6 refers to a scenario which is representative of the MAGICC Carbon-cycle/climate model of “reduced complexity,” here literature on mitigation scenarios aiming to limit the increase applied in a probabilistic set-up to provide “best-guess” global- of global mean temperature to 2°C above the pre-industrial mean warming projections, with uncertainty ranges related to period. This emissions path is used by many studies that are the uncertainties in carbon-cycle, climate system and climate being assessed for the IPCC´s Fifth Assessment Report and is sensitivity. The model is constrained by historical observations the underlying low emissions scenario for impacts assessed in of hemispheric land/ocean temperatures and historical estimates other parts of this report. In this report we refer to the RCP2.6 for ocean heat-uptake, reliably determines the atmospheric as a 2°C World. burden of CO2 concentrations compared to high-complexity carbon-cycle models and is also able to project global-mean RCP8.5 RCP8.5 refers to a scenario with no-climate-policy baseline near-surface warming in line with estimates made by GCMs. with comparatively high greenhouse gas emissions which is used by many studies that are being assessed for the upcoming Pre-industrial levels (what it means to have present 0.8°C IPCC Fifth Assessment Report (AR5). This scenario is also the warming) The instrumental temperature records show that underlying high emissions scenario for impacts assessed in the 20-year average of global-mean near-surface air tempera- other parts of this report. In this report we refer to the RCP8.5 ture in 1986–2005 was about 0.6°C higher than the average as a 4°C World above the pre-industrial period. over 1851–1879. There are, however, considerable year-to- year variations and uncertainties in data. In addition the Severe & extreme Indicating uncommon (negative) consequences. 20-year average warming over 1986–2005 is not necessarily These terms are often associated with an additional qualifier 20 G lossary like “unusual” or “unprecedented” that has a specific quanti- Unusual & unprecedented In this report, unusual and unprec- fied meaning (see “Unusual & unprecedented”). edented heat extremes are defined using thresholds based on the historical variability of the current local climate. The SRES The Special Report on Emissions Scenarios (SRES), published absolute level of the threshold thus depends on the natural by the IPCC in 2000, has provided the climate projections for year-to-year variability in the base period (1951–1980), which the Fourth Assessment Report (AR4) of the Intergovernmental is captured by the standard deviation (sigma). Unusual heat Panel on Climate Change (IPCC). They do not include mitiga- extremes are defined as 3-sigma events. For a normal distri- tion assumptions. The SRES study includes consideration of 40 bution, 3-sigma events have a return time of 740 years. The different scenarios, each making different assumptions about 2012 U.S. heat wave and the 2010 Russian heat wave classify the driving forces determining future greenhouse gas emissions. as 3-sigma and thus unusual events. Unprecedented heat Scenarios are grouped into four families, corresponding to a extremes are defined as 5-sigma events. They have a return wide range of high and low emission scenarios. time of several million years. Monthly temperature data do not necessarily follow a normal distribution (for example, SREX In 2012 the IPCC published a special report on Managing the distribution can have “long” tails, making warm events the Risks of Extreme Events and Disasters to Advance Climate more likely) and the return times can be different from the Change Adaptation (SREX). The report provides an assessment ones expected in a normal distribution. Nevertheless, 3-sigma of the physical as well as social factors shaping vulnerability to events are extremely unlikely and 5-sigma events have almost climate-related disasters and gives an overview of the potential certainly never occurred. for effective disaster risk management. 21