verely affect rice crop production in ESAP [ESAP Chapter 4; Global Chapter 5].
     Extreme climate events are expected to increase in fre­quency and severity and all regions will likely be affected by the increase in floods, droughts, heat waves, tropical cyclones and other extreme events with significant consequences for food and forestry production, and food insecurity. This was demonstrated during the summer 2003 European heat wave that was accompanied by drought and reduced maize yields by 20 percent. There is likely to be an increase in incidence and severity of forest fires in next decades, partly as a result of climate change [NAE Chapter 2].
     Climate change is expected to threaten livestock holders in numerous ways: animals are very sensitive to heat stress; they require a reliable resource of water and pasture is very sensitive to drought. In addition, infectious and vector-borne animal diseases will continue to become increasingly frequent worldwide [Global Chapter 3].
     The effects of climate change on crop and tree yields, fisheries,   forestry  and  livestock  vary  greatly  by  region [Global Chapter 1; SSA Chapter 4] and climate scenarios project that local biomes and terrestrial ecosystems will change. Although climate projections cannot tell us exactly what and where the changes will be and when they will be experienced, it is known that climate change will affect re­gional patterns of temperature and precipitation.
     Global climate change is expected to alter marine and freshwater ecosystems and habitats. Rising sea levels will alter coastal habitats and their future productivity, threaten­ing some of the most productive fishing areas in the world. Changes in ocean temperatures will alter ocean currents and the distribution and ranges of marine animals, including fish populations. Rising atmospheric CO2 will lead to acidifi­cation of ocean waters and disrupt the ability of animals (such as corals, mollusks, plankton) to secrete calcareous skeletons, thus reducing their role in critical ecosystems and food webs [Global Chapter 6; SSA Chapter 4]. Sea level rise could lead to saltwater intrusion causing a reduction in agri­cultural productivity in some coastal areas [ESAP Chapters 2, 4; Global Chapter 1; NAE Chapter 3; SSA Chapter 3]. It is expected that climate change will lead to significant reduc­tions in the diversity fish species with important changes in abundance and distribution of fresh water fish stocks such as in rivers and lakes in SSA.
     Climate change is affecting and will affect the geographic range and incidence of many human, animal, and plant pests, disease vectors and wide variety of invasive species that will inhabit new ecological niches, [ESAP Chapter 3; Global Chapters 1, 5, 6, 7]. These anticipated changes may have a negative impact on agricultural activities through their effect on the health of farmers and ecosystems, par­ticularly in developing countries. For example, an increase in temperature and precipitation is projected to expand the range of vector-transmitted diseases making it possible for these diseases to become established outside limits of their current range, and at higher elevations [LAC Chapter 1]. In addition, increased irrigation as an adaptive response to better control water scarcity due to climate change may in­crease incidences of malaria [Global Chapter 5] and other water-related diseases.
     Pests and diseases are strongly influenced by seasonal

weather patterns and changes in climate. Established pests may become more prevalent due to favorable conditions that   include   higher  winter  temperatures   (thus  reduced winter-kill) and more rainfall. New pest introductions al­ter   pest/predator/parasite   population   dynamics   through changes in growth and developmental rates, the number of generations produced per year, the severity and density of populations, the pest virulence to a host plant, or the sus­ceptibility of the host to the pest. Changing weather patterns also increase crop vulnerability to pests, weeds and inva­sive plants, thus decreasing yields and increasing pesticide applications  [Global Chapter 3]. Increased temperatures are likely to facilitate range expansion of highly damaging weeds, which are currently limited by cool temperatures [Global Chapters 3,6].
     Climate simulation models indicate substantial future increases in soil erosion. Tropical soils with low organic matter are expected to experience the greatest impact of erosion on crop productivity. Desertification will be exacer­bated by reductions in average annual rainfall and increased evapotranspiration especially in soils that have low levels of biological activity, organic matter and aggregate stability. [CWANA Chapter 1; Global Chapter 6] In addition, con­tinued migration to urban areas of younger segments of the population can lead to agricultural land degradation thus exacerbating the effects of climate change, as those left on the land are mostly old and the vulnerable.
     There is a serious potential for future conflict, and possible violent clashes over habitable land and natural re­sources, such as freshwater, as a result of climate change, which could seriously impede food security and poverty reduction. An estimated 25 million people per year al­ready flee from weather-related disasters; global warming is projected to increase this number to some 200 million before 2050, with semiarid ecosystems expected to be the most vulnerable to impacts from climate change refugees [Global Chapter 6]. In addition, climate change combined with other socioeconomic stresses could alter the regional distribution of hunger and malnutrition, with large negative effects on sub-Saharan Africa.

Options for Action
The IPCC concluded that "warming of the climate system is now unequivocal" and that "most of the observed increase in globally averaged temperatures since the mid-20th cen­tury is very likely due to the observed increase in anthro­pogenic greenhouse gas concentrations." With these strong conclusions the focus should now shift from defining the threat to seeking solutions.
     In considering responses to the threat of climate change there are important policy considerations. Tackling the root cause of the problem, which is the emissions of greenhouse gases into the atmosphere, requires a global approach. The earlier and stronger the cuts in emissions, the quicker con­centrations will approach stabilization. While emission re­duction measures clearly are essential, further changes in the climate are now inevitable and thus adaptation becomes imperative. Climate change is not simply an environmental issue but can also be framed in terms of other issues such as sustainable development and security. Actions directed at addressing climate change and efforts to promote sus-