4

Food Security ...................................................... 87 4.4 Climate Change and Food Security in the

Near Future................................................................... 87 4.4.1 Climate Change and Length of Growing

Season in 20th Century ..................................... 88 4.4.1.1 Length of Growing Season on

All Land................................................. 88 4.4.1.2 Length of Growing Season on

Current Cropland ................................. 89 4.4.2 Climate Change and Food Security

Projections for 2012.......................................... 100 4.4.3 Discussion ......................................................... 101

4.5 Summary and Conclusions ......................................... 105 Acknowledgments................................................................. 107 References............................................................................. 107

4.1 INTRODUCTION

Many people in the world are food insecure and are expected to remain so for some time to come (Rosegrant et al., 2001; Food and Agriculture Organization [FAO], 2003c; Shapouri and Rosen, 2003). Food insecurity is associated with low levels of agricultural productivity and/or inadequate purchasing power. Low levels of agricultural productivity may also result in inadequate purchasing power in regions in which sales of agricultural commodities are a major source of income. Emissions of greenhouse gases are expected to affect food security because of their potential impacts, both positive and negative, on agricultural productivity. Of particular concern, however, are the potentially damaging effects of rising temperatures associated with global climate change. Tropical and subtropical nations, which already experience temperatures that are higher than optimal for crop production, are especially vulnerable (Reilly et al. 1996; Gitay et al., 2001). Many of these nations are already food insecure as well.