Global climate change is the result of the complex system of atmospheric processes and their products. A main factor in this system is the increase in surface level ultraviolet (UV)-B radiation, which is known not only to cause human melanoma but also to affect terrestrial and aquatic life in general. This book illuminates the effcts of UV-B on global agriculture. It reviews the assessment methodology, the mechanisms of action and the effects of elevated UV-B on crops, weeds and pathogens.