A major difference in this second edition is that I have tried to emphasize the role of global changes and desertification more than in the first edition. In my opinion, too much emphasis has been placed on global warming and not global changes per se. While, ultimately, the world will continue to heat up as fossil fuels are burned, many people struggle to understand that it is human-induced changes in the world rather than a simple case of warming that is likely to occur. Thus, decreases in temperature and increased rainfall are also consequences of the ways that we are altering our world. Among these varied effects, desertification is often among the most egregious. Desertification usually occurs on the periphery of deserts, leading ultimately (and unfortunately) to the increasing size of arid and semi-arid regions. Hopefully, more researchers and policy-makers will take up the defence of deserts and means of combatting desertification. The cause is usually due to one effect or another of an increase in human population sizes. Controlling human population sizes is likely to be a very slow process, if it happens much at all. Hence, we need to strive to minimize the effects of desertification on our environments by increasing our efficiency of resource use. I have also tried to link the chapters on plant and animal physiology more than in the first edition through emphasis on heat shock proteins. In this second edition, I have updated many of the references I believed important to change. Science is, of course, a continually progressive topic that is always in need of updating. However, there are also many things that have stood the test of time—these references I have retained.

excerpt from the biology of deserts