Government planners and social scientists from many countries are developing a number of strategies to help us adapt to global warming. For example, what should people living in coastal areas do? They can move inland away from the dangers of storm surges, although this solution has high economic costs. An alternative plan, which is also extremely expensive, is to build dikes to protect coastal land. The Dutch, who have been doing this sort of thing for several hundred years, have offered their technical expertise to several developing nations threatened by a rise in sea level. We also have to adapt to shifting agricultural zones. Many temperate countries are in the process of evaluating semitropical crops to determine the best ones to substitute for traditional crops if or when the climate warms. Drought-resistant species of trees are being developed by large lumber companies now, because the trees planted today will be harvested many decades later when global warming may already get much worse.