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16 IMPACTS OF GLOBAL CHANGE Jose Goldemberg In reality global change in some areas is both a cause and a con- sequence, particularly in agriculture and industry: 14 percent of the greenhouse gases originate in agriculture, 3 percent in industry (plus the 17 percent due to chlorofluorocarbons (CFCs)), and 9 percent in modifications of land use and deforestation. The remaining 57 percent originate in the industry of energy production. A discussion of impacts is important to determine priorities for action: How real and important impacts are will make us move more rap- idly or slowly. This was clearly the case with CFCs. As soon as the dramatic impacts on the ozone layer in the Antarctic were clearly demon- strated, governments and the diplomatic establishment--often described as slow and inefficient--moved quickly and agreed on the Montreal Protocol. The dilemma of most people facing impacts of any kind is whether to take preventive measures to eliminate them or adaptive and corrective measures to live with them. What one does depends frequently on relative costs, on who pays for changes, and on the time frame of the changes. Frequently one acts only when it is too late or too expensive to take preventive measures. A good example is the cost of afforestation as compared to the cost of deforestation and the advantages one gets from deforestation. Typically it costs U.S.$1000 to reforest 1 hectare, and it is very dubious that one gets more than that by destroying the forest for short- term gain. In the Amazon forest, a good part of the 25 million hectares burned so far (at a rate of approximately 2 million hectares per year), has proven to be unfit for sustained agriculture. This seems to be a very unproductive way to go. It is therefore in the self-interest of Brazilians to prevent that from happening at the risk of contributing some 7 percent to the amount of carbon thrown into the atmosphere per year. The reason we are so keen on discussing global change these days is that we want to prevent it before it is too late. In dealing with such problems, externalities are what really count, and one cannot rely on market forces. Government intervention is ac- cepted naturally, and we see more and more of it happening all over the world. The recent example of Los Angeles, where the local Environmental Board decided to clean up the city at a cost of some $3 billion per year (U.S.$250 per person per year), is very impressive. 172

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173 Our responsibility therefore is to characterize clearly and convinc- ingly the problems or impacts. When the problems are clear cut, govern- ments move quickly. Some impacts are not very clear, and the usual overcautious position adopted by scientists is frequently used by governments as an excuse for not acting. One example of an impact about which we could be more ag- gressive than we are today is energy production. Fifty-seven percent of the greenhouse effect is due to carbon dioxide and other gases emitted in the burning of fossil fuels. One could, in principle, face the im- pacts of this part of the greenhouse problem by spending a lot of money to recapture the carbon dioxide in stacks, practice afforestation, or simply cope with higher temperatures and rising sea levels. There are estimates that this approach could be taken with a few hundred billion dollars. This is called adaptive behavior. The other approach is preventive: one reduces energy production and thereby reduces carbon dioxide emissions. It has been exhaustively dem- onstrated that this is the cheaper road to take and that it can be done in industrialized countries through improved efficiency in the produc- tion and use of energy. It is not clear, however, that the same can be done in developing countries, where energy is so essential for development and where eco- nomic activities are bound to grow much more than in the industrialized nations. Estimates indicate that by the year 2020, two-thirds of the energy consumed in the world will be consumed in the less-developed countries, up from the one-third presently being used. Therefore the magnificent opportunity lies ahead to steer this evo- lution in the right direction, introducing in the developing countries energy systems that have built in the improved energy technologies already available in the industrialized countries. In doing so, the less-developed countries could leapfrog the painful adaptation going on in the developed part of the world and make an important contribution to reducing the impacts of energy use on the biosphere.

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