Adapting to Life in a Greenhouse

Despite a good deal of uncertainty about the subject, there is the growing consensus among scientists that the atmospheric accumulation of carbon dioxide, through the so-called greenhouse effect, eventually will lead to a significantly warmer planet.

The principal risks of warmer global temperatures are distorted agricultural patterns and flooded coastal cities (by rising sea levels caused by melted polar ice), and the principal villains are the combustion of fossil fuels, like coal, and of less importance, the destruction of forests throughout the world, whether for timber, or agricultural land clearing, or firewood. Combustion releases carbon dioxide, and trees and other vegetation store it. The growing pace of both fuel combustion and deforestation thus combine to deliver a double dose of carbon dioxide to the atmosphere. A doubling of the atmospheric load and a consequent average temperature rise of perhaps 2 to 3 degrees Celsius is possible within the next fifty years, with the mid and high latitudes affected much more than the Equator.

What is to be done about this very uncertain but potentially grave threat? Not much, suggest many who are studying the problem. Indeed, most articles conclude that learning to live with a warmed-up earth may prove the most realistic option. Charles F. Cooper's 1978 Foreign Affairs article offers a good illustration: ". . . If the geophysical assumptions are correct, the process of climatic change due to industrialization is probably almost irreversible; the only practical strategy is adjustment."

It may be, however, that adjusting incrementally to the slow changes in temperature, as they come along, is the worst thing that we can do. Adaptability normally is a distinctive human strength, but in this case it may be self-destructive.

Humankind at times has demonstrated foresight and ability to make rational decisions in the face of uncertainty. But people also are prone to discount the future—to give more weight to current than to future consequences—and this tendency is greater as the uncertainty about future events increases. In everyday commercial and economic life, such discounting is built into the structure of interest and profit rates: a dollar delivered today is always worth more than a dollar promised for delivery in the future. If people believed that there was, say, a 20 percent chance that the human race would become extinct in 200 to 300 years unless certain changes were made, no doubt they would be willing to make substantial sacrifices today to avoid it. That is, they would use a lower discount rate than in ordinary life.

But on this issue they are not convinced; there is an insufficient basis for convincing them; and all the pressures—from budgetary limitations to conventional thought processes—are in the opposite direction. Given the nature of the carbon dioxide problem—in particular, the long time period involved and the immense degree of uncertainty—these pressures will dominate and could lead to behavioral responses that not only are inappropriate but also potentially disastrous.

There are three broad categories of possible responses: one is to restrict fossil fuel combustion; another is to reverse the destruction of forests; and the third is to allow carbon dioxide to continue to accumulate and to adjust as the effects are felt.

Restricting combustion

The only pervasive tool to restrict combustion worldwide is the price mechanism. All other mechanisms—taxes, import regulations, and so on—can be applied on a country-by-country basis but require cooperation between countries to accomplish much. Since important nations are likely to see their self-interest in quite different ways, there is little basis for agreement. On the other hand, what if the price of energy continues to rise?

On the demand side, there is no doubt that the long-run effects would be beneficial as far as carbon dioxide is concerned. But the supply responses are likely, on net, to be negative. Importantly, the increased price will stimulate the search for and use of other sources of fossil fuels (new sources of oil, shale, tar sands, coal, and others), all of which will generate carbon dioxide emissions. Moreover, particularly in developing countries, an increase in the price of commercial fuels will induce greater cutting of forests.

There are a number of things government programs could accomplish, especially on the supply side. Greater efforts could be put into the development of nuclear fusion, for example, and massive hydroelectric projects could be set along, say, the Amazon and Brahmaputra rivers, with the excess power used to produce hydrogen for export. And energy could be beamed to earth by solar-powered satellites.

But all such projects have serious difficulties. Some, like fusion, have technological problems; others, like the damming of the Amazon, raise ecological unknowns; yet others, like building hydro plants along the Brahmaputra, which flows through three countries, present political problems. And most require massive amounts of capital and have very long gestation periods and unfavorable benefit—cost ratios. Apart from fusion research, which is reasonably well funded in only a few countries, no serious work is going ahead on any of these projects. Nor will there be any until energy becomes vastly more expensive or the carbon dioxide problem far more immediate.

Forest conservation

Global, cooperative efforts to halt deforestation, or better, to reverse the process are thwarted by the desperate need for additional agricultural land, a need that clearly is going to take precedence, and by the increasing need for cheap fuel, particularly in poor countries. Governments could combine to mount a massive global program of reforestation. But the trees would have to be left standing, not grown for timber or fuel, if the program were to have much effect. And that is not a bankable proposition.

Adjustments

Thus, given the slowness and the uncertainties of the postulated effects, the most likely social response is to allow carbon dioxide to build up and to adjust only as the effects are felt. Where does this lead us? Given the two most probable principal effects—climatic changes affecting agriculture and the eventual melting of the polar ice caps—what kinds of responses might be expected?

The most likely response in areas that slowly become more arid is to resist the change, to keep out foreign competition, to call for subsidies, and to build irrigation systems. Unless the change is relatively sudden and dramatic, such responses will appear to be more cost-effective and less risky to the current generation of farmers than abandoning the land and opening up new lands in the north. Once an irrigation system is built, it will continue to appear more cost-effective to marginally expand it to offset further changes in climate. Given this tendency, plus the high cost of investing in the whole package of factors involved in developing farming on new lands, the movement of agriculture from areas hurt by climate change to areas benefited by that change could take a long time. Thus, the cost of food and the risks of crop failure will rise, at least during the transition period, if not permanently.

A more clear-cut example of myopic adjustment can be seen by considering how coastal populations are likely to adjust to a slow but inevitable rise in sea level. Such a rise may proceed by only 10 feet or less each century, but once begun, it is likely to continue long after all the fossil fuels have been burned. If all the water now trapped as ice in Greenland and Antarctica were added to the oceans, the sea level eventually could rise by a very significant amount, perhaps as much as 100 feet.

Only two responses to this situation appear possible: low-lying lands can be evacuated, or seawalls and dikes can be built. Given the slowness of the change in sea level and the use of anything other than a zero rate of discount in deciding such matters, seawalls and dikes are all but certain. And once built, it will appear cheaper to make them a bit thicker and higher than to evacuate the area. Eventually, much of the human race could find itself living below sea level, with the probability of a catastrophic breach in the dikes growing over the centuries. Under such conditions a repetition of the legendary sinking of Atlantis is highly probable. Only the date of the event is uncertain.

This is perhaps the clearest possible example of a situation in which the normal human processes of adapting to changing circumstances eventually can become self-destructive. But other, less dramatic, examples exist, such as the excessive use of pesticides that induce the evolution of more resistant strains or the diking of rivers to avoid flooding of adjacent lands, when silt continually raises the level of the riverbed.

Compared with other living things, humankind is very adaptable. But people also are stubborn and unlikely to alter their behavior until faced with what is perceived to be a necessity. Even then, there is a tendency to take the line of least resistance, which ultimately may be self-defeating.

Human adaptation patterns put a heavy burden on scientists studying the carbon dioxide problem, for they suggest that only by sharply reducing the range of uncertainty surrounding this problem is there any hope of escaping the trap laid for us by our normal responses to change. Granted that the hazards posed by the greenhouse effect now seem remote and many even question their existence, will we ever be certain enough to abandon our attempts at incremental adjustments? Learning to live with a warmed-up earth ultimately may be more risky than other more radical options.

This article is based on material from Ronald G. Ridker, formerly a senior fellow in RFF's Renewable Resources Division, and now on the staff of the World Bank.