In defense of the atmosphere

Global warming is an environmental threat unlike any the world has faced. While human activities during the past century have damaged a long list of natural systems, most of these problems are local or regional in scope and can be reversed in years or decades if sufficient effort is exerted. Changes to the earth's atmosphere, on the other hand, are global and irreversible not only in our lifetimes but in our children's and grandchildren's as well.

Coping effectively with global warming will force society to move rapidly into uncharted terrain, reversing powerful trends that have domi­nated the industrial age. This challenge cannot be met without a strong commitment on the part of both individuals and governments. Among the unprecedented policy changes that have now become urgent are a cur­tailment of chlorofluorocarbon production, a reversal of deforestation in tropical countries, enactment of a carbon tax on fossil fuels, and a new commitment to greater energy efficiency and the development of renew­able energy sources. Rich industrial countries such as the United States, which have caused most of the warming so far, should logically take the lead in adopting national programs to slow it. The biggest challenge, however, is at the international level. Slowing global warming will require that countries strengthen international environmental institutions and en­act strong new treaties, working together as a world community as never before.

Lending urgency to the problem is the fact that chemical composi­tion of the earth's atmosphere, normally stable for millennia, is already substantially different than it was just a century and a half ago. While nitrogen and oxygen are still the main constituents, several more com­plex gases are building steadily: carbon dioxide is up 25 percent, nitrous oxide 19 percent, and methane 100 percent. Chlorofluorocarbons, a class of synthetic chemicals not normally found in the atmosphere, have added further to this warm blanket of gases that allow sunlight in but trap the resulting heat. Scientists estimate that the resulting greenhouse ef­fect is equivalent to the heat produced by one Christmas tree light - ra­diating approximately one watt of energy each - on every square meter of the earth's surface.

Global average temperatures are now about 0.6 degrees Celsius warmer than they were a century ago. There is as yet no conclusive proof linking this recent heating to the greenhouse effect, but circum­stantial evidence has convinced many scientists that this is the cause. Scientists are more concerned, however, about the much faster warming that is predicted by a half dozen computer models - reaching 2.5-5.5 degrees Celsius late in the next century. The difference between the warming of the past century and that expected in coming decades is like that between a mild day in April and a late-summer scorcher.

Some have suggested that "greenhouse effect" and "global warm­ing are mild terms for a coming era that may be marked by heat waves that make some regions virtually uninhabitable. Frequent droughts could plague areas of North America and Asia, imperiling their ability to meet food needs. More violent weather is projected for other regions. Many forests could be at risk as climate zones suddenly shift. And many low-­lying areas with dense population or extensive agriculture will be threat­ened by rising seas.

Considerable change in the earth's climate is now unavoidable, but societies still have the choice of an accelerating, cataclysmic warming or to act to slow it to a more manageable rate. Self-interested voices have recently argued for more research before any action to stabilize the cli­mate. While it is true that climate change is a young science, many as­pects of which are uncertain, this is no excuse for years of delay. If hu­manity waits until detailed regional climate predictions are possible, it will be too late to avert disaster.

Societies already invest in many areas, such as defense programs, to protect against an uncertain but potentially disastrous threat. Similarly, investing in strategies to slow global warming is a sort of insurance pol­icy - against catastrophes that have far greater odds of occurring than most of the events for which we commonly buy insurance. Many of these strategies have the additional attraction of being economical investments in their own right, cutting energy bills and air pollution at the same time as they help stabilize the climate.

The world energy system is responsible for more than half of the greenhouse effect, releasing not only 21 billion tons of carbon dioxide to the atmosphere annually but substantial quantities of two other important greenhouse gases as well - methane and nitrous oxide. Carbon­-containing fossil fuels provide almost four-fifths of the world's energy, and their use continues to grow 3 percent annually. Reversing this trend and moving the world gradually away from its massive dependence on fossil fuels are essential to stabilizing the climate. In fact, global warming has emerged as the most important limit facing the world's energy sys­tem; if the use of fossil fuels continues to grow, the earth will become uninhabitable long before all of its fuel reserves are exhausted.

A plan to improve energy efficiency is the essential centerpiece of any workable strategy to limit production of the energy-related green­house gases. Only improved efficiency has the potential to get societies off the fossil fuel growth path in the near term. Meanwhile, an immediate start on a transition to renewable energy sources will allow the world to switch ultimately to clean and sustainable power supplies, such as solar, wind, and geothermal.

There are two other key elements of a credible global warming ac­tion plan. The first is reversing the destruction of the world's tropical for­ests. Deforestation contributes about 20 percent of the carbon dioxide being added to the atmosphere and is increasing. Turning this trend around is an enormous challenge that not only will help stabilize the cli­mate but help many developing countries attain sustainable economies. The second element is eliminating the production and use of chloro­fluorocarbons (CFCs) within the next decade.

These specialized chemicals account for one-quarter of the green­house problem, and they can be eliminated with relatively minor adjustments the United states, the world leader in the use of CFCs, they account for about 40 percent of its contribution to global warming. Be­cause CFC emissions are growing faster than those of any other green­house gas, and because they can be eliminated rapidly and completely, they deserve immediate attention by policymakers.

The most fundamental challenge presented by global warming is to society's ability to confront a common threat. This raises complex equity issues, since the contribution of individual countries to the problem var­ies widely, as do their stakes in a solution. Overall, the industrial market countries are responsible for about 46 percent of the problem, the For­mer Soviet Union and Eastern Europe for 19 percent, and developing nations (with four-fifths of the world population) for 35 percent. The rich industrial countries have caused most of the damage to the global at­mosphere so far, and thus have a clear responsibility to take the lead in formulating solutions. A few are already considering unilateral actions, but most are not. Leadership on the part of the world's largest green­house gas producers - the United States, the Former Soviet Union, China, Brazil, and Japan - is essential if a global strategy is to be suc­cessful.

While developing countries burn only a small fraction of the world's fossil fuels, some contribute heavily to global warming through defores­tation. (Brazil, for example, is the fourth largest emitter of carbon diox­ide). A long-term response to global warming should include developing countries, but they will need financial assistance from industrial nations in slowing deforestation, harnessing alternative energy sources, and obtaining substitute chemicals and appropriate technologies to eliminate CFC emissions.

International negotiations to slow global warming have begun, but they are moving too slowly. While some smaller nations have proposed bold and innovative strategies, the economic and environmental super­ powers are still formulating their positions. That, however, will not be enough. It is important that a "Law of the Atmosphere" be more than a vague statement of intentions. To be effective, a global warming treaty will have to lay out stringent goals, cutting worldwide carbon emissions by at least 10 percent by the year 2000, en route to eventually reducing emissions by more than half. In addition, specific national goals are needed, recognizing each country's contribution to the problem and abil­ity to respond. Finally, the international community will have to establish guidelines and provide support for climate stabilization programs (such as improved energy efficiency and reforestation), but allowing individual nations some flexibility in meeting their targets.

While the challenge is a daunting one, climate change is a problem with which humanity still has the ability to cope. But time is short if we are to avoid a cataclysmic warming.

Flavin Christopher, Worldwatch Paper