Climatic Warming

Scientists typically devise solutions to problems and then test the solution to determine if it indeed solves the problem. But sometimes the problem is only suggested by the evidence, and there are no chances to test the solutions. A current example of such a problem is climatic warming.

Data recorded from various locations around the world over the past century indicate that the average atmospheric temperature is 0.5°C higher now than it was 100 years ago. Although this sounds like a small amount, such an increase can have pronounced effects. Increased temperatures may eventually cause the ice in polar regions to melt, causing ocean levels to increase, which in turn may flood some coastal areas.

Small changes in temperature can also affect living organisms. Most trees can tolerate only about a 1°C increase in average temperature. If a tree does not reproduce often or easily enough to "migrate" through successive generations to a cooler location, it can become extinct in that region. Any organisms dependent on that type of tree also will suffer.

But such disasters depend on whether global temperatures continue to increase. Historical studies indicate that some short-term fluctuations in climate are natural, like the "little ice age" of the seventeenth century. If the current warming trend is part of a natural cycle, the dire predictions may be overstated or wrong.

Even if the warming is continuous, climatic systems are very complex and involve many unexpected factors. For example, if polar ice melts, a sudden increase in humidity may result in snow in polar areas. This could counter the melting, thus causing ocean levels to remain stable.

Greenhouse Gases

Most of the current attention and concern about climatic warming has been focused on the increase in the amount of "greenhouse gases," primarily carbon dioxide and methane, in the atmosphere. Molecules of these gases absorb energy that is radiated from Earth's surface, causing their temperature to rise. These molecules then release energy as heat, causing the atmosphere to be warmer than it would bo without these gases.

While carbon dioxide and methane are natural components of the air, their levels have increased rapidly during the last hundred years. This has been determined by analyzing air trapped in the ice layers of Greenland. Deeper sections of the ice contain air from earlier times. During the last ice age, there were about 185 ppm of carbon dioxide, CO2, in the air, but the concentration from 130 years ago was slightly below 300 ppm. Today, the levels are 350 ppm, an increase that can be accounted for by the increase in combustion reactions, primarily from coal and petroleum burning, and by the decrease in CO2- consuming trees through deforestation.

But does the well -documented increase in greenhouse gas concentrations enable detailed predictions? Atmospheric physicists have greatly improved their models in recent years, and they are able to correctly predict past ice ages and account for the energy-absorbing qualities of oceans. But such models remain oversimplified, partly because of a lack of detailed long-term data. In addition, the impact of many variables, such as fluctuations in solar energy output and volcanic processes, are poorly understood and cannot be factored into predictions. To take all factors into account would require more-complex models and more-sophisticated supercomputers than are currently available. As a result, many question whether meaningful decisions and planning can occur.

Risk of Action and Inaction

The evidence for climatic warming is suggestive but not conclusive. What should be done? Basically, there are two choices: either do something or do nothing. The risks of doing nothing are that the situation may worsen. But it is also possible that waiting for better evidence will allow for a greater consensus among the world's nations about how to solve the problem efficiently. Convincing the world's population that action taken now will have the desired benefit decades from now will not be easy.

Acting now also involves risks. Gas and coal could be rationed or taxed to limit consumption. The development of existing energy-efficient technologies, such as low-power electric lights and more efficient motors and engines, could cut use of coal and gasoline in half. However, the economic effects could be as severe as those resulting from climatic warming. But none of these options can guarantee results. Even if the trend toward climatic warming stops, it will be hard to prove whether this was due to human reduction in greenhouse gases, to natural cyclic patterns, or to other causes.

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