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by Patrick Barickman
The rapid spread of technology to developing and newly industrializing countries has created a situation where actions, that in the past may have had only a local or regional effects, now have global repercussions. This is especially true with the effects of pollution. Currently, the consensus of the international scientific community is that some type of global climate warming is very likely. The uncertainties revolve around the degree of warming, how such change is likely to affect the planet (the burdens are not likely to be evenly distributed), and the appropriate response strategies.
By its very nature this issue presents a complex set of problems which evade comprehensive solutions. Researchers are modeling global environmental systems with complicated interactions. Some relationships are understood with a high degree of confidence in our knowledge. Other aspects are known, with serious reservations about our capacity to fully grasp them in their entirety; and finally, there are important questions that cannot be answered with our present understanding.
Natural Processes:
Natural warming of the atmosphere, or the greenhouse effect, is a natural process; an aspect of planetary homeostasis (balance, stability). Although trace gases such as carbon dioxide (CO2), methane, CFC's, and others make up less than 0.1% of the chemical composition of the atmosphere, it is these gases, along with water vapor (clouds) which keep temperatures as we know and like them. Estimates are that without natural greenhouse warming the average global temperature would be about -15o C (5o F). Average surface temperature now is about 15o C or (60o F). This much we know and are confident about our understanding of the processes involved.
Over the last 130 years the average global temperature has risen about 0.5o C. However, this rise has not taken place in a smooth progression. From 1910-1940 and since the early 1970's there have been two noticeable jumps in temperature. Six of the warmest years on record occurred during the 1980's with 1990 much warmer than even those record years. What cannot be said with any degree of certainty is whether this rise in temperature is due to human influences, or whether this is a natural variation in the long term cycle. In other words, because of our incomplete understanding we cannot detect the signal from the background noise.
Seeking Understanding:
The Intergovernmental Panel on Climate Change, an international body of scientists, was formed in 1988 and was charged with two objectives: First, to evaluate the scientific information related to different aspects of the climate change issue. Second, to come up with realistic strategies to respond to this challenge. Their report, Climate Change the IPPC Response Strategy, published in 1991, is widely considered to be the most thorough assessment of the issue.
In this report the working groups basically made assumptions about five possible future scenarios. They then made their best estimate of the likely changes in the chemical composition of the atmosphere in each of these possible futures. The first scenario, the "2030 high emission scenario", is also known as the business-as-usual approach. This assumes that there is very little attempt to control the various greenhouse gas emissions in the next forty years. The four other scenario's assume increasing levels of government and industrial control policies on emissions.
The "business-as-usual" scenario projects an increase in greenhouse gases that would be the equivalent of doubling the level of CO2 in the atmosphere that was present at the beginning of the industrial revolution. This leads to the following predictions of average global temperature rise: About 1o C by the year 2025. By 2100, perhaps 3o C.
What can be said about those figures above? Is 1o C a big deal? Are those possibilities likely? Again, there are some things we are pretty confident about from our knowledge of the past. A rise of 3o C by the year 2100 would be a larger variation than anything that has been experienced in the last 10,000 years. However, we do not fully understand the global feedback mechanisms involved, nor are we yet able to predict regional climate changes. Consequently, modeling future climate conditions is fraught with uncertainty at this juncture. For instance, one of many uncertainties which cloud our understanding of these systemic processes is the role of oceans as heat sinks.
The oceans may actually absorb a great deal of this "extra" heat. This is not fully understood; however, if the oceans do turn out to be a significant heat sink this could delay the temperature rise to sometime later in the future. Another uncertainty is the role of cloud cover in shielding the earth's surface from the sun's radiation. Increased surface temperatures could cause more evaporation from the ocean surfaces, causing cloud cover to significantly increase, which would serve to offset an average temperature increase. In fact, such a scenario could actually cause a decrease in global average temperature.
The other side of the coin is that the highest credible estimate by the IPPC for a temperature rise in the next century is 5.5o C. A rise of that magnitude would create climate conditions that are assumed to have existed 100,000,000 years ago. In fact, we do not know for certain what types of changes we may be influencing. Even assuming a much less dramatic change, adaptive strategies will be required for environmental and socio-economic systems to adapt to such an unprecedented rate of change.
Assessing the Options:
As is so often the case in complex situations, "what to do about it" has become a fairly polarized debate. On the one hand there is an approach which could be characterized as a "wait and see" attitude. The contention here is that without full knowledge of complex environmental processes, ill conceived solutions may require huge expenses that could otherwise go towards more productive causes. In addition, some of these solutions could actually make matters worse.
A quite different response to the problem is often characterized as a "no regrets" policy. This approach holds that the potential for major economic and social disruptions is great enough to require action. Policies which help address these problems can be crafted in such a way that they are actually good for the economy and the environment and so, in any event, should be considered now.
From both a scientific and policy perspective the social, economic, and environmental questions which need to be asked and understood are large, complex and interrelated. Solving them will take a great deal determination and an ability to work with the complex interactions between socio-economic and environmental systems. We can be certain that there will be surprises to our understanding in the future and so it is wise to create mechanisms for public policy which are as adaptable and resilient as possible.
References:
IPPC Intergovernmental Panel on Climate Change. 1991. Climate Change the IPPC Response Strategies. Washington D.C. Island Press.
Mintzer, I.M. Confronting Climate Change. 1992. Cambridge. University Press.
Reilly, J.M. and Anderson, M. Eds. 1992. Economic Issues in Global Climate Change. Boulder. Westview Press.
Stern, C.P., O.R. Young, and D. Druckerman, Eds. 1992. Global Environmental Change. Washington D.C. National Academy Press.