Before Al Gore, before cap and trade, there was . . .
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Testimony of G.M. Woodwell before the Committee on Energy and Natural Resources, U.S. Senate
June 23, 1988
Rapid Global Warming: Worse with Neglect
I. Introduction: The Villach-Bellagio Report
I am a scientist, Director of the Woods Hole Research Center in Woods Holes, Massachusetts. I am also a member of the Board of Trustees of the Natural Resources Defense Council, a conservation law group with more than 75,000 members around the country. I appear before you in both capacities. My colleagues and I in science have done research on various aspects of climatic change for more than 25 years; my colleagues and I in the NRDC have made formal efforts spanning nearly two decades to make better connections in public affairs between what we know and what we do.
I am reporting on experience gained through two conferences held during the fall of 1987 in Europe dealing with climatic change. The first was in Villach, Austria, and was a review by scientists of the details of the global climatic warming that appears to be underway. The second, held in Bellagio, Italy, was an exploration of the implications of the changes in climate for governmental policies. A report of these conferences has been published by the World Meteorological Organization (WMO 1988) and is available to you. I am emphasizing in what follows the biotic interactions involved in climatic change because those interactions affect people most directly and have the potential for affecting the course of the climatic changes. I am also giving emphasis to the need for general solutions to the regional and global problems that will become increasingly acute through the next years. I find it necessary to do so because we tend to overlook the fact that 5 billion people now occupy the globe, twice the number present as recently as 1950. Before 2030 the human population could be 10 billion. The 5 billion we now have use half or more of the energy available from plants globally. Big changes in the human condition will be occurring without climatic changes. The climatic changes will compound the difficulties in accommodating such extraordinary rates of growth.
II. A Consensus among Scientists
Several points about climatic change now constitute a consensus held by meteorologists and other scientists who have worked on the problem. Most of these points have been made in slightly different form in the Villach-Bellagio report.
1. The dominant influence on global climate for the indefinite future is expected to be a continuous warming caused by the accumulation in the atmosphere of infrared absorptive gasses, especially carbon dioxide and methane, but including nitrous oxide and the CFC’s.
2. The warming marks the transition from a period of stable climates to climatic instability. Stable or very slowly changing climates have prevailed during the development of civilization. We are now entering a period of continuous warming accompanied by changes in precipitation. The changes in climate are predictable in general at continental and broad regional levels; they are not predictable locally.
3. The rate of the warming is uncertain. Estimates based on models suggest that a doubling of the carbon dioxide content of the atmosphere (or the equivalent through increases in other gasses) above the levels present during the middle of the last century will produce a global average warming of 1.5-5.5 degrees C. Such an effect [doubling] is expected by the period 2030-2050.
4. The earth has warmed between 0.5 and 0.7 degree C over the past century and the rate appears to be accelerating.
5. The warming in the tropics will be less than the mean for the earth as a whole; in the middle and high latitudes the warming will exceed the mean by two fold or more and will fall in the range of 0.5-1.5 degrees C/decade.
6. The current sources of carbon dioxide are the combustion of fossil fuels and deforestation. The dominant source of methane is anaerobic decay.
7. A rate of warming in the middle and high latitudes that approaches 1 degree C/decade exceeds the rate at which forests can migrate and will result in the destruction of forests at their warmers and drier margin without compensating changes elsewhere. Such destruction of forests and soils release additional carbon into the atmosphere as carbon dioxide.
8. It is possible that the warming already experienced is stimulating the decay of organic matter in soils globally, increasing the total releases of carbon dioxide and methane.
9. No stimulation of the storage of carbon in forests or soils that is large enough to compensate for such rapid releases is known.
10. The warming will cause accelerated melting of glacial ice and an expansion of the water in the oceans. The effect will be an increase in sea level of 30 cm to 1.5 m over the next 50-100 years.
11. The changes in climate anticipated over the next decades extend beyond the limits of experience and beyond the limits of accurate prediction. Surprises such as the discovery of the polar ozone holes are common in such circumstances. The possibility exists that a rapid warming will change the patterns of circulation of the oceans and produce sudden but profound changes in climate in regions such as western Europe, now kept warm by the Gulf Stream. The same changes may have equally surprising effects of the storage or release of carbon from forests and soils.
The warming will move climatic zones generally poleward, shift the arable zones of the earth continuously, cause large and continuous dislocations of natural vegetation, and cause flooding of low-lying areas globally. The arid zones of the northern hemisphere will expand because there is more land at higher latitudes in the northern hemisphere. The warming will be greatest in winter and will be accompanied by increased precipitation in high latitudes.
A one degree C change in temperature is equivalent to a change in latitude of 100-150 km, 60-100 mi. Rates of warming, if they occur as anticipated over the next decades, will exceed the capacity of forests to migrate or otherwise adapt. In that circumstance forest trees and other plants will die at their warmer and drier limits of distribution more rapidly than forests canb be regenerated in regions where climates become favorable. The destruction of forests will add further to the releases of carbon to the atmosphere. The seriousness of this problem will depend heavily on the rate of warming. There is sufficient carbon in forests and soils of middle and high latitudes to affect the atmosphere significantly. While there is no proof of this process and there will probably not be proof until the changes are well underway, the process will hinge heavily on rates of warming. Rates that approach 1 degree per decade exceed by a factor of 10 or more tha capacity of forests to accommodate the changes.
III. What Can be Done?
The earth will warm as a result of the changes in the composition of the atmosphere that have already occurred. But an open-ended, continuous warming that speeds the rise in sea level and destroys forests over large areas is so thoroughly disruptive of the human enterprise as to preclude any thought that civilization might “muddle through.” Can the warming be checked?
The annual increase in the atmospheric burden of carbon dioxide alone is about 3 billion tons currently. The global warming has the potential for increasing this net accumulation by speeding the release of carbon from forests and soils without causing an equivalent increase in the rate of storage. No estimate is available of the extent to which this additional source of carbon dioxide is likely to compound the problem. But the new source will diminish as the warming diminishes.
At least three possibilities exist for reducing or eliminating the imbalance and moving toward long-term stability of climate:
1. a reduction in the use of fossil fuels globally, now estimated as the source of about 5.6 HG-tons of carbon annually;
2. a reduction in or cessation of deforestation, now estimated as releasing 1-3 G-tons annually;
3. a vigorous program of reforestation that would remove from the atmosphere into storage in plants and soils about 1 G-ton of carbon annually for each 2×10(6) km(2) tract in permanent forest.
Further adjustments in emissions will be appropriate as experience accumulates. Such steps are appropriate now and possible. They will bring widespread ancillary benefits to the human enterprise. Further delay increases the accumulation of greenhouse gasses in the atmosphere, the severity of the warming that must be accommodated, and the risk of unexpected consequences that lie beyond the limits of current prediction.
These changes are possible now. They will require adjustments in the efficiency of use of energy in the industrialized nations and imaginative and far-reaching changes in the patterns of development of the less industrialized nations. Recognition of the need for the transition to a new era in the management of the earth’s resources opens new opportunities for industry and governments to pursue new paths for sustainable economic development on a global basis.
References
WMO. 1988. Developing Policies for Responding to Climatic Change. TD-No.255. World Meteorological ORgnaization. 53 pp.
June 23, 1988
Rapid Global Warming: Worse with Neglect
I. Introduction: The Villach-Bellagio Report
I am a scientist, Director of the Woods Hole Research Center in Woods Holes, Massachusetts. I am also a member of the Board of Trustees of the Natural Resources Defense Council, a conservation law group with more than 75,000 members around the country. I appear before you in both capacities. My colleagues and I in science have done research on various aspects of climatic change for more than 25 years; my colleagues and I in the NRDC have made formal efforts spanning nearly two decades to make better connections in public affairs between what we know and what we do.
I am reporting on experience gained through two conferences held during the fall of 1987 in Europe dealing with climatic change. The first was in Villach, Austria, and was a review by scientists of the details of the global climatic warming that appears to be underway. The second, held in Bellagio, Italy, was an exploration of the implications of the changes in climate for governmental policies. A report of these conferences has been published by the World Meteorological Organization (WMO 1988) and is available to you. I am emphasizing in what follows the biotic interactions involved in climatic change because those interactions affect people most directly and have the potential for affecting the course of the climatic changes. I am also giving emphasis to the need for general solutions to the regional and global problems that will become increasingly acute through the next years. I find it necessary to do so because we tend to overlook the fact that 5 billion people now occupy the globe, twice the number present as recently as 1950. Before 2030 the human population could be 10 billion. The 5 billion we now have use half or more of the energy available from plants globally. Big changes in the human condition will be occurring without climatic changes. The climatic changes will compound the difficulties in accommodating such extraordinary rates of growth.
II. A Consensus among Scientists
Several points about climatic change now constitute a consensus held by meteorologists and other scientists who have worked on the problem. Most of these points have been made in slightly different form in the Villach-Bellagio report.
1. The dominant influence on global climate for the indefinite future is expected to be a continuous warming caused by the accumulation in the atmosphere of infrared absorptive gasses, especially carbon dioxide and methane, but including nitrous oxide and the CFC’s.
2. The warming marks the transition from a period of stable climates to climatic instability. Stable or very slowly changing climates have prevailed during the development of civilization. We are now entering a period of continuous warming accompanied by changes in precipitation. The changes in climate are predictable in general at continental and broad regional levels; they are not predictable locally.
3. The rate of the warming is uncertain. Estimates based on models suggest that a doubling of the carbon dioxide content of the atmosphere (or the equivalent through increases in other gasses) above the levels present during the middle of the last century will produce a global average warming of 1.5-5.5 degrees C. Such an effect [doubling] is expected by the period 2030-2050.
4. The earth has warmed between 0.5 and 0.7 degree C over the past century and the rate appears to be accelerating.
5. The warming in the tropics will be less than the mean for the earth as a whole; in the middle and high latitudes the warming will exceed the mean by two fold or more and will fall in the range of 0.5-1.5 degrees C/decade.
6. The current sources of carbon dioxide are the combustion of fossil fuels and deforestation. The dominant source of methane is anaerobic decay.
7. A rate of warming in the middle and high latitudes that approaches 1 degree C/decade exceeds the rate at which forests can migrate and will result in the destruction of forests at their warmers and drier margin without compensating changes elsewhere. Such destruction of forests and soils release additional carbon into the atmosphere as carbon dioxide.
8. It is possible that the warming already experienced is stimulating the decay of organic matter in soils globally, increasing the total releases of carbon dioxide and methane.
9. No stimulation of the storage of carbon in forests or soils that is large enough to compensate for such rapid releases is known.
10. The warming will cause accelerated melting of glacial ice and an expansion of the water in the oceans. The effect will be an increase in sea level of 30 cm to 1.5 m over the next 50-100 years.
11. The changes in climate anticipated over the next decades extend beyond the limits of experience and beyond the limits of accurate prediction. Surprises such as the discovery of the polar ozone holes are common in such circumstances. The possibility exists that a rapid warming will change the patterns of circulation of the oceans and produce sudden but profound changes in climate in regions such as western Europe, now kept warm by the Gulf Stream. The same changes may have equally surprising effects of the storage or release of carbon from forests and soils.
The warming will move climatic zones generally poleward, shift the arable zones of the earth continuously, cause large and continuous dislocations of natural vegetation, and cause flooding of low-lying areas globally. The arid zones of the northern hemisphere will expand because there is more land at higher latitudes in the northern hemisphere. The warming will be greatest in winter and will be accompanied by increased precipitation in high latitudes.
A one degree C change in temperature is equivalent to a change in latitude of 100-150 km, 60-100 mi. Rates of warming, if they occur as anticipated over the next decades, will exceed the capacity of forests to migrate or otherwise adapt. In that circumstance forest trees and other plants will die at their warmer and drier limits of distribution more rapidly than forests canb be regenerated in regions where climates become favorable. The destruction of forests will add further to the releases of carbon to the atmosphere. The seriousness of this problem will depend heavily on the rate of warming. There is sufficient carbon in forests and soils of middle and high latitudes to affect the atmosphere significantly. While there is no proof of this process and there will probably not be proof until the changes are well underway, the process will hinge heavily on rates of warming. Rates that approach 1 degree per decade exceed by a factor of 10 or more tha capacity of forests to accommodate the changes.
III. What Can be Done?
The earth will warm as a result of the changes in the composition of the atmosphere that have already occurred. But an open-ended, continuous warming that speeds the rise in sea level and destroys forests over large areas is so thoroughly disruptive of the human enterprise as to preclude any thought that civilization might “muddle through.” Can the warming be checked?
The annual increase in the atmospheric burden of carbon dioxide alone is about 3 billion tons currently. The global warming has the potential for increasing this net accumulation by speeding the release of carbon from forests and soils without causing an equivalent increase in the rate of storage. No estimate is available of the extent to which this additional source of carbon dioxide is likely to compound the problem. But the new source will diminish as the warming diminishes.
At least three possibilities exist for reducing or eliminating the imbalance and moving toward long-term stability of climate:
1. a reduction in the use of fossil fuels globally, now estimated as the source of about 5.6 HG-tons of carbon annually;
2. a reduction in or cessation of deforestation, now estimated as releasing 1-3 G-tons annually;
3. a vigorous program of reforestation that would remove from the atmosphere into storage in plants and soils about 1 G-ton of carbon annually for each 2×10(6) km(2) tract in permanent forest.
Further adjustments in emissions will be appropriate as experience accumulates. Such steps are appropriate now and possible. They will bring widespread ancillary benefits to the human enterprise. Further delay increases the accumulation of greenhouse gasses in the atmosphere, the severity of the warming that must be accommodated, and the risk of unexpected consequences that lie beyond the limits of current prediction.
These changes are possible now. They will require adjustments in the efficiency of use of energy in the industrialized nations and imaginative and far-reaching changes in the patterns of development of the less industrialized nations. Recognition of the need for the transition to a new era in the management of the earth’s resources opens new opportunities for industry and governments to pursue new paths for sustainable economic development on a global basis.
References
WMO. 1988. Developing Policies for Responding to Climatic Change. TD-No.255. World Meteorological ORgnaization. 53 pp.
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