Policy Implications of Greenhouse Warming Mitigation, Adaptation, and the Science Base (1992) / Chapter Skim
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34 Sesitivities, Impacts, and Adaptations
34 Sesitivities, Impacts, and Adaptations
Pages 541-652
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From page 541... ...
Uncertainties range from those about climate scenarios to ones about sensitivities and future technology. We do not know whether people will choose to adapt more or suffer more from harmful climate changes and benefit less from helpful climate changes.
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Adaptations would include costs for air conditioning and irrigation. They might include $1 million for an adapted wheat variety and some portion of the $33 million per year for the agricultural experiment station of a state in the Grain Belt.
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From page 551... ...
Most plants in natural landscapes fall into the slower class. Leaf Pores CO2 arrives at the site of photosynthesis inside leaves through minute pores in the leaves.
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From page 552... ...
It should especially favor the many plants in the natural landscape that have a responsive photosynthesis like wheat. Where ones with responsive photosynthesis compete with ones with unresponsive photosynthesis, the enrichment with CO2 should make the former more competitive.
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From page 553... ...
The generality of plants with a responsive photosynthesis gaining on others in rising CO2 has been demonstrated by crops and weeds. The responsive weed, velvet leaf, increased its growth more than the less responsive corn when CO2 was raised.
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From page 554... ...
The standing crop of plants on an area is a function not only of the primary production from plants but also of the amount of plant material removed by grazers and pests. Thus, even if increasing CO2 implies more plant growth, any change in the standing crop is uncertain.
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From page 555... ...
Although even this conclusion is clouded by uncertainties, it appears that the accumulation of biomass on the planet is either increasing or is steady, not decreasing (Revelle and Kohlmaier, 1986~. Summary Because plants are sensitive to CO2 in the air, its concentration in the air is one of the things that will modify the change in the primary production of food as climate changes.
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. There is a tendency in discussions of the potential effects of climate change on crops to consider only temperature and precipitation effects.
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From page 557... ...
Agricultural research and the farmers who apply its results have been highly successful. The clear question is: If climate changes during several decades, can these same people maintain the foundation of natural resources and raise more food for the escalating demands and numbers of people?
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Also, they cannot be used to deal with CO2 enrichment effects. Process models or simulators that simulate plant growth, yield, and water use offer the best alternative to the regression model.
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assessment of the potential effects of climate change for U.S. agriculture (Smith and Tirpak, 1989~.
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may lessen their productive potential. Estimating Impacts Whether one calculates the change in evaporation, the change in yield of crops in the southeastern United States or Great Plains, or the economic effect, the differing climate scenarios from reputable predictors produce farm impacts even more strikingly different than the scenarios themselves.
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From page 561... ...
Adaptation of Food Production Adaptation Also Makes Impacts Uncertain Added to the uncertainty about climate in, say, 2050 is uncertainty about the sensitivity of farming then to any climate. The impact of a temperature change on, say, corn in Missouri is irrelevant if the Corn Belt moves somewhere else.
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From page 562... ...
Nonetheless, there are some indications that adaptations can be effected even to large changes in climate. The first is the adaptation of wheat to both colder and warmer climates (see Figure 34.25.
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This trend is already occurring in the arid West and would likely be accentuated by any climatic change that decreases supplies or increases demand.
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The average lifetime of a successful cultivated plant variety shows how fast varieties of a crop can be adapted. In 1981 plant breeders estimated that varieties lasted 7 years in corn, 8 in sorghum and cotton, and 9 in soybean and wheat.
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There is no reason to believe that the developing countries as a group will be exposed to worse climatic changes than the developed countries. Not everywhere in the developing countries are the climates marginal.
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will be like when climate changes are finally felt. The MINK study described above attempts to do this.
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The managed pastures may be considered part of farming, dealt with in the preceding section, "Farming." The unmanaged forests and ranges are the subject of the next section, "The Natural Landscape." Figure 34.4b shows, of course, that forests managed for timber and unmanaged ones are not distinct classes. Here, however, the concentration is on managed ones.
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Nonindustrial private forest land is held by farmers and other private entities who do not own mills. Industrial forest land is held by companies that also own mills.
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Although the longer growing seasons of a warmer climate would raise productivity, ill-adapted trees could suffer frost damage during their prolonged growth and others might not be chilled enough to germinate (Cannel! and Smith, 1986; Cannell, 1987; Kimmins and Lavender, 1987~.
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From page 570... ...
If none of the species in the forest are adapted to the warmer climate, total biomass will decline, perhaps rapidly. Estimating Impacts As on the farm, climate change-warming, changes in soil moisture, and changes in the composition of the atmosphere raises the specter of more pests in the forest.
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Adaptation The natural pace of adaptation may be too slow to maintain a particular forest on a particular tract of land. Using climate scenarios like our assumptions, some researchers (Franklin et al., 1989; Urban and Shugart, 1989)
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Although knowledge of the genetics of commercially important trees is 0 -a advanced, the seed of most species of trees In the un~tect States has not been collected and screened. On the other hand, since pines evolved from Mexico and a large number of species of this tree are found there, there is r -- ~ -- -- -- - a- At, Expecting warmer climates, foresters should look for candidates in places that are warmer today.
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From page 573... ...
Just as the speed of replacement of capital stock was relevant in the discussion of innovation in Chapter 33, the section "The Tools of Innovation," a shorter rotation from planting to harvesting a forest raises its adaptability. Surprisingly, middle-aged forests are at most risk if climate changes;
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From page 574... ...
The costs in carbon must also be estimated lest the management practices we adopt actually worsen the production of greenhouse gases. Shortening rotations will reduce the amount of carbon stored in forests because little carbon is absorbed during regeneration and the small trees grown on short rotations TABLE 34.3 Flexibility and Robustness of Management Activity Flexibility Robustness Federal Support Regenerate Low Low Yes Weed Moderate High No Thin High Moderate No Protect from fire and pests Low Moderate Yes Cut partially High Moderate No Shorten rotation Moderate Moderate No NOTE: The third column shows that two of the measures are supported by a federal program.
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From page 575... ...
Finding the will and way to apply them widely enough to make a difference is a challenge. THE NATURAL LANDSCAPE Difference from Farming and Forestry The natural landscape is made of unmanaged terrestrial ecosystems.
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From page 576... ...
The chief effects on animals would be via climate changes induced by CO2 and by climatically induced changes in the plants that feed and shelter the animals. Natural ecosystems are more vulnerable to climate change than are managed ones like farms or plantation forests, because, for example, natural ecosystems would not be irrigated nor would their components be replaced to adapt them to a climate change.
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Mathematical simulations of natural landscapes have been run that incorporate physiological processes of plants much as GCMs incorporate atmospheric processes. The simulators mimic the present zones of plants in North America.
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The simulated landscapes resulting from doubled greenhouse gases support altered communities of plants rather than barrens. Nevertheless, achieving these goals for natural landscapes will be difficult.
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Intervening in Natural Landscapes Intervening to maintain species diversity, ecosystem functioning, and evolution can take two broad forms. Components of an area can be saved off the site, which saves some diversity and may permit evolution.
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They have yet to organize themselves for this work (International Union for Conservation of Nature and Natural Resources, Botanic Gardens Conservation Secretariat, 19891. Zoos Zoos are increasing their role in propagating and reintroducing rare and endangered animals.
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Finally, helping systems of plants and animals migrate is a method particularly important if climate change moves climate zones faster than plants and animals can follow. All these methods are already being used to maintain biological diversity in the face of harvesting of plants and animals and destruction of their habitats.
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Because growing numbers of people and their power inevitably press the natural landscape, we must remember that the impacts and adaptations to any climate change will be added to other enormous changes. THE MARINE AND COASTAL ENVIRONMENT This section examines the relationship between the postulated effects (global temperature rise is of primary relevance)
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For example, the worldwide average sea level rise for the last century is 10 to 15 cm, but the level has risen about eight times that amount in Louisiana and generally about three times that global average on the Atlantic and Gulf coasts of the United States (Smith and Tirpak, 1989~. The magnitude of local vulnerability to sea level rise, of course, depends on the local topography, as rising seas will affect more land area in low deltas than where coastal elevation profiles are steep.
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One measure of their commercial significance is that well over half (one estimate is 80 percent) of all fish caught spend part of their life cycles in coastal wetlands (Intergovernmental Panel on Climate Change,
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Second, human development may restrict a wetland's inland expansion, if a wetland is bounded by a dike or bulkhead constructed to protect agriculture or manmade structures. Initial attempts have been made to quantify the potential net loss of wetland areas as a function of sea level rise.
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From page 586... ...
The consequences of sea level rise to shoreline ecosystems would vary according to the type of organism and type of community. Shallow subtidal marine ecosystems, such as kelp beds in temperate regions and coral reefs in tropical waters, would probably not be affected much by changes in sea level.
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From page 587... ...
Whether such barriers disintegrate as they are overwashed or are repositioned in such a way to continue to protect coastal habitats is uncertain and may depend crucially on local conditions and the actual rate of sea level rise (Intergovernmental Panel on Climate Change, l990b)
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. Although all of these conditions are known to cause stress and result in the expulsion of the algae from corals, the available evidence strongly suggests increased water temperatures as the most likely cause of the recent bleaching events (Glynn, 1991)
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Valuable insight into effects of increased water temperatures may be gained by examining the effects of thermal discharge from nuclear power plants on nearby shoreline ecosystems (Lubchenco et al., 1991~. Thermal discharge of 4° to 6°C above ambient in the Diablo Canyon Nuclear Power Plant resulted in a dramatic change in the species composition of nearby habitats.
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~ ~ 1 Adaptation Coastal Environment With regard to the possible loss of tidal wetlands, one adaptation to rising sea levels could be to prevent future coastal development activities
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A sea level rise of 1 m could cause a loss of 30 to 70 percent of U.S. coastal wetlands.
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A tabulation of climate changes affecting water resources shows regional averages for both soil moisture and stream runoff to undergo from a-50 to +50 percent change for an equivalent doubling of CO2 (Schneider et al., 1990~. The regional differences among scenarios that make predictions of farm yields conflict also make opposing predictions of water resources.
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From page 593... ...
For a change in evaporation it is 1 to 2. The classic nomogram relating runoff to precipitation shows similar elasticities, although recent analyses show runoff is somewhat less sensitive to temperature changes than the nomogram showed (Langbein et al., 1949; Karl and Riebsame, 1989; Schaake, 19901.
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From page 594... ...
They actually show where supply and use are matched, so that a change would bring significant harm or benefit, depending on which way the climate changed. A climate change would make water resource matters considerably worse or better in the Great Basin, the Missouri, and the California water regions, especially.
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* Upper Colorado 2 *
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The lack of adverse effects of wider transfers, however, is often hard to prove, they find their way to court, and they become expensive and slow. Forecasts of water supply make the control of use more efficient.
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The estimate from the Hudson River includes delivery. Just as supply can be smoothed by storage that diversifies it over time, it can be smoothed by the diversity of joint operation of water supplies.
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Sheer, Water Resources Management, Columbia, Maryland, 1990. eNew Bureau of Reclamation, Central Valley Project.
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Unless, however, those changes are adverse and rapid relative to changes in the population-driven demands for water management, the overall impact of climate change is unlikely to be substantially more serious than that of the vagaries of the current climate. Essentially, the chance of climate change introduces more uncertainty into the already uncertain realm of water management.
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Energy and utilities Energy (electric, gas, oil) 1.90 Electricity demand -1.7 Nonelectric space heat 1.2 Water and sanitary0.24 Negative Real estate-land-rent component2.12 Sea level rise damage Loss of land -1.6 Protection of sheltered areas -0.9 Protection of open coasts -2.8 Hotels, lodging, recreation1.05 ?
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Department of Energy, 1989b,. IPCC Working Group II began its summary of energy with threats to biomass and fuelwood rather than with electric power (Intergovernmental Panel on Climate Change, 1990a)
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Examples of such statements are, "This greenhouse effect may by early next century have increased average global temperatures enough to shift agricultural production areas, raise sea levels to flood coastal cities, and disrupt national economies.... A rise [in sea level]
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states that the economic impact of any greenhouse effect will most likely be in terms of the rising cost of agricultural displacement and adaptation in the face of climatic instability. He places the impact on agriculture and water supply as a second-order impact and lists the economy (nonagriculture)
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From page 604... ...
The potentially recoverable reserves from the Arctic region are between 17 billion and 55 billion barrels for the United States and between 50 billion and 80 billion barrels for the former Soviet Union. If all these reserves were proven and recovered, they would extend the life of the oil reserves for the United States by roughly 10 years and the oil reserves for the former Soviet Union by roughly 20 years.
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The second surprise could be changes in runoff following changes in precipitation. This was discussed in the section "Sensitivity of Water Resources to Climate," above.
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The adoption during a half century of an efficiency like superconductivity of transmission lines would, of course, sharply decrease demand for electricity, and such possibilities add to the uncertainty. Another example of the ability of industry to adapt to climate warming, and that the adaptation required is relatively modest, was reported in The New York Times on December 20, 1989.
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The section "Water Resources," above, addresses the relationship of water resources to climate.~° One-third of Americans swim and one-fifth fish. Expenditures on outdoor recreation are substantial.
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From page 608... ...
The pertinent questions, then, relate to the extent to which the costs of adapting existing settlements to the new conditions and of maintaining the settlements under the new conditions lead to abandonment or to important modification of the lifestyle or standard of living of the inhabitants. Sensitivities Direct climate changes of importance to human settlements are primarily changes in the extremes and seasonal averages of temperature, and changes in the spatial and temporal distribution of rainfall.
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From page 609... ...
Sea level rise will cause other water-related difficulties in urban areas besides those that result from inundation, high water level, and erosion. The associated rise in the groundwater table may reduce the ability of the soil to assimilate rainfall and result in larger surface runoff.
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Changes in Precipitation Patterns Flooding difficulties are not limited to communities affected by sea level rise. Global circulation models indicate that in global warming in some communities the month with the highest rainfall could have 50 percent more rainfall than currently.
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A few estimates, however, can serve to provide a rough cost range. The Committee on Engineering Implications of Changes in Relative Sea Level estimated the annual costs of beach nourishment on the east coast of Florida in a sea level rise situation to be $13 to $82 per foot, amounting to 0.1 to 3.4 percent of the value of beachfront property (National Research Council,
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From page 612... ...
synthesized the results of three different studies to estimate the nationwide costs of holding back the sea for various sea level rises. Using a set of plausible and believable assumptions, they calculated the cumulative costs of protecting barrier islands and developed mainland through the year 2100 to be $32 billion to $309 billion (1986 dollars)
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From page 613... ...
(1989) suggest that in the city of Miami the cost of dikes and levees to protect from direct sea level rise will be relatively small, while the upgrading of storm sewers and drainage will be very expensive.
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The added cost to accommodate now for the sea level rise was $260,000, 5 percent of the cost of the overhaul; the cost of the later retrofit was $2.4 million. However, anticipatory modification is not always cost effective.
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All permanent human settlements are in climates where the maximum temperature is 55°C and the minimum temperature is -60°C. These seem to be the limits of human tolerance.
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Injuries and maladjustments caused by climate are summarized in Table 34.7. Probably more important than injury by exposure in a warmer climate are maladjustments from insufficient adaptation to a change in climate.
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Anhidrotic heat exhaustion Psychoneurotic disorders Mild heat fatigue Chronic heat fatigue Skin disorders Prickly heat Anhidrosis Congenital sweat gland deficiency Dermatitis or excema Cold Frostbite Hypothermia Chilblains Contact dermatitis Snow-blindness Cold exhaustion Autoimmune hemolytic anemias (cold agglutinin disease) Altitude Anoxia Acute pulmonary edema Mountain sickness Sickle-cell anemia SOURCE: Weihe (1979)
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From page 618... ...
From the evidence about influenza, one would reason that a warmer climate could decrease the incidence of influenza, whereas increased climate variability could increase the incidence. Vector-borne Diseases In these diseases, the pathogen is transmitted to a person by another agent, called the vector, such as a tick, flea, or mosquito.
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So, a warmer climate could increase this mortality. Indirect Effects of Climate Change on Human Health Lack of safe drinking water and adequate sanitation are currently problems in many parts of the world.
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Changes in the severity and frequency of storms could add to or subtract from these deaths. Summary The climatic changes anticipated are within the range now experienced among existing habitats and to which people who move from place to place have generally learned to adapt.
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Although international migrations are Increasing, most migrations take place within nations and, if international, within regions. Restrictive policies of the industrialized countries are the major constraint on immigration, and, without those Policy constraints levels of interna .
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Preference for warmer regions has been a key determinant of internal population shifts in the United States and other industrialized countries in the post-World War II era (Figure 34.71. Internal migrations toward the Sunbelt have been eased by science and technology developments that, for 140 420 cl: 1 00 O 80 60 40 20 _ _ _ it, == _ 1860 1920 1980 PEOPLE Warm CD Coo/ FIGURE 34.7 Change in the American population living in the warm Savannah, desert, steppe, Mediterranean, and humid subtropical zones of the United States versus the other cooler zones.
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From page 623... ...
Generally, places that were almost too cool, too dry, or too something became more so, and people were driven out. Migration sensitivity to climate change appears to be correlated with three factors: the proportion of population living in regions prone to unstable political situations, the proportion of population that is poor or economically vulnerable, and the proportion living in coastal regions.
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The third source of sensitivity to climate change the proportion of population living at sea level correlates closely with the other two sources. Developed countries have greater resources and capabilities to respond to sea level rises than do developing countries.
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. Thus, sea level rise is unlikely to stimulate migration from coastal areas in the United States, but it could in countries where development is too scanty to afford the adaptation of protection.
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Summary Historically, people have adapted to a wide range of climates and climate changes. In the United States and other industrialized countries in recent decades, people have migrated toward warmer climates, indicating that they are not averse to hot weather.
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DOMESTIC TRANQUILITY Basics Most people surely share the goal enshrined in the Preamble to the U.S. Constitution, "to insure domestic Tranquility." While some nations have the economic resources and political institutions that allow them to cope with failing harvests and flooded lands, other nations do not.
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From page 630... ...
For instance, sea level rises could disrupt populations living in coastal zones and trigger migrations to other poor areas that will have difficulty feeding and housing them. To the extent that these migrations become international ones, political relationships between the sending and receiving countries could be strained.
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All adaptive strategies, and hence domestic tranquility, will be helped by effective government. The nations most vulnerable to climatic stress may be those with the weakest governments today.
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. Assistance toward rapid, sustainable, balanced growth in per capita income and help in slowing population growth.
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Although it is impossible to assess in a scientific manner the contribution that climate change may make to global political tensions, the possibility that climate change will disrupt domestic tranquility cannot be ignored. An analytic base needs to be developed that would allow us to specify the conditions under which this outcome is likely to occur.
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From page 634... ...
The adaptability of farming and even the forestry of managed trees is considerable and that of the natural unmanaged landscape or shore is less so. Cities and irrigated farms in dry regions show that water supply can be adapted, and there is room in many areas for further adaptation.
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From page 635... ...
So with reasonable adaptation by humanity, it is natural landscapes, shores, and water supply that will be left to suffer more. Will Changes in Extreme Climatic Conditions Be More Important Than Changes in Average Conditions?
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refers to an anomalous ocean/atmosphere interaction in which sea surface temperatures are warmer than usual in the central and eastern equatorial Pacific, and air pressure is high over the southeastern Pacific and low over the Indian Ocean. Changes in ocean upwelling, sea level, and rainfall accompany ENSO.
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1989. Effects of project CO2-induced climatic changes on irrigation water requirements in the Great Plains states (Texas, Oklahoma, Kansas, and Nebraska)
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1990. Possible impacts of and adjustments to sea level rise: The cases of Bangladesh and Egypt.
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In Climate Change and U.S. Water Resources, P
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In Consequences of the Greenhouse Effect for Biological Diversity. New Haven, Conn.: Yale University Press.
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In Effects of Changes in Stratospheric Ozone and Global Climate, Volume 4, Sea Level Rise, J
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Chicago: Illinois Division of Water Resources, Illinois Department of Transportation. Intergovernmental Panel on Climate Change.
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In Woody Plant Growth in a Changing Chemical and Physical Environment. Proceedings of the International Union of Forestry Research Organizations Workshop, Vancouver, British Columbia, Canada, July 2731.
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In Potential Impacts of Sea Level Rise on Coastal Drainage Systems. Washington, D.C.: U.S.
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1989. Sensitivity of Ecological Landscapes and Regions to Global Climatic Change.
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1983. Effects of a carbon dioxide-induced climatic change on water supplies in the western United States.
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From page 647... ...
1989. Potential effects of climate change on agricultural production in the Great Plains: A simulation study.
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From page 648... ...
In Greenhouse Effect and Sea Level Rise: A Challenge for This Generation, M
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In The Potential Effects of Global Climate Change on the United States, Appendix B Sea Level Rise, J
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1987. Impact of Sea Level Rise on Gap Creek Watershed in the Fort Walton Beach, Florida Area.
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1989. Potential effects on tourism and recreation in Ontario.
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1990. Potential Health Effects of Climatic Change.
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