Division of Energy
Global Climate Change: Potential Impacts
The potential consequences of global climate change have been widely discussed by scientists, governments and the news media. Most of the concern has focused on the potential for increased global temperatures caused by man's increased emissions of greenhouse gases. Nevertheless, current scientific knowledge does not offer any clear cut guidance to predict what the effect would be of increased average surface temperatures that are theorized to result from global climate change. It is reasonably well established, however, that a temperature rise of 3 to 8 degrees Fahrenheit would significantly alter world climate and weather patterns.
Changes in Temperature and Precipitation
The projections of several mathematical climate models (general circulation models) suggest that the earth may experience profound changes in atmospheric circulation patterns leading to significant changes in temperature and seasonal precipitation. Changes in temperature and precipitation could threaten water supplies, agricultural production, natural ecosystems, as well as human settlement patterns.
Changing temperatures and precipitation patterns would influence water availability. An increase in temperatures would increase surface water evaporation, which would cause a decrease in river runoff. Increased evaporation, especially in summer, would likely increase the demand for irrigation, which would further add to the strain on water supplies. At the same time, water quality might suffer as the same waste volumes were diluted in lower stream volumes. Agricultural, industrial and urban water users could all be affected. Changes in the frequency, seasonality and the variability of droughts and floods could also result from altered atmospheric circulation patterns.
Changes in seasonal temperature and precipitation patterns could alter growing seasons and require shifts in crop and variety selection, planting schedules and irrigation patterns. Regional redistribution of agricultural growing patterns could also result. The ranges and populations of agricultural pests would likely change. Agricultural losses to pests and diseases, which at present may be limited by cold winters, could lead to lower agricultural yields.
The fluctuations in temperature and moisture associated with climate change could cause serious consequences to terrestrial ecosystems. Altered seasonal temperatures and precipitation rates could cause forest growth to shift geographically. The composition and diversity of all plant and animal species would also be susceptible to the increased environmental stress resulting from climatic changes.
Potential impacts on water resources could increase or decrease flood threats on a regional basis. Traditional flood control and floodplain management and land use patterns would have to be altered and redirected as a result of the potential for more frequent flooding. At the same time, the possibility for more frequent droughts could require expensive modifications to existing reservoir and river management systems.
Some experts theorize that an increase in average global temperature could result in more frequent hurricanes. They also predict a rise in sea level as a result of thermal expansion of the oceans and the melting of ice sheets and mountain glaciers. Rising coastal cities and ecosystems worldwide. Salt water intrusion into rivers and groundwater aquifers would contaminate drinking water supplies and threaten ecosystems.
The greenhouse effect is a well established scientific concept; evidence indicates that human activities are increasing greenhouse gases such as carbon dioxide and methane. But uncertainty dominates every other aspect of global climate change theory, from the projections of rising global temperatures to environmental consequences to socioeconomic impacts.
Current science is unable to predict with confidence the timing, magnitude or regional distribution of the theorized consequences of climate change. Projections of how much wetter, drier, or hotter it will be, in which regions and in which seasons are not yet possible. Improvements in the computer models and better remote sensing data from observation satellites may give us a clearer picture within a few decades.
Yet, the potential impacts that have been theorized to result from global climate change are enormous. Such effects include altered seasonal temperature and rainfall patterns, changes in the frequency and variability of droughts and floods, rising sea levels and fundamental impacts on agriculture and global ecosystems.
Clearly, such effects would have powerful economic, social and political consequences. The risks of global climate change should continue to be assessed and societal responses to the potential impacts should continue to be proposed and debated. Most of all, it is important to search for actions which will have major economic and environmental benefits regardless of whether global warming becomes a reality.