The Magazine of the Union of Concerned Scientists
Volume 19 Number 2 Summer 1997
Published by permission
"The Road to Ruin"
By Darren Goetz
Global warming is no game. The risk to human beings- to our health, our food supply, and our housing-are great. And the risk to animals and plants with which we share the earth is also enormous. We are standing at a crossroads. Continuing on our path will lead us down the road to ruin. But we don't necessarily have to choose that path. We can choose a different road and a different destination if we make the right choices soon.
Evidence. In 1995 the Intergovernmental Panel on Climate Change, an international body of climate scientists brought together by the United Nations, concluded that global warming is already a serious problem. The average surface temperature of the earth has already increased by 0.5 F to 1.1 F since the last half of the 19th century. And the climate has already begun to change: all of the 10 warmest years on record have occurred in the last 15 years.
Could these changes be due only to the climate's natural variability? The Intergovernmental Panel thinks not. Their Second Assessment Report provides evidence that the heat trapping gasses related to human activities- such as carbon dioxide from burning coal, oil and gas- are in part driving global warming by increasing the amount of the sun's heat trapped in the earth's atmosphere. This excess heat makes the global climate system unstable. The Intergovernmental Panel concluded that the rise in temperature and change in climate are unlikely to be entirely natural in origin" and that the balance of evidence suggests a discernable human influence on Global climate".
Impacts. If increases in concentrations of carbon dioxide and other heat trapping gasses go unchecked, more changes in global climate patterns will occur. Because the climate system is complex, scientists cannot predict precisely how much and how fast the climate will change. But sophisticated computer simulations project a range of scenarios for increases in average surface temperature between 1.8 F and 6.3 F by the year 2100. (Bear in mind that seemly small changes in temperature can produce major changes in climate. During the last ice age, global temperatures were only 5 F to 9 F cooler than the are today, but that was sufficient to bury what is now Canada, New York and New England under a kilometer of ice.)
Global warming will not generally mean more pleasant temperatures. Within the next 20 years, various regions of the world may experience severe changes in climate. Some may be vulnerable to longer droughts, others more to coastal flooding, and many to more frequent bouts of extreme weather. And if global warms continues unchecked, we could well see
|Greater risks to human health as diseases previously found in tropical areas spread to higher latitudes and elevations|
|Severe stress on forests from higher temperatures and/or less rainfall.|
|Decreases in mountain habitats and the plants and animals that live in them|
|Expansions of deserts.|
|Disruption of agriculture through regional changes in temperature and water resources.|
|A rise of 6 to 37 inches in sea level, with persistent flooding endangering coastal wetlands and human settlements|
Human Health. According to a 1996 World Heath Organization report Climate Change and Human Health, changes in the global climate could increase the frequency of extreme weather, such as heat waves, floods, and storms.these events heighten the risk of injury, disease and death, but also threaten health through shortages and interruptions in the supply of food, water and power. For example, major flooding could contaminate drinking water supplies, even in the United States
The reduction of fresh water supplies because changes in regional rains and snowfall may cause a higher incidence of some water and food-borne diseases and parasites. Also, insect-borne diseases such as malaria and dengue fever are already moving northwards from tropical regions. These changes are unlikely to cause large epidemics in the United States because of the high standards of public hygiene and health care quality. But public health care may require more resources as the number of people affected by these diseases grows. Americans who are poor or have inadequate access to health care may suffer disproportionately.
Agriculture. While impacts of global warming on crop yields and productivity will vary considerably by geographic region, several studies suggest that maintaining agricultural productivity will be difficult in many areas. For example, a study by the US Department of Agriculture indicates that soil moisture losses could reduce agricultural opportunities in the Corn belt and the Southeast. Maintaining agricultural production may require costly adaptation strategies. Farmers may need to change the types of crops they grow (from corn to wheat, for example) and the cultivation methods they use, and increase the amount of land under cultivation. The USDA study found that if corn production were to suffer significantly, livestock production would also suffer, since animal feed would be less available.
Many regions of the world are likely to be far worse off because they lack the economic resources to adapt agriculture to climate changes. Scientists expect agricultural productivity in parts of sub-Saharan Africa, southeast Asia, tropical Latin America and some Pacific island nations to be highly vulnerable. The poorest people in these regions may be at greatest risk for hunger and famine.
Natural Habitats. Forests and wetlands provide critical benefits to human health, by filtering out our air and water, and to human welfare, by providing opportunities for recreation and commerce. Changes in regional climate put many such ecosystems at risk by hindering their ability to grow and regenerate. For example, changes in temperature and rainfall could shift habitat boundaries dramatically-alpine ecosystems could shift to higher elevations, and forests could be forced northward Since climate changes may well occur rapidly, some species may be unable to adapt or migrate. Many could face extinction
Aquatic habitats, such as coastal wetlands, are also vulnerable to global warming. The survival of these wetlands-often areas of high biodiversity that also provide protection against floods-depends on the water's temperature, flow and level. Scientists are confident that global warming will reduce the area of wetlands and change their distribution. Arctic and subarctic wetlands, which are critical refuge and breeding grounds for large numbers of migratory species, are among the most vulnerable. Other coastal habitats-including marshes, mangroves, coral reefs and atolls, and river deltas-will also be threatened.
Solutions. Avoiding these costly damages justifies immediate action to turn off the road to ruin. But the United states shows no sign of such action. It will not meet its 1992 commitment made at the Rio Earth Summit, to stabilize emissions of heat trapping gasses at 1990 levels by 2000; by 1995, US carbon dioxide emissions were up 5.5% over 1990 levels.
But this doesn't mean that emissions can't be reduced. Scientists and economists have identified many technically feasible, cost-effective opportunities for emissions reductions (one of which is discussed in The Road Less traveled" on page 4 [ Nucleus",Vol 19, #2]) including energy efficiency measures, advanced vehicle technologies, cuts in oil and coal subsidies, and investments in clean, renewable energy sources like wind and solar power. These strategies would yield bonus benefits by reducing local air pollution (see Hitching a Ride" on page 4 [ Nucleus",Vol 19, #2]) and creating high technology jobs. But to take advantage of these opportunities, governments and industry must work together to design policies to reduce the emissions of heat trapping gasses. Recently, 2000 prominent economists issued a statement affirming that climate friendly policies will not harm the US economy and can, in fact, strengthen it. The Union of Concerned Scientists is working in various states, in the capital, and in the international community to advance policies that will turn our society aside from the ruinous road to a global future. Darren Goetze is a UCS staff scientist)
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