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The Planet

A Few Degrees Makes a World of Difference

The Planet, July/August 1997, Volume 4, number 6

by Sarah Fallon

[Caribou]
Hot and bothered. Warming temperatures
mean spring comes earlier to the Arctic
and caribou like this one miss out on
their chance to take advantage of the
most abundant and nutritious plant
growth.

Climb into your car on a sunny day when the air inside is baking and you'll experience the greenhouse effect. Just as car windows allow sunlight in and then trap the heat inside, certain types of gases trap the sun's heat within the Earth's atmosphere. Without the naturally occurring greenhouse effect the Earth would not be inhabitable. But in the past 100 years, industrial waste gases have upset the equilibrium of our greenhouse, leading to global warming.

Man-made pollution in the form of carbon dioxide (released by burning gasoline, coal and oil), methane(from mining operations, landfills, leaking natural gas pipelines, and cattle) and nitrous oxides (from coal burning and the breakdown of fertilizers) is increasing the intensity of the greenhouse effect. Massive deforestation also contributes because trees help absorb carbon dioxide.

Concentrations of carbon dioxide (the prime greenhouse gas) in our atmosphere have increased by 30 percent just in the last 100 years. The average global temperature has already risen 1 degree Fahrenheit during that period (which is as long as we've been keeping accurate records). If we don't act to curb our pollution, scientists predict that the Earth could warm between 1.8 to 6.3 degrees Fahrenheit by 2100.

That would be the biggest change in the Earth's climate in 10,000 years. In the same way that even a few degrees of fever can incapacitate a human, a few degrees' increase in global average temperatures could devastate entire ecosystems.

Oceans on the Rise

Warming temperatures have already raised sea levels around the world by about one foot in the last 100 years. As global warming worsens, ocean levels will continue to rise. Melting ice caps and glaciers are slowly increasing the amount of water in the oceans, and as ocean water warms, it expands, further raising sea levels.

This could flood the 30 percent of the world's population that lives within 30 miles of the coastline, contaminate freshwater supplies and damage delta ecosystems such as the Amazon, the Ganges, the Mississippi and the Nile. The Environmental Protection Agency estimates that a one-meter sea level rise by 2100 will result in a loss of 25 to 80 percent of U.S. coastal wetlands.

Coastal flooding would be compounded by the loss of outlying coral reefs. Warming oceans kill the reefs that serve as buffers from the ravages of storms, hurricanes and typhoons, and thereby provide a barrier against coastal erosion and flooding.

Disease on the Upswing

Warmer weather and abnormally mild winters may bode well for orange growers, but they also encourage the proliferation of mosquitoes that carry diseases such as malaria and dengue fever. The incidence of infectious diseases is already on the rise in the United States and outbreaks are occurring in areas previously too cold for them to inhabit. In recent years cases of malaria have been reported as far north as Michigan, New Jersey and New York. A recent study by the Centers for Disease Control and Prevention suggests that the proliferation of disease-carrying mosquitoes could increase the percentage of the world's population at risk for malaria from 42 percent to 60 percent. Dutch researchers have reported that global warming could cause an additional million deaths per year from malaria in the next century.

Lethal heat waves, such as the 1995 event that killed over 700 people in Chicago alone, will be another deadly consequence of global warming. As temperatures rise, major cities around the world could experience thousands of additional heat-related deaths annually. One recent University of Delaware study found that by 2020, global warming could cause up to a 145 percent rise in heat- related mortality in New York City.

Wildlife on the Move

It seems counterintuitive that a slight increase in temperature in the Arctic could severely impact caribou herds. Over thousands of years, however, these herds have adapted their migrations to coincide with the burst of spring plant growth and recent studies have shown that plants are sprouting sooner in the year. As spring arrives earlier and earlier, these migrating animals cannot adjust their schedules accordingly, and as a result may not arrive at their feeding grounds in time to take advantage of maximum plant growth.

Birds like the red knot, the ruddy turnstone and the sanderling stop on Delaware Bay to feed on the eggs of horseshoe crabs to store fat for their flight to the Arctic. If the climate changes, the birds arrive earlier and leave earlier -- thereby missing the nutritious horseshoe eggs. This could lead to drastic declines in these species, as increasing numbers of the birds die from starvation during the migration.

These and other species cannot tolerate rapidly changing habitat conditions, and would therefore be threatened with extinction if the Earth's climate continues to change.

Evidence Mounts

Because global warming is a gradual process, it's impossible to blame the buildup of greenhouse gases for one species extinction or one dried-up wetland. But the vast majority of the world's leading climate scientists now agree that human activity -- burning oil, coal and natural gas in our cars, trucks, power plants and factories -- is changing our environment. Natural systems around the world are already offering some of the most compelling evidence that global warming is under way. Scientists have detected large changes in migration patterns in birds. They have found numerous plant and animal species shifting their ranges northward and to higher elevations. Glaciers and snow cover are disappearing on five continents, and two Rhode Island-sized chunks of Antarctic ice shelf have broken off in the last two years.

The 10 warmest years in the past 100 have occurred since 1980. Both the Goddard Institute of Space Studies, an arm of NASA, and the British Meteorological Office declared that 1995 was the hottest year on record, and that 1991-95 was the hottest five-year period on record. Despite brutal winter storms, 1996 was also one of the warmest years on record.

Soil temperatures are also rising. In ongoing measurements in the Alaskan Arctic, the U.S. Geological Survey has used bore holes to determine that the temperature of the permafrost there has risen 3.6 to 8 degrees over the past 40 to 90 years. During the past 10 years, scientists have measured ground warming averaging 1.8 degrees in Cuba, Australia, Greenland, Russia, France, China and Italy, among other countries. Sea levels are rising too. During the past century, global sea levels have risen 3.9 to 9.7 inches, according to the Intergovernmental Panel of Climate Change.

Research by the National Climate Data Center shows that violent and extreme weather has become more commonplace in recent years. An increase in global temperature means the moisture levels in the atmosphere are higher, which in turn causes more storms. We can't say that global warming caused the massive floods that ravaged the Dakotas and the Midwest this spring, but we can say that global warming increases the likelihood of such occurrences.

The costs of damage from hurricanes has tripled in the past 10 years, according to Sir John Houghton, Science Working Group chair of the IPCC. Record- setting storms or floods have hit China, Ecuador, Peru, eastern Australia, Israel, India, southern Africa, Nepal and the United Kingdom. In the United States, we have had three "100-year floods" in three years, and one "500-year flood" this year.

We have strong evidence, supported by a consensus of the world's leading scientists, that the Earth's climate is warming. We can make reasonable predictions about what will happen if this pollution-induced rise in temperatures continues.

If we are to ensure that our children and grandchildren inherit a world that is not altered for the worse by global warming, we must begin taking steps now to curb global warming pollution. We can do this now by taking modest steps like improving auto fuel efficiency, accelerating development of renewable energy sources and halting deforestation.

No doctor waits to see how high a patient's fever will rise before offering treatment, and we can't afford to wait until the Earth's temperature climbs another several degrees to cut pollution. Our children only have one Earth, and they can't afford to have us gamble with its future.


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