In nature s infinite book of secrecy a little I can read. -William Shakespeare, Antony and Cleopatra (Christianson 210).
It starts with heat. Slowly, almost imperceptibly, it starts to get hotter. The increase in average temperatures is gradual; what we notice are the scorching spikes, as heat records fall one after another. Winters are milder, but punctuated by deluges and blizzards. Spring starts early, but toorapid snowmelt leads first to floods, and then to summer drought (Roan 30-45).
Weather becomes more extreme--storms more powerful, hurricanes more damaging. What once was unusual becomes common; "100-year floods" become routine. Ecosystems start to shift, subtly at first. Familiar trees, weakened by drought and disease, brown and burn in the more frequent fires. Grasslands replace what once were forests, and deserts replace grasslands. Species accustomed to cooler temperatures move north--if they can find suitable habitat not covered by malls and housing developments. Fewer songbirds visit your backyard feeder. Then, none. Species you never heard of are declared extinct. Then, species you have heard of. Then, familiar favorites like polar bears and manatees (Roan 49).
Around the periphery, in low-lying coastal areas, storm surges rush farther inland than ever before. Melting icecaps and glaciers cause sea levels to rise; beaches erode and then disappear. Cities build dikes to keep out the rising seas. Inevitably, the dikes sometimes fail (Christianson 196).
With warmer winters and earlier springs, mosquitoes are everywhere. People get sick from diseases you thought occurred only in the faraway tropics. In those distant places, crops fail year after year and people take to the roads, looking for food. You don't think much about those people until they start showing up in your town (Christianson 199).
By the end of your life, you realize that everything is different, that this is not the world you meant to pass on to your children and grandchildren. And it keeps getting hotter.
This is what we call global warming, it is just beginning. It is impossible, of course, to point at natural events and say that this one is caused by global warming and that one not. But we can study the past, look at what is happening around us, and listen to what climatologists say global warming will mean for our future. Their projections are already being borne out (EDF 2).
Over the past century, humans have raised our planet's temperature. We do this through industrial activity and by using internal combustion engines, generating gases that trap the sun's rays in the atmosphere and thus greatly enhancing the natural "greenhouse effect." These gases include methane and nitrous oxide, but especially carbon dioxide. The inevitable product of the combustion of fossil fuel, CO2 is released whenever we burn oil, coal, or natural gas. The greater the concentration of CO2 in the atmosphere, the hotter it gets. Before the Industrial Revolution, the atmosphere contained about 280 parts per million of CO2. Today, that figure is 360 ppm. The Intergovernmental Panel on Climate Change (IPCC), an assembly of the top climatologists on the planet, estimates that by the end of the next century, the CO2 level will be somewhere between 480 and 800 ppm. (Most of the projections presented here assume a doubling of pre-industrial concentrations to 560 ppm) (Marshall 2).
Not coincidentally, 1995 was the warmest year since global records started to be kept in 1856. Despite brutal winter storms, 1996 was still among the warmest years, and 1991 to 1995 was the warmest five-year period in recorded history. Human activity has increased the earth's average temperature by one degree this century. The IPCC predicts a further increase of 2 to 6 degrees over the next century. A 2 degree rise would be very serious; 6 degrees would be catastrophic (Marshall 2).
These temperature rises will not be uniform. In the United States, many areas of the West, Midwest, and Northeast are already 3 degrees warmer than they were a century ago. In the future, we can also expect to experience more deadly heat waves like the one that hit Chicago in the summer of 1995, killing so many people that the morgue couldn't handle all the bodies (Bellini 86).
A hotter world means more than higher air-conditioning bills. It means that vermin will spread to newly suitable habitats, bringing diseases to afflict newly vulnerable human populations. Mosquito-borne malaria, for example, is generally restricted to humid regions with average temperatures above 61 degrees--at present, about 45 percent of the world. Global warming in the range of 6 to 10 degrees would unleash malaria-carrying mosquitoes on 60 percent of the globe (Goldstein 3).
The consequences are expected to be most devastating for less-developed nations in the Tropics. At present, many people living in tropical highlands are protected by their altitude's cooler weather. In Rwanda in 1987, a 2 degree increase in temperature led to a 337 percent rise in malaria rates. At present, malaria kills about 2 million people annually. According to a study in the Journal of the American Medical Association, by the middle of the next century global warming could cause an additional million malaria deaths every year (Roan 134).
Climate change is also increasing the range of Aedes aegypti, the species of mosquito that carries both dengue and yellow fever; scientists in New Zealand have already linked outbreaks of dengue in the South Pacific to global warming. A hot summer in 1995 led to 140,000 cases of dengue fever from Argentina to Texas. Aedes aegypti have already been identified in Houston and other parts of Texas, as well as throughout the Southeast. Another dengue-carrying mosquito has reached Chicago (Roan97).
The weather extremes caused by global warming can also lead, indirectly, to outbreaks of deadly hantavirus, the acute, often fatal respiratory illness that broke out in the Four Corners region of New Mexico in 1993, eventually killing 76 people nationwide. Hantavirus is transmitted to humans by rodents, whose populations boom when plentiful rainfall follows an extended drought--both more frequent occurrences with global warming (Christianson 213).
Another deadly threat is the resurgence of cholera, which thrives in the higher water temperatures of a warmer world; it has already been found in the Chesapeake Bay. A 1991 cholera epidemic in South America killed 5,000 people. How many will die next time? (Fumento 46)
As global warming causes low-lying coastal areas to flood or former cornfields to turn into sandtraps, humans can pack up and move. It is not so easy for trees, insects, fish, and wildlife, which are dependent on particular climatic conditions. In the past, climate change has generally occurred gradually enough for whole populations to migrate. In the 10,000 years following the end of the last ice age, the globe has warmed by about 5 degrees, and ecosystems have gradually adapted. We now face a similar temperature hike, but this time within the span of only 100 years (Roan 111-120).
Can plant species keep up with the rapid change? Given the right conditions, fast-growing trees like spruce can move up to 100 yards a year. For most species, however, progress is measured in feet per decade. A shift of 40 miles north (or 60 yards in altitude) has already been necessary to compensate for the one-degree rise in temperature. On the West Coast, Edith's checker-spot butterfly has shifted its range 100 miles to the north, and entire populations of sea life in Monterey Bay have moved north in response to a water temperature 4 degrees warmer than it was 60 years ago (Fumento 145).
Freshwater fish don't have the luxury of such mobility. Species dependent on cold water--salmon, trout, walleye, pike, and muskie, to name a few--are in big trouble. A 5 degree rise in average water temperatures would devastate many trout populations; an EPA study last year concluded that 24 states could lose 50 to 100 percent of their cold-water fish populations (Fumento 146).
The future belongs to the omnivores and the opportunists, fast-moving creatures who aren't too particular about what they eat. Slow-moving plants--and the animals that depend on them--may lose the race. Alpine species that must move up mountainsides in order to find cooler temperatures will eventually run out of mountain. Species already stressed by loss of habitat to human development may run out of luck (Marshall 2).
The forests of the next century will be dramatically different. The sugar maple, for example, could virtually disappear from the United States. (Good-bye Vermont maple syrup!) With a doubling of atmospheric CO2, the ranges of birch, hemlock, and beech trees could also shift 300 to 600 miles to the north. This would mean, of course, huge areas of dead and dying trees left behind, fuel for catastrophic fires that would further contribute to the atmosphere's heavy carbon burden, deforming even more habitat. University of California researchers estimate that global warming could render 20 to 50 percent of the state's natural areas unsuitable for their current species (Christianson 226).
Climate change is already playing havoc with the seasons. Worldwide, from 1981 to 1991, the start of springtime plant growth has advanced by eight days; major changes in vegetation are occurring over one-eighth of the planet. Migrating red-winged blackbirds now arrive in Michigan 21 days earlier than they did in 1960. Migratory birds who depend on solar cues to know when to move on may find that local temperatures--and thus vital local food sources--are no longer in sync. Shorebirds migrating through Delaware Bay, for example, depend on the eggs of horseshoe crabs to fuel their flight; if global warming means the birds arrive before the crabs lay their eggs, they might not make it to their arctic breeding grounds (Christianson 229).
Even if they did make it to the Arctic, they might find a dangerously unfamiliar environment. Spruce forests are already advancing into what is now tundra; a doubling of CO2 is expected to reduce the tundra's size by 30 percent. In 1990, caribou migrating to the coastal plain of northern Alaska found that the earliest spring in nearly 40 years had caused their principal forage to go to seed, depriving them of crucial nourishment. In the High Arctic, unseasonable warmth could collapse the snow dens of the ringed seal, leaving the pups vulnerable. Together with a reduction in the extent of pack ice, this decline in the seal population could spell the end for the king of the north, the polar bear (EDF 2).
"Everyone talks about the weather but no one does anything about it," claims the old joke. Now we are doing something about it: we are making it worse. A warmer atmosphere means the evaporation of more water from the oceans, leading to greater precipitation. It also means the exchange of more energy, leading to greater atmospheric violence (EDF 2).
According to the National Climatic Data Center, weather extremes are becoming more and more frequent: hurricanes, tornadoes, blizzards, flooding, droughts. So far this century, extreme weather events have increased by 20 percent. Annual precipitation is up 6 percent since 1900, and total winter precipitation is up 8 percent. What used to be "100-year" events are now commonplace. "I talked with one mayor who said his community had had six hundred-year floods in the last ten years," reported Vice President Al Gore, after his visit to flood-stricken North Dakota in April (Fumento 69).
North Dakotans should keep their sandbags ready. Rather than the light rains and gentle snowfalls of the past, future precipitation is increasingly likely to come in the form of deluges or blizzards, both of which are more likely to lead to floods. Last winter, a couple of major blizzards buried California's Sierra Nevada, but a New Year's warm spell melted much of it, resulting in massive flooding in the Central Valley, causing 36 deaths and billions of dollars in damage.
Despite such extreme storms, the overall snowpack is expected to be much reduced in the future, leading to summer droughts (Fumento 75).
Warmer ocean temperatures in the Atlantic might also spawn more frequent and intense hurricanes. While these storms have always varied widely, hurricanes in the past two years have been as strong as or stronger than any this century. A Japanese government study predicts a 60 percent increase in the number of hurricanes hitting the eastern United States (Bellini 32).
Hotter seas might also result in widespread flooding of coastal areas, not to mention the complete inundation of low-lying island nations like the Maldives in the Indian Ocean. One reason is simply that the warmer the water, the greater its volume. In addition, large amounts of the world's moisture currently trapped as ice are melting. The world's glaciers have shrunk 11 percent in the past century (those in the Alps by 50 percent); in the next, according to the IPCC, one-third to one-half of all mountain glacier mass could disappear (Bellini 58).
Another major contributor to ocean mass could be the Antarctic ice shelves, which are deteriorating at a rapid rate; two huge chunks, each the size of Rhode Island, have fallen off in the past two years. The mean temperature in Antarctica has risen by 2 degrees since 1950, and the enormous Larsen B ice shelf is riven with cracks, leading some scientists to predict its demise within two years (Roan 72).
The IPCC predicts that sea level will rise by as much as three feet by the end of the next century. At that rate, most East Coast beaches would vanish within 25 years (they are already disappearing at a rate of two to three feet per year). The Everglades and Atchafalaya swamps would be totally under water. Storm surges and hurricanes would subject areas far inland to catastrophic flooding, including much of southern Florida, New Orleans, and the San Francisco Bay Area. Chesapeake Bay and the Sacramento Delta would be inundated by saltwater, drastically changing their roles as marine-life nurseries. Huge dikes would have to be constructed to protect low-lying metropolitan areas--at a cost, based on Dutch experience, of $1 billion per mile (Roan 88).
Like the vision shown to Ebenezer Scrooge by the ghost of Christmas Yet to come, this nightmare need not come to pass. Given current CO2 levels, some warming is bound to occur, but the worst can still be prevented. Humankind has demonstrated the awesome power to heat the entire globe; now we must demonstrate the wisdom to turn the thermostat down.