The Heat Is On: Global Warming Threatens the Natural World

by Norman Myers

(From Greenpeace, May/June 1989)

Everyone knows that we are pushing countless plants and animals to the brink of extinction. And we all have heard about our role in raising the Earth's temperature -- the infamous greenhouse effect. But we don't hear much about how the two are connected. In fact, global warming may prove to be the single greatest threat to our fellow species. At the same time, this connection may provide the incentive for a global solution to our most serious environmental crisis.

For many of the Earth's plant and animal species, a few degrees makes the difference between survival and extinction. As the planet warms up, temperature bands will move away from the equator and toward the poles. Vegetation will try to adapt by following the temperature bands, though with limited success. For one thing, climatologists project that changes will not only be large, they will also arrive suddenly, almost overnight as compared with previous climate changes. At the end of the last ice age, when the glaciers covering much of North America retreated, trees and other plants followed the ebbing ice northward. But they moved slowly, at a rate of only 25 miles per century. The sudden arrival of the greenhouse effect will require communities of plants and animals to migrate at a rate ten times faster. Many, if not most, species will find it impossible to adapt and will die out.

Species that can make the quick transition will encounter another problem. In the past, they have enjoyed a "free run" with only geographic obstacles -- mountains, oceans, rivers -- blocking their paths. Following the last ice age, wild papaya and oranges migrated to Toronto, tapirs and peccaries to Pennsylvania. This time, wildlife species will find their way blockaded by farmlands, cities and other paraphernalia of human communities, which are "development deserts" for wildlife. To a migrating forest, a city presents just as big a barrier as a mountain range. As Dr. Robert Peters of World Wildlife Fund says, "Few animals or plants would be able to cross Los Angeles on the way to the promised land."

Realistically, if the greenhouse-affected future unfolds as anticipated, it will eliminate species in huge numbers. The impact of the rifle and harpoon, the chain saw and plow, the bulldozer and pesticide pack could well be matched, if not exceeded, by the factory chimney, the auto exhaust and other sources of greenhouse gases.

Nor will present networks of parks and preserves provide much help to threatened species. Protected areas have been set up to reflect natural conditions that are fast disappearing. So a rainforest park might soon start to desiccate into woodland vegetation, leaving its rainforest species high and dry. A desert preserve might be overcome by wetter conditions to which its desert-type creatures cannot adapt. In each case, of course, the park's creatures will seek refuge elsewhere. But they will find themselves thwarted by the park's boundaries and the alien, human-dominated lands beyond. What was once a sanctuary will become a trap.

This, then, is the general outlook for wildlife species in a world of accelerating climatic change. But how will things work out for particular species and regions, such as North American forests, wetlands and tropical coral reefs? Here is a closer look at some environments.

The Northern Forests

Many tree species will have to migrate northward at a speed ten times greater than they have moved in the past -- and do it while sidestepping cities and other impediments that people have put in their way. Difficult as this prospect is, much of its success depends on the mode of migration. If a tree reproduces by spores, it could conceivably keep up. But if, as is the case with the common beech of the eastern United States, it depends on birds and mammals to carry its seeds into new areas, the realistic range for a century-long migration (according to the past record) drops to a mere 15 miles. Meanwhile, the climate will have moved 250 miles north.

Of course, we can give the poor old beech a helping hand by transplanting its seeds into new habitats. But this will reduce the species to a plantation tree. As Dr. Margaret Davis, a professor at the University of Minnesota, says, "massive and very expensive intervention" would be required to save a species we do not now view as threatened at all.

So much for a single species. How about an entire biome, such as the boreal forest that spans much of northern Canada and Alaska? The outlook is dire. Although this forest will not disappear entirely, it will be reduced from 23 percent of all the world's forests to 1 percent or less. The rising temperature (with the greatest increase projected for the poles) will cause its present range to give way to vegetation patterns invading from the south. Yet the boreal forest itself will have little place to go northwards: it will simply run out of space. The great assemblage of plants and animals that make up one of the Earth's glories will fade from the scene.

Fens, Bogs and Moors

Different sorts of greenhouse threats are creeping up on the rich stocks of species that reside in wetlands. For instance, rising sea levels will threaten coastal wetland species. According to Dr. Jim Titus, a scientist at the Environmental Protection Agency (EPA) in Washington, DC, a one-foot rise in sea level would allow seawater to penetrate 35 yards inland along the average coastline. A three-foot rise would inundate low-lying coastal areas almost 1,000 yards inland. A mere three-inch rise would cause tidal rivers to advance even farther -- more than half a mile inland, thus drowning many estuarine wetlands. Given predicted levels of warming, these are the most likely amounts of sea level rise. Less probable, but still plausible, is a six- foot rise: this would eliminate 80 percent of all U.S. coastal wetlands. Of course wetland wildlife will try to move inland. But it will find its way blocked by levees, seawalls, housing, sea-front highways and other structures. All in all, the demise of coastal wetlands as a result of sea level rise could prove to be the greatest wildlife-related impact of the greenhouse effect in the United States.

As for wetlands inland, the outlook is scarcely better. Marshes, fens, peatlands, mires, swamps, bogs, sloughs, swales, wet heaths and moors cover about 6 percent of the Earth's land surface, an area roughly the size of the United States. They comprise some of the richest wildlife communities anywhere. But due largely to draining, one-half of the world's wetlands have been lost since the year 1900, most of this loss in developed nations. According to Dr. R. W. Buddemeir, a scientist at the Lawrence Livermore Laboratory who has studies the issue extensively, the drying-out impact of the greenhouse effect will cause many remaining wetlands to evaporate.

The Cote d'Azur

Mediterranean-type zones, which are characterized by cool wet winters and hot dry summers, are also rich in species, particularly endemic species (those found nowhere else). California contains 5,050 higher plant species, or roughly one- quarter of the total for the United States and Canada combined. Thirty percent of them are endemic. Southwestern Australia contains 3,630 species (80 percent of them endemic) in just 2,340 square miles, an area one-seventieth the size of California. The Cape Floristic Province in South Africa contains 8,600 species (73 percent endemic) in 30,000 square miles and is ultra-rich in animal species (a roughly similar proportion is endemic).

As the greenhouse effect overtakes these exceptional ecosystems, they may well experience not only increased temperatures but declining rainfall, according to Dr. Bert Bolin of the University of Stockholm. Naturally enough, vegetation communities in these zones will seek to migrate toward territories with customary climates. But the California biome will find its way blocked by human settlements in Oregon and Washington states. And according to Dr. Barry Pittock of the Australian National University and Dr. Anthony Hall of the Bolus Herbarium in Cape Town, South Africa, species in the other two zones will find no land at all to receive them, only sea.

Tropical Coral Reefs

The tropics are far richer in species than temperate zones, but as noted previously, they may suffer less climate change. Least affected of all could be equatorial rainforests, containing at least 80 percent of all species on Earth. But coral reefs, the second richest biome after tropical forests, could be in deep trouble.

Coral reef species tend to live close to their temperature limits. When heated wastewater from industrial installations and domestic sources is dumped into a coral reef, as is sometimes done in Hawaii, the reef suffers. Moreover, natural warmings in recent years have caused mass fatalities in several localities. The unusual 1983 warming of the southern Pacific current, known as "El Nino," increased the temperature three to four degrees Celsius for just six months. But this was enough to do widespread damage to coral reefs in the South Pacific. A greenhouse warming of tropical seas will be impossible for corals to tolerate.

Still more harmful will be a rise in sea level. As the ocean's surface waters warm up, they will expand. Scientists at the Climatic Research Unit at the University of East Anglia, the National Center for Atmospheric Research in Boulder, CO, and the United Nations Environmental Program in Nairobi project that the sea level will rise from 1.5 feet to 7 feet during the next century. Although corals can grow upwards, of course, they cannot generally do it at even half the pace they will need to keep up with the rising sea level. So they will eventually drown. Moreover, the increased depths of sea water will reduce available sunlight, which will inhibit and even halt coral growth. These factors in themselves could be enough to kill off entire coral reef ecosystems.

Of course certain coral species will probably respond better than others. For instance, "antler" corals grow more rapidly than others. But because they have branched forms, they are particularly susceptible to storm damage, and the greenhouse effect could increase the incidence of tropical storms.

The Deep Blue

How will open-ocean (non-coastal) species fare in a greenhouse- affected world? Alas, more bad news. So far as we can tell, marine species could be in for considerable turmoil. In addition to ocean-surface warming, major ocean currents could shift. The Gulf Stream could stop flowing northeastward as far as Europe, and instead swing southward into the mid-Atlantic. This would leave northwestern Europe with a colder climate overall and possibly push to final oblivion the North Atlantic herring and the 20-odd other species already threatened by over-fishing in the North Atlantic.

In addition, the global warming could trigger crucial changes in upwelling zones, such as the famous anchovy site off Peru, in sea salinity and in sea ice patterns, which could affect fish species long accustomed to stable environments. Incidence of sea storms, including hurricanes, will probably increase, though this would affect coastal wetlands more than deep water species. And all this will take place in ecosystems where threatened species are beyond helping hands. As EPA's Titus puts it, "We'll be mere spectators in the adjustments to climate change [in the oceans]. People will have to adapt to whatever the fish decide to do."

The combined effects of global warming and ozone layer depletion, at least in Antarctica with its wealth of marine life, could be the most significant development of all. On top of greenhouse mayhem, Antarctica will suffer the consequences of increased ultraviolet radiation (UV-B) as a result of the United States- sized "hole" punched in the ozone layer over that continent. Excess ultraviolet light reduces the productivity of phytoplankton and weakens the basis of ocean food webs.

This will harm the rich marine ecosystem surrounding Antarctica, where ultraviolet radiation will be most pronounced. Were the phytoplankton to decline, herbivorous krill -- small crustaceans that abound in the Southern Ocean and serve as a primary food resource for many other creatures -- would be immediately affected. There would be adverse repercussions for the many other creatures that depend on krill, including the spectacular throngs of penguins, seals, dolphins and whales.

What Can We Do?

There are a few things we could do about the impending debacle. First, where possible, we could extend parks and reserves northwards (and southward in the southern hemisphere). This will help provide migration corridors through human-dominated territories. Several private sector groups are planning a network of "greenways" across the United States.

Second, we could establish a host of new parks and reserves designed to counter the greenhouse effect. This does not mean they will all have to be long sausage-shaped areas. They can include areas with an unusual array of uplands and mountains: a species moving 1,500 feet uphill could achieve the same result climate-wise as migrating 200 miles northwards.

Third, we could manage our present parks and reserves to compensate for climate change. For instance, if an area becomes too dry, we could irrigate it. We could employ similar "heroic" measures by transporting species from one place to another. To be sure, these environments would no longer be "natural," and the very notion of wild lands may be something our descendants will know about only through books and films. It is ironic that jut as we are remaking zoos in order to replicate natural surroundings, so we shall have to manage our parks as something akin to mega-zoos, with highly intensive intervention on all sides, if they are to retain much wildlife at all. This will require expensive and never-ending efforts. After doing our best, we will probably discover we have lost more species than we have saved.

There is, of course, another solution. Losing species may be the built-in price for responding to symptoms of problems rather than to problems themselves. How about tackling the greenhouse effect head-on? So far many political leaders, as well as some in the general public, have talked about it as if the most acceptable response is to learn to live with the problem, to adapt in a thousand ways. But as the threatened species problem is added to the problems of dust-bowl agriculture, coastal cities afloat and mass migrations away from the excessive-sun belt, shouldn't we ask whether it might be less costly in the long run to try to tame the greenhouse problem? We cannot eliminate it altogether. We are too late for that. But we still have time to cut back on the problem severely.

What would it take? Primarily we need to cut down on fossil fuels. We can do this, without any decline in living standards. But we must cut out the absurd waste and mobilize the clean sources of energy (solar, tidal, etc.) forthwith. In individual terms, we can forego some private driving in favor of mass transit, conserve energy within the home, recycle energy-costly materials, and apprise ourselves of the myriad other ways to practice energy efficiency. It would also help to halt the burning of tropical forests and plant a few trillion trees to soak carbon dioxide out of the atmosphere. It could all be done at a cost small in comparison to the cost of living in a greenhouse.

The Good News

After such a welter of bad news, here is the payoff: the good news. Because we stand to mess things up irrevocably this time, we might decide that enough is enough and pull together to set things right. If we do, we might not only fix the greenhouse effect, or at least reduce it to a level that we and the Earth's ecosystems can live with. We might also solve a few other problems. By reducing our careless use of fossil fuels and increasing our use of pollution control and energy efficiency devices, we could surely reduce acid rain. And by cutting out the most potent of all greenhouse gases, the chlorofluorocarbons, we would start to contain the ozone-layer problem.

To be sure, this would take an unprecedented effort. But after coping with the fossil-fuel problem, we might find it is possible to deal with pollution, desertification, soil erosion, population growth, Third World poverty and the many other issues that plague us and our Earth. If ever we manage to regulate our human appetites and numbers, we can surely find that we have made room for our fellow species as well. Nothing less will do.

For a long time it has seemed that nothing would be dramatic enough to spur both citizens and leaders to action. Politicians continue to adjust this and tinker with that, as if we had another planet parked out there in space, ready to inhabit after we foul up this one. Will it take a Chernobyl, a Bangladeshi flood and an Ethiopian famine every month before the politicians finally get the message?

Perhaps the greenhouse effect can be a catalyst for global awakening and action. It is going to affect people in all parts of the world. We must realize that the greenhouse-effect flooding of Bangladesh will ultimately mean that a quarter of that country disappears beneath the waves, and for good; that African droughts could be more severe than anything we have seen to date; that America's grain belt will come unbuckled; that a dried-out Central America will send many times more people north across the Rio Grande; and that barricading America's shorelines will cost a cool $110 billion. That is just for starters. The greenhouse effect is not some new challenge a political leader should try to handle before the next election, but something we must head off while there is still time.

Who knows, one day we may thank the greenhouse effect for sending a message that even the most optimistic politician could not ignore. Wouldn't it be sweet irony for our fellow species if the greatest threat they have ever encountered turned out to be a source of relief, the only one that really made a difference?

THE GREENHOUSE EFFECT: QUICK RECAP

The burning of fossil fuels and tropical forests throws so much carbon dioxide into the atmosphere that a significant percentage of the sun's heat, which would ordinarily escape into space, becomes trapped. Other "greenhouse gases" (methane, nitrous oxide, chlorofluorocarbons) are also produced by industrial processes, and these contribute to carbon dioxide's warming effect. Because carbon dioxide has building up in the atmosphere since the industrial age began, it will be almost impossible to stop it. To slow down the process, it will be necessary to develop new energy policies, agricultural systems, human settlements and coastal infrastructures.

The Earth's temperature has already warmed up by about one-half of a degree Celsius (C) this century. According to the National Center for Atmospheric Research (NCAR) in Boulder, CO, and the United Nations Environment Program, the average worldwide temperature is expected to rise between 1.5 and 5 degrees C by the year 2030. (This increase could come sooner or later.) An increase of a few degrees may not sound like much, but it is at least as large as the warming that brought an end to the last ice age. It will make our Earth as warm as it has been for at least 100,000 years.

But warmer temperatures will not be spread evenly around the globe. At the equator there will be hardly any change. In mid- latitudes and in temperate zones such as North America and Western Europe, the warming will be about the same as the average worldwide, a rise of perhaps 2.5 degrees C. At the poles things will get really warm, with an increase in temperature of between 5 and 9 degrees C, which is high enough to melt much of the pack ice in short order (though the ice caps themselves could be safe for centuries).

Climate and temperature predictions are based on sophisticated computer model simulations. We do not know how fast the greenhouse effect will overtake the planet or what its particular manifestations will be. But there is broad agreement that we shall shortly be living in a greenhouse-affected world. According to Dr. Stephen H. Schneider, a scientist at NCAR, the greenhouse effect is one of the least controversial concepts among the entire climatological community. Of course, there is still much uncertainty, but it is no longer a case of "if," but rather of "when," "how much" and "where?"

In addition to rising temperatures, rainfall patterns will shift. Although the planet could receive about seven percent more rainfall, certain areas will receive less. Much of North America and parts of Europe could dry out considerably. Stronger winds, more hurricanes and assorted storms, shifting ocean currents, and a rising sea level could accompany changes in temperature and precipitation. These changes will drastically affect agriculture, forestry, fisheries, energy, pollution, cities, communications and threatened species. "The inhabitants of planet Earth are quietly conducting a gigantic environmental experiment," says Dr. Wallace S. Broecker, a professor at Columbia University in New York City. "So vast and so sweeping will be the impacts of this experiment that, were it brought before any responsible council for approval, it would be firmly rejected as having potentially dangerous consequences."

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Norman Myers, Ph.D., a consultant in environment and development, lives in Oxford, England. He is editor of the Gaia Atlas of Planet Management and the author of many acclaimed environmental books, including "The Primary Source" and "The Thinking Arc".