Revisiting the canary in the coal mine. (Note from a World Watcher).

The environmental movement is now old enough to have a real history, as outlined in the chronology on pages 30-35 of this issue. In the course of that history, we have experienced some momentous changes, both in our understanding of the threats we face and in how we are responding to them. In the early years, the ozone hole was known to be a major threat, for example, whereas global warming had not even entered our consciousness. Today, the ozone-hole problem has at least begun to stabilize, but global warming has become a looming danger. As suggested by the guest editorial on page 2, it may pose a far larger threat than that of terrorism.

As our environmental perceptions have changed, so have our means of quantifying and communicating them. In the 1970s and 80s, much consciousness-raising played on sentimental and emotional hooks--concern about the decline of whales, wolves, and other charismatic mammals, or the heart-wrenching tragedies of Bhopal or Love Canal. Now, the biggest news is being generated by dispassionate climate models and lab studies of obscure microorganisms--and by hard analysis of a global economy that has enriched many but left many more in a state of untenable discontent.

Our language, too, has changed. Some of the metaphors that made sense a quarter-century ago are now dated. One of the popular metaphors of the early environmental activists was that of the canary in the coal mine--based on the 19th-century British coal miners' practice of taking a caged bird into a coal mine to serve as an early warning of accumulating methane or ethylene gas. If the canary flopped over, it was time for the miners to get out fast. Later, the capitulating canary came to be a useful symbol of impending ecological collapse. Just as miners who wished to survive needed to beware the asphyxiation of their birds, humanity at large needed to beware the dying of forests and eutrophication of lakes.

Eight years ago, this magazine published an article on the global decline of birds. At the time, we thought it quite appropriate to invoke the canary-in-the-coal-mine metaphor. If thousands of avian species were endangered by human activities, it was as though the whole Earth had become one vast coal mine. Coal, of course, was a big part of the threat literally as well as metaphorically; it was the largest source of global warming gases and acid rain, and a major source of urban smog. For this issue, we decided to update that 1994 story. As we began to work on it, I realized that I no longer see the old metaphor the same way.

What gives me pause is not the coal, but the bird. A canary in a cage is a helpless creature. If it dies, it is a passive victim. But that passive death sadly misrepresents both the real nature of a bird in the world at large, and the real dangers that death might warn of. In the wild, a canary is a very active creature. Its ancestors survived tens of millions of years of environmental threats, from volcanic eruptions to hungry lizards. In fact, it was the canary's own family, the finch family, that focused Charles Darwin's attention on how evolution works. Birds, it turns out, are highly enduring organisms; so far, in one form or another, they've been here about a hundred times as long as our own species has.

Birds vary greatly in their characteristics and capabilities, which shows that they've used a wide range of strategies for survival--reflecting the great diversity of the planet's resources. They adapted to the rigors of long-distance migration by developing spectacular mechanisms of energy efficiency, enabling them to fly over oceans or continents without eating. For example, according to the animal physiologist Bernd Heinrich of the University of Vermont, birds developed a respiratory system that doesn't depend on an energy-consuming compression of the diaphragm to expand the lungs and draw air in, the way the human system does. They developed a body that has the thermally extraordinary capacity to dissipate heat when they're flying under the sun and conserve it when the air turns cold at night. Some birds, such as the bar-headed goose, can fly at 30,000 feet altitude--as high as a commercial airliner. It's alarming enough when a bird in a cage suddenly keels over. But when whole populations of uncaged bird s that can fly high and far, and that have the use of a wide variety of adaptive protections, begin dying off-that's alarming on a very different note.

In our 1994 article, author Howard Youth wrote about some of the strategies people can undertake to stem the undermining of the birds' environmental security. Since then, much more has been learned about what kinds of strategies really work. What's particularly interesting is that these are mostly the same strategies that experts have identified as essential to achieving a sustainable and just human environment.

For example, as Brian Halweil explains in an article on pages 36--40 of this issue, the most effective means of achieving a sustainable relationship between tropical forests and people in coffee-growing countries is for farmers to grow their coffee under the shade of a rainforest canopy, rather than in open-field plantations. A sign that this is so is the presence of numerous hummingbirds, which play key ecological roles in these forests. When rainforests are cleared to grow plantation coffee, the hummingbirds are no longer seen.

Similarly, when coastal sea walls replace dunes, or when cattle ranching kills off native grasslands, native birds quietly disappear.

We call ourselves sapiens, yet we seem to dismiss the signals we are being sent as just so much background noise.

The omnipresence of these signals may be particularly apparent to a reader of this issue of WORLD WATCH, in which the articles turned out to be curiously linked, despite the fact that none of the authors were in communication with each other during the writing. When Howard Youth (who was based in Spain) made an incidental notation in his update on birds that shade-grown coffee production provides an economic incentive for preserving tropical bird habitat, he didn't know that a whole article about shade-grown coffee--providing a more in-depth look at how this incentive can work--was being prepared in our Washington office by Brian Halweil. Youth also mentioned the ravages of DDT on birds-not knowing that Anne McGinn (who was based in Rhode Island) was writing a full feature on the dilemmas faced by countries that still use the pesticide DDT to combat malaria. Youth wrote of the complex strategies that are needed to arrest the cycle of poverty and environmental decline, because this cycle is now driving thousan ds of bird species toward extinction. And lo, on page 30 begins our chronology by Curtis Runyan (in Washington) and Magnar Norderhaug (in Norway) of the efforts people have made to stop this same cycle over the past four decades, in the hope of arresting the destabilization of the human world.

In the final analysis, the image of that hapless canary in the coal mine is still compelling, but not quite right. Yes, the coal is a primary source of carbon, which has now dispersed over the whole globe. And yes, the vulnerability of a small bird is a vulnerability we all share. But no, we are not hapless or helpless.