In her 1962 book, "Silent Spring," Rachel Carson described some of the early warning signs that DDT and other pesticides were harming the environment.
A vivid example occurred at a vacation spot called Clear Lake, near San Francisco, after pest-control officials started using insecticide in 1949 to eradicate gnats. Water birds began to die in large numbers during the 1950s, and scientists didn't understand why -- until they realized that the poisons were being absorbed by plankton in the lake, which were being eaten by the fish, which were being eaten by the birds.
With dozens of examples like these, Carson's book helped launch the environmental movement, which among its many accomplishments stopped the indiscriminate use of deadly pesticides.
Today, there are similar early warning signs that global warming is starting to affect plants and animals around the world. Most of this evidence is not questioned by mainstream scientists. Yet nothing serious is being done about the problem -- least of all in the United States.
Here's a sampler of evidence that even the most jaded among us (a club in which I'm normally happy to claim membership) shouldn't ignore. It was assembled by Adam Markham, the director of energy and climate policy for the World Wildlife Fund. Think of these examples as ecological alarm bells -- the canaries in our global coal mine:
The Arctic region is taking the first blows, according to a recent study by the International Arctic Science Committee. In Fairbanks, the number of 40-below days is now half what it was in the 1950s. The permafrost is warming, by an estimated two to four degrees, centigrade. And sea ice is shrinking: In the Bering Sea, it has been reduced by about 5 percent over the past 40 years.
These climate changes appear to be harming wildlife, according to a paper presented last month in Norway by Gunter Weller and Manfred Lange. One species of sea lion declined by 50 percent to 80 percent over the past two years. The number of northern fur seal pups declined by half between the 1950s and '80s in the Pribilof Islands, the major breeding ground in the Bering Sea.
One haunting sign of change comes from Caleb Pungowiyi, an Inuk who works with the Eskimo Walrus Commission in Nome. He told colleagues last month that because of warming in the arctic, the traditional Inuk name for the month of October no longer is accurate. That name literally means "time of crossing" and referred to the hardening of the ice in Alaskan rivers. But in recent years, he says, the rivers haven't yet frozen in October.
Salmon are dying in the North Pacific. The World Wildlife Fund will present evidence next month of a massive threat to salmon stocks, due to changing climate and ocean conditions. According to the Alaska Department of Fish and Game, last year's catch of sockeye salmon in Bristol Bay -- the largest sockeye fishery in the world -- was half what was expected and the lowest in more than 20 years.
David Welch, a scientist with the Canadian Department of Fisheries and Oceans who has studied the issue carefully, warns that salmon may not be able to survive in the warmer ocean temperatures that have been measured recently in the North Pacific. Welch believes that if current trends continue, sockeye salmon could disappear from the Pacific by the middle of the next century.
Coral reefs are dying. Last year, coral around the world was devastated by "bleaching," which is caused by loss of the algae that give the coral its food and color. According to a report presented two months ago by the State Department, it was the most severe epidemic of bleaching ever recorded -- in some parts of the Indian Ocean, up to 90 percent of the coral was affected.
Many scientists blame warmer tropical water temperatures, which last year were the highest ever recorded. The State Department study noted: "Even under the best of conditions, many of these coral reef ecosystems will need decades to recover."
Species are rapidly disappearing in the cloud forests of Costa Rica. As sea-level temperatures have risen, the air in these highlands has become warmer and dryer -- affecting the animals that live there. The golden toad appears to have become extinct, and 20 other species of toads and frogs have disappeared since 1987. Bird and lizard populations have also been affected.
What seems to be causing all these disparate effects is the measurable global warming trend that has taken place over the past century -- with an increase in the average surface temperature of about 0.5 degrees centigrade. Among scientists, there is a growing conviction that this global warming trend is directly linked to the increase in carbon dioxide and other greenhouse gases in the atmosphere over the past century -- due to burning fossil fuel and other activities associated with industrialization.
And what does Congress do, in response to the evidence of global warming? Because of pressure from business lobbyists, it refuses even to consider the issue. The Kyoto agreement, a fledging international pact hammered out last year, is deader than a Costa Rican golden toad.
Here's how bad it is: Rep. Joseph Knollenberg, a Republican from the Detroit area, sponsored a successful rider last year that effectively bans the federal government from spending any new money to curb greenhouse gas emissions.
Is there intelligent life on earth? You sometimes have to wonder.