Earth Day is here again, but few people seem interested any more in global warming. It's plausible to inquire whether people realize we've got a duty to protect the environment. Actually, "protecting the environment" is not necessarily the same topic as "global warming." Confusion about the two needs to be cleared up.

The earliest written indication that mankind is responsible for taking care of the earth is probably in the Bible, in Genesis 1 (v. 26-28) where God gives mankind dominion over everything else. Thus began the notion of stewardship, that we are responsible for properly using all things on earth.

For thousands of years the prevailing attitude was that the earth was huge and unlimited, so if you messed things up in one place you'd just move on.  Certainly the settlement of the American west displayed that mentality. But later in the 19th century people saw the damage and became conscious of the need to preserve some of nature's beauty, and National Parks became established.

By the mid-20th  century incidents of major pollution were becoming too frequent, and some tragedies occurred (example: in London England in 1952, thousands died from air fouled by burning soft, high-sulfur coal). A new word, smog, entered the vocabulary as polluted air in cities like Los Angeles burned the eyes. Within 25 miles of a paper mill, it really stunk. Still, "The Environment" didn't mean enough to motivate changing. "The price of progress" was the standard excuse.

Then in 1968 came the flight around the moon by Apollo 8, which returned the photo of the earth hanging like a bright blue marble against the backdrop of the vast emptiness of space.

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That one photo instantly told everyone that this is the only place we've got. The Biblical concept of stewardship suddenly became real once again.

With overwhelming national agreement, Congress quickly passed laws to clean up air and water. The Environmental Protection Agency was chartered, and issued standards for industrial facilities and automobiles. Before long every state had its own environmental department. Things got better as factories were retro-fitted and old cars disappeared from the roads. Today you can eat the fish from some rivers that were sterile a half century ago.

Non-senior citizens either never knew or  have forgotten what it used to be like, but examples of the cleaner environment abound when you stop to think about them. For example, a modern sewage-treatment plant is so good that it goes totally unnoticed in a community.

People realize the need for vigilance, to preserve the environment from future threats of pollution. Today there are many precautionary measures, notably government regulations requiring that before any new technology can be introduced, an evaluation of the environmental impact must be done. (Actually, the locomotive, the automobile and the airplane would never make it through environmental permitting today, even though they polluted less than what they replaced.)

Sadly, not all countries have learned from America's experience. In China the demand for electricity is so great that coal is burned very inefficiently, without any controls, and the air makes Los Angeles of the 1950s look good. Of the ten most air-polluted cities in the world, eight are in China. India likewise needs to clean up. It's easy for Americans to criticize, but they're sacrificing air quality to get faster economic growth. The sooner they retrace the half-century path of America, the better off the entire world will be.

The concern about global warming grew out of the environmental movement. The Earth has been warming very slowly since the "Little Ice Age" ended almost two centuries ago. In recent decades, fear was expressed that it may be warming too fast, due to the influence of mankind. Specifically, carbon dioxide emitted by burning coal, oil and natural gas was blamed for the warming. Large computer models were run to predict decades into the future. A lot of people concluded "we've got to do something to prevent further temperature rises."

Then reality set in. The models, for all their mathematical complexity, could not even "predict" the past reliably. The global temperature stopped rising, even though the CO₂  kept right on rising. The worrisome phrase "global warming" got replaced by "climate change."

Moreover, studies of the long-term behavior of Earth's climate showed that warm and cold periods come and go over time frames of several centuries. There are wobbles in Earth's orbit around the sun, and the sun erupts with activity occasionally (evidenced by sunspots). Natural variations in climate, as compared to humanity's contribution, are gradually being recognized as an important factor.

It is impossible to prevent natural climate change, and therefore efforts toward mitigation are fruitless. Adaptation is the way to respond to the  ever-changing climate. That's what plants and animals have always done -- migrating, growing fur, increasing the density of stomata in leaves, and so forth. Recent analysis indicates that the computer-predicted rise in temperature was too high by a factor of two, which provides a much larger cushion of time for a response.

For mankind to be effective stewards of the planet, to protect the environment, we must use our intelligence. That begins with learning the basic chemistry and biology that underlie the intricate complexities of environmental science. We can't "fix" a problem we don't understand. Too many political leaders and environmental activists have lost sight of that prerequisite. Even the best of intentions cannot compensate for a deficiency in scientific understanding.

The issue isn't closed, and scientific agreement is lacking. That's quite a change from the popular "consensus" of a decade ago. This year's Earth Day might be a good time to focus on asking the right basic questions, so that we can work with nature to improve the planet.