In Johannesburg over the next few weeks, the biggest talk fest there's ever been will ensure that few people on the planet remain unaware of environmental issues such as global warming, sustainability and rapidly decreasing biodiversity.

Among these key issues, though, the outcome of the United Nations World Summit on Sustainable Development is likely to have least impact in the area of biodiversity. After all, at the UN Conference on Environment and Development held in Rio in 1992 -- which is why the Johannesburg meet is being called "Rio+10" -- the resulting document on biological diversity was never signed by the United States, even under the relatively liberal Clinton administration. And although Japan put its pen to the paper, it has done little to live up to the agreement.

Now, 10 years on and with an ultra-conservative, unilateralist White House with former executives of oil and energy corporations at the very top, it is unlikely that biological diversity is even clearly understood -- or that action to foster it will receive any real attention.

In Japan, too, the situation is not particularly promising, though many people may be surprised to learn that Gov. Akiko Domoto of Chiba Prefecture is a world expert on biological diversity. Hopefully, she will be able to increase awareness of the issue, at least in her prefecture, which -- with its huge number of diversity-destroying golf courses -- certainly needs to become better informed.

However, the sad truth about biodiversity is that the problem of its rapid decline seems remote and unreal to most people -- like a science-fiction story or a computer game. In particular, what makes it so difficult to initiate positive action is that its effects are far less apparent to people than, say, changing weather patterns. And even if perceived, the value of conserving species of wildlife and their habitats seems very difficult for most people to understand.

This is especially the case when conservation may involve nixing a multimillion-yen dam-building project that would give work to hundreds of local people while, possibly, providing flood-control and electricity, merely to save a few species of fish, snails and worms -- most of which cannot be eaten and are unpleasant to touch or even look at.

Yet a few shocking facts may help to explain the urgency of protecting biodiversity. At the end of the last century, the renowned Professor E.O. Wilson of Harvard University wrote that as many as 50 percent of all living organisms on the planet will, at present rates of extinction, be gone forever by the end of the 21st century. In other words, at that rate three species will have been lost in the time it takes me to write this article.

In his body of work, Wilson has mainly focused on terrestrial biodiversity, especially the destruction of the Amazon and other tropical rain forests and the resulting loss of habitats vital to the survival of tens of thousands of organisms. But what about the oceans, which make up roughly 70 percent of our planet?

Coral reefs are often referred to as the "rain forests of the sea," as they, too, provide a habitat for an immense diversity of marine organisms. A UN report in 2000 shocked the scientific world with the prediction that, by 2010, 30 percent of the world's coral reefs would be gone -- and that by 2050 there would be none left alive on this planet.

Most of the problems afflicting coral reefs seem to be directly related to global warming and steadily rising sea-water temperatures. Humans, however, continue to discard vast quantities of unwanted materials, lethal or not, into the sea, contributing greatly to coral destruction.

A Worldwide Fund for Nature report recently pointed out that in only 30 years, we have destroyed roughly a third of our natural world, with our forest cover 12 percent down and ocean biodiversity down by more than 30 percent.

As a 73-year-old naturalist, I have lived as much of my life as possible surrounded by nature, both terrestrial and marine. I have witnessed this tragic decline in living creatures.

In the 1940s, while in high school and university, I spent a lot of time studying wildlife in a particular unspoiled forest in the Green Mountains of Vermont in New England. Wildlife was abundant then, and it was easy to observe wild deer, beavers, an occasional bear, eagles, peregrine falcons and an abundance of forest birds. Porcupines were common, too, and I even learned to locate them at night by their smell.

Less than 20 years later, the peregrine falcon was extinct in the United States east of the Mississippi, due to the use of DDT as an insecticide. Today, the vast area of forest where I explored nature so many years ago has been replaced by two immense ski resorts -- and with them has come a tragic loss of wildlife diversity. Such a great price to pay for a few winter weekends of human leisure.

My attention turned to marine life in the 1950s, and by 1970 I had begun to study fish seriously in the waters of Miyake Island, in the Izu Islands south of Tokyo.

Every bit as shocking as the recent WWF report, my own research data shows that since 1970, roughly 70 percent of Miyake's corals have disappeared, mainly in Ofunato Bay, Igaya, where construction has been excessive. Equally, 70 percent of my study population of more than 100 anemone fishes at four sites on the island have disappeared due to habitat destruction.

Even worse, more than 90 percent of the striped cowfish population I studied in the late '70s and early '80s has been similarly destroyed.

And finally, the entire populations of both a dragonet species and a goby, that I studied in the same era, were destroyed by habitat changes caused by great influxes of mud spewing from concrete drains along the road above the study site.

All of this destruction was prior to the volcanic eruption of 2000. But, depressingly, I have considerable data from Okinawa, Miyako Island, the Yaeyama Islands and the Philippines telling a similar story. And my data comes from merely the few species I have had time to study in detail -- so what about the tens of thousands of species I didn't study?

Unfortunately, this dramatic loss of biodiversity is lost on many new divers who, not knowing what the oceans used to be, perceive what remains as beautiful, still relatively diverse -- and so of no cause for concern. They will never know what it was like before.

However, as most people do not dive, they have even less knowledge of the rapidly shrinking marine biodiversity, and one of my biggest frustrations is my inability to convince either the public or government leaders of the severity of the biodiversity problem.

We owe it to our children and grandchildren to stop our selfish destruction of the planet's life forms (including our own) -- and to save what remains for future generations.