Second of two parts

I consider the British naturalist, writer and broadcaster David Attenborough (now Sir David) to be one of the greatest figures alive in terms of environmental conservation and education. Thanks to him, the beauty, mystery and excitement of the world's natural history have been revealed to many millions of readers and viewers around the world as they have been exposed to his landmark television series and accompanying books.

His extensive catalog of programs includes no fewer than nine groundbreaking "Life" series: "Life on Earth" (1979); "The Living Planet" (1984); "The Trials of Life" (1990); "Life in the Freezer" (1993); "The Private Life of Plants" (1995); "The Life of Birds" (1998); "The Life of Mammals" (2002); "Life in the Undergrowth" (2005); and "Life in Cold Blood" (2008).

In addition, there were many other superb series, titled "State of the Planet" (2000), "The Blue Planet" (2001), "Planet Earth" (2006), "Are We Changing Planet Earth?" (2006), "Nature's Great Events" (2009), "Life" (2009) and, most recently, this year's "First Life."

Any one of those astounding productions would have been a great credit to the average person's career as an educator about the natural world. However, it was in fact his 1954-63 "Zoo Quest" series of books and BBC TV programs that were partly instrumental in engendering my own interest in natural history and conservation. Similarly, though, his subsequent series have been the impetus for generations of young people to pursue careers in the natural sciences, conservation and the media.

Even as a young boy, our human dependence on nature seemed to me self-evident. Then, as a teenager, the shock I felt upon realizing the extent to which we were already trashing our only planet was overwhelming. Through the slowly passing years of my youth my interest focused in on birds, largely because they were active and colorful, could be found easily and watched with satisfaction through borrowed binoculars — and because they represented to me a sense of unconstrained freedom.

On initial nature rambles I was bewildered by diversity. Certainly it all seemed fascinating, but with no mentor — other than figures such as David Attenborough via books and TV — I was lost in all the details and didn't know where to concentrate. In attempting to focus, my childhood reasoning was that "flowers are for girls" and "if I study dragonflies or butterflies, which are active only in summer, what will I do for the rest of the year?"

I had, I realize now, crossed an important bridge, and the idea of studying nature, not just being absorbed in nature, was established in me. As the speed of the years began to accelerate, it was inevitable that I should become a student of biology — yet that alone was not enough. How could I justify studying something academically if that very habitat or species might be gone before I was? But what could I do about it?

My youth had coincided with the world's "first oil shock" — in 1973 — and the beginnings of a global realization that natural resources were perhaps not limitless. My tertiary education then coincided with a steady barrage of new information about the extent of life on Earth (between 10 and 100 million species); while our understanding of evolutionary relationships and histories also expanded rapidly — along with, of course, our understanding of the plight of species, habitats and ecosystems.

Knowledge of the great waves of extinctions became more prevalent, too — and with that knowledge, the notion of a "sixth extinction" was born.

Through geological history, it appears, five massive extinction events have occurred, during each of which more than 50 percent of all species on Earth disappeared during relatively short (geologically speaking) time frames.

In the previous such event around 65 million years ago, it is estimated that 50 percent of all plant species and a staggering 75 percent of all animals species were wiped out. But as the overwhelming effects of humans' 20th- century actions became more widely understood, increasing reference began to gain momentum of that ongoing "sixth extinction" event — this time caused not by some massive meteoritic impact or catastrophic climatic or atmospheric shift, but by human activities.

With extinction rates that are 1,000 times greater than the natural background rate, species are slipping away around us. Yet with more than half of our human population now concentrated in urban areas, fewer and fewer people are directly aware of those losses.

Consequently, I saw that the primary responsibility of researchers was not simply to gather and analyze data, but to interpret it, via various media, to the public in order to provide insight into the natural world. So it was that my own involvement in writing and radio and TV media began — emulating in a small way one of my childhood heroes.

In the 84 years of Sir David's life, our human population has more than tripled, from 2 billion to nearly 7 billion. Hence the answer to the question of where the world's biodiversity is disappearing to is incontrovertible — we are converting the polyculture of natural ecosystems and the diversity of the species they support into monoculture and human biomass: us!

Like members of a massive ant colony, our armies are out scouring the world for supplies — from rare-earth metals and mineral resources to support our technologies, to plants and animals for foods and medicines to support us.

We are compromising our vital food supplies, our freshwater supplies and our soils by contaminating them with our cocktails of chemical and hormonal pollutants, and by the steady accumulation of plastic particulates that are clogging our oceans and threatening all life there (a recent survey reported a minimum of 250,000 species — and perhaps more than 10 times that number — living in our oceans).

With 12.5 percent of all bird species currently threatened with extinction, 24 percent of mammals considered threatened, and some 40 percent of all species considered in danger, it is not surprising that many sober scientists are talking of the probability that 50 percent of all species on Earth will disappear in the next 100 years.

For most species, the issue boils down to habitat loss: We are destroying their only home. That is an extraordinary legacy for our race.

In a very simplistic way, our gross inability to recognize the limits of our precious planet reminds me of a mountain hut I reached in the highlands of Scotland in the late 1970s. Previous visitors, presumably cold and without fuel, had used the stone fireplace to burn most of the floorboards and part of the roof beams, making it uninhabitable for later visitors such as me!

Another analogy that springs to mind is to compare what we do on Earth with a group of astronauts on a space station who have decided to accept four times as many people on board, smoke in their confined atmosphere and use their food store as a toilet. Aren't the inevitable and catastrophic consequences, as they say, a "no-brainer"?

Emotionally and politically, as a species we have yet to mature sufficiently to manage ourselves and our population. Astonishingly, we are still able to concoct bizarre and untenable arguments in support of destroying other political leaders, systems and cultures. We can justify spending trillions of dollars on the destruction of infrastructure, ideology and even population — as long as it's someone else's. Yet we cannot justify spending the very same amount on dealing with the worst global crisis we all face — the breakdown of the very ecological services on which we depend.

How strange that "going to war" is acceptable, but "going to peace" is not. How odd that we have the capacity to deal with the global environmental issues we all face, but choose instead to bury our heads in the sand, like the proverbial ostrich, and spend our financial and manpower resources instead on destruction and the alienation of whole peoples at the same time.

Alas, rather like many ant or wasp species, we humans seem to have inherent tendencies toward aggression, so expenditure on warfare is not only rarely questioned, but is accepted as being so fundamental that funds are diverted away from far more critical issues. If, as nations, we have those resources to expend, then it is our choice on what we expend them — and we could as well direct them toward solving future problems, not creating them.

We have spent more than $1 trillion on wars in the last decade alone, with some $739 billion being expended on Iraq and another $358 billion on Afghanistan (www.costofwar.com) . Imagine what, in terms of environmental issue-solving and employment, could have been achieved had an environmental equivalent of the Bill & Melinda Gates Foundation had that kind of money to save and restore global ecosystems using their very own motto, "All lives have equal value."

Mark Brazil is a naturalist and author who has written "Wild Watch" since April 1982. He currently leads wildlife excursions around Japan and worldwide by land and sea. Both his latest book, "Field Guide to the Birds of East Asia," and his "A Birdwatcher's Guide to Japan" are available in good bookstores, or by contacting the author at [email protected] or via his website at www.wildwatchjapan.com.