We ended our four-day hike with an ascent over Farewell Gap, a 10,587-foot pass with vertigo-producing vistas. Farewell Gap is breathtaking: the geology of California stretches before you. But we also knew that a tragedy had occurred at Farewell Gap. On the drive home, a poem popped into my head about that day so long ago in the High Sierras that left us listening for ghosts.

Song of Solace

We lean our bodies into the wind
ascending the last oxygen-starved quarter mile
to Farewell Gap.
In this rocky portal
lie nine melted aluminum markers
supported in cairns of granite
that are remembrances of those who died here.

It was just after the war ended,
a night-training mission gone awry,
the pilots guiding their crippled aircraft toward the pass
fighting the plane’s uncontrolled and deadly descent.
Farewell Gap: a final gamble to reach the safety
of the outstretched valleys in the dark distance,
their only chance to evade the mountains’ teeth.

Imagine those last desperate moments:
milking every last bit of altitude from the shuddering fuselage,
bracing their bodies against the fireball to come.
As Farewell Gap loomed ahead,
they must have known
they had missed salvation by mere yards.

We eat our snacks in silence.
Blue shooting stars
bloom on the slopes below.
The landscape falls away,
to generous valleys: flat, wide, placid, welcoming.
The wind softens,
embracing the mountains with warmth,
whispering a song of solace.

But when the Gulf catastrophe eventually recedes, we will still be faced with the steep price exacted on the biosphere by the human release of massive amounts of CO2 into the atmosphere.

On June 9, a daylong symposium, Moving by Degrees, will explore ways to create a more sustainable world. You can click on the link to listen to an array of scientists, journalists, and business people discuss our future. The Society of Environmental Journalists is one of the sponsors.

These are images of biologist Jack Barclay banding burrowing owls that were nesting in artificial burrows at the margins of a golf course in Davis, CA.

And finally, one more image from wildlife photographer Susan McConnell.

Here’s a quote from a CBS interview with Carson a year before her death about humanity’s place on this planet.

“We still talk in terms of conquest. We still haven’t become mature enough to think of ourselves as only a tiny part of a vast and incredible universe. Man’s attitude toward nature is today critically important simply because we have now acquired a fateful power to alter and destroy nature.

“But man is a part of nature, and his war against nature is inevitably a war against himself.

“Now, I truly believe, that we in this generation, must come to terms with nature, and I think we’re challenged as mankind has never been challenged before to prove our maturity and our mastery, not of nature, but of ourselves.”

This old, sad story is so unnecessary.

In 1984, it was first proved that condors—who are carrion eaters—were being poisoned when they inadvertently ingested lead bullet fragments left behind in deer or pigs or other game animals.

It turns out it’s not just condors that are affected but golden eagles and ravens and turkey vultures and dozens of other birds and mammals that scavenge at kill sites.

The commonsense solution—require hunters to use the excellent nonlead ammunition that is available—has been opposed by some gun groups. These organizations still don’t believe the Everest of evidence linking lead bullet fragments to the poisoning of wildlife, and they fear that requiring nonlead bullets somehow represents a threat to their right to hunt.

Now there’s more to this story. Recent research has shown that lead bullets have the potential to cause sub-lethal lead poisoning in humans who eat hunter-shot game. Here’s an article I wrote for Smithsonian telling this story.

California recently began requiring hunters to use nonlead bullets in condor country. It’s a model to emulate.

For the sake of condors and other wildlife as well as humans, it’s time to stop spreading tons of toxic lead bullets across our landscape.

So what’s the most important year in environmental history? Ummm, well, maybe not so obvious.

I would like to propose the year 1859 as a candidate for one of the significant turning points in humanity’s relationship with the biosphere.

In 1859 three seminal events occurred. The first was immediately perceived as revolutionary: the publication of ORIGIN OF SPECIES that laid the groundwork for modern biology and redefined humanity’s place as part of Earth’s vast dance of life.

But two other discoveries occurred in 1859 that were greeted with little fanfare; only in hindsight would they be recognized as transformative.

A few months before Darwin published his book, a Belgium scientist, Etienne Lenoir, introduced a new invention: the spark-ignited internal combustion engine. His invention led to the mass production of billions of carbon-spewing vehicles that have altered the Earth’s geography and atmosphere.

Ironically, the introduction of the internal combustion engine coincided with an Irish chemist, Sir John Tyndall, proving that some gases—notably carbon dioxide—possessed powerful heat-absorbing properties. Yes, the same carbon dioxide discharged by Lenoir’s engines. Tyndall understood some of the implications of his discovery, linking fluctuations of atmospheric carbon dioxide with the theory of cyclic glacial episodes. But unlike Darwin controversial book, Tyndall’s discovery provoked no debate. In 1859, no one understood that he had established the basis for anthropogenic global warming because at the time it seem inconceivable that human activity could actually change the planet.

So there we have it: the theory of evolution, the internal combustion engine, and the chemistry behind global climate change—all in 1859.

From today’s vantage point, 1859 seems like such an innocent time. Back then, if you had looked at Earth from a distance, you would have seen intact rain forests and robust glaciers and ice caps. At night, a few of the world’s cities glowed with a new invention: gas lighting. But most of the planet still held back the night with candles and oil lamps. Humanity was just beginning its grand experiment to see how much we can alter the planet and how little biodiversity we need before we jeopardize our own survival.

And that leaves us with a question: What will our Earth look like in 2059—on the 200^th anniversary of these discoveries.

When I was eight years old, I undertook the hardest hike of my life, a seven-mile roundtrip trek up and down 2,000 feet of High Sierra granite to the top of Nevada Falls.

My dad had suggested the hike the night before while we were sitting by our campfire in Yosemite Valley. “We could just give it a try, see how far we can go,” he said. And then, as if to seal the deal, he added: “You know, the best tasting water in the world is at the top of Nevada Falls.”

I remember thinking I really wanted to do it. I also remember knowing in my bones that I could not possibly hike that far.

We set out the next morning, taking it slow, making our way skyward through pines and cliffs. The trail was steep, and I soon grew tired. But I kept putting one foot in front of the other, and at some point it dawned on me that I was going to make it. All it took was to keep going—one step at a time.

When we arrived, we had to raise our voices to speak over the roaring water; clouds of spray filled the air and far below stretched the glorious Yosemite Valley. We ate lunch on a granite slab a few yards past the top of Nevada Falls.

My dad dipped his canteen into the river, and we drank the pure mountain snowmelt. And, he was right, it did have an exquisite taste which was heightened by the satisfaction of having achieved something I thought was impossible.

Twenty-five years later, when my dad was dying, I returned to Nevada Falls. I wanted to bring him a canteen filled with the best water in the world. But when I reached the top of the falls, I found a sign reading:

Caution: Contaminated water.

Do not drink.

My dad died more than 20 years ago, but I can’t forget that sign. For me, it represents how much of the natural world we have lost.

We live in the strangest of times, an unprecedented era of human-caused extinctions. Whales and rain forests and condors and tigers and wetlands are disappearing—just like the river from my childhood at Nevada Falls.

As a species, Homo sapiens face a daunting task to preserve as much of Earth’s biodiversity as possible as we navigate what biologist E. O. Wilson calls “a bottleneck of overpopulation and overconsumption.” What humans do in the next few decades will determine how much of the richness of Earth’s life makes it through to the other side.

At times, it seems like an impossible task. But like so many others, I am determined to do what can be done, to keep moving up the mountain one step at a time, to remember the river.