Often self-proclaimed "ecologists" assume that we can save Nature simply by removing Man. The most extreme version of "Deep Green" thought advocates exterminating our species with tailored viruses, in the belief that Nature is immortal if undisturbed. The bowdlerized version insists that Mankind is OK as long as we throw away our penicillin, vaccines, and computers, living as illiterate peasants at the mercy of plague and famine. For many (usually those who have never actually been illiterate peasants, or had an untreated toothache for a few months), this is a comforting vision of a return to a simpler time. But in reality it would be a prescription for the quick death of Nature.
We can save Nature only if we do not return to it ourselves. Primitive humans displace other species by competing for their energy sources. Hunter-gatherers exterminate their prey species; peasants cut down forests and take their sunlight for their food crops. It is only modern peoples with high-productivity agriculture who have the option of living off energy from fossil or nuclear sources, thus leaving the sunlight for wild ecosystems. Modern developed nations can leave space for forest and large mammals; Indian peasants cannot.
Saving Nature: More Intelligence, Not Less
The pop-culture, anti-scientific attitude is that all ecological problems are man-made, thus the logical conclusion is that Ebola is the perfect ecological solution. This viewpoint cannot survive a look through a telescope.
The telescope shows how small the Earth's biosphere is. Outside it, all of the observable Solar System is dead. There are no Martian canals, no Venusian swamps. Of course there may be hidden homes for life; it has been suggested that the internal oceans of Jupiter's moons have more stable conditions than the surfaces of planets. We know for certain that there is a vast reservoir of subterranean bacterial life on this planet, perhaps outmassing all aboveground life. But single-celled slime does not satisfy our human definition of Nature.
Most of the surface real estate in this System is unoccupied by the sort of "Nature" that we aesthetically prefer. For water-based terrestrial life to live on its surface, a planet must stay in a very narrow range of temperatures for a long time. This is astronomically improbable. Usually, it just doesn't happen.
Most planets die. They freeze, or they fry, or they don't have enough heavy elements because there weren't any supernovae to make them, or supernovae irradiate them from light-years away and kill all the surface-dwelling species. The Earth is the lucky or Providential exception. But luck runs out, and perhaps so does the patience of Providence with species too lazy to develop nuclear rocket engines (or in our case, to bother to build them after they are developed).
One of the stars in the Big Dipper is a future supernova, and it will arrive in our Solar System's neighborhood in six million years or so. It only has to explode within ten light years to kill most life on land. If Earth's luck suddenly returned to that of the average planet, it could get hit by one of the hundreds of Apollo-Amor asteroids in a 100 million megaton explosion, and a supernova irradiation at the same time. This would make recycling our cans somewhat inefficacious.
Even if Earth's luck holds, the geological history of the Pleistocene shows that the planet is growing colder since the warm times of the dinosaurs. There was much more life on Earth in the Jurassic Period then there is now, in the Holocene. The CO2 on which plants depend is almost gone; from over one percent of the atmosphere while the dinosaurs reigned, it had fallen to .028% when we could first measure it in the 1800s. When the ice sheets cover the planet from poles to Equator, nothing will live but the volcano-vent worms and the underground bacteria. "Nature" as we know it will be dead.
Unless we save it. Over the last century humans have managed to move the CO2 content of the atmosphere up from that near-absent 0.028% to… 0.037%. This isn't enough to stave off every possible volcano or asteroid-impact Ice Age. But it is a start. No other organism can dig up carbon from miles underground and put it back into the biosphere for flowers and trees to use; humans are uniquely capable of this benevolence. Nor can any other species deflect killer asteroids, or freeze the DNA of dying species and store it for their future rebirth.
A living Nature needs humans, or at least an intelligent species of some sort. For the life forms that surrounded our ancestors to survive cosmic catastrophes, there must be intelligence capable of controlling the caprices of the unliving parts of Nature. The atmosphere must be guarded from Ice Age depletion as well as greenhouse runaway. To have a significant probability of surviving unexpected events in the really long term, Life must be taken to other worlds. Terraforming is the only way to turn the cosmos a Deep Green.
What Nature To Save?
If we choose to live in freedom, to progress technologically, we will be rich. There will be enough resources both to live fuller, more complex human lives, and to save Nature. But saving "Nature" is not so simple… for first we must decide what Nature we want to save. Do we want to let Nature change over time until it becomes as unrecognizable to us as our Nature would be to the dinosaurs? Or do we want to preserve our Ancestral Environment; to make the Earth into a museum instead of a living world?
If we wish to hold Life in stasis, with no change in species mix, then vast interventions will be required. If the Earth's climate could be kept perpetually in the Holocene, evolution will destroy old species and raise up new ones. Even if Man leaves the planet completely, new species will quickly move into the "tool-user" niche. Then they will kill off another series of the megafauna as our forebears did… If the Earth is to be a museum it will have to be a highly artificial one. Genetic mutations will have to be suppressed and the old life forms replanted. Eventually life on Earth will become, not the actual Ancestral Environment, but merely a best guess at what it was, maintained by a complex system of robotic intervention. Nature will be completely unnatural.
There is no one "original state" of nature. The species mix in North America in 1492 was missing most of the original megafauna. For example, the relatively small bison and wolf species of the 15th century were recent adaptations to the overhunting of the Amerinds, who exterminated many species. North America looked completely different in 30,000 BC; there were dire wolves, plains lions the size of horses, ground sloths, huge bison species, and plant life that had coevolved with them all.
Of course, all the previous ecosystems could claim to be the "original" state of nature. Should we try to reconstruct the dinosaurs, the trilobites, and all Nature's extinction victims? Yes, I think we should… but they won't all fit onto one planet, nor can they all live under the same climate conditions or even breathe the same kind of air. We would quickly hyperventilate and pass out on the atmosphere respired by Tyrannosaurus, and I doubt whether the one-meter-wingspan dragonflies of previous periods could take off in the thin stuff we breathe. There is no one-size-fits-all way to restore Nature.
It's A Big Universe
There are and will be many views on how to "save" Nature. Trying to force one viewpoint onto the whole planet will merely cause fruitless conflict, just as the many attempts to force one religious vision onto all Mankind have led inevitably to blood and destruction. Fortunately there is no need for such cataclysmic megalomania. Individual property ownership can allow evolution to progress without destroying old ecosystems.
Under a market system, with different people free to use their own resources as they choose, Nature will thrive and change. There will be areas where people attempt to maintain species in their current relationships. Other places, the Pleistocene may return. Mammoths, dire wolves, and saber-tooths will rise from the dead and walk again. Even reconstructions of the dinosaurs, the true masters of fang and claw, will stomp the ground once more. All this won't fit on one planet, but fortunately we are not restricted to Only One Earth. (If even the ESA can put ten tons into geosynchronous orbit, how hard can it be?) Terraformed Mars may well make a better Pleistocene habitat than the original.
So many long-dead species can live again, and this is a good thing for the Nature that killed them off. A diversity of eco-systems on different worlds will be an insurance policy for Life itself; after all, there is no cosmic guarantee against extinction for any species, no matter how advanced. Even if we fall, perhaps smart raccoons or smart dinosaurs will rise up from our museum worlds and take up the banner of Intelligence.
But the main line of Nature in the long run will be new forms, born from a marriage of design and evolution, of silicon and DNA. Evolution cannot advance to all possible goals, because like politicians it cannot think past the "next selection." Human driven design can take life where it has never gone before. This is not a thing to fear, but to celebrate. Life is not life if it cannot grow and change.
The universe is billions of light-years across. There is room for preservation of old species and the growth of new forms as well. There is plenty of room for a living Nature; most of the universe is full of energy but dead. Man needs Nature; but Nature needs Man even more.
February 16, 2005