The Science of Avatar

¹ THE GREEN APOCALYPSE

In the movie Avatar we see very little of Earth. There are just a few brief scenes of Jake Sully with the body of his twin brother Tommy. What we hear about it makes for a grim scenario, however. As Jake tells Eywa, the forest goddess of Pandora, there’s no green left.

There’s a little more detail in deleted scenes in a draft screenplay by James Cameron (dated 2007 and available online): “Jake stares upward at the levels of the city. Maglev trains whoosh overhead on elevated tracks, against a sky of garish advertising… Most of the people wear filter masks to protect them from the toxic air… It is a marching torrent of anonymous, isolated souls.”

Jake’s Earth is evidently a world where the problems we face today have run to extremes, a world of overpopulation and over-development, of resource exhaustion and climate collapse, of pollution and extinctions. And it’s a world of warfare too. Miles Quaritch and Jake Sully, as serving soldiers, fought in such diverse arenas as Nicaragua and Venezuela—and we see plenty of military technology on Pandora in the course of the movie (see Chapter 20).

Unfortunately this is a future that is all too plausible. And it’s all because of farming.

Ten thousand years ago every human on the planet lived much as the Na’vi do, by hunting, fishing, and harvesting the fruits of the great wildwoods. And there were very few of them, only around three thousand people in the whole of Britain, say.

But with the development of farming much higher population numbers began to appear. The Earth’s resources were exploited much more intensively, including the planet’s mineral wealth. We began this process by digging deep mines to extract the best flint, working chalk seams with reindeer-bone axes.

Today there are around seven billion of us. We are reaching global limits on such essential resources as oil, coal, even fresh water. We use about a third of the planet’s land for our farms and cities, and consume perhaps forty per cent of its biological productivity—an astounding amount for a single species.

And we are increasingly aware of the impact we are having on the planet. There is an intense controversy about the extent to which the climate change we appear to be experiencing is affected by human action, and whether further impact can be averted if we change our ways. I think it’s fair to say that some environmental scientists believe that humans have been affecting the climate since the Industrial Revolution, if not even earlier; some are sceptical.

But whether it has been caused by human intervention or not, the evidence of climate change is all around us, and alarming news about the planetary life-support systems on which we all depend has become all too familiar.

How bad are things, and how bad might they get? It’s not an easy question. The way aspects of the environment interact with each other is poorly understood, and it’s an irony that we are only coming to understand the biosphere just as it is fraying at the seams.

However, in 2009 a team of environment and earth science specialists at Sweden’s Stockholm Environment Institute made a systematic map of the planet’s natural life support systems, to see how far we have pushed them already, and how much further we can go before our own survival is threatened. The exercise was a comparatively cool appraisal of where we are now and where we are going. The team came up with nine “dimensions,” each with an estimated safe boundary.

The bad news is that of the nine dimensions we have already exceeded three boundaries. The team’s measure of climate change is the level of carbon dioxide in the atmosphere. This crucial greenhouse gas occurs naturally in the air, but we are injecting more through burning fossil fuels. The “safe” boundary the scientists established is around twenty-five per cent higher than the “natural” pre-industrial level, but we passed that mark twenty years ago. Our impact on biodiversity is measured by extinction rates, which far exceed the background “natural” rate. We are destroying habitats, introducing alien species like weeds and rats, generating pollution and perhaps causing climate change—or we are just over-hunting. It’s thought that a tenth of all bird species, a fifth of all mammals, and a third of all amphibians are under threat. We know the ecosystems on which we depend, natural communities of plants and animals, rely on biodiversity, but we don’t know how much biodiversity they can afford to lose before they collapse, as happened after the great mass extinctions of the past such as the asteroid strike that killed off the dinosaurs. The nitrogen cycle is a relatively newly identified problem area. Nitrogen is essential for all living things, but only a small proportion of the planet’s inventory (most of the atmosphere is nitrogen) is of a usable form. We are “fixing” far too much of the useful stuff out of the air (by a factor of four) through the industrial manufacture of fertilisers, inefficient farming, and other processes.

The middling–bad news is that we seem to be approaching the boundaries in three other areas. We are using up far too much of the planet’s available fresh water supply—about a quarter of the world’s rivers no longer reach the ocean for at least part of the year. We are devoting too much land to human uses, such as crop-growing and urban development, and as a result we are losing the “ecosystem services” performed by forests, grasslands and wetlands, such as replenishing the air and stabilising the soil. Rising acidity in the ocean is another problem we’ve only recently identified; acidity eventually kills off such species as corals, and a less fertile ocean is less able to absorb carbon dioxide from the air.

In two more areas the science is too patchy even for the boundaries to be established: aerosol loading, the injection of soot, sulphates and other particles into the air through industrial processes and burning, and chemical pollution, where we have a handle on the impact of some pollutants such as DDT but the effect of others is unknown.

At least there is still time for recovery on all the dimensions. And there is actually some good news! The last dimension is ozone depletion: one environmental issue with a (relatively) happy ending.

In 1982 British scientists discovered a thinning of the ozone layer in the stratosphere over the Antarctic. This reactive form of oxygen screens Earth’s surface from the sun’s invisible but lethal ultraviolet radiation. Chemist Paul Crutzen and others confirmed that the culprit was CFCs, chlorofluorocarbon compounds. CFCs were used in spray cans, refrigerators and Styrofoam. Once released into the air, CFCs were broken up by sunlight and released free chlorine that reacted with ozone, thus removing that isotope of oxygen from the stratospheric layer where it collects. Life on Earth has evolved under the shield of the ozone layer, and has no natural protection against the sun’s ultraviolet. If the ozone layer had collapsed completely, allowing the world to be blasted by solar radiation, humans would have been afflicted by skin cancers and cataracts, and whole ecosystems would have been damaged.

However, the danger was recognised in time. In 1987 a protocol banning the release of CFCs was signed, the ozone depletion was halted, and Crutzen and others shared a Nobel Prize. At least this example shows that we are capable of concerted action on a global scale to avert the threats we face.

But—as seems to be the case in the Avatar future—what if we fail? How bad could it get?

² ECOCIDE

Jake Sully’s Earth is a world where, he says, there is no green—where, we have to infer, the natural order has entirely broken down. Is this possible? And could humanity even survive on such a world?

As we face a bottleneck of resource depletion and environmental collapse, it’s not hard to imagine a nightmarish future of warfare and famine, social collapse, disease and mass migration, punctuated by climate catastrophes like drought, flood, and hurricanes spinning off the warming oceans. Richer countries or groups of countries may become fortified blocs. As always, the poorest will be most vulnerable, for they live close to the limit of sustainability anyhow. But none of us would be immune.

And things could get a whole lot worse than that.

Climate change could stop being gradual. Some scientists predict that if the world’s natural cycles are pushed too far we could reach a “tipping point” into a sudden, much greater disaster. Among the tipping-point triggers could be the abrupt release of deposits of methane and carbon dioxide, currently trapped under permafrost layers around the rim of the Arctic Ocean and elsewhere. These vast volumes of greenhouse gases would make global warming suddenly accelerate.

Another much-discussed tipping point is the possible collapse of the ocean current known as the Gulf Stream, which brings warm water (and air) to the north Atlantic. If this were to fail, coastal regions, including the east coast U.S., Britain and Scandinavia, could suffer a dramatic and sudden cooling. This scenario was (over) dramatised in the movie The Day After Tomorrow (2004). And it may have happened in the real world, triggering the “Younger Dryas” episode beginning around thirteen thousand years ago, in which the world’s emergence from the last Ice Age was interrupted by a thousand-year reversion back to glacial conditions.

A 2003 report commissioned by the Pentagon imagined sudden climate collapse triggered by something like the Younger Dryas. The consequence would be a sharp reduction in the world’s “carrying capacity,” its ability to feed us all. Amid the subsequent wars, droughts and huge population movements there would be a collapse of states and federations like the European Union, and a breakdown of international order. This was an extreme scenario, but then it’s the job of defence departments like the Pentagon to dream up and prepare for the worst case.

The very bleakest future predictions of all make grim reading. In the 1970s James Lovelock devised the famous theory of “Gaia,” our world seen as a network of flows of energy and matter, “a dynamic physiological system that has kept our planet fit for life for more than three billion years” (and perhaps Gaia has a parallel in Pandora’s Eywa; see Chapter 29). Now, Lovelock says in his latest book The Revenge of Gaia, “The world is fighting back… The bell has started tolling to mark our ending… Only a handful of the teeming billions now alive will survive.”

Is there anything we can do about this?

For a start we might go beyond the “green” activities already prevalent in the modern world: recycling, saving energy, conserving the remaining wild.

Perhaps we could rescue threatened portions of the biosphere itself. There are already over a thousand gene banks around the world, storing millions of plant seeds. Animals are being “stored” as frozen tissue samples, for example at the Frozen Zoo at San Diego Zoo in California, in the hope that if all else fails these creatures could be revived as clones some day. The Zoological Society of London is even considering a bank of frozen corals. And some scientists are considering how to preserve ecosystems on a larger scale—whole landscapes, perhaps—in order to allow evolution a large enough arena in which to continue.

But there are gentler possibilities. American environmentalist Paul Wapner argues that we should soften the lines between “us” and “nature.” For example, Wapner suggests, instead of building a fence to divide forest from city, we should create zones of selective logging. Forests would gradually shade into suburbs that would be intentionally wildlife-friendly, and there would be migration corridors for wildlife and plenty of exposed ground. There might be no wilderness, but the suburbs would be wilder, and we would all become wardens of the wild things around us. Ecologist Dickson Despommier has another interesting proposal: we should raise crops and animals in the cities, in “vertical farms,” large high-rise buildings. Then we could afford to allow the countryside to return to the wild—and we would drastically cut the cost of transporting food.

But if the situation continues to deteriorate, such small-scale initiatives might not be enough. We can imagine frantic efforts to put Gaia back together again on a much larger scale. This is geoengineering: rebuilding the Earth.

Geoengineering solutions can be vast in scale, but are generally based on two simple principles. Earth intercepts heat from the sun; and an excess of carbon dioxide in the air traps that heat. So to reduce the retained heat you either reduce the amount of solar energy the planet soaks up in the first place, by reflecting it away—“albedo manipulation”—or you take carbon dioxide out of the air—“carbon sequestration.”

One sequestration method is to liquefy atmospheric carbon dioxide and pump it under pressure into deep rock layers, or into the deep sea. (It was in 1970s studies of solutions like this that the term “geoengineering” was first coined.) This is already being done, for instance at natural gas plants in Norway. The challenge is not to generate more heat in the process than you’re saving by removing the carbon dioxide.

On the other hand the most ambitious albedo-manipulation schemes are to assemble immense solar reflectors in space. In 1929 the German-Hungarian space visionary Hermann Oberth suggested using huge orbiting mirrors to reflect sunlight to the polar regions, to alleviate the Arctic night. The Russians actually tested a twenty-metre space mirror in 1993, unfolded in Earth orbit from the Mir space station. The idea of using space mirrors to deflect light from an overheating Earth has been explored by American energy analysts. There are less dramatic schemes, such as using naval guns to fire aerosol particles into the high atmosphere, and thus to screen out the sunlight. Other possibilities have been explored in science fiction. Kim Stanley Robinson’s Forty Signs of Rain and its sequels (from 2004) dramatised the collapse and artificial restarting of the Gulf Stream, and in my own Transcendent (2005) I had engineers stabilise the methane deposits at the poles.

Many people instinctively recoil from such drastic tinkering with the planet. It feels hubristic, arrogant. In our myths only the gods fooled around with the weather, like the deities in Homer’s Odyssey who created storms to blow Odysseus around the Aegean Sea. And the science is definitely uncertain. As I said, Lovelock’s “Gaia” hypothesis depicts the Earth as a complex web of interlocking feedback processes. Until we understand how this web works it’s hard to be sure if our meddling will make things better, or worse. There is even a danger that a geoengineering solution would actually encourage us to continue to commit our biospheric sins in the mistaken belief that we could clear things up later.

However, there is plenty of serious talk about geoengineering. In 2009 Britain’s prestigious Royal Society produced a major report on the “science, governance and uncertainty” of geoengineering, and in 2011 the idea was debated by the highly influential Intergovernmental Panel on Climate Change (IPCC), the UN’s climate science body.

Your optimism in our ability to handle something like geoengineering might be dented if you read some of the fractious arguments being waged today in public forums about climate change, but at least we are talking. Perhaps even the arguments are a sign of a (slowly) emerging global consciousness, of how we’re groping towards becoming a mature planetary civilisation. Certainly if things deteriorate there might come a point where we have no choice but to try drastic solutions.

But perhaps, in the end, if things got bad enough, a new and shocking paradigm would emerge: let it die.

With enough power and raw materials I suppose it would be possible for mankind, or a large chunk of it, to survive even on a world with little or no ecology left at all. It might be like colonising an alien world, with domes over the cities, and gigantic air-scrubbing machines, and food factories churning out processed blue-green algae. The tremendous energies that had been devoted to failed geoengineering efforts could now be devoted to artificial life-support systems for a planet.

I wouldn’t underestimate what it would take to replace the lost “services” of the ecology. Consider the humble tree, for example—the tree, so central to the Na’vi’s culture and lifestyle. Trees prevent land erosion, they provide a weather-sheltered ecosystem in and under their foliage, they help maintain the atmosphere by producing oxygen and reducing carbon dioxide, they provide crops from apples to rubber—and, when they die, they give us a remarkably flexible building material, in wood. There are thought to be some four hundred billion of these giant servants on the planet (see Chapter 29). We would have to spend some serious money to build mechanical equivalents of all that. (And if we did, perhaps the last trees would end up in a tree museum, as in the Joni Mitchell song.)

How would it be to live on such a world? The fragmentary visions in Avatar give us a hint. There have been all-city planets in science fiction, such as in Isaac Asimov’s 1954 novel The Caves of Steel, which depicted a world of claustrophobic metal-walled corridors. And consider the dismal dead-Earth vision of Cormac McCarthy’s novel The Road.

I imagine a world of vast mines and huge engines, of foul, smog-choked air and dead oceans, where every sip of water and breath of air has to be passed through a filter first. (Maybe the exopacks used on Pandora are based on technology developed to survive on Earth.) I imagine a world still flaring with war over its remaining resources, just as in Avatar. I imagine a world of intense control and surveillance, mediated by the super-powerful artificial minds of the future (see Chapter 19). I imagine a planet like a vast shanty town, where the plight of the poor and the vulnerable would be dreadful.

And we would miss mother Earth badly. Already we are disconnected from the ecology that nurtured us, and don’t fit the world around us. Our brains are still hardwired to avoid long extinct predators, which is why our bodies are flooded with adrenaline in response to everyday hassles, as if they were lethal threats. This is the “pronghorn principle.” The pronghorn is a North American antelope-like creature that runs ridiculously fast, a now useless ability it evolved to flee the vanished predators that once hunted it. We would be desperately unhappy on a dead Earth, and we might not even understand why.

For better or worse however this does seem to be the sort of world into which Jake Sully was born—and a sense of what we’d have lost is dramatised in Jake’s first wondrous reaction to the living world of Pandora. But our world isn’t like this yet.

³ GREEN SHOOTS OF HOPE

We always have to be aware that Avatar is a movie, and what we see onscreen is there primarily to serve a narrative purpose. Avatar is a movie of hopeful awakenings, from Jake Sully emerging from cryosleep (suspended animation) in orbit around a new world, to the movie’s very last frame when he makes a final wakening as a Na’vi, fully committed to his new world. But hopeful awakenings are much more effective, for story purposes, if you have a nightmare to wake up from.

There’s nothing new in dark portrayals of the future. My generation, born in the fifties, was brought up with the Cold War, a mind-numbing stalemate that could have triggered a mass nuclear war: a future terminated by a wall of blinding light. Western culture has a deep-rooted expectation of apocalypse just around the corner that seems to date back at least as far as the Book of Revelation. We’re always fearing the worst; it’s just that the worst we can imagine changes with time.

Perhaps apocalyptic thinking is valuable, in some circumstances. Maybe our habitual pessimism about the future is a kind of folk memory, a grandmother instinct warning us not to be complacent, to make us expectant of drastic future change, as we have experienced change in the past (such as the Ice Ages). None of this minimises the real threat posed by such problems as climate change. But a recognition of our habit of apocalyptic thinking casts a clearer perspective on our hopes and fears.

And as regards the near future, maybe we’ve still got time to avert the green apocalypse.

I doubt we really could kill off our “mother.” I’m lucky enough to live in a rural community in the north of England. Looking out of my window as I write I can see “nature”: hills, a river, forests, fields. But in fact almost everything I see save for the basic shape of the landscape is artificial, made that way by human intervention, and almost all of it is less than two centuries old. The green I see is mostly crops, or grass for the sheep, or the pine trees of the managed forests. But the wild creatures persist, at the edges: in the hedgerows, underground, at the coast, in the river valleys, the birds in the air.

It’s the same even in the heart of our greatest cities. The city of Pripyat was built to house nuclear workers from Chernobyl, and was abandoned after the disaster. After just a couple of decades its open spaces were green, and the paving stones were so smashed and lifted by tree roots they looked as if they had been through an earthquake.

Gaia has proven pretty resilient in the face of mega-disasters such as the impact of asteroids, like the one that knocked out the dinosaurs sixty-five million years ago. The daddy of all extinction events, the “end-Permian” catastrophe possibly triggered by eruptions in Siberia a quarter of a billion years ago, nearly ended multicelled life on Earth altogether. But life, though much depleted, made it even through the end-Permian, and the grand story of recovery and evolution began again.

Compared to such horror shows our feeble efforts at “ecocide” really don’t amount to much. For example we’ve barely touched the hardy old life forms believed to live in the “deep hot biosphere,” inside the rocks, kilometres down beneath our feet (see Chapter 22). Even if we blasted off the topsoil and irradiated the oceans, those ancient survivors would some day emerge to begin the story of life once more. It is a kind of cold comfort that if we were to disappear tomorrow the wild would take back a recovering world remarkably quickly.

There’s no doubt we face a complex and challenging near future. But, as the example of the ozone layer recovery shows (Chapter 1), we are capable of facing up to problems on a global scale, and resolving them. I think we’ll survive the green apocalypse, chastened and changed perhaps, and by the time those now young grow old, their children will have found something entirely new to worry about.

But we may need the resources of other worlds to save this one.