Kitabı oku: «End Game: Tipping Point for Planet Earth?»

CONTENTS

Cover

Title Page

Copyright

Frontispiece

Dedication

Introduction: The Journey

1: Past or Future?

2: People

3: Stuff

4: Storms

5: Hunger

6: Thirst

7: Toxins

8: Disease

9: War

10: End Game?

Acknowledgements

Index

About the Publisher

Introduction

The Journey

This is a story of a journey. Like most journeys, it started out as a personal quest, but for us it has also been a professional one. It began when we were young scientists, driven mostly by curiosity and looking for the next big adventure. We found adventures aplenty, because our jobs as palaeoecologists – people who study how our planet changes through time – took us to remote places all over the world. Along the way we fell in love and got married, and then the personal and professional adventures started inexorably to intertwine. We had one daughter, and a few months later got her a passport and hopped a plane to Australia. Then another daughter, same routine, but this time it was six weeks in Patagonia. By the time our kids were two-year-olds, they’d spent many nights in wilderness tents with us, buried their fingers in koala fur, been carried on our backs as we forded waist-deep rivers and stared down grizzly bears, and fallen sound asleep in their snugglies as we skied back-country trails. By the time they were fifteen, they had their own list of exploits: they’d hunkered down in their own tent as lions paced through camp, taught our graduate students the Latin names of various species, trapped rodents in Patagonia, faced off angry rattlers in the Oregon desert, and watched grapefruit-sized chicken-eating spiders lead around their hundreds of young on a dark Amazonian night.

By now we’ve travelled to every continent in the world, save Antarctica; sometimes together, sometimes alone, sometimes with our daughters, sometimes not. All those trips were research expeditions as well as adventures, each of them undertaken to learn something about how nature worked in the places on which we hoped humans had not yet laid a heavy hand. And we did discover answers to some of the questions we were asking – like how animals respond to climate change that isn’t caused by people, what causes mass extinctions, how ecosystems are assembled, and how evolution works at the genetic level to keep species alive.

But we also discovered that as the years went by and the personal and professional experiences added up, the questions we were asking ourselves began to change. From the personal perspective, the more different places we visited, the more they seemed the same in a very important respect: the values that people hold dear. Eventually we came to understand that the basic wants, needs and emotions that draw people together are much more deep-seated than those that separate cultures and countries. It didn’t matter whether we were with the native Inupiat in an Arctic fishing village, with an indigenous tribe in the jungle of Peru, with scientific colleagues in India, or with executives imbibing at a fancy hotel in one of the great cities of the world. Everyone seemed united in wanting a healthy, comfortable life, putting family and friends first, and in the joy they took in basic pleasures like a good meal, a good laugh, or a pleasant stroll through a pretty place. And without exception, no matter the religion, the country, the political views or the economic class, everyone wanted the best for their children, and hoped that as their sons and daughters grew up, the world would just get better and better. As we watched our own daughters grow up, listening to their own dreams and hopes, we realised that we were no different from anyone else in those respects. Adventure and curiosity were no longer the be-all and end-all; giving our kids, and everyone else’s, the future they deserve became much more important. And our lives in science began to change.

The more we saw, the more our professional perspective shifted. At some point the individual expeditions came to seem more and more like beads on a string, each bead distinct, but when all were taken together, forming a pattern that was hard to miss. And the pattern was that the world was changing before our eyes, much faster than any past changes we were familiar with from our studies of the deep-time history of the planet. Much of our earlier work had revolved around climate change before people got in on the act, so we knew what pace and magnitude of warming temperatures could be considered normal in the planet’s history, and there was no doubt about it: what was happening today was way too much and way too fast. Likewise, we’d worked hard to figure out why species died out in the past, and what normal levels of biodiversity should be, both in terms of numbers of species and their genetic diversity. Again, the losses we were seeing now – from giant otters in Amazon lakes, to wild dogs in Africa, to amphibians in the Rocky Mountains – were way too many.

We started to wonder, long and hard, about what exactly was driving the unusual and rapid changes that were happening all over the world. We knew, of course, the broad brush of the answer: people. The ecologists whose articles we had studied and who we now worked with on a daily basis were more senior than us, and had been publishing research about how people were changing the planet for decades. In some cases they had been reaching out and trying to spread that message to the world. But reading it in a scientific journal or book, or hearing about it in a professional presentation, didn’t resonate at the gut level as much as it should have. Yes, we knew we’d been born into a world that held fewer than three billion people, and that as we progressed through our lives and careers, that number had more than doubled. But like most people, we’d also grown up in a world of limited horizons that made it pretty hard to observe first-hand the connection between more people and planet-sized changes – Tony was born into a poor working-class family in small-town Colorado and never saw much else until well into his twenties, and Liz grew up as a military brat, moving from one army base to another every couple of years, each one looking very much like the next, albeit in many different states and different countries. But eventually we began to connect the dots from all the places we’d travelled to in our careers, and we saw the links between the added billions of people in our lifetime, and hunger, poverty and unhappiness.

Through the years we also saw how it was getting harder and harder to find places that felt they hadn’t been changed in a big way by people. The haze from faraway cities or power plants or wildfires would often obscure our view, even when we thought we were in the middle of nowhere. On our plane journeys from one part of the world to the next, the features we saw on the landscape below were usually farms and pastures, unless they were barren desert, open ocean or rough mountainous terrain. On night-time flights, the lights from cities and highways seemed to spread out below us everywhere. When we started compiling some numbers, we knew why: almost 50 per cent of Earth’s land has been changed from forests and prairies to farms and pavement. That meant that each person on Earth requires about two acres of land, on average, to survive, given current diets, expectations and ways of doing business. We realised that the ratio of used land to people can’t keep up for very much longer, given how fast we’re adding human bodies to the world, and that we’ve already used up nearly all the good land.

As more years went by, we did more research, and we found that the number of humans and their domestic livestock on Earth now is about ten times higher than the planet could support before we – people – discovered how to increase its carrying capacity for big animals, including us, by mining fossil fuels from the ground. We watched HIV/AIDS take the world by storm, and realised that new diseases can, and do, crop up to kill us, and can change things as basic as people’s sex lives. We went into the jungles of Costa Rica and found out that as far as disease goes, HIV/AIDS is not unusual in being transmitted from wild animals to humans, and that such transfer of disease happens more frequently as more people, looking for places to live and make a living, take over rapidly diminishing areas of wild lands.

All of these things made us wonder, just what was the future up against? It didn’t help that in recent years we read seemingly ever more often about conflicts and genocides that were springing up around the world, many of them triggered by scarcities in such basics as food, water or oil. We knew about wars from our growing up – in elementary school, duck-and-cover drills, which amounted to hiding your head so you wouldn’t see the nuclear bombs fall before they vaporised you, were an ingrained part of the routine. We dodged that bullet, but not the Vietnam War – Liz’s dad did two tours of duty, and our generation lost friends there. Nobody wants that for their children. And then came the ever-present crises in Africa, the breakup of Yugoslavia and the USSR, 9/11, Iraq, Afghanistan, Ukraine, recurrent Israel–Palestine tensions, and now the rebel Islamic State. Was the world going into a downhill slide?

We grasped that, strange as it would have seemed to us when we started out as palaeoecologists, the kinds of data we had spent decades examining held the answer to that question. At that point our lives and careers, as lives and careers do, took an unlikely turn. About the time we were pondering the magnitude of current global changes and how they compared with those past, along came one of the most exciting and revolutionary realisations in ecology in recent years: that what we like to think are gradual environmental changes in fact turn into sudden ones that we don’t expect. In popular parlance, these are tipping points, and they happen because, in all walks of life, gradual change accumulates slowly until it hits a certain threshold, and then all hell breaks loose. We saw that in our own lives, when we fell in love – a gradually developing friendship, and then, boom, things suddenly changed forever, luckily in a good way. The sudden changes can just as easily be bad, though – like the death of a loved one, which also changes lives forever. On a larger scale, ecologists and theoreticians now know that sudden tipping points are not unusual in biological systems of all scales – think about a lake going overnight from clear, clean water to green algae scum, once the water reaches a certain temperature and nutrient load.

As we reflected on our palaeoecological research, we realised that we’d actually seen the entire Planet Earth hit tipping points before. Times like sixty-six million years ago, when an asteroid struck the planet and acted as the coup-de-grâce in killing three out of every four of the species known at the time. Or twelve thousand years ago, when the one–two punch of natural climate change and growing human populations wiped out half the big-bodied animals on Earth, at the same time that it went from a cold planet largely covered in ice to the warmer one we know today, which then fostered the growth of human civilisation.

Those past tipping points made us sit up and take notice. Since it has happened before, could Earth be headed for yet another planetary tipping point? And if so, just what does that mean for our children, and for theirs? Or, for that matter, given the lightning speed at which we have seen the world change, what does it mean for our own future?

We’ve now spent a few years, along with many other scientists, trying to answer those questions. And what we’ve discovered has surprised us: first dismaying us, and then giving us hope. The dismay is that if we keep on with the way we’ve been doing things, it is inevitable that the world will soon tip into a permanent state that is worse than what we are used to now. That end game will not be one we want for ourselves, and certainly not one we want for our children. The hope comes from learning that there are feasible ways to change the future, heading it towards an end game with the outcome of a better life, a better world – but only if we, as in all of us, act fast.

These things are what this book is about – our journey of discovery about ourselves, and about the planet we love. We hope that reading it will be a journey for you as well, one that ends in your own personal tipping point, where you comprehend that you really do have the power to change the world.

1

Past or Future?

Liz, in the Himalayas of Nepal, April 2012

It all happened pretty fast. One minute, I was sitting outside sipping my tea. The next, I was hunkered down in a cold, smoky hut, patching up a Tamang woman’s bloody scalp, which she was lucky to have at all, given the machetes that were swinging around. Like most activities around sundown in that part of the world, it was a race against time, because darkness was coming on fast, and candlelight just wasn’t going to be up to the task.

When I had boarded the plane for Nepal a few days before, that kind of adventure was the last thing on my mind. I had set out with one of my Ph.D students, Katie Solari, to meet up with my Indian colleague, Uma, and her Nepali student, Nishma Dahal, in Kathmandu. Our four-woman crew was then going to head into the Himalayas to figure out which species of pika, a fluffy but short-eared cousin of rabbits, occupied which elevations in the world’s highest mountain range. We wanted that information in order to learn how the pikas are responding to the rampant climatic warming that is now heating up that part of the world, as a kind of bellwether for predicting how global warming will change wildlife in general. Pikas, it turns out, are the perfect natural experiment in that regard, because their physiology prevents them from tolerating warm temperatures. As warming climate causes mountain environments to heat up, the pikas move upslope, taking advantage of the fact that for every hundred metres of rise in elevation, temperature falls by a little less than 1°C. Our thought was that by tracking their upslope movement over a series of years, and performing genetic tests on them to see how the animals we trapped were related to each other, we could use the pikas as the proverbial canaries in the coalmine to help forecast Earth’s ecological future.

Since we left Kathmandu, we’d been moving upslope at a much faster rate than the pikas, and we were glad of it. After hiking for two days we were above three thousand metres. The high mountain air felt fresh, if a little thin, after our time in the valley, where brick kilns and fires thickened and darkened the air with a blanket of dense smog. That was far behind and below us now, and we revelled in being in one of the world’s treasured landscapes, ascending through hillsides covered with startlingly vivid arrays of red, pink, white and purple rhododendrons. I scanned the forests for signs of the red panda, since we were in one of the last strongholds of the species. What caught my eye instead, though, was that there was no real forest understorey, and although the trees were straight and tall, all but the highest branches were gone, leaving no cover for birds, much less for red pandas.

Just before reaching the ridgetop that day we met a striking Tamang girl who invited us to stay at her family’s teahouse overlooking the slopes where the red panda was said to reside. Her smile was warm, the afternoon was cold, and we did not hesitate about taking her up on her offer. We didn’t have any better options anyway. Despite the constant signs of humanity along the trail – trash everywhere, even the steepest slopes levelled into slivers of land to grow a few meagre crops – dwellings were few and far between. Our hosts’ hut was one of only two built on the narrow ridgeline, both doing double duty as homes and as teahouses for people like us. Outside each, the family matriarch was sitting in her Tibetan garb, knitting the woollen hats that are so popular among the trekkers who pass through. I shared my binoculars and field guide with a young boy in my hut’s family; he was tan from being outside, and ready with his smile. He pointed to the birds he knew in the guide, miming the places in the forest where they lived. I scrambled around the rocks near their small cabbage garden, looking for evidence of pikas, but didn’t find any. Nishma translated that the boy had not seen any for a while, and that he thought the weasels had eaten them all in the last couple of years.

So I sipped my tea outside, reflecting on the day, waiting for the daily dinner of dal bhat (Nepali lentils and rice). That’s when the shrieks jerked me out of my reverie.

All of a sudden mothers, fathers, kids, aunts, uncles and who knows who else – all the residents of the two houses – were pouring down the hill. The boy who had been so interested in my field guide had been caught stealing wood from a pile collected by the son of the other family, who had done all the hard work shimmying up the trees, cutting off branches as he climbed. The fight was on. Both boys swung their kukris (curved machetes) at each other. Their entire families – parents and children alike – joined in the fray, beating each other with sticks, pulling at braids, grabbing at clothes, scratching and screaming. All the while, the kukris kept swinging.

At the end, all were bruised, some were bleeding, clothes were ripped and shoes were lost. While another trekker patched up the gash on the head of the matriarch from the other teahouse, the matriarch from ours asked me for medical help. Fist-sized clumps of her hair had been torn out, her face was cut, and large bumps had appeared on her head and brow. As I patched her up, the two families continued to hurl curses at each other.

The violence in this spectacular, top-of-the-world setting was jarring – the wood they were fighting over was for our evening’s cook fire. For me, the pieces fell into place. Every day, young Tamang boys travel from higher, barren elevations down to the upper treeline to collect wood. That’s why we noticed as we climbed higher that all the low branches were gone. The trees were being stripped bare where they stood, leaving no cover for the red pandas, which ironically are a major lure for the trekkers, the profits from whom the Tamang rely on for the few things they have that they don’t take from the land – like mobile phones, and the small solar panels to charge them.

The problem is, the land is starting to let them down. Or maybe it’s vice versa. For the days we worked in the Himalayas, we, through our Tamang hosts’ cooking, depended on the wood collected from those trees that were being stripped bare, the water that was syphoned from the melting glaciers above, the cabbage and potatoes grown in small family gardens, and the rice and lentils carried up the mountain on their backs. I had climbed above five thousand metres, and thought I had escaped the smog and chaos of the ‘modern world’. But what became all too apparent was that there is now no place clear of humanity’s impact. And that the farther you get from our creature comforts, the closer you live to the land, and the more apparent is our dependence on Earth’s natural resources.

Even more of a wake-up call was seeing that where those human impacts get to be too much, you end up in the middle of a machete fight, the result of tensions that boil over as an inevitable byproduct of depleting what you need to stay alive. I was left with an uncomfortable question in my mind. Had I seen civilisation’s past in those mountains of Nepal, or had I caught a glimpse of the future?

Judging by the trends of the last few decades, that machete fight, and what led to it, is all too plausibly the world of the future. What is now normal – not only in places we usually think of as economically underprivileged like Nepal, India and Africa, but in fact through most of the world – is a landscape and seascape that has been so changed by humanity that our life-support systems are teetering precariously on the brink of collapse. And in systems as complex as those that keep society ticking along in the way we’re now used to, collapse has a habit of sneaking up so stealthily that you’re blindsided. Suddenly you’re in the middle of a new normal, and suffering devastating consequences that are happening too fast to do anything about.

In popular parlance, that’s known as hitting a tipping point. Things may seem to be changing gradually, or at face value even not at all, until you reach some critical threshold, and everything becomes different. Think, for example, of water heating up on the stove. The reason it seems a watched pot never boils is because you don’t observe any major changes until the water reaches a critical temperature, which (depending on the heat of the flame) can take a long time to happen. When the temperature does hit the boiling point (about 100°C, or 212°F, at sea level), however, instantly everything changes. Bubbles roil, and the water changes its state, turning into steam. Boiling water exemplifies what scientists mean when they talk about tipping points: a rapid change from an ‘old’ state of being to a new, very different state, caused by pushing the system past some important threshold value. The actual change from the old state to the new one is called a ‘critical transition’.

Tipping points (or, if you want to sound like a scientist, critical transitions) are not confined to boiling water. At just about any scale and in any system you care to name, you can think of one. The egg gradually rolls towards the edge of the counter, until it drops over it and reaches its new state of being broken on the floor. A butterfly metamorphoses from a caterpillar, or a frog from a tadpole. The canoe rocks, then all of a sudden tips over and is upside down. Your car runs perfectly well, then one day it won’t start. Property values build up over decades, then crash in a year.

For people too, tipping points are the rule rather than the exception. In fact, if you think about what happens to you and your loved ones, tipping points are the defining moments. A woman is pregnant for nine months, then in the space of minutes a baby is nursing at her breast. Tipping point. The baby grows, gradually learns to talk, walk, play, reason, and then all of a sudden hits puberty. Big tipping point. More gradual change through the teen years, young adulthood, and then that special someone comes along and two previously separate lives join together in marriage – once again, a tipping point. Gradually the two grow old together, accumulating their respective aches and pains as middle age gives way to the retirement years, then a fall breaks a hip. Another tipping point. And finally, of course, the biggest state-change of all, from life to death.

The ubiquity of tipping points has prompted a great deal of research among theoreticians of late, which has made it very clear why living things tend to experience major changes in such fits and starts. Basically, it has to do with how many parts something is built of, and how those parts are connected to one another. The more parts there are, and the more intricate their connections, the greater the likelihood that the resulting system will remain stable for long periods of time. But by the same token in such systems, the greater the likelihood that when change does come, either by tweaking lots of parts simultaneously, or by damaging just one super-critical part, it will come fast, and it will hit hard, flipping the system from its ‘old normal’ to a ‘new normal’. These sorts of systems – with many intricately connected parts that influence each other – are called, not surprisingly, ‘complex systems’ in the jargon of science.

Living things are extremely complex systems, composed as they are of millions of mutually interacting parts that are connected to each other in spaghetti-tangle ways. The scale of the complexity begins to boggle your mind when you realise that anything alive is actually built of many smaller-scale complex systems, separate entities in themselves, but connected together to form ever-larger and even more complex systems. Starting at the molecular level, for instance, DNA replication itself is a complex system that we are just barely beginning to get a working knowledge of. That, of course, is intimately dependent on the workings of, and at the same time influences, the slightly larger-scale complex systems that we call cells. And so it goes, with connections between cells, organs, individuals, groups of individuals, species, communities, and entire ecosystems. The human body has more cells of microbes than human cells; the complexity of our own body’s ecosystem is not remotely well understood. The most complex system of all is the global ecosystem, which is composed of all life on Earth, and the myriad ways that life forms interact with each other and with the inanimate environment around them (like air, water, soil, and so on).

Which means that humans, being life forms ourselves, are not at all separate from the rest of the global ecosystem; on the contrary, we’re intimately embedded in it, just like every other animal (and plant, and microbe – it’s a long list). We count on it for such essentials as a place to live, air to breathe, food to eat, water to drink, and for comfort and solace. But there is no denying that, unlike other animals, our place in the global ecosystem has taken on an unusual role – because we now dominate it. So much so that, just like the flame heating that pot of water towards a boil, we have been inexorably pushing key pieces of our planetary life-support systems towards a tipping point. The tipping point we are pushing towards, however, differs from the boiling of water in an important respect. Once you cool steam, it returns to its previous state, liquid. By contrast, there is no going back once we cross the sort of threshold we’re marching towards, which is more like the one an egg crosses when it tips off the edge of the counter.

People who study tipping points for a living have a name for crossing those thresholds of no return – the system is said to exhibit ‘hysteresis’. The resulting irreversible kinds of state-changes become more and more likely as the complex system gets, well, more and more complex. Intuitively, that makes a certain amount of sense. The more parts to a system, and the more interdependencies between those parts, the harder it is to get all the pieces back in the same order if it happens to fall apart – say because a critical part wears out, or because you inadvertently broke it. Think of the watch you took apart as a kid, or the cars we drive today.

At the huge scale of the global ecosystem, the number of parts, their diversity of function, and the number of connections between them are so enormous that it is little wonder that hitting a tipping point means big, irreversible changes. That isn’t just theory: the geological and palaeontological record is replete with evidence of past threshold crossings that changed the planet forever. One of the most famous is dinosaur extinction, which happened about sixty-six million years ago. In that case, the global ecosystem was almost literally pushed past a critical threshold by an asteroid slamming into it, with cascading impacts throughout the planet. For tens of millions of years prior to that, the Earth had maintained a supersized version of the food chain, where Tyrannosaurus rex and its cousins hunted prey that in some cases stood as high as a two-storey house and weighed thirteen tons or so. In the course of what may have amounted to a bad weekend, all that was over, and the new state of the world was one where puny mammals, and eventually us, began to rule the Earth.