The reason? It wasn’t just hitting a critical threshold in the climate system. It was hitting that climate threshold at the same time that Homo sapiens expanded their populations, colonised the world, and began to hunt and to compete with other large-bodied species. Where climate change hit in places where humans had not arrived there were sometimes a few extinctions, but nothing too major. Where humans arrived on a continent before climate change hit – for example in Australia fifty thousand years ago – they caused more extinctions than happened with climate change alone, but those extinctions were spread out over several thousand years. But where human arrival and climate change hit at the same time – as in the Americas – the number of extinctions was multiplied many times over what you’d expect by simply adding up the anticipated effects of a few extinctions by climate change, plus a few more by human impacts. It is this multiplying effect that may be the big issue if we exceed several thresholds simultaneously, or if exceeding a threshold in one part of the global ecosystem causes a domino effect of exceeding thresholds in other interacting parts of the system. Unfortunately, those simultaneous threshold crossings are all too plausible from a complex systems point of view, because the individual systems of our world – human population growth and consumption, climate change, environmental contamination, and so on – are so interconnected.
Just how close are we to hitting those thresholds on the various fronts? Very close indeed. It’s already happening in certain regions of the world – that machete fight in Nepal, and the lack of basic natural resources that caused it, is just one tiny indication. Substitute guns for machetes, and all of a sudden you have a world that is not too different from that portrayed in 1981’s The Road Warrior, the second of the Mad Max movies, in which a leather-clad Mel Gibson defends one of the last remaining supplies of oil in the outback of Australia with his mute sidekick, the perpetually dirt-smudged ‘Feral Kid’. In March 2013 in Egypt, at least briefly, that became reality, as reported by David Kirkpatrick in the New York Times: ‘Qalyubeya, Egypt – A fuel shortage has helped send food prices soaring. Electricity is blacking out even before the summer. And gas-line gunfights have killed at least five people and wounded dozens over the past two weeks’ (30 March 2013). And in developed nations like the United States and the United Kingdom, there are people who are so worried about something similar happening that they have been laying in stockpiles of guns, ammunition, food, and whatever else they think it will take to ensure the survival of themselves and their families if the worst should come to pass. A perusing of survivalist (or ‘prepper’) websites shows just how seriously these people take the threat of disaster, spending millions of dollars on be-prepared merchandise, setting up specialist dating websites and developing products like filters that can make urine taste like bottled water and the $449 ‘Centurian children’s tactical vest’.
What the preppers are worried about are the things we are all reading in the news, realities that are pointing in the direction of crossing dangerous environmental thresholds, which would lead to huge societal problems, if not outright collapse. Climate change has already begun to ramp up storms so much that in 2005 the sea swallowed New Orleans. Waterfalls poured into the tunnels of New York City’s subway system in 2012. Massive droughts sparked crop losses and wildfires over huge areas of the United States and Australia in 2012 and 2013. Shortages of things we once took for granted are now becoming commonplace, to the extent that even big business is getting worried. Coca-Cola, for example, cited water availability as one of the key challenges to its continued success in its 2010 report to the Securities and Exchange Commission. Environmental contaminants are so rampant that fish are growing two heads in some places, and that’s just from the obvious pollutants. Sneaking in under the radar are things like hormones (such as endocrine disruptors), which we have unwittingly been spreading everywhere, recently implicated in causing such things as children hitting puberty earlier, increased heart disease, obesity and type II diabetes. Even small-scale oil and chemical spills, such as those occurring regularly in the North Sea, can dramatically impact local marine diversity. And global mercury levels in the ocean surface have tripled since Industrial Revolution levels, trickling into our seafood, which when eaten can result in developmental disorders in children.
Just how close we may be to a global tipping point becomes apparent when you take a helicopter view and see what is happening at the scale of the entire planet. The statistics look pretty stark. The deforestation that caused that machete fight in Nepal is all too common worldwide – as has already been noted, more than 40 per cent of the world’s forests have been cut down, and we’re continuing to clear-cut an area about the size of Greece every year. Nearly 50 per cent of all of Earth’s land has been paved, bulldozed, dammed or turned into agricultural fields and pasturelands. That means we humans have caused more sledgehammer, chainsaw-style change on Earth than took place at the last global tipping point, when only about 30 per cent of the planet’s surface was totally transformed, back then by retreating glaciers. We’ve used almost all the arable land that exists for agriculture, and we’ve fished 90 per cent of the big fish out of the sea.
If those obvious transformations aren’t enough, we also have to add tremendous amounts of energy into the global ecosystem to keep society operating at its present level, and the way we have traditionally done that, by burning fossil fuels (the stored remnants of previous life on the planet), is beginning to bite us from behind, by raising Earth’s temperature abnormally. If we keep going at the rate we have been, it will become hotter in the next six decades than it has been for some fifteen million years. The increase in temperature will be so fast that many of Earth’s species won’t be able to keep up, and in some places where lots of people currently live it will be too hot for any mammal – including us – to survive outside. That, of course, presumes that we don’t run out of the easily obtainable oil first, which would escalate what happened in Egypt in 2013 by increasing energy prices across the world. Of course there are alternative sources of energy, but the world hasn’t been pursuing them too actively.
You get the message – there’s lots of global change under way. The underlying driver of it all is that there are just so many people now, all needing their slice of the pie. And we keep on coming. As of 2014 we were adding eighty-two million people per year. That is three orders of magnitude higher than the average yearly growth from ten thousand years to four hundred years ago (which averaged sixty-seven thousand people per year). Most of the population growth has been in the last century, over which time the number of humans has nearly quadrupled. Just since 1950, we’ve increased our numbers almost threefold, and since 1969, we’ve doubled ourselves. The problem is that each of us requires our own portion of air to breathe, a place to live that is comfortable and dry, enough water to drink and food to eat, and myriad ways to amuse ourselves. And we produce a lot of waste – waste from our bodies, waste from our structures and vehicles, waste from our fun.
As a result, each of us ends up requiring a lot of ‘stuff’ – the average American, for example, uses up about ninety kilograms of things each day. Some people, particularly those in developed countries, use more stuff than others, to be sure, but nevertheless, every one of us has needs and wants that we attempt to meet by tapping into the global ecosystem, which means that each of us leaves a usage footprint – in truth, an environmental footprint – that is much bigger than the actual footprint we leave in the sand. The average size of each individual’s environmental footprint is truly staggering. For instance, it takes (on average) about 1.7 acres of land per person per year to sustain us in the manner to which we’ve become accustomed. The ‘average’ person uses about 4.6 barrels of oil per year (although the figure varies enormously: if you live in Singapore, you use eighty-one barrels; in the US or the Netherlands, twenty-two barrels; in China, three barrels; in Nepal or Bangladesh, about a fifth of a barrel). The average American’s water footprint is about 665,000 gallons per year – enough to fill an Olympic-size swimming pool. Multiply such numbers by the over seven billion people now in the world, and you begin to see the magnitude of the problems.
Then take into account that the population is continuing to grow, albeit at slower rates than in the last fifty years. Even conservative demographic