Extract II from 'Ten Billion' by Stephen Emmott

Our emissions of CO₂ modify our atmosphere. Our increasing water use had started to modify our hydrosphere. Rising atmospheric and sea-surface temperature had started to modify the cryosphere, most notably in the unexpected shrinking of the Arctic and Greenland ice sheets. Our increasing use of land, for agriculture, cities, roads, mining – as well as all the pollution we were creating – had started to modify our biosphere. Or, to put it another way: we had started to change our climate.

There are now more than 7 billion of us on Earth. As our numbers continue to grow, we continue to increase our need for far more water, far more food, far more land, far more transport and far more energy. As a result, we are accelerating the rate at which we're changing our climate. In fact, our activities are not only completely interconnected with but now also interact with, the complex system we live on: Earth. It is important to understand how all this is connected.

Let's take one important, yet little known, aspect of increasing water use: "hidden water". Hidden water is water used to produce things we consume but typically do not think of as containing water. Such things include chicken, beef, cotton, cars, chocolate and mobile phones. For example: it takes around 3,000 litres of water to produce a burger. In 2012 around five billion burgers were consumed in the UK alone. That's 15 trillion litres of water – on burgers. Just in the UK. Something like 14 billion burgers were consumed in the United States in 2012. That's around 42 trillion litres of water. To produce burgers in the US. In one year. It takes around 9,000 litres of water to produce a chicken. In the UK alone we consumed around one billion chickens in 2012. It takes around 27,000 litres of water to produce one kilogram of chocolate. That's roughly 2,700 litres of water per bar of chocolate. This should surely be something to think about while you're curled up on the sofa eating it in your pyjamas.

But I have bad news about pyjamas. Because I'm afraid your cotton pyjamas take 9,000 litres of water to produce. And it takes 100 litres of water to produce a cup of coffee. And that's before any water has actually been added to your coffee. We probably drank about 20 billion cups of coffee last year in the UK. And – irony of ironies – it takes something like four litres of water to produce a one-litre plastic bottle of water. Last year, in the UK alone, we bought, drank and threw away nine  billion plastic water bottles. That is 36 billion litres of water, used completely unnecessarily. Water wasted to produce bottles – for water. And it takes around 72,000 litres of water to produce one of the 'chips' that typically powers your laptop, Sat Nav, phone, iPad and your car. There were over two billion such chips produced in 2012. That is at least 145 trillion litres of water. On semiconductor chips. In short, we're consuming water, like food, at a rate that is completely unsustainable.

Demand for land for food is going to double – at least – by 2050, and triple – at least – by the end of this century. This means that pressure to clear many of the world's remaining tropical rainforests for human use is going to intensify every decade, because this is predominantly the only available land that is left for expanding agriculture at scale. Unless Siberia thaws out before we finish deforestation. By 2050, 1bn hectares of land is likely to be cleared to meet rising food demands from a growing population. This is an area greater than the US. And accompanying this will be three gigatons per year extra CO₂ emissions. If Siberia does thaw out before we finish our deforestation, it would result in a vast amount of new land being available for agriculture, as well as opening up a very rich source of minerals, metals, oil and gas. In the process this would almost certainly completely change global geopolitics. Siberia thawing would turn Russia into a remarkable economic and political force this century because of its newly uncovered mineral, agricultural and energy resources. It would also inevitably be accompanied by vast stores of methane – currently sealed under the Siberian permafrost tundra – being released, greatly accelerating our climate problem even further.

Meanwhile, another 3 billion people are going to need somewhere to live. By 2050, 70% of us are going to be living in cities. This century will see the rapid expansion of cities, as well as the emergence of entirely new cities that do not yet exist. It's worth mentioning that of the 19 Brazilian cities that have doubled in population in the past decade, 10 are in the Amazon. All this is going to use yet more land.

We currently have no known means of being able to feed 10 billion of us at our current rate of consumption and with our current agricultural system. Indeed, simply to feed ourselves in the next 40 years, we will need to produce more food than the entire agricultural output of the past 10,000 years combined. Yet food productivity is set to decline, possibly very sharply, over the coming decades due to: climate change; soil degradation and desertification – both of which are increasing rapidly in many parts of the world; and water stress. By the end of this century, large parts of the planet will not have any usable water.

At the same time, the global shipping and airline sectors are projected to continue to expand rapidly every year, transporting more of us, and more of the stuff we want to consume, around the planet year on year. That is going to cause enormous problems for us in terms of more CO₂ emissions, more black carbon, and more pollution from mining and processing to make all this stuff.