Extract III from 'Ten Billion' by Stephen Emmott

But think about this. In transporting us and our stuff all over the planet, we are also creating a highly efficient network for the global spread of potentially catastrophic diseases. There was a global pandemic just 95 years ago – the Spanish flu pandemic, which is now estimated to have killed up to 100 million people. And that's before one of our more questionable innovations – the budget airline – was invented. The combination of millions of people travelling around the world every day, plus millions more people living in extremely close proximity to pigs and poultry – often in the same room, making a new virus jumping the species barrier more likely – means we are increasing, significantly, the probability of a new global pandemic. So no wonder then that epidemiologists increasingly agree that a new global pandemic is now a matter of "when" not "if".

We are going to have to triple – at least – energy production by the end of this century to meet expected demand. To meet that demand, we will need to build, roughly speaking, something like: 1,800 of the world's largest dams, or 23,000 nuclear power stations, 14m wind turbines, 36bn solar panels, or just keep going with predominantly oil, coal and gas – and build the 36,000 new power stations that means we will need.Our existing oil, coal and gas reserves alone are worth trillions of dollars. Are governments and the world's major oil, coal and gas companies – some of the most influential corporations on Earth – really going to decide to leave the money in the ground, as demand for energy increases relentlessly? I doubt it.

Meanwhile the emerging climate problem is on an entirely different scale. The problem is that we may well be heading towards a number of critical "tipping points" in the global climate system. There is a politically agreed global target – driven by the Intergovernmental Panel on Climate Change (IPCC) – to limit the global average temperature rise to 2C. The rationale for this target is that a rise above 2C carries a significant risk of catastrophic climate change that would almost certainly lead to irreversible planetary "tipping points", caused by events such as the melting of the Greenland ice shelf, the release of frozen methane deposits from Arctic tundra, or dieback of the Amazon. In fact, the first two are happening now – at below the 2C threshold.

As for the third, we're not waiting for climate change to do this: we're doing it right now through deforestation. And recent research shows that we look certain to be heading for a larger rise in global average temperatures than 2C – a far larger rise. It is now very likely that we are looking at a future global average rise of 4C – and we can't rule out a rise of 6C. This will be absolutely catastrophic. It will lead to runaway climate change, capable of tipping the planet into an entirely different state, rapidly. Earth will become a hellhole. In the decades along the way, we will witness unprecedented extremes in weather, fires, floods, heatwaves, loss of crops and forests, water stress and catastrophic sea-level rises. Large parts of Africa will become permanent disaster areas. The Amazon could be turned into savannah or even desert. And the entire agricultural system will be faced with an unprecedented threat.

More "fortunate" countries, such as the UK, the US and most of Europe, may well look like something approaching militarised countries, with heavily defended border controls designed to prevent millions of people from entering, people who are on the move because their own country is no longer habitable, or has insufficient water or food, or is experiencing conflict over increasingly scarce resources. These people will be "climate migrants". The term "climate migrants" is one we will increasingly have to get used to. Indeed, anyone who thinks that the emerging global state of affairs does not have great potential for civil and international conflict is deluding themselves. It is no coincidence that almost every scientific conference that I go to about climate change now has a new type of attendee: the military.

Every which way you look at it, a planet of 10 billion looks like a nightmare. What, then, are our options?

The only solution left to us is to change our behaviour, radically and globally, on every level. In short, we urgently need to consume less. A lot less. Radically less. And we need to conserve more. A lot more. To accomplish such a radical change in behaviour would also need radical government action. But as far as this kind of change is concerned, politicians are currently part of the problem, not part of the solution, because the decisions that need to be taken to implement significant behaviour change inevitably make politicians very unpopular – as they are all too aware.