Using crops such as corn for biofuel doesn't cut carbon emissions and increases the price of food such as corn.
Credit: iStockphoto
It's no coincidence that our atmosphere happens to have the right amount of oxygen, nitrogen and carbon dioxide for us to survive in: we, and all the living things on Earth, evolved jointly with the geological development of the planet.
Humanity has, however, now reached the point where we, as a single species, are having a dramatic impact on those ecosystems. We are using resources, including food, much faster than natural processes can replenish them, and - I fear - faster than we can find alternatives for them. This is the biggest challenge that our civilisation has had to face up to, and as a global species, doing things the way we've always done them is no longer an option.
Let me take you back to central China around 1400 during the Han Dynasty. The area that the Han came from - Loess Plateau - was originally a verdant area with high rainfall and what is now the Yellow River supplying it. Because of the Han's success, but also their lack of understanding of good agricultural practices, they soon over-farmed this area and the soil began to wash away.
Even today, the Yellow River still has desert sand blowing into it and blocking it - there are even places where you can walk across the river, and it's like walking over a mattress.
After realising that the Loess Plateau could no longer provide food for his people, the Chinese Emperor had the luxury of moving the population East to what is now Beijing, and starting a new economy.
Humans have often done this in the past. But today, if we destroy a piece of the planet, there's nowhere else for us to move. We have, in effect, ploughed the last furrow and become a global population.
Our challenge last century was to improve human wellbeing and we did that extraordinarily well. The enormous advantages that arose from science, medicine, agriculture and technology in the 20th century allowed the human lifespan to double. We entered the century with 1.5 billion people and left with six billion.
Now, our challenge is to manage a single planet with a population that, if you take the median projection forward, will be eight billion by 2030 and nine billion by 2050. We need to start planning for these eight billion people, because even with our current six billion, our resources are being depleted at a remarkably rapid rate. And there is a carousel of challenges on the way, which will probably hit us all at once: food and water shortages being two significant ones.
There are several major areas of the planet today where water is being mined faster than it is being replenished.
Take South Australia or the state of Victoria: water aquifers have been mined far faster than rainfall can replenish them. Victoria has now faced eight successive years of drought. Further water shortages and even desertification is likely to occur in these areas over the next few decades as a result of climate change, while other regions face more frequent flooding.
Desalination has been suggested as one solution to water shortages. But desalination is energy intensive and in Australia the process is powered by burning coal, which puts more carbon dioxide into the atmosphere and furthers the carbon problem.
