Addressing the impact of aviation on climate change through the use of biofuels is not the solution because of the scale of the industry and the shortage of arable land for growing the necessary crops, says Greenpeace chief scientist Doug Parr (pictured)
Biofuels sound like a great idea - we can grow our fuel. All that carbon dioxide that goes into the atmosphere when we burn the fuel is sucked back in when the plants are growing again. Unfortunately it's not that simple.
First, there's food - these crops need to be grown somewhere. There's a finite amount of arable land on the planet and virtually all of it is already being used to feed the six billion plus population. Relying on crops for our fuel supplies will set up a competition for food between cars and people. The Worldwatch Institute has estimated that the amount of grain needed to make enough biofuel to generate one tank full for an SUV is the same as that needed to feed a person for a year. This is one of the reasons why the growth in the popularity of biofuels is causing increasing concern among international development groups such as Oxfam and CAFOD.
Rising crop prices
Secondly, are they really that good on climate change? Aviation requires a replacement for the current aviation fuel, kerosene. The biofuels for this need to come from crops that produce vegetable oil, such as palm oil. With prices for crops rising, partly because of biofuel demand, the temptation to open up new areas of land for crops is very high. For example, in Indonesia vast areas that were once virgin forest are being replanted with palms. The oil from palm goes into a multitude of supermarket products and, increasingly, biofuels. The consequence of opening up virgin rainforest to cultivate biofuels is an enormous loss of precious species and also huge emissions of greenhouse gases. So instead of helping the fight against climate change, biofuels will in fact make the situation worse.
Thirdly, it's very complicated to predict the impacts of biofuels because it's difficult to tell the "good" biofuels from the "bad". For example, even though the majority of palm still goes into cosmetics and food, it is widely understood that the doubling of imports of palm oil into Europe between 2000 and 2006 was to replace locally sourced rape seed oil that was being used as biofuel instead of for food.
Recent research illustrates these effects, showing that over 30 years a major US biofuel programme that involves extracting ethanol from corn will actually double greenhouse gas emissions compared to the "calculated" saving of 20% when not looking at these knock-on effects. We would be better off burning plain old petrol, diesel and kerosene.
Virgin Atlantic's use of relatively obscure crops like coconut oil in its recent trial, in which it operated a Boeing 747-400 flight from London Heathrow to Amsterdam Schiphol with one of its four General Electric CF6 engines running on a 20% mix of biofuel, does not change this basic problem.
Tackling aviation emissions cannot be done through the use of biofuels because of the scale of the industry, the land required and the knock-on effects it would have. Stopping the seemingly relentless growth of flights and airport capacity at present seems the only viable option. This might not suit the aviation industry but ultimately it is in all our interests.
Air travel is the world's fastest growing source of greenhouse gases including carbon dioxide, which cause climate change. Globally the world's 16,000 commercial jet aircraft generate more than 700 million tonnes of carbon dioxide per year. Indeed aviation generates nearly as much CO2 annually as that resulting from all human activities in Africa. The United Nation's Intergovernmental Panel on Climate Change, a widely-respected international group of scientists, estimates that aviation is responsible for 3.5% of climate change. But for industrialised nations - who will have to lead the fight against climate change - the proportion is much greater. For example, the UK government estimates that aviation contributes 13% of the country's greenhouse gas emissions, and is rising fast.
The starting point for any discussion on energy, including the growing significance of aviation, now needs to be climate change. Billions of people are likely to experience water scarcity this century because of climate change, and key "tipping points" like die-back of the Amazon or the future melting of the Greenland ice cap will depend upon whether or not we are able to reduce our greenhouse emissions rapidly. Crossing such tipping points would lead to huge changes in human society and function including large-scale migration, insecurity and, almost inevitably, conflict. This is, no doubt, why climate change has been referred to as a greater threat than terrorism, and it shows the importance of taking urgent action.