Izzy Braithwaite, a student at Clare College, Cambridge, writes:

I have always liked food. At my 2nd birthday party, I sang 'Happy Cake' instead of 'Happy Birthday.' And I'd agree with George Bernard Shaw that "there is no sincerer love than the love of food." But - whilst I still love food - I'm now most interested in other questions about it. How can we provide food for 7+ billion people, in a warming world, in a way that doesn't destroy what remains of wild nature or further mess up our atmosphere?

It's never possible to attribute a single event to climate change, but there's been a long-term trend of increasing frequency and severity of droughts recently. Last year, East Africa suffered the worst drought in 60 years, putting millions of lives at risk, and tens of thousands are believed to have died before aid arrived. As Amartya Sen pointed out in 1981, political and economic factors are often at least as important in famines as the food shortage itself: in Somalia it was greatly compounded by the activity of the Al-Shabaab rebel militia. Nonetheless, climate change is clearly (excuse the pun) starting to bite.

This year droughts are also affecting India and the US, which is experiencing the worst drought in decades: corn has already doubled in price. And although these changes seem to be happening even faster than predicted, we still cannot achieve a global emissions agreement. Meanwhile, funding for climate adaptation or biodiversity conservation in developing countries remain only a fraction of global spending on pet food, which totalled $80 billion in 2010.

Subsidies, short-sightedness and the biofuel boom

Global agricutural subsidies contribute indirectly both to the conversion of natural habitats, to our increasingly unhealthy diets and to agricultural greenhouse gas emissions. Half a trillion dollars is spent annually by developed countries alone subsidising food production and processing, and the US's immense corn subsidies have been linked to the widespread use of unhealthy high-fructose corn syrup, and an increase in corn-fed over grass-fed cattle (producing much more methane). And in the EU, most of the €40 billion currently spent on direct agricultural subsidies goes to larger, wealthier farms, supporting intensive livestock farming and undercutting developing countries.

It's not just on land that subsidies are a problem: the World Wildlife Foundation states that fishing subsidies create "a huge incentive to expand fishing fleets and overfish. Today's global fishing fleet is estimated to be up to two and a half times the capacity needed to sustainably fish the oceans. Even as stocks of valuable fish have shrunk, the size of the world's fishing fleets has exploded." Channelling tax money into fishing will only drive stocks nearer to the brink. Propping up a failing industry with subsidies is a bit like trying to get out of financial troubles by printing money. In the long run, it won't work.

In view of the 0.8 billion people who go to bed hungry each night and the growing ranks of cars worldwide, current biofuel policies are a terrible idea. When grown on land that was previously forest or, worse still, peatland, they don't even help to combat climate change - the carbon released by clearing peat bog to grow palm oil takes over 1500 years to offset through reduced emissions, and about 75 years for tropical forest. As former World Bank president Ian Goldin put it, biofuel policies are "economically illiterate, environmentally destructive, politically short-sighted and ideologically unsound."

Biofuels helped create the 2007-8 global food price spike and - alongside growing demand for beef, soy and palm oil - are a major reason for the conversion of tropical rainforest. The Food and Agriculture Organisation estimates that an area of primary forest approximately the size of Greece is lost per year (nearly 15000 hectares per hour). Some land is returned to forest each year, but secondary forest has much lower biodiversity and stores much less carbon than so-called 'old growth' forest. Some scientists believe that - unless we change course soon - most tropical rainforest could be gone within a decade.

Treading more lightly

It's not all up to governments of course: the food we choose to buy is probably the second most important decision we make in terms of our environmental impact, after flying. It's certainly the biggest one most of us make regularly. Agriculture accounts for 17-32% of the world's carbon footprint, including deforestation, and much of this is associated with livestock. Food miles are often discussed, but cutting back on red meat and dairy is by far the biggest thing most of us could do to reduce our 'foodprint'. A 2006 UN report concluded that cows might be more damaging to the climate than trucks and cars combined - especially with worldwide beef and dairy production expected to double by 2040. Health could also benefit: Professor Ian Roberts argues that if we had to pay more for higher-carbon food, "healthy eating (would) become the easy option."

Reducing food waste, currently estimated at around a third of all food produced globally, is a particularly easy win, simultaneously reducing land use, greenhouse gas emissions, landfill and saving money. We can also harness the potential of the internet to make more informed food choices. LandShare's 'FoodPrint' calculator lets you work out the land, water and fossil fuel required for any given diet, whilst 'Hugh's Fish Fight' is an i-Phone app with up-to-date information about sustainable fish.

A more global, science-based perspective to our food choices would be useful too: opposing GM isn't going to help prevent billions from going hungry, and organic food, however well-meaning, may just contribute to the continuing expansion of cropland. Most importantly, we need to think differently: to start thinking of meat as a luxury, to reduce food waste and put pressure on food suppliers to do the same.

Will we have to face food shortages ourselves before we start taking these problems seriously? As Franz Kafka wrote, "so long as you have food in your mouth, you have solved all questions for the time being". Admittedly, this was from the perspective of a dog. But the problems with our food system won't solve themselves: let's hope we can address them, even if we still have enough to eat now. If we don't, we may find we've sleepwalked to a much hotter, hungrier place.

Food - and its relationship to sustainability - needs to be much higher on the political agenda, and to receive much more funding for research into developing higher yielding, more climate-resilient crops. Knowledge transfer to developing countries is also essential, but a shift in diets and tackling food waste are at least as important. Our food system isn't working - for us or for the planet - and it's up to all of us to fix it.

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