The aim of the "hunger summit" to be hosted by David Cameron tomorrow is a laudable one: bringing together heads of state, charities and athletes – including Somalia-born gold medal winner Mo Farah – to talk about the problem of malnutrition in the developing world.

There is certainly much to discuss. An appalling 170 million children across the world are malnourished: some will die; those that live will not reach their full physical or mental potential. The contrast with the soaring human capability on display at London 2012 is stark.

But it is not only the Olympics that will help to focus minds this weekend. Severe droughts in the US have sent global prices for commodities such as wheat, corn and soybeans spiralling dangerously high. The situation may not yet be as bad as in 2008, when the last price spike led to rioting from Somalia to Bangladesh to Haiti, but with as many as 53 million people already facing food shortages worldwide, the situation is rapidly becoming critical.

There is much to be done: more food aid, more micronutrient supplements and better healthcare for the hungry would all help, as would a boost to broader initiatives such as education programmes. But the solution is not just about aid. Soaring global prices must also be tackled globally. Since the last crisis, however, there has been limited progress.

One of the trickiest issues is biofuels. Oxfam says all subsidies should be ended forthwith, and the UN has this week called for Washington to suspend the ethanol targets that siphon off 40 per cent of US corn. But with the corn lobby gearing up for a fight and Barack Obama facing an election, the debate is no more easily resolved now than when it first surfaced in 2008.

Questions as to how far futures markets exacerbate price gyrations are also yet to be satisfactorily answered. And the world continues to rely overwhelmingly on a few "breadbaskets" – such as the US – leaving supplies vulnerable to both local weather and to the panic-struck export bans that added to the crisis last time around.

There are, of course, no easy answers. But we are facing the third food crisis in five years. As the world population continues to rise, and climate change continues to disrupt weather patterns, the problem is not going to resolve itself. Mr Cameron is right to try to create some momentum on the issue, ahead of Britain's presidency of the G8 next year. But it is only the most modest beginning to tackling a truly global challenge.