So the end is in sight. Another world summit spectacularly fails to agree anything of real significance for most of the people living on the planet. Yesterday, a billion people went to bed hungry; tomorrow, that number will almost certainly grow. More than just a terrible waste of time, Rio+20 has been a scandal.

Billed as the second earth summit, Rio+20 is about to be wrapped up. The pre-cooked outcome document - ready from day one - is being signed off as I write by a collection of leaders and deputy leaders. Collectively, they and their officials have had the privilege of ensuring that there is almost nothing in the text that moves the world forward, nothing that will make tomorrow's world a better place for people to live in.

After innumerable hours and days and months of meetings and discussions and negotiations, almost every commentator is agreed: Rio+20 is a wash out. With the developed world so far unwilling to make real new commitments, so the developing world has also refused to dance along to the 'green economy' tune that the North has been playing. While Rome is burning, there's not even a fiddle in sight. All we get is -in Nick Clegg's own words - an 'insipid' text drawn up by civil servants, and rubber stamped by world leaders.

Is this a surprise? Not really. Rio+20 has been hard work from the beginning. World leaders, including Obama, Merkel and our own David Cameron (despite the Summit being rescheduled to fit around the Queen's Jubilee) were absent from the attendance list. In the end, while the Deputy PM and Secretary of State Spelman were there, even the Secretary for State for International Development didn't invest in a plane ticket.

The first Earth Summit created a mountain of hope as even the US president joined others setting out an ambitious agenda for change. This second Summit - twenty years later - will have the opposite effect, leaving only mounting frustration.

But let's not lay all the blame on Rio+20 either. It is just one of a series of summits, that have failed to tackle the real issues, with this week's G20 barely even mentioning in their communique, the need to tackle the causes of food insecurity - most critically, biofuels. Avoiding Eurozone meltdown is undoubtedly important, but isn't it also a good excuse to turn a blind eye to problems facing the poorest people now? The question in everyone's minds now is: what will it take to get our leaders to focus on real issues that actually affect people's lives?

All eyes now turn to David Cameron's Olympics 'Hunger Summit'. After several summit false starts, we can but hope that the Hunger Summit will truly mark the beginning of a process to tackle the causes of the world's food crisis.

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