One-and-a-half-million children are in imminent danger of starvation in West Africa, according to The United Nations Children's Fund, despite recent pledges of international aid.

As world leaders gathered for the Rio+20 conference on sustainable development, aid workers warned there were only four weeks left to treat the effects of acute hunger before the rainy season makes huge swathes of the Sahel region inaccessible.

Across western Africa, communities are caught between climate change, conflict and poverty -- yet the global economic crisis means international priorities lie elsewhere.

For example, during its financial crisis Greece has received a hundred times more from the International Monetary Fund (IMF) than Niger during the last few years.

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In hospitals here in southern Niger, a crisis is developing. Many children are at serious risk of dying and for each bed there is a skeletal frame as yet another hunger crisis strikes.

Hair turned red by hunger
Patients include a girl, Amina, whose hair has turned red by a lifetime without enough food, and Ibrahim, an eight-month-old whose tiny body is consumed by the effects of severe malnutrition.

From many miles around, more young patients arrive all the time -- more work for the doctors who've rarely seen anything like this.

Women complain about a lack of rain, but also about a lack of food. Their families may not survive the coming months, they say.

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“What you’re looking at are communities across wide areas that need assistance because, despite best efforts, they have been pushed off their ability to cope,” said Martin Dawes, regional spokesman for UNICEF.

UNICEF Niger overview

Some help is here: The international response has been swifter than it has been in the past. Earlier this month, the United States pledged over $81 million in additional assistance.

But this is a crisis across many counties, affecting many millions, leaving many lives on a knife-edge – and the U.N. has already said it needs another $1.5 billion to tackle the problem.

The months ahead are crucial here, amid grim warnings about more dry weather, even an influx of locusts. The world has been warned.

Editor's note: Yahaman, the eight-month-old boy featured in our video report on the hunger crisis in Niger died late Tuesday night.

Rohit Kachroo is NBC News' Africa Correspondent. Additional editing by Alastair Jamieson, msnbc.com.

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