SIR – This week the world has once again gathered in Rio de Janeiro to discuss how we can all continue to develop and prosper while protecting the planet.

In 1992, at the Rio ‘Earth Summit,’ leaders set the world on track for sustainability, uniting development and environment efforts. They agreed to pursue sustainable development.

Now, 20 years later, 18 million people in the Sahel region of west and central Africa simply do not have enough to eat. Persistent droughts, rising food prices and almost nonexistent investment in agriculture are the major causes of what could turn into a catastrophe if international action is not taken.

The Rio Summit this week must not be a mere international talking shop – it must be an opportunity to take significant action and save lives and the future of the planet.

Leaders meeting at Rio +20 this week must recognise the urgency needed to overhaul the way we grow and distribute food, especially in the face of constrained natural resources like land, water and energy, and the gathering pace of climate change.

Improving access to land and investing in small holder farmers is vital if we are to produce food in a sustainable way and make sure that children, whether in Bradford or the Sahel, have enough to eat.

David Hewitt, Oxfam fundraiser, Damems Lane, Keighley