Rio+20 is a chance to secure our children's future Over the last decade the Chinese and Indian economies have doubled in size, and markets are booming across Asia, Latin America and Africa. The rise of so-called middle-income countries means that a majority of the world's poor no longer live in the world's poorest countries, and nearly half of the world's children are now living in towns or cities. These shifts will be mirrored in the Rio negotiations as the middle-income BRIC countries of Brazil, Russia, India and China exert their growing influence. The "developing world" will have its strongest voice ever, at an international conference that could set the path for global development over the next two decades. The timing of Rio+20 is particularly important as it comes as discussions, co-chaired by David Cameron, start about how to replace the Millenium Development Goals (MDGs). Reducing the risks of natural disasters was not explicitly referenced in the MDGs. However, a combination of climate change, rapid urbanisation and volatile food prices has lead to an increase in the frequency and intensity of natural disasters. There is an urgent need to invest in helping people adapt to their changing world and the new risks it brings. Right now an estimated 18 million people in the Sahel region of west Africa are being affected by drought, disease and conflict. In 2011 alone UNICEF, the world's leading children's organisation, responded to 292 humanitarian emergencies in 80 countries. Children are always the most vulnerable in such situations, typically representing over 50 per cent of those affected by disasters, equating to between 100 and 175 million children each year. This is why helping children to cope with, and avoid being harmed by, disasters must be central to discussions at Rio. How can we create a sustainable future for our planet without first prioritising their protection and development? It will be children and our children's children who will face the consequences of decisions made this week. Their generation will be the ones attending Rio+40, Rio+60 and Rio+80. Last month I met with Ellen Johnson Sirleaf, Africa's first female president, in Monrovia. She talked to me about how investing in her country's children is the best guarantee for Liberia's future and how she and has fought to ensure a child-centred approach in all her government's policy. While I was there President Sirleaf signed a new comprehensive children's law enshrining the principles of the Convention on the Rights of the Child in national law. This week President Sirleaf will be at Rio with Nick Clegg. She will also be working closely with David Cameron as they co-chair the panel responsible for creating the new set of development goals to replace the Millennium Development Goals which expire in 2015. In her autobiography President Sirleaf writes: "If your dreams do not scare you, they are not big enough." If Rio+20 is to steer us on a path of co-operation rather than conflict and a sustainable future for our children it is vital that David Cameron, Nick Clegg and other world leaders are not afraid to dream. Lord Ashdown is a Liberal Democrat peer and president of Unicef UK