Tens of millions of people in southern and eastern Africa are facing emergency food insecurity partly caused by climate change – with half of them children, according to the charity Save the Children. The area has been hit by extreme cyclones, flooding and drought in recent months - and scientists warn the region is warming much faster than other parts of the world. As Henry Ridgwell reports, aid agencies are calling on world leaders meeting at the climate conference in Madrid to commit to bigger cuts in greenhouse gases.