Crops have failed in several countries, with 27m people at risk of hunger according to World Food Programme

Emmanuel Himoonga paced his dry field, picking up stalks of maize that had been bleached almost to bone white.

The 61-year-old chief of Shakumbila, a mainly agricultural community of about 7,000 people roughly 70 miles west of Zambia’s capital, Lusaka, had seen droughts before.