Gum arabic, golden blobs of resin tapped from thorny acacia trees, is an emulsifying agent virtually irreplaceable for global industry. The ingredient is used in everything from soft drinks to chewing gum and pharmaceuticals.

Sudan, in northeastern Africa, is among the countries hardest hit by climate change but is also the world's largest producer of the raw gum.

"It's an important tree to fight desertification as it is drought resistant—and also increases the soil fertility, essential to increasing crop production," said Fatma Ramly, coordinator of the Gum Arabic Farmers' Association, which counts seven million members.

To harvest the amber-coloured resin, farmers must suffer the same climatic extremes as their trees.

"We work for hours on end under a burning sun," said Mohammed Moussa, who collects resin at the state-owned Demokaya research forest, about 30 kilometres (20 miles) from the North Kordofan state capital, El Obeid.

Moussa faces a constant struggle with the shortage of water in largely desert Sudan. His earnings from the trees barely "provide enough money to buy water to cover us until the autumn" rainy season.

'Laborious'

Recorded temperatures in Sudan's Kordofan region have increased by almost two degrees Celsius in less than three decades, more than double the global average, according to the UN Food and Agriculture Organization (FAO).