The world remains torn between the politics of economic development and dire predictions of global warming if greenhouse emissions are not reined in. This dilemma was captured last weekend at China's summit with African nations in which generous no-strings economic assistance was offered to help secure the oil and other resources that China needs to fuel economic growth. It is not uncommon to read of oil and gas deals that seem to guarantee jobs and prosperity, and the next day of a climate-change scenario in which rising oceans drive populations back on an environmentally stressed Earth. The focus of the dilemma has shifted to the United Nations climate conference in Kenya, at which signatories to the Kyoto treaty on limiting greenhouse emissions will try to agree on the next steps to combat the worst effects of climate change. Warnings of global warming and climate change evoke a range of emotions from scepticism to a feeling of helplessness. Desertification does not get the same reactions. But it goes to the heart of climate change, as is evident from today's report on a smaller UN conference in Israel on desertification - or the spread of arid land. Why Israel? Because it is recognised as a leader in innovative development of dry lands. But there is another reason. In the words of an official of the UN Convention to Combat Desertification, if current climate scenarios continue, conflict in the 21st century will be over water, not oil. Indeed, China's vice-minister for water resources says the mainland looks set to use 89 per cent - if not all - of its water resources by 2030. Deserts comprise about 18 per cent of the mainland's land area, and desertified land another 4 per cent. Northwestern deserts are advancing south and east at a rate of 3,650 sq km a year. Cultivation, grazing, deforestation and irrigation, and now a severe drought consistent with climate change, have helped giant dunes advance, forcing people to move. The UN has said 400 million Chinese live in areas threatened by desertification. Unless the trend is reversed, millions of people could be on the move in coming years, looking for new homes and livelihoods. The deserts have given rise to another threat every spring across northern China, North and South Korea, Japan and sometimes even the west coast of North America - dust storms. Sand and dust carried by Siberian winds, often coated with industrial pollutants trapped in the atmosphere, are depositing grit that is causing economic damage and affecting the health of tens of millions of people. The central government must allocate greater funds to preventing desertification and ensure they are effectively used. Sharing the knowledge gained with African nations could be a precious reward to that continent for helping fuel China's economic rise.