Almost 10% of the 8 billion people on earth are already undernourished with 3 billion lacking healthy diets, and the land and water resources farmers rely on stressed to “a breaking point.” And by 2050 there will be 2 billion more mouths to feed, warns a new report from the United Nations Food and Agriculture Organization (FAO).

For now, farmers have been able to boost agricultural productivity by irrigating more land and applying heavier doses of fertilizer and pesticides. But the report says these practices are not sustainable: They have eroded and degraded soil while polluting and depleting water supplies and shrinking the world’s forests.