By Gloria Dickie LONDON (Reuters) – Decades of deforestation, mining and industrial pollution have taken a toll on the planet, leaving as much as 40% of its land degraded and putting economies at risk, a U.N. report says. Nearly half of the world’s land area is now taken up by agriculture, which has seen swathes of forest cleared for livestock rangeland and crop fields. If trends continue, another 11% of the world’s land surface – about the size of South America – could be degraded by 2050, the U.N. Convention to Combat Desertification (UNCCD) said on Wednesday in its global land outlook. The …