Guardian: The US south-west, a region that is experiencing one of the fastest rates of population growth, faces dramatic challenges in the next 50 years from drought, wildfires and changing ecosystems caused by global warming, a report from the Bush administration warns. The paper, commissioned by the US department of agriculture, looks at the likely impact of rising temperatures caused by higher emissions of CO2 during the next 25 to 50 years on America’s agriculture, land and water resources …