redOrbit: The Earth’s forests serve as crucial carbon sinks due to their ability to absorb greenhouse gases, but that ability is “at risk of being lost entirely”, according to a new United Nations report. Currently, the Earth’s forests soak up about 25 percent of greenhouse gas emissions, but that capability could be reversed if the Earth heats up 2.5 degrees Celsius (4.5 degrees F) more. A rise in temperature could cause severe droughts and heat waves that would kill off many of the …