Global Warming - Natural vs. Manmade Causes Compared By NASA | Video

When you compare possible natural causes (orbital, solar and volcanic activity) over the course of the last 100+ years, to manmade causes (aerosols, deforestation and greenhouses gases), the winner is clear. Greenhouse gases directly correlate to an increase in Earth temperature. 

Climate Change Is 'Single Biggest Risk' to Global Economy

credit : NASA/GSFC GISS