Unit1-1-R2-Earth4Systems

Go to the links below to learn more about

 * the Earth's four systems or spheres, go to @http://goo.gl/kimk
 * the 4 interactions that occur between an event ( for example, forest fires) and each Earth system, go to @http://goo.gl/YzHu
 * the 8 interactions that occur among the four systems when an event occur, go to @http://goo.gl/49SI

How Global Warming Affects Polar Bear Natural Habitat??
Watch the following video to find the answer media type="youtube" key="mA3PkrZO3GI?fs=1" height="385" width="480"