Perhaps no other place on Earth plays a more crucial role in sustaining life as we know it than the Amazon rainforest, the largest in the world. The Amazon spans nine countries in South America including Ecuador, where this pristine ecoregion is protected by the Yasuní National Park, shown here. Today is set aside as World Rainforest Day, to remember the vital role of this and other rainforests and to champion efforts to protect them. The world"s rainforests are under threat like never before from deforestation driven by agriculture and cattle ranching. Some studies indicate that humans have degraded or destroyed more than half of the world"s rainforests. Fewer trees means warmer temperatures, which increases the risk of drought and wildfire and compounds the damage of deforestation.