Tipping Point for Planet Earth explains why Earth is headed for a tipping point, a change so fast, dramatic, and unexpected that humanity will reel at the consequences. Midway through this century, there will be more than nine billion people on the planet. Already we are using most of the arable land that exists and overfishing the oceans. Water, too, is becoming scarce in many places. The services that humans depend upon--like a supply of clean water, food production, and protection from disease--are subject to dangerous threats as well. We can still keep humanity moving forward by ensuring that the negative changes that are accumulating do not outweigh the positive ones. Tipping Point for Planet Earth offers sensible solutions to our most pressing problems. The grand challenge of the 21st century is to change the endgame from one that looks like a train wreck, to one that sees the train carrying us all into a bright future.