How Much Human Activity Can Earth Handle?

The scientific name is the Holocene Age, but climatologists like to call our current climatic phase the Long Summer. The history of Earth's climate has rarely been smooth. From the moment life began on the planet billions of years ago, the climate has swung drastically and often abruptly from one state to another — from tropical swamp to frozen ice age. Over the past 10,000 years, however, the climate has remained remarkably stable by historical standards: not too warm and not too cold, or Goldilocks weather. That stability has allowed Homo sapiens, numbering perhaps just a few million at the dawn of the Holocene, to thrive; farming has taken hold and civilizations have arisen. Without the Long Summer, ... http://www.time.com/time/health/article/0,8599,1925718,00.html