Resumen de Human Activities and Greenhouse Gases.

• The article presents a timeline of human activities and their impact on greenhouse gases. Our human ancestors invented agriculture about 11,000 years ago--around the same time that atmospheric concentrations of methane and carbon dioxide peaked in the wake of the last ice age. The declining trends of both gases reversed direction several thousand years ago and have risen steadily ever since. The timing of keg agricultural innovations--namely, deforestation and rice irrigation--may explain these surprising reversals.