evidence: In 2013, research published in the journal Science analyzed even earlier temperatures, dating back 11,000 years. The conclusion was the same: our planet has warmed faster in the past century than at any time since the end of the last ice age. The study also revealed that for the last 2,000 years Earth has actually been in a natural cooling period in terms of its position relative to the sun. But this natural cooling has gone unregistered due to unprecedented warming caused by human emissions of greenhouse gases, the paper explains.