Study: Global warming worst in 1,200 years

WASHINGTON, Feb. 9 (UPI) -- Warm temperatures around the world are higher than in any period over the last 1,200 years, a study published in the journal Science on Thursday shows.

A research team from the University of East Anglia in Britain measured changes in tree rings, fossil shells, ice cores and temperature records, including people's diaries from 750 years ago. Their findings linked a warming of the climate with human activity.

Their study showed significant warmth in the Northern Hemisphere from 890-1170 A.D. and colder periods from 1580-1850.

The present warm phase is longest temperature anomaly since the 9th century, it said.