WASHINGTON The planet's temperature has climbed to levels not seen in thousands of years, warming that has begun to affect plants and animals, researchers report in Tuesday's issue of Proceedings of the National Academy of Sciences.
The Earth has been warming at a rate of 0.36 degree Fahrenheit per decade for the last 30 years, according to the research team led by James Hansen of NASA's Goddard Institute for Space Studies in New York.
That brings the overall temperature to the warmest in the current interglacial period, which began about 12,000 years ago.
The researchers noted that a report in the journal Nature found that 1,700 plant, animal and insect species moved poleward at an average rate of about 4 miles per decade in the last half of the 20th century.
The warming has been stronger in the far north, where melting ice and snow expose darker land and rocks beneath allowing more warmth from the sun to be absorbed, and more over land than water.