Earth's Temperature At Highest Level In 12,000 Years

Earth's temperature has climbed to a level not seen for 12,000 years, warns a new study published online in Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0606291103).

The research, led by James E. Hansen, head of NASA's Goddard Institute for Space Studies, finds that the mean surface temperature of the planet has been warming at a rate of 0.2 °C per decade for the past 30 years. The global mean temperature is now within 1 °C of the maximum for the past million years, the study concludes.

"This evidence implies that we are getting close to dangerous levels of human-made pollution," Hansen says. If additional warming is kept lower than 1 °C, "the effects of global warming may be relatively manageable. But if further warming reaches 2 to 3 °C, we will likely see changes that make Earth a different planet than the one we know." The last time Earth was this warm was about 3 million years ago when sea level was about 25 meters higher than today, he explains. If CO₂ emissions are not curbed, global temperatures are likely to rise 2 to 3 °C by 2100, he warns.

Hansen collaborated with David W. Lea and Martin Medina-Elizade of the University of California, Santa Barbara, to compare recent temperatures with temperatures derived from sea sediments deposited over the past million years.

The study explains that global warming is already affecting species. Research has found that 1,700 plant and animal species are moving toward the North or South Poles at a rate of 6 km per decade, but over the past 30 years, climate zones have been moving poleward at a rate of 40 km per decade, Hansen says.