Sea level rise: Scientists uncover worrisome signals
The findings in the journal Science show that ocean surface temperatures during the Earth's last warm period, some 125,000 years ago, were remarkably similar to today.
But what concerns scientists is that sea level back then was 20-30 feet (six to nine meters) above what it is today.
"The trend is worrisome," said the report led by researchers at Oregon State University, University College Dublin, the University of Wisconsin and the Science Museum of Virginia.
"Collectively, these results may help scientists better understand how oceans will respond to modern warming."
Our planet goes through periods of warm and cold that last tens of thousands of years, and are influenced by changes in Sun exposure caused by natural variations in the Earth's orbit, combined with the influence of greenhouse gases in the atmosphere.
These naturally occurring shifts are different than the much faster pace of warming facing the Earth today, as humans burn fossil fuels for energy and send heat-trapping carbon emissions into the air, leading to ice melt and sea level rise.
The last time the climate was unusually warm -- in the absence of human influence -- was about between 116,000 and 129,000 years ago, during what is known as the Last Interglacial Period.