Study: Recent sea level rise is highest in 6,000 years

Melting glacial ice and ice sheets have driven seas to levels unmatched in the past 6,000 years, says a study out this week in the Proceedings of the National Academy of Sciences.

Researchers studied examples of past sediments in Australia and Asia that dated back 35,000 years and found that overall, the planet's sea level was fairly stable for most of the past 6,000 years.

Things began to go haywire about 150 years ago, the same time humanity began to pump greenhouse gases into the atmosphere by burning fossil fuels.

"There's something going on today that wasn't going on before," said Kurt Lambeck of the Australian National University, who was lead author of the study, in an interview with the Australia Broadcasting Corp. He said the sea level rise is affected by increasing temperatures.

As the Earth's temperature warms, so do the seas. Heat-trapping greenhouse gases cause more land ice (glaciers and ice sheets) to melt and water to expand.

Lambeck told the Guardian that the sea level increase of the past 100 years is "beyond dispute."

Sea level has risen nearly 8 inches worldwide since 1880, but it doesn't rise at the same level. In the past century or so, it has climbed about a foot or more in some U.S. cities such as Charleston, Norfolk and Galveston because of the added influence of ocean currents and land subsidence.

Global sea level will rise 1 to 3 feet around the world by the end of this century, according to this year's Fifth Assessment Report by the United Nations' Intergovernmental Panel on Climate Change.

Contributing: Wendy Koch, USA TODAY