As Ice Sheets Melt Faster, Sea Level Rise Is Accelerating Every Year

Increased surface melting of the Greenland ice sheet has created vast networks of streams and rivers on top of the ice to carry meltwater to the ocean

Increased surface melting of the Greenland ice sheet has created vast networks of streams and rivers on top of the ice to carry meltwater to the ocean

Scientists had previously estimated that global sea levels were increasing at a steady 3 millimeters (0.1 inches) per year.

The study, by USA scientists, has calculated the rate of global mean sea level rise is not just going up at a steady rate of 3mm a year, but has been increasing by an additional 0.08mm a year, every year since 1993.

The result is a "climate-change-driven" acceleration: the amount the sea levels are rising because of the warming caused by manmade global warming. That accords with the latest International Panel on Climate Change report, which is based on computer models; the IPCC pegged the rise by 2100 to be to be between 20-28 inches (52-98 centimeters) by 2100.

If the trend continues, it is likely to lead to an annual average sea-level rise of at least 1cm per year by 2100.

Leaders in coastal cities from NY to Shanghai are debating how to handle rising sea waters.

'For example, the Tampa Bay area has been identified as one of ten most vulnerable areas in the world to sea level rise and the increasing rate of rise is of great concern'.

The acceleration is driven mainly by more and more of the ice in Greenland and Antarctica melting away, according to the scientists, who are warning that more data needs to be gathered to prepare for the effects of sea level rise.

"Our extrapolation assumes that sea level continues to change as it has over the last 25 years".

Analysis of first 25 years of satellite data shows rate going up by 3mm a year, plus 0.08mm a year, every year.

He also says that his models are extremely conservative, as he didn't consider any major events such as the collapse of important ice sheets or accelerating global warming.

La NINA and El NINO and (the opposing phases of the El Nino Southern Oscillation, or ENSO) influence ocean temperature and global precipitation patterns. Satellite data revealed that the acceleration stems from melting ice in Greenland and Antarctica. "In 2100, people ... would be able to go on vacation to the beach and come back 10 or 20 years later and see a difference", he said.

So Nerem and his team used climate models to account for the volcanic effects and other datasets to determine the ENSO effects, ultimately uncovering the underlying sea-level rate and acceleration over the last quarter century.

In addition to NASA's involvement in missions that make direct sea level observations from space, the agency's Earth science work includes a wide-ranging portfolio of missions, field campaigns and research that contribute to improved understanding of how global sea level is changing.

The team also used tide gauge data to assess potential errors in the altimeter estimate. "They provide the only assessments of the satellite instruments from the ground".

"This is the first satellite-based estimate of an acceleration number", Professor Nerem said. Secondly, warmer temperatures melt land ice which then flows into the ocean, adding to the increase.