Sea levels rise faster



Significantly, the projected sea level rise is a "conservative" estimate and may likely be higher, the researchers warn. It could be compared to driver merging onto a highway.

The rate of global sea level rise is accelerating as ice sheets in Antarctica and Greenland melt, an analysis of the first 25 years of satellite data confirms. Our extrapolation assumes that sea level continues to change in the future as it has over the last 25 years.

The report, published Monday in the journal Proceedings of the National Academy of Sciences, finds that rather than swelling at a consistent rate of 3 millimeters a year, global sea level rise is accelerating by roughly 0.08 millimeters each year and could exceed 10 millimeters a year, or more, by 2100.

"We are already seeing signs of ice sheet instability in Greenland and Antarctica, so if they experience rapid changes, then we would likely see more than 65 centimeters of sea level rise by 2100".

The result is a "climate-change-driven" acceleration: the amount the sea levels are rising because of the warming caused by manmade global warming.

Currently, over half of the observed rise is the result of "thermal expansion": As ocean water warms, it expands, and sea levels rise.

Climate change can lead to rising seas in two ways. - file picMIAMI, Feb 13 - Sea level rise is accelerating and could reach 26 inches (66 centimetres) by century's end, in line with United Nations estimates and enough to cause significant problems for coastal cities, a study said yesterday. "That's why I think that this is a conservative estimate, because it doesn't consider what if the ice sheets really start to go".

While other researchers have used tide gauge data to evaluate the acceleration in global sea-level rise, they have struggled to identify other important details from this information including changes over the past couple of decades stemming from more active ice sheet melting.

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.

He said the length of the new study and the correction of the satellite data was important. But detecting acceleration is challenging, even in such a long record. Research had previously suggested that sea levels were not only rising but rising faster and faster. El Ninos and La Ninas (the opposing phases of the El Nino Southern Oscillation, or Enso) influence ocean temperature and global precipitation patterns.

"It's a big deal", University of Colorado lead author Steve Nerem said.

The second was that of melting ice flowing into the oceans from places such as Greenland and Antarctica.

By what is presumably a complete coincidence, the funding for the NASA satellites that provide this data is now in danger of being axed as part of the government's current crack-down on various scientific projects.

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