Sea Level Rise Accelerated by Climate Change

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As Steve Nerem, Associate Director of the Colorado Center for Astrodynamics Research at the University of Colorado Boulder and one of the study's authors, told ThinkProgress, the study's conclusions are based on the assumption that "the ice sheets [will] just continue going along at what they've been doing for the last 25 years".

Scientists analysing 25 years of satellite data discovered that global sea level is not rising at a steady 3mm per year, as previously thought.

Such rises are feared to be likely to cause "significant difficulties" for coastal cities and low-lying regions, especially once storm surges are taken into consideration.

The team, driven to understand and better predict Earth's response to a warming world, published their work February 12th in the journal Proceedings of the National Academy of Sciences.

First, the natural expansion of warm water has contributed to roughly half of the 2.76 inches of global average sea-level rise the planet has experienced over the past 25 years, Nerem said. 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. And if this rate of acceleration continues, by the end of the century sea levels will rise by just over 2 feet.

In Earth's atmosphere, growing concentrations of greenhouse gases increase the temperature of air and water, which causes sea level to rise in two ways.

That could mean an annual rate of sea level rise of 10 mm/year, or even more, by 2100.

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The Jason-3 satellite is the most recent in a series of four satellites to measure sea levels since 1993. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the USA portion of these missions for NASA's Science Mission Directorate. At this rate, the levels could go up to 10mm per year by 2100.

Outside scientists said even small changes in sea levels can lead to flooding and erosion.

Satellite data is said to provide a more precise estimate of global sea levels over the normal tide-gauge data, which is predominately used to measure open ocean levels. Over this short time period, the rate of sea level rise waxed and wane and it was hard to tease out whether its pace was steady or picking up. In addition, global sea level can fluctuate due to climate patterns such as El Ninos and La Ninos (the opposing phases of the El Nino-Southern Oscillation), which influence ocean temperature and global precipitation patterns.

The result is a "climate-change-driven" acceleration: the amount the sea levels are rising because of the warming caused by manmade global warming. They also used so-called tide gauge data to assess potential errors in the measurements. The scientists, who used last 25 years of satellite data to make this observation, say the acceleration in sea level increase can be seen as something similar to a "driver merging onto a highway".

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

A section of ice sheet is seen from NASA's Operation IceBridge research aircraft along the Upper Baffin Bay coast on March 27, 2017, above Greenland.