Studies: Rising Oceans to Wreak Havoc this Century

Published on
by
Common Dreams

Studies: Rising Oceans to Wreak Havoc this Century

Separate studies show dramatic sea level increases along Pacific and Atlantic coasts in US

by
Common Dreams staff

A stormy Atlantic ocean hits the coast of Buxton, North Carolina. (Photographer: Ted Richardson/Bloomberg via Getty Image)

Rates of sea level rise due to global warming and climate change are increasing three-to-four times faster along highly populated sections of the US northeast Atlantic Coast than they are globally, according to a new US Geological Survey report released Sunday in the journal Nature Climate Change.

Though global sea level has been projected to rise roughly two-to-three feet or more by the end of the 21st century, it will not climb at the same rate at every location. Differences in land movements, strength of ocean currents, water temperatures, and salinity can cause regional and local highs and lows in sea level. 

"Many people mistakenly think that the rate of sea level rise is the same everywhere as glaciers and ice caps melt, increasing the volume of ocean water, but other effects can be as large or larger than the so-called 'eustatic' rise," said USGS Director Marcia McNutt. "As demonstrated in this study, regional oceanographic contributions must be taken into account in planning for what happens to coastal property."

“Cities in the hot spot, like Norfolk, New York, and Boston, already experience damaging floods during relatively low-intensity storms,” Asbury Sallenger, a Geological Survey oceanographer and lead author of the study, told the Boston Globe. “Accelerated sea-level rise,” he said, will add to “the height that storm surges and breaking waves reach on the coast.”

The impacts of the rising seas are potentially devastating, USGS scientists told The Guardian. "As an example, 1 metre of sea level rise could raise the frequency of severe flooding for New York City from once per century to once every three years," said Stefan Rahmstorf, at the Potsdam Institute Germany, who published a separate study in the same journal, Nature Climate Change, on Sunday. Low lying countries like Bangladesh are likely to be severely affected, he told said. His colleague Michiel Schaeffer, at Wageningen University in the Netherlands, said: "Sea level rise is a hard to quantify, yet a critical risk of climate change. Due to the long time it takes for the world's ice and water masses to react to global warming, our emissions today determine sea levels for centuries to come."

The USGS report focused on sea level increases in the Atlantic Ocean, but a similar report focusing on the Pacific US coast was released on Friday with similar and ominous findings. That report, commissioned by California, Oregon, Washington and several federal agencies,  looked at how global warming — which causes ocean water to expand and ice to melt — will raise sea levels along the West Coast. It found that sea levels along the California coast are expected to rise up to 1 foot in 20 years, 2 feet by 2050 and as much as 5 1/2 feet by the end of the century, climbing slightly more than the global average and increasing the risk of flooding and storm damage.

"Sea level rise isn't a political question, it's a scientific reality," said Gary Griggs, director of the Institute of Marine Sciences at UC Santa Cruz and a member of the committee that produced the report.

*  *  *

USGS: Sea Level Rise Accelerating in U.S. Atlantic Coast

During the 21st century, the increases in sea level rise rate that have already occurred in the hotspot will yield increases in sea level of 8 to 11.4 inches by 2100. This regional sea level increase would be in addition to components of global sea level rise.

To determine accelerations of sea level, USGS scientists analyzed tide gauge data throughout much of North America in a way that removed long-term (linear) trends associated with vertical land movements. This allowed them to focus on recent changes in rates of sea-level rise caused, for example, by changes in ocean circulation.

The report, Hotspot of accelerated sea-level rise on the Atlantic coast of North America, was published in the journal Nature Climate Change.

*  *  *

Boston Globe: Rising sea level a threat to East

The seas along the East Coast from North Carolina to New England are rising three to four times faster than the global average, and coastal cities, utilities, beaches, and wetlands are increasingly vulnerable to flooding, especially from storm surges, according to the US Geological Survey study published Sunday.

“Cities in the hot spot, like Norfolk, New York, and Boston, already experience damaging floods during relatively low-intensity storms,” said Asbury Sallenger, a Geological Survey oceanographer and lead author of the study in the journal Nature Climate Change. “Accelerated sea-level rise,” he said, will add to “the height that storm surges and breaking waves reach on the coast.”

The findings come as Boston and Massachusetts officials are taking the first of a range of responses to the threat of rising seas. The report did not project how much levels would rise in the Northeast, but globally, oceans are projected to increase between 2 feet and 6 feet by the end of the century, and as much as an additional 5 feet during the heaviest storms. Climate scientists say such storms are likely to increase in intensity and frequency over the coming decades.

*  *  *

Los Angeles Times: California sea levels to rise 5-plus feet this century, study says

Sea levels along the California coast are expected to rise up to 1 foot in 20 years, 2 feet by 2050 and as much as 5 1/2 feet by the end of the century, climbing slightly more than the global average and increasing the risk of flooding and storm damage, a new study says.

That's because much of California is sinking, extending the reach of a sea that is warming and expanding because of climate change, according to a report by a committee of scientists released Friday by the National Research Council.

In Washington and Oregon, where geological processes are flexing the land upward, researchers predict a less dramatic sea level rise that will register below the global average.

The report, commissioned by California, Oregon, Washington and several federal agencies, is the closest look yet at how global warming — which causes ocean water to expand and ice to melt — will raise sea levels along the West Coast.

Tide gauges show that the world's oceans have risen about 7 inches in the last century, and that rate is accelerating, the report notes.

"Sea level rise isn't a political question, it's a scientific reality," said Gary Griggs, director of the Institute of Marine Sciences at UC Santa Cruz and a member of the committee that produced the report.

Globally, the study predicts up to 9 inches of sea level rise by 2030, 1 1/2 feet by 2050 and 4 1/2 feet by 2100.

The projections are largely in line with other recent scientific estimates but substantially higher than the 2007 figures by the United Nations' Intergovernmental Panel on Climate Change because they factor in a greater contribution from melting ice.

#  #  #

Share This Article

More in: