In another startling reminder of the dangers of unrestrained man-made carbon emissions, a new scientific study concludes that the global sea level rose faster in the 20th century than in any of the 27 previous centuries reaching back to the founding of ancient Rome.
Global sea levels rose by about five and a half inches between 1900 and 2000 because of global warming, according to the study produced by researchers at Rutgers University and Potsdam Institute for Climate Impact Research in Germany. While a 14 centimeter rise in the levels may not seem like much to the layman, scientists view the increase with great alarm. They warn it poses a mounting threat to coastal states like Florida, Louisiana, South Carolina and New Jersey and other vulnerable, low-lying coastal areas.
There is no evidence yet of large numbers of coastal homes and developments disappearing into the surge due to the rising sea level. However, there have been widespread reports of related flooding in low-lying areas, causing many nuisances and problems – such as standing salt water disrupting traffic in neighborhoods, dying lawns, polluted fresh water supplies and clogged drains.
“The 20th-century rise was extraordinary in the context of the last three millennia — and the rise over the last two decades has been even faster,” Robert Kopp, the lead author and an associate professor at Rutgers University, said in a statement.
Kopp and other scientists and geologists said that if it hadn’t been for the worsening effects of climate change, global seas likely would have risen by less than half the measured increase throughout the 20th century. The sea level might have even fallen.
The Obama administration, congressional Republican leaders and coal industry leaders have bitterly clashed over the president’s efforts – both domestically and on the international stage -- to reduce greenhouse gas emissions and combat global warming. The debate has mostly centered on the economic impact of sharply reducing industrial carbon emissions and coal production.
However, administration officials, environmentalists and scientists are alarmed by the threat that climate change poses with regards to storms even worse than Hurricanes Katrina and Sandy, vanishing coastal areas and less dramatic but destructive flooding in low-lying areas.
White House Budget Director Shaun Donovan has cautioned that unabated global warming will have massive budget and economic consequences for the United States, potentially draining federal and state coffers of hundreds of billions of dollars in the coming years in response to storms, droughts, flooding and other natural catastrophes.
Other research suggests that rising global temperatures and sea levels could radically damage the global economy and slow growth in the coming decades. A study published in the journal Nature last year concluded that temperature change fostered by global warming will leave worldwide Gross Domestic Product 23 percent lower per capita in 2100 than it would be without any warming. “We’re basically throwing away money by not addressing the issue,” Marshall Burke, an assistant professor at Stanford University, told Time. “We see our study as providing an estimate of the benefits of reducing emissions.”
This week’s study, published in the Proceedings of the National Academy of Sciences, relied on a new statistical model pioneered during the past two to three years by Kopp, his postdoctoral associates Carling Hay and Eric Morrow and Jerry Mitrovica, a professor at Harvard University. It addressed the problem that scientists throughout the world measure sea level at their particular locations. The measurement techniques may vary from place to place, with no truly uniform global measurement.
“Each measures sea level at a particular location, where it is buffeted by a variety of processes that cause it to differ from the global mean. The statistical challenge is to pull out the global signal,” Kopp explained. “That’s what our statistical approach allows us to do.”
Kopp’s database includes records from 24 locations around the world. The geologists devised a way to reconstruct how sea level changed at a particular site in particular periods. A companion report released this week found that, absent a rising sea level induced by climate change, “more than half of the 8,000 coastal nuisance floods observed at studied U.S. tide gauge sites since 1950 would not have occurred,” according to a summary of the report.