|December 24, 2014|
U.S. could see damage of at least $1.1T through 2100 from sea level rise, storm surge
|The combination of sea level rise due to global warming as well as storm surges from tropical storms and hurricanes could cost a cumulative total of about $1 trillion by the end of this century, a study has found. |
The research, published Dec. 14 in the journal Climatic Change, attempts to combine data on sea level rise with coastal property information and computer model simulations of future tropical cyclones.
The results show that the U.S. is facing what until now has been a hidden financial risk, not unlike the mortgage backed securities that helped blow up the U.S. economy in 2008. Scientists have improved their tracking and projections of sea level rise --- but they have not, until now, figured out a way to estimate the combined economic impact of storm surges and sea level rise nationwide.
The results are startling, but they only represent the first word in what is likely to be an evolving field of research into this topic.
The study, produced by researchers from MIT, the University of New Hampshire and the EPA, among other institutions, found that when property-specific projections of sea level rise includes episodic storm surge events, national damage estimates double.
According to the most recent report from the U.N. Intergovernmental Panel on Climate Change (IPCC), the rate of global average sea level rise is accelerating as the oceans expand due to warming, and ice sheets in Greenland and Antarctica melt. The rate of global average sea level rise during the 1993 to 2010 period was 0.13 inches per year, the IPCC said.
Global average sea level is projected to increase by at least one to two feet by the end of the century, perhaps higher, depending on the rate of ice loss. Many climate scientists consider the IPCC's figures to be a conservative projection that may need to be revised upwards based on new data.
According to the new study, the combined costs from sea level rise and storm surge events, including sea level rise adaptation measures like raising home elevations, abandoning some properties and building new sea walls to defend others, comes to between $930 billion to $1.1 trillion nationally by 2100, which is 84% to 110% higher than the projected costs from sea level rise alone, the study says.
"We think it's really important to look at storm surge and SLR together," lead author James E. Neumann, a researcher at Industrial Economics in Cambridge, Massachusetts, told Mashable.
Reductions in the emissions of greenhouse gases, such as carbon dioxide, that are causing global warming would save up to $100 billion by the end of the century by reducing the severity of sea level rise and storm surges, the study found, with most of the savings realized after the year 2050. Most of the sea level rise before that point is already considered to be baked into the climate system due to the long lag time between greenhouse gas emissions and the responses from land-based ice sheets and ocean temperatures.
Reversing sea level rise, Neumann says, "is like turning around a big aircraft carrier, there's a lot of inertia built up in the system," Neumann says.
The study's results, as eye-popping as they may be, likely represent an underestimate of the total economic impacts from sea level rise and storm surge events --- because it does not include several key factors. For one, it doesn't incorporate storm surges from storms that are not tropical storms and hurricanes, such as nor'easters.
Also absent is wave action, which tends to increase the damage from storm surge events.
The study also doesn't factor in regional variations in sea level rise, with the Mid-Atlantic and Northeast projected to be a regional hotspot for sea level rise due to regional ocean currents and other factors.
Damage to infrastructure, such as coastal roads and airports, and ecosystem damages are not included either.
The researchers, including well-known hurricane specialist Kerry Emanuel of MIT, conducted the study in part because of recent storm surge events that proved to be extraordinarily costly. Damage from Hurricane Sandy cost $50 billion in 2012 alone. Most of the deaths from Sandy came from the roiling sea, with a record high storm surge observed in parts of New York and New Jersey.
Low lying areas that have a lot of coastal development, such as New York City and much of the Florida coastline, show the greatest increase in costs when storm surge is included alongside gradual rates of sea level rise. Tampa is overdue for a major hurricane and would see a 420% increase in costs. New York shows a 220% jump, along with 210% for New Orleans, Louisiana and 190% for Galveston, Texas.
There are several sources of uncertainty in the study, considering it combines different models that include a tropical cyclone simulation model, a storm surge model and a model for estimating economic impacts and adaptation measures in coastal areas. These models each have their own potential biases, and the sea level rise scenarios used may be too low or too high.
"Anybody who is projecting 85 years into the future needs to be a little humble about the fact that these estimates are a little uncertain," Neumann said.
The "reference scenario" used in the study, which includes ice sheet melting, shows a higher sea level rise through 2010 than historical observations do, for example. However, it is in line with sea level projections in the 2014 National Climate Assessment and a 2010 report from the National Research Council, Neumann said.
The main point of the study is difficult to dismiss. Sea level rise is going to be an extremely expensive problem for the U.S., in large part because it will make extreme events like storm surges more destructive. And the U.S. coast is "poorly adapted" to the threats that lie ahead, Neumann says.
There have already been real-life examples of storm surges having a greater reach due to sea level rise. The sea level in the New York City area rose by about a foot between 1900 and 2012, when Hurricane Sandy struck --- meaning about 80,000 more people were affected by flooding in New York and New Jersey than would have been without that increase.
"The next step is really going local; this is a national scale study," Neumann said. "We've already had interest from states like Rhode Island and Massachusetts in thinking about ways to apply this to local adaptation planning."