Nav: Home

Rising sea levels will boost moderate floods in some areas, severe floods in others

June 07, 2017

Rising seas are making flooding more common in coastal areas around the country. Now, a new study finds that sea-level rise will boost the occurrence of moderate rather than severe flooding in some regions of the United States, while in other areas the reverse is true.

The study by researchers at Princeton and Rutgers universities found that along the southeastern coast, where severe flooding due to hurricanes is relatively frequent, cities such as Charleston, South Carolina, will see a disproportionate increase in moderate flooding. However, areas that have little history of severe flooding, such as Seattle, are likely to experience a greater uptick in the number of severe, or even historically unprecedented, floods.

The study, published June 7 in the journal Environmental Research Letters, looked at how climate-driven sea-level rise is likely to amplify coastal flooding -- which already costs municipalities along the East and Gulf coasts $27 billion annually -- over the next 50 to 100 years.

Improving the accuracy of flooding estimates is important as coastal cities and states take actions to protect themselves against future storms, according to Michael Oppenheimer, Princeton's Albert G. Milbank Professor of Geosciences and International Affairs. "To make these decisions, local governments need an understanding of the frequency with which extreme floods will return in the future," Oppenheimer said. "A key element is getting the science right, and that was our main objective in this study."

The researchers sought to improve the accuracy of a set of flood predictions included in a 2013 Intergovernmental Panel on Climate Change (IPCC) report. That analysis did not consider the possibility that sea-level rise might amplify some levels of flooding more than others.

"Treating the change in flood risk due to sea-level rise as the same at all levels of flooding oversimplifies the flood hazard characterization and could lead to costly policy missteps," said Maya Buchanan, the first author on the study and a doctoral student in Princeton's Woodrow Wilson School of Public and International Affairs.

The new study combined historical data on flood-heights collected at tide gauges with estimates of local sea-level changes developed previously by study co-author Robert Kopp, professor of earth and planetary science at Rutgers, and other colleagues.

Sea level is an important factor in the frequency and amount of coastal flooding because even modest increases can cause floods to inundate larger areas of land, or submerge areas more deeply. "For example, to produce a six-foot flood," Kopp said, "if the ocean is a foot higher, you only need as much storm surge as you would have previously needed to produce a five-foot flood."

The researchers calculated the "amplification factor" -- the amount by which a given rise in sea level drives the increase in the number of floods -- for numerous locations around the country. "The amount of sea-level rise that occurs will change the number of both moderate and severe floods," Buchanan said. "Climate change-driven sea-level rise is usually thought of as slow and steady, but actually a relatively small amount of increase in sea level can amplify the flood level significantly."

The study suggests that cities like Seattle will need to prepare for largely unprecedented, severe flooding, while other areas may need to prepare especially for more common but less severe events. For example, if current carbon emissions continue, by 2050 a moderate flood -- of the size that historically has occurred approximately every ten years -- would recur 173 times more often in Charleston but only 36 times more often in Seattle. A severe flood, defined as occurring about once every 500 years, would happen six times as often in Charleston but 273 times as often in Seattle.

"We hope that this study provides additional information that cities and municipalities can use to start planning the defense against climate change and sea-level rise," said Oppenheimer, who serves as an adviser on the New York City Panel on Climate Change. "This is especially important as federal programs for planning for climate adaptation are on the chopping block." Oppenheimer and Kopp were also authors of the most recent report of the IPCC.
-end-
The paper, "Amplification of flood frequencies with local sea-level rise and emerging flood regimes," by Maya Buchanan, Michael Oppenheimer and Robert Kopp, was published June 7, 2017, in the journal Environmental Research Letters. https://doi.org/10.1088/1748-9326/aa6cb3

Princeton University

Related Climate Change Articles:

The black forest and climate change
Silver and Douglas firs could replace Norway spruce in the long run due to their greater resistance to droughts.
For some US counties, climate change will be particularly costly
A highly granular assessment of the impacts of climate change on the US economy suggests that each 1°Celsius increase in temperature will cost 1.2 percent of the country's gross domestic product, on average.
Climate change label leads to climate science acceptance
A new Cornell University study finds that labels matter when it comes to acceptance of climate science.
Was that climate change?
A new four-step 'framework' aims to test the contribution of climate change to record-setting extreme weather events.
It's more than just climate change
Accurately modeling climate change and interactive human factors -- including inequality, consumption, and population -- is essential for the effective science-based policies and measures needed to benefit and sustain current and future generations.
Climate change scientists should think more about sex
Climate change can have a different impact on male and female fish, shellfish and other marine animals, with widespread implications for the future of marine life and the production of seafood.
Climate change prompts Alaska fish to change breeding behavior
A new University of Washington study finds that one of Alaska's most abundant freshwater fish species is altering its breeding patterns in response to climate change, which could impact the ecology of northern lakes that already acutely feel the effects of a changing climate.
Uncertainties related to climate engineering limit its use in curbing climate change
Climate engineering refers to the systematic, large-scale modification of the environment using various climate intervention techniques.
Public holds polarized views about climate change and trust in climate scientists
There are gaping divisions in Americans' views across every dimension of the climate debate, including causes and cures for climate change and trust in climate scientists and their research, according to a new Pew Research Center survey.
The psychology behind climate change denial
In a new thesis in psychology, Kirsti Jylhä at Uppsala University has studied the psychology behind climate change denial.

Related Climate Change Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#532 A Class Conversation
This week we take a look at the sociology of class. What factors create and impact class? How do we try and study it? How does class play out differently in different countries like the US and the UK? How does it impact the political system? We talk with Daniel Laurison, Assistant Professor of Sociology at Swarthmore College and coauthor of the book "The Class Ceiling: Why it Pays to be Privileged", about class and its impacts on people and our systems.