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Tag Archive: sea level rise

  1. Iconic coast threatened as rising seas ‘drown’ beaches

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  2. Extreme coastal sea levels more likely to occur- new projections

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    Extreme coastal sea levels more likely to occur, new data, advanced modeling techniques suggest

    Posted: 07 Jul 2017 10:38 AM PDT

    …a new international study that incorporates extreme events may have just given researchers and coastal planners what they need. The study uses newly available data and advanced models to improve global predictions when it comes to extreme sea levels.

    The results suggest that extreme sea levels will likely occur more frequently than previously predicted, particularly in the west coast regions of the U.S. and in large parts of Europe and Australia.

    …Because of the rising sea levels, which research has confirmed has occurred steadily during the past century and is expected to accelerate in the future, extreme events that are now expected to happen, on average, only once every hundred years, could occur every decade or even every year, in many places by 2050, the study said.

    “Storm surges globally lead to considerable loss of life and billions of dollars of damages each year, and yet we still have a limited understanding of the likelihood and associated uncertainties of these extreme events both today and in the future,” said Thomas Wahl, an assistant engineering professor in the University of Central Florida who led the study….

    T. Wahl, I. D. Haigh, R. J. Nicholls, A. Arns, S. Dangendorf, J. Hinkel, A. B. A. Slangen. Understanding extreme sea levels for broad-scale coastal impact and adaptation analysis. Nature Communications, 2017; 8: 16075 DOI: 10.1038/ncomms16075

  3. Seaside sparrows caught between predators, rising seas

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    Posted: 12 Jul 2017 04:28 AM PDT  read full story at ScienceDaily

    Sea-level rise is a problem for saltmarsh birds, but so is predation, and birds sometimes find themselves caught between two threats: They can nest lower in vegetation to avoid predators, putting them at risk of flooding, or move up to keep dry but risk getting eaten. A new study finds that pressure from predators increases flooding risk for seaside sparrow nests — but that protecting them from predators could also mitigate the effects of climate change.

    Nest predation rates are so high right now that even under extreme sea level rise conditions, more nests are likely to be eaten than flooded,” says Hunter. “However, predation and flooding threats act synergistically, meaning that any estimates of the negative effects of sea level rise on the nesting success of Seaside Sparrow or other species are likely underestimates if they do not also consider the negative effects of predation on flooding risk. The flip side of this is that management actions to reduce nest predation could also reduce the risk of nest failures from flooding.” If measures such as fencing nest sites to exclude predators are taken, birds may place their nests higher in the salt-marsh vegetation, avoiding flooding from extreme high tides.

    …”Regardless of the threat, it is increasingly clear that tidal marsh birds and their habitats are in trouble, and that we need to explore a range of potential solutions to find ways to help them persist in light of the many ways that humans are changing coastal habitats”…

    Elizabeth A. Hunter. How will sea-level rise affect threats to nesting success for Seaside Sparrows? The Condor, 2017; 119 (3): 459 DOI: 10.1650/CONDOR-17-11.1

  4. U.S. Coastal Cities Will Flood 40x More Often by 2050 and More Severely, Study Warns

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    • Major coastal flooding—expected to occur only once every 100 years—will inundate coastal cities an average of 40 times more often by 2050
    • Researchers took a detailed look at the risks as sea level rises. Their conclusion? Get ready now

    Cities lining the U.S. coasts should brace for a lot more flooding — from “nuisance” floods that shut down streets during high tides to deluges that take lives and wipe out infrastructure. In a new study published Wednesday, researchers from Princeton and Rutgers universities warn that the current flooding predictions, including those widely used by policy makers, don’t accurately reflect the frequency and types of floods that are likely to challenge American cities in the coming decades as global temperatures and sea levels rise.

    Their research found that major coastal flooding—expected to occur only once every 100 years—will inundate coastal cities an average of 40 times more often by 2050, likely overwhelming the cities’ abilities to protect themselves.

    After 2050, the picture looks worse. Major flooding could slosh through the streets of New York City every other month by the end of the century, while major floods could sweep into Seattle nearly every week

    Maya K Buchanan1,4, Michael Oppenheimer1,2 and Robert E Kopp3 Amplification of flood frequencies with local sea level rise and emerging flood regimes Published 7 June 2017 © 2017 IOP Publishing Ltd  Environmental Research Letters, Volume 12, Number 6

    Abstract The amplification of flood frequencies by sea level rise (SLR) is expected to become one of the most economically damaging impacts of climate change for many coastal locations. Understanding the magnitude and pattern by which the frequency of current flood levels increase is important for developing more resilient coastal settlements, particularly since flood risk management (e.g. infrastructure, insurance, communications) is often tied to estimates of flood return periods. The Intergovernmental Panel on Climate Change’s Fifth Assessment Report characterized the multiplication factor by which the frequency of flooding of a given height increases (referred to here as an amplification factor; AF). However, this characterization neither rigorously considered uncertainty in SLR nor distinguished between the amplification of different flooding levels (such as the 10% versus 0.2% annual chance floods); therefore, it may be seriously misleading. Because both historical flood frequency and projected SLR are uncertain, we combine joint probability distributions of the two to calculate AFs and their uncertainties over time. Under probabilistic relative sea level projections, while maintaining storm frequency fixed, we estimate a median 40-fold increase (ranging from 1- to 1314-fold) in the expected annual number of local 100-year floods for tide-gauge locations along the contiguous US coastline by 2050. While some places can expect disproportionate amplification of higher frequency events and thus primarily a greater number of historically precedented floods, others face amplification of lower frequency events and thus a particularly fast growing risk of historically unprecedented flooding. For example, with 50 cm of SLR, the 10%, 1%, and 0.2% annual chance floods are expected respectively to recur 108, 335, and 814 times as often in Seattle, but 148, 16, and 4 times as often in Charleston, SC.

  5. Coastal Green Infrastructure Effectiveness Database

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    Digital Coast Launches Green Infrastructure Effectiveness Database

    June 22, 2017 OFFICE FOR COASTAL MANAGEMENT (OCM) | NATIONAL CENTERS FOR COASTAL OCEAN SERVICES (NCCOS)

    Decision-makers want to understand how to effectively use nature-based practices to protect people, property, and infrastructure from storms and sea level rise. For this purpose, OCM assembled a collection of sources on the effectiveness of green infrastructure. NCCOS and the NOAA Climate Program Office provided input. The new Green Infrastructure Effectiveness Database provides a means of quickly searching for source information and studies. The database also illuminates gaps in information and areas for enhanced study.

  6. Rising groundwater from sea level rise impacts coastal roads

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    Seacoast roads under new threat from rising sea level

    June 1, 2017 University of New Hampshire

    Some roads, as far as two miles from the shore, are facing a new hazard that currently cannot be seen by drivers — rising groundwater caused by increasing ocean water levels….
    ….Groundwater levels are higher than sea levels and that drives the groundwater discharge to the ocean. But as sea levels begin to rise, this forces groundwater to slowly move up to maintain the equilibrium, inching closer to the pavement base layers that need to stay dry to defend their strength….

    Jayne F. Knott, Mohamed Elshaer, Jo Sias Daniel, Jennifer M. Jacobs, Paul Kirshen. Assessing the Effects of Rising Groundwater from Sea Level Rise on the Service Life of Pavements in Coastal Road Infrastructure. Transportation Research Record: Journal of the Transportation Research Board, 2017; 2639: 1 DOI: 10.3141/2639-01

  7. Larsen C Iceberg on Brink of Breaking Off

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    By Brian Kahn Published: May 31st, 2017  full ClimateCentral article here

    …the Larsen C crack is… in the final days of cutting off a piece of ice that will be one of the largest icebergs ever recorded….The crack has spread 17 miles over the past six days, marking the biggest leap since January.

    …The vast majority of ice shelves are losing volume due to rising ocean and air temperatures. That’s helped prime parts of West Antarctica for what might be unstoppable melt that could raise sea levels at least 10 feet. Researchers also recently found meltwater ponds are much more common than previously thought. They even discovered a roaring seasonal waterfall on the Nansen Ice Shelf.

    These and other findings make clear that the Larsen C crack is just one of many changes happening to Antarctica. Global warming has pushed temperatures up to 5°F higher in the region since the 1950s and they could increase up to 7°F further by the end of the century, putting more stress on ice…

  8. Interior Department agency removes climate change language from news release

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    May 22 2017 Washington Post
    A group of scientists, including three working for the U.S. Geological Survey, published a paper that highlighted the link between sea-level rise and global climate change,[see more on their seminal publication here] arguing that previous studies may have underestimated the risk flooding poses to coastal communities.However, three of the study’s authors say the Department of Interior, under which USGS is housed, deleted a line from the news release on the study that discussed the role climate change played in raising Earth’s oceans.“While we were approving the news release, they had an issue with one or two of the lines,” said Sean Vitousek, a research assistant professor at the University of Illinois at Chicago. “It had to do with climate change and sea-level rise. We did end up removing a line,” he added…..Vitousek and five co-authors wrote the study, which was published in the journal Nature Scientific Reports. Three of the authors worked for USGS and the other three worked for universities.

    That deleted line, they said, read: “Global climate change drives sea-level rise, increasing the frequency of coastal flooding.”….

  9. Pace of sea level rise has nearly tripled since 1990

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    May 22 at 3:01 P M

    Their paper, just out in the Proceedings of the National Academy of Sciences, isn’t the first to find that the rate of rising seas is itself increasing — but it finds a bigger rate of increase than in past studies. The new paper concludes that before 1990, oceans were rising at about 1.1 millimeters per year, or just 0.43 inches per decade. From 1993 through 2012, though, it finds that they rose at 3.1 millimeters per year, or 1.22 inches per decade.

    The cause, said Dangendorf, is that sea level rise throughout much of the 20th century was driven by the melting of land-based glaciers and the expansion of seawater as it warms, but sea level rise in the 21st century has now, on top of that, added in major contributions from the ice sheets of Greenland and Antarctica.

    “The sea level rise is now three times as fast as before 1990,” Dangendorf said….Kopp added that in the past five years, there is some indication that sea level rise could already be even higher than the 3.1 millimeter annual rate seen from 1993 through 2012. He cautioned, though, that “those higher rates over a short period of time probably include some level of natural variability as well as continued, human-caused acceleration.”…“Sea levels will continue to rise over the coming century, no matter whether we will adapt or not, but I think we can limit at least a part of the sea level rise. It will further accelerate, but how much is related to how we act as humans,” Dangendorf said

    Sönke Dangendorf, Reassessment of 20th century global mean sea level rise. PNAS 2017 doi: 10.1073/pnas.1616007114

  10. Doubling of coastal flooding frequency within decades due to sea level rise

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    Sea level rise will double coastal flood risk worldwide

    Small but unstoppable increases will double frequency of extreme water levels with dire consequences, say scientists

    Guardian UK May 19, 2017

    ….The rise of 5-10cm, likely to occur within a couple of decades, would mean major cities including San Francisco in the US, Mumbai in India, Ho Chi Minh in Vietnam and Abidjan in Ivory Coast facing a doubled risk of coastal floods. “The maps of increased flooding potential suggest a dire future,” write the scientists.

    This study shows how even small changes in mean sea level can significantly increase the frequencies with which critical thresholds are exceeded,” said Thomas Wahl, professor of coastal risks at the University of Central Florida, who was not part of the research team.

    For coastal communities that means they need to adapt in order to prevent flood events from happening much more often,” Wahl said. “In the end, however, it still needs more localised studies in order for coastal managers to make important decisions on the ground.”

    Scientific Reports Publication:

    Doubling of coastal flooding frequency within decades due to sea-level rise

    Sean Vitousek,,Patrick L. Barnard, Charles H. Fletcher, Neil Frazer, Li Erikson & Curt D. StorlazziScientific Reports 7, Article number: 1399 (2017) doi:10.1038/s41598-017-01362-7   Published online:

    Abstract: Global climate change drives sea-level rise, increasing the frequency of coastal flooding. In most coastal regions, the amount of sea-level rise occurring over years to decades is significantly smaller than normal ocean-level fluctuations caused by tides, waves, and storm surge. However, even gradual sea-level rise can rapidly increase the frequency and severity of coastal flooding. So far, global-scale estimates of increased coastal flooding due to sea-level rise have not considered elevated water levels due to waves, and thus underestimate the potential impact. Here we use extreme value theory to combine sea-level projections with wave, tide, and storm surge models to estimate increases in coastal flooding on a continuous global scale. We find that regions with limited water-level variability, i.e., short-tailed flood-level distributions, located mainly in the Tropics, will experience the largest increases in flooding frequency. The 10 to 20 cm of sea-level rise expected no later than 2050 will more than double the frequency of extreme water-level events in the Tropics, impairing the developing economies of equatorial coastal cities and the habitability of low-lying Pacific island nations.