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.”….
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.
A new scientific analysis finds that the Earth’s oceans are rising nearly three times as rapidly as they were throughout most of the 20th century, one of the strongest indications yet that a much feared trend of not just sea level rise, but its acceleration, is now underway. “We have a much stronger acceleration in sea level rise than formerly thought,” said Sönke Dangendorf, a researcher with the University of Siegen in Germany who led the study along with scientists at institutions in Spain, France, Norway and the Netherlands.
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
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.”
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.
There are two versions of Game of Floods- creative approaches to advancing adaptation understanding and action. The first, developed by Marin County (CA) targets the general public and students. The second, was developed by the City of Baltimore and targets key stakeholders including local government officials, utility officials, community stakeholders and others.
1- The “Game of Floods” was developed by the County of Marin as a public education activity on sea level rise adaptation, including traditional flood protection measures such as levees and seawalls; green infrastructure approaches including horizontal levees, wetland restorations, and beach nourishment; and policy/zoning changes. The Game of Floods is a small group activity, with 4-6 participants tasked with developing a vision for ‘Marin Island 2050,’ a hypothetical landscape that highlights the conditions that will be experienced in Marin in coming years with sea level rise and increased storm impacts causing the loss or deterioration of homes, community facilities, roads, agricultural land, beaches, wetlands, lagoons, and other resources.
2- Climate Training Toolkit: The City of Baltimore led an effort to develop a climate training toolkit for local governments to utilize as they train their own staff on opportunities to support climate adaptation and resilience progress. Products include: 1) the Climate Toolkit How-to Guide; 2) Case Studies; 3) Exercise Track; 4) Game of Floods Track; and 5) a Training Presentation (USDN- Urban Sustainability Directors Network– Innovation Fund, 2016). » Download
1 Scientific understanding of sea-level rise is advancing at a rapid pace. Projections of future sea-level rise, especially under high emissions scenarios, have increased substantially over the last few years, primarily due to new and improved understanding of mass loss from continental ice sheets. These sea-level rise projections will continue to change as scientific understanding increases and as the impacts of local, state, national and global policy choices become manifest. New processes that allow for rapid incorporation of new scientific data and results into policy will enable state and local agencies to proactively prepare.
2 The direction of sea level change is clear.Coastal California is already experiencing the early impacts of a rising sea level, including more extensive coastal flooding during storms, periodic tidal flooding, and increased coastal erosion.
3 The rate of ice loss from the Greenland and Antarctic Ice Sheets is increasing.These ice sheets will soon become the primary contributor to global sea-level rise, overtaking the contributions from ocean thermal expansion and melting mountain glaciers and ice caps. Ice loss from Antarctica, and especially from West Antarctica, causes higher sea-level rise in California than the global average: for example, if the loss of West Antarctic ice were to cause global sea-level to rise by 1 foot, the associated sea-level rise in California would be about 1.25 feet…
4 New scientific evidence has highlighted the potential for extreme sea-level rise. If greenhouse gas emissions continue unabated, key glaciological processes could cross thresholds that lead to rapidly accelerating and effectively irreversible ice loss. Aggressive reductions in greenhouse gas emissions may substantially reduce but do not eliminate the risk to California of extreme sea-level rise from Antarctic ice loss.
5 Probabilities of specific sea-level increases can inform decisions. A probabilistic approach to sea-level rise projections, combined with a clear articulation of the implications of uncertainty and the decision-support needs of affected stakeholders, is the most appropriate approach for use in a policy setting….. These projections may underestimate the likelihood of extreme sea-level rise, particularly under high emissions scenarios, so this report also includes an extreme scenario called the H++ scenario. The probability of this scenario is currently unknown, but its consideration is important, particularly for high-stakes, long-term decisions.
6 Current policy decisions are shaping our coastal future. Before 2050, differences in sea-level rise projections under different emissions scenarios are minor but they diverge significantly past mid-century. After 2050, sea-level rise projections increasingly depend on the trajectory of greenhouse gas emissions. For example, under the extreme H++ scenario rapid ice sheet loss on Antarctica could drive rates of sea-level rise in California above 50mm/year (2 inches/year) by the end of the century, leading to potential sea-level rise exceeding 10 feet. This rate of sea-level rise would be about 30-40 times faster than the sea-level rise experienced over the last century.
7 Waiting for scientific certainty is neither a safe nor prudent option. High confidence in projections of sea-level rise over the next three decades can inform preparedness efforts, adaptation actions and hazard mitigation undertaken today, and prevent much greater losses than will occur if action is not taken. Consideration of high and even extreme sea levels in decisions with implications past 2050 is needed to safeguard the people and resources of coastal California.
Melting ice sheets in Antarctica will wallop California with greater sea-level rise than the world average, threatening the state’s iconic beaches and important infrastructure, according to a report issued yesterday.
The latest science shows that the rate of ice loss from Greenland and Antarctica is increasing. That soon will become the primary contributor to global sea-level rise, overtaking ocean expansion from warming waters and the melting of mountain glaciers and ice caps, said the study, submitted to the California Ocean Protection Council.
That ice loss causes higher sea-level rise in California, it said, due to how the Earth rotates and gravitational pull on the waters. If the ice melt is from West Antarctica, impacts extend further. “For California, there is no worse place for land ice to be lost than from the West Antarctic Ice Sheet,” the study said. “For every foot of global sea-level rise caused by the loss of ice on West Antarctica, sea-level will rise approximately 1.25 feet along the California coast.”
Melting in Antarctica puts the California coast essentially “in the bull’s-eye” of the magnified sea-level rise, said Dan Cayan, director of the Climate Research Division at the Scripps Institution of Oceanography in San Diego….
Ice caps and glaciers along the coast of Greenland passed a tipping point in 1997, when a layer of snow that once absorbed summer meltwater became fully saturated. Since then, the coastal ice fields—separate from the main Greenland Ice Sheet—have been melting three times faster than they had been, according to a new study published Friday in the journal Nature Communications.
“The melting ice caps are an alarm signal for the ice sheet. It means long-term ice mass loss is inevitable. It will increase and accelerate if nothing changes,” said lead author Brice Noël, a scientist at the University of Utrecht Institute for Marine and Atmospheric Research. “It’s very unlikely the ice caps will recover. It’s a climate tipping point—the time at which a change or an effect cannot be stopped.”
Climate scientists are wary of tipping points, when a series of small changes make a much larger change inevitable. The fear is a total meltdown of the Greenland Ice Sheet, which would raise global sea level by 24 feet, Noël said. Overall, the rate of ice sheet melting is accelerating, according to peer-reviewed studies cited in the most recent Arctic report from NOAA.
“On a warming planet, there will be less snow and more rain. That will limit the formation of healthy snow that could absorb the runoff in summer. Additional melt will just run off toward the ocean, raising sea level,” he said. “What we saw there in normal conditions, before 1997, is that the snow was able to absorb most of the melt and then refreeze. So the melting was not contributing to sea level rise before 1997, even though warming was already ongoing.”
The new study, which included scientists from the Netherlands, Switzerland, Norway, Denmark and the United States, focused on coastal ice caps and glaciers at 12 locations around Greenland, tracking the melt-freeze cycle from 1958 to 2015. The sites represent a total of 38,000 square miles of ice, a little larger than Indiana….
The year 2016 made history, with a record global temperature, exceptionally low sea ice, and unabated sea level rise and ocean heat, according to the World Meteorological Organization (WMO). Extreme weather and climate conditions have continued into 2017.
WMO issued its annual statement on the State of the Global Climate ahead of World Meteorological Day on 23 March. It is based on multiple international datasets maintained independently by global climate analysis centres and information submitted by dozens of WMO Members National Meteorological and Hydrological Services and Research Institutes and is an authoritative source of reference. Because the social and economic impacts of climate change have become so important, WMO partnered with other United Nations organizations for the first time this year to include information on these impacts. WMO also prepared an interactive story map to highlight some of the main trends and events in 2016.
“This report confirms that the year 2016 was the warmest on record – a remarkable 1.1 °C above the pre-industrial period, which is 0.06 °C above the previous record set in 2015. This increase in global temperature is consistent with other changes occurring in the climate system,” said WMO Secretary-General Petteri Taalas….
Global climate change is being felt in many coastal communities of the United States, not always in the form of big weather disasters but as a steady drip, drip, drip of nuisance flooding. These smaller events can actually be more expensive overall, researchers report…
“Catastrophic storms get a lot of media attention and are studied, but we wanted to know more about the non-extreme events,” said Amir AghaKouchak, UCI associate professor of civil & environmental engineering and co-author of a new study on cumulative hazards in the American Geophysical Union journal Earth’s Future…..
Climate change is driving the growth of cumulative hazards, they noted. A full moon on a clear night triggering higher tides is now enough to cause flooding, because ocean levels are so high. “The frequency is increasing because of sea level rise,” AghaKouchak said. “We call it clear-sky flooding. There’s no rain, but if you have a higher-than-usual tide, you get flooding in these coastal areas.”
While not catastrophic at the time, these episodes degrade infrastructure and can damage roads and building foundations. More immediately, nuisance flooding forces municipalities to expend resources to pump water out of streets. Communities suffer school closures, traffic interruptions, and reverberating waves of cost and inconvenience. Degraded sewer infrastructure results in heightened public health risks….
Hamed R. Moftakhari, Amir AghaKouchak, Brett F. Sanders, Richard A. Matthew. Cumulative hazard: The case of nuisance flooding. Earth’s Future, 2017; DOI: 10.1002/2016EF000494
An invasive species of marsh grass that spreads, kudzu-like, throughout North American wetlands, may provide similar benefits to protected wetlands as native marsh grasses. According to new research, the invasive marsh grass’s effects on carbon storage, erosion prevention and plant diversity in protected wetlands are neutral….
…Phragmites australis, known as the common reed, is an invasive marsh grass that can spread at rates up to 15 feet per year. It thrives throughout North American wetlands, and studies have demonstrated that its densely packed growth pattern chokes out native marsh plants, thereby reducing plant diversity and habitat used by some threatened and endangered birds.
However, other studies have shown that Phragmites may help reduce shoreline erosion in marshlands and store carbon at faster rates than native grasses… The findings were encouraging.The team found no significant differences between ecosystem services of the marshes they studied, indicating that Phragmites‘ effect was largely neutral. However, Theuerkauf points out that the neutral effect could be due to the protected status of the wetlands they studied and the specific ecosystem services evaluated.
“Studies that associate Phragmites with negative impacts on wetlands are often conducted in areas that have seen significant human interventions, such as shoreline development or construction of drainage canals, whereas our study was conducted in undisturbed marsh habitat within a protected reserve system,” Theuerkauf says….
Seth J. Theuerkauf, Brandon J. Puckett, Kathrynlynn W. Theuerkauf, Ethan J. Theuerkauf, David B. Eggleston. Density-dependent role of an invasive marsh grass, Phragmites australis, on ecosystem service provision. PLOS ONE, 2017; 12 (2): e0173007 DOI: 10.1371/journal.pone.0173007