Sea Level Rise
It’s absolutely guaranteed’: the best and worst case scenarios for sea level rise
by Karen McVeigh 6/26/23 the Guardian
It is accelerating, too: the ocean rose more than twice as fast (4.62mm a year) in the most recent decade (2013-22) than it did in 1993-2002, the first decade of satellite measurements, when the rate was 2.77mm a year. Last year was a new high, according to the World Meteorological Organization. It is no coincidence that the past eight years were the warmest on record.
First sea-level records for coastal community protection
by European Space Agency 25/6/25 PHYS ORG
Our ability to monitor sea-level rise is thanks largely to the long-term record of sea-surface height from satellite radar altimeters, initially provided by the French–US Topex Poseidon satellite and the Jason series of satellites, and now by the Copernicus Sentinel-6 mission.
Modeling study finds early signs of widespread coastal marsh decline
by Colorado State University 23/6/25 PHYS ORG
Researchers have revealed the declining health of coastal marshes several years before visible signs of decline, providing an early warning and an opportunity to protect an ecosystem that serves as the first line of defense against coastal flooding.
First sea-level records for coastal community protection
by European Space Agency 25/6/25 PHYS ORG
Our ability to monitor sea-level rise is thanks largely to the long-term record of sea-surface height from satellite radar altimeters, initially provided by the French–US Topex Poseidon satellite and the Jason series of satellites, and now by the Copernicus Sentinel-6 mission.
Modeling study finds early signs of widespread coastal marsh decline
by Colorado State University 23/6/25 PHYS ORG
Researchers have revealed the declining health of coastal marshes several years before visible signs of decline, providing an early warning and an opportunity to protect an ecosystem that serves as the first line of defense against coastal flooding.
New Climate Study Highlights Dire Sea Level Warnings
by Bob Berwyn 13/6/25 Inside Climate News
Due to regional variations, sea level would rise twice that much in some tropical areas, causing misery for millions of people living in low-lying coastal zones, including islands like the Maldives, in the Indian Ocean, which would be completely swamped by 6 feet of sea level rise.
New Climate Study Highlights Dire Sea Level Warnings
by ob erwyn 13/5/25 Inside Climate News
A new set of detailed clues gleaned from ancient fossil reefs on the Seychelle Islands shows an increasing likelihood that human-caused warming will raise the global average sea level at least 3 feet by 2100, at the high end of the projections by the Intergovernmental Panel on Climate Change.
Land-based sensors reveal high frequency of coastal flooding
by Miyuki Hino 2/6/25 Communications earth & environment
Rising sea levels threaten to inundate coastal communities globally, with 190-340 M people at risk of inundation by the end of the century1. Long before communities are permanently inundated, they begin to experience chronic flooding. With higher average sea levels, tides alone cause sunny-day flooding2,3. Tides also now impair stormwater drainage systems such that ordinary rain storms lead to flooding4,5. While rates of sea-level rise and its potential impacts have been well documented, data on the frequency of such floods occurring outside of extreme storms are scarce. Instead, estimates of coastal flood frequency based on tide gauge and elevation data are widely used: once water levels as measured at the tide gauge exceed a certain elevation threshold, flooding on land is inferred.
How do we mourn an island? Where do we mark its grave?
by Kathy Jetnil kijiner 1/11/22 The Guardian
On a trip to the islet of Kalalen, eight years ago, a man named Yoster Harris ran out to meet me. Yoster is married to the alap, or landowner, of Kalalen and he took my hand and led me to point out Ellekan, a neighbouring islet at the very end of the Majuro atoll lagoon, in my home of the Marshall Islands in the north Pacific.
The Thwaites glacier is holding back global coastal devastation by only the skin of its teeth
by Pakalolo 6/9/22 DAILY KOS
Thwaites glacier in West Antarctica is the size of the State of Florida. It has been under scrutiny for decades over fears of warming waters below the ice by tunneling through like a block of swiss cheese. A massive cavity has formed that funnels even more heat into the ice streams underbelly. Sea levels worldwide could rise by as much as 16 feet, submerging cities such as Lagos, Shanghai, London, New York City, and Miami.Abrupt Sea Level Rise Looms As Increasingly Realistic Threat
BY NICOLA JONES • MAY 5, 2016 Yale Environment 360
Ninety-nine percent of the planet’s freshwater ice is locked up in the Antarctic and Greenland ice caps. Now, a growing number of studies are raising the possibility that as those ice sheets melt, sea levels could rise by six feet this century, and far higher in the next, flooding many of the world’s populated coastal areas.
The Earth has seen sudden climate change and rapid sea level rise before. At the end of the planet’s last glaciation, starting about 14,000 years ago, sea levels rose by more than 13 feet a century as the huge North American ice sheet melted. But researchers are hesitant about predicting similarly rapid climate shifts in our future given the huge stakes involved: The rapid collapse of today’s polar ice sheets would erase densely populated parts of our coastlines.
“Today, we’re struggling with 3 millimeters [0.1 inch] per year [of sea level rise],” says Robert DeConto at the University of Massachusetts-Amherst, co-author of one of the more sobering new studies. “We’re talking about centimeters per year. That’s really tough. At that point your engineering can’t keep up; you’re down to demolition and rebuilding.”
New Data Shows an ‘Extraordinary’ Rise in U.S. Coastal Flooding
<embed> https://www.nytimes.com/2020/07/14/climate/coastal-flooding-noaa.html?fbclid=IwAR2yvXDbrCX14LqlNi129dsB4pTfzwKr_KC-4okBUgw8fset1nJw_jVrlmk </embed> NY Times 7/14/2020
Rising seas are bringing water into communities at record rates, the National Oceanic and Atmospheric Administration said Tuesday. The increase in high-tide flooding along the Atlantic and Gulf Coasts since 2000 has been “extraordinary,” the National Oceanic and Atmospheric Administration reported, with the frequency of flooding in some cities growing fivefold during that time. That shift is damaging homes, imperiling the safety of drinking water, inundating roads and otherwise hurting coastal communities, the agency said. NOAA defines high-tide flooding, also called sunny-day or nuisance flooding, as water rising more than half a meter, or about 20 inches, above the normal daily high-tide mark. The frequency of that flooding has increased because of rising sea levels, which were roughly 13 inches higher nationally last year than in 1920, the agency reported.
Island 'drowning' is not inevitable as sea levels rise
<embed>https://phys.org/news/2020-06-island-inevitable-sea.html</embed>
The results show that islands composed of gravel material can evolve in the face of overtopping waves, with sediment from the beach face being transferred to the island's surface. This means the island's crest is being raised as sea level rises, with scientists saying such natural adaptation may provide an alternative future that can potentially support near-term habitability, albeit with additional management challenges, possibly involving sediment nourishment, mobile infrastructure and flood-proof housing.
Climate explained: why coastal floods are becoming more frequent as seas rise
<embed>https://theconversation.com/climate-explained-why-coastal-floods-are-becoming-more-frequent-as-seas-rise-127202</embed>
The background sea level rise has been only 20cm around New Zealand’s coasts so far, but even that makes a noticeable difference. An apparently small rise in overall sea level allows waves generated by a storm to come on shore much more easily. Coastal engineers use the rule of thumb that every 10cm of sea level rise increases the frequency of a given coastal flood by a factor of three.
The occurrence rates change so quickly because in most places, beaches are fairly flat. A 10cm rise in sea levels might translate to 30 or 40 metres of inland movement of the high tide line, depending on the slope of the beach. So when the tide is high and the waves are rolling in, the sea can come inland tens of metres further than it used to, unless something like a coastal cliff or a sea wall blocks its way.
Rising Sea Level
<embed>https://scied.ucar.edu/longcontent/rising-sea-level</embed>
Change in global sea level in the future is predicted to occur at a faster rate. The amount of sea level rise depends in large part on the amount of warming. According to the IPCC Forth Assessment Report (2007) by the mid-2090s global sea level may be 22 to 44 centimeters above its 1990 level and rising at about 4 mm per year.
Greenland Ice Sheet Melt from European Heat Wave
Twitter Xavier Fettweis 7/29/2019
A heat wave is starting tomorrow over Greenland with Tmax reaching 25°C in tundra. The integrated anomaly of melt over the next 5 days (resp. over Summer 2019) will be 40Gt ~0.11mm (resp. ~0.65mm) sea level equivalent. Summer 2019 = what the models project for 2050 using RCP85.
Tidewater Glaciers Melting Faster Than Expected
<embed>https://www.aaas.org/news/tidewater-glaciers-melting-faster-expected</embed>
Alaska's LeConte Glacier is melting underwater at rates nearly a hundred times greater than what is currently estimated, according to a detailed sonar survey of the glacier's submerged surfaces.
The newly observed melt rates are up to two orders of magnitude greater than those calculated by some current predictive models. The findings, published in the July 26 issue of Science, are the first based on direct subsurface measurements of a tidewater glacier and suggest that similar glaciers worldwide may be in far "hotter water" than previously known. "Beyond proving that [the method] is doable, we found that melt rates over most of the glacier were extremely high compared to those predicted by theory," said Sutherland, and that they changed seasonally, increasing from spring to summer. For example, melt rates based on these direct observations suggest melt rates of more than eight meters per day in August, whereas theoretical models predict a single meter of daily change.
Based on the physics of ice melt along the ice-ocean interface, Sutherland is confident that similar submarine melt is occurring elsewhere, particularly at the far larger tidewater glaciers in Greenland or west Antarctic Peninsula.
Greenland unraveling rapidly as feedback loops bring the ice sheet closer to the tipping point
Feedback loops make the problem of a warming Arctic that much worse and according to Thomas Growther, a professor at the Department of Environmental Systems Science of ETH Zurich, “It’s already begun, the feedback is in process”. Yahoo news, reports that “carbon dioxide and methane emissions from thawing soils are “accelerating climate change about 12 to 15 percent at the moment,” and said past IPCC reports that left out the feedback “were way more optimistic than they should have been.”
