Coral reefs aren’t just threatened by pollution, ocean acidification and over-heated ocean temperatures. In some places they are being undermined by erosion of the seafloor, U.S. Geological Survey scientists said in a new study that looked at reefs in Florida, the Caribbean and Hawaii.
In the five study sites, the reefs can’t keep pace with sea level rise. As a result, coastal communities protected by the reefs are facing increased risks from storms, waves and erosion.
The degradation of reefs and the subsiding seafloor go hand-in-hand, as sand and other sea floor materials have eroded over the past few decades. In the waters around Maui, the sea floor losses amounted to 81 million cubic meters of sand, rock and other material – about what it would take to fill up the Empire State Building 81 times, the researchers calculated. Continue reading “Sea level rise overwhelming some coral reefs”→
Without expensive measures, some strands will vanish by 2100
Scientists are warily watching the impacts of rising sea levels along the world’s coastlines, where a high percentage of the global population lives and works. In some areas — especially narrow strands are pinned between the open ocean and coastal mountains, beaches may vanish by 2100 as higher waves and bigger storm surges wash away the precious sand.
Study documents cesspool inundations with possible discharges of effluent to the environment
Sea level rise caused by global warming may not be as obvious along the rugged and often steep coast of Hawaii as it is in low-lying areas like Holland, but it’s nonetheless going to present huge challenges in the decades ahead.
As scientists learn more about the dynamics of the ocean around Antarctica, they’ve discovered a climate warming signal. Distinct layers of water, marked by temperature boundaries, are forming right now, leading to conditions similar to about 14,000 years ago, when Antarctic ice sheets melted rapidly, raising global sea level by more than 10 feet. Continue reading “Ocean layering around Antarctica could signal major meltdown”→
New measurements taken in the ocean near a massive East Antarctica ice sheet confirm that warm water is melting the ice from below. The new data will help scientists determine how fast the Totten Ice Shelf will melt. In all, it contains enough water to raise global sea level by 3.5 meters, according to a new study published last week in Science Advances.
Ecologically critical tidal wetlands along the U.S. Gulf Coast are being swallowed up by rising sea level and coastal development, but they expand inland if planners consider climate change in their equations.
“Tidal saline wetlands along the northern Gulf of Mexico are abundant, diverse, and vulnerable to sea-level rise,” said Nicholas Enwright, USGS researcher and lead author of the study. “Our findings provide a foundation for land managers to better ensure there is space for future wetland migration in response to sea-level rise.”
Tidal saline wetlands include mangrove forests, salt marshes, and salt flats, which all provide important wildlife habitat and help buffer the impacts of extreme weather. Without areas for these wetlands to move to, people and wildlife will lose the beneficial functions they provide. Continue reading “Can coastal wetlands survive sea level rise?”→
‘Our study is for sea level what the now well-confirmed famous ‘hockey stick’ diagram was for global temperature’
The global rise of sea level may not be as dramatic or as easily visible as some other signs of global warming like melting glaciers, but it will be one of the most destructive and expensive long-term impacts. With a huge percentage of the world’s population living in coastal regions, society will need to take costly measures to protect people. In some cases, there will no option but to move entire communities away from the rising waters.
“Our study is for sea level what the now well-confirmed famous ‘hockey stick’ diagram was for global temperature,” said Stefan Rahmstorf, co-author of the paper on past sea-level rise and Co-Chair of PIK’s research domain Earth System Analysis. “We can confirm what earlier, more local sea-level data already suggested: during the past millennia sea-level has never risen nearly as fast as during the last century.”
The researchers said greenhouse gas emissions have caused at least half of the observed sea level rise in the 20th century, and possibly even all of it.
While the study didn’t break new ground in terms of projections, it’s important to be able to show with great certainty how much sea level will rise, Rahmstorf said.
“The new sea-level data confirm once again just how unusual the age of modern global warming due to our greenhouse gas emissions is – and they demonstrate that one of the most dangerous impacts of global warming, rising seas, is well underway.”
Barring any catastrophic climate feedback loops that could accelerate the meltdown of Arctic and Antarctic ice, the researchers said sea-levels worldwide will rise by 50 to 130 centimeters by the end of this century if greenhouse gas emissions are not reduced rapidly.
“With all the greenhouse-gases we already emitted, we cannot stop the seas from rising altogether, but we can substantially limit the rate of the rise by ending the use of fossil fuels,” said PIK’s Anders Levermann, who specializes in climate adaptation.
“We try to give coastal planners what they need for adaptation planning, be it building dikes, designing insurance schemes for floodings, or mapping long-term settlement retreat.”
Even if the world’s countries live up to the 2015 Paris climate agreement, sea level will rise 20 to 60 centimeters by 2100.
“This is quite a challenge, but less expensive than adaptation to unabated sea-level rise which in some regions is impossible”, Levermann adds. “If the world wants to avoid the greatest losses and damages, it now has to rapidly follow the path laid out by the UN climate summit in Paris.”
The likely future sea-level rise cannot be brought down to just one number, but is represented as a range, which at first sight might seem large.
“The range allows for a risk assessment,” said Ben Marzeion from the University of Bremen, Germany. “Coastal Planners need to know how a reasonable worst-case scenario as well as a well-founded best-case scenario look like to weigh chances and costs. The best available science is now converging towards a common uncertainty range of future sea-level rise. Curbing greenhouse gas emissions now gives us the chance to prevent sea level rise to accelerate further.”