By Marlene Cimons
Scientists know that sea levels have risen more in some places during the past century than in others. They've gone up faster along the Mid-Atlantic States, particularly near Cape Hatteras and the Chesapeake Bay, compared to north along the Gulf of Maine and south along the South Atlantic Bight. But why?
"Sea-level rise affects us all," said Chris Piecuch, assistant scientist at the Woods Hole Oceanographic Institution and lead author of a new study recently published in the journal Nature that explains the reasons for sea-level rise variations on the East Coast. "Those of us who live on the coast are feeling, and will continue, to feel more acutely its effects. But even those who don't live on the coast will feel the effects. Going into the future, over the coming centuries, multiple meters of global sea-level rise are possible. And even if the nature of storms doesn't change in the future, the higher 'baseline' of rising seas will make the impacts of coastal storms worse. Sea-level rise will come, making the bad worse."
Piecuch and his colleagues attribute the "unequal" sea-level rise in the East to a phenomenon known as "post-glacial rebound."
Thousands of years ago, large ice sheets covered large parts of northern North America, including large swaths of Canada and the northeastern U.S. As a consequence—because the ice sheets were so massive and heavy—they weighed down Earth's crust, causing it to sink directly beneath the ice sheet. "As a result, places that were around the edges or periphery of that ice sheet were actually levered up," Piecuch explained. "It's an imperfect analogy, but you can perhaps think of a see-saw. When you sit on one end of a seesaw, it goes down, whereas the other end of the seesaw goes up. Again, this was the picture thousands of years ago."
In the intervening time, the ice sheets melted, reducing the weight. As a result, the areas formerly sunken down under that massive weight could relax and rise up, whereas those regions around the edges that were formerly levered or bulged up sank, he said. "The seesaw is again helpful here," he said. "If you imagine stepping off the seesaw now, the end you'd been sitting on can rise back up, whereas the other end now sinks down."
Even though the ice sheets had disappeared by 7,000 years ago, the see-sawing of post-glacial rebound continues to this day, he said. "Because the Earth responds so gradually—and is, in a sense, still feeling the last ice age—that 'reverse' see-sawing is still ongoing, with land moving up in some places and down in others," he said. "And it's that spatially variable land motion that gives the effect of different rates of sea-level rise at different places on the East Coast."
While the differences on the East Coast are due mainly to naturally occurring post-glacial rebound, the exacerbating effects of climate change are "felt everywhere along the east coast commonly," he said. "The oceans are warming and expanding thermally, and land ice is melting, and that water is running off into the ocean, both causing sea level to rise. We know that global sea-level rise over the last century was faster than any other time during the last three millennia, that sea levels wouldn't have risen nearly the amount we observe if it weren't for human influence, and we know that—even over just the last 25 years—the rate of global sea-level rise has been accelerating. These and other evidences are telling us that what has been happening during the recent past is unusual and anomalous. And, based on our best understanding of the science, we can only anticipate that things will continue to accelerate, and problems of coastal impacts worsen."
To figure out why sea levels rose faster during the last 100 years in such areas as Norfolk Naval Station in Virginia and the Outer Banks in North Carolina, Piecuch and his team collected tidal gauge measurements of sea levels, GPS satellite data showing the extent of up-and-down land movement over time, and fossils in sediment from salt marshes, a record of past coastal sea levels. They combined this observational data with complex geophysical models—which hasn't been done before, they said—for a more complete interpretation of sea level changes since 1900.
Norfolk, Virginia and the Outer Banks, North Carolina.Google Maps
They found that post-glacial rebound accounted for most of the variation in sea-level rise along the East Coast. But even after eliminating the post-glacial rebound factor, "sea level trends [still] increased steadily from Maine all the way down to Florida," Piecuch said. "The cause for that could involve more recent melting of glaciers and ice sheets, groundwater extraction and damming over the last century.
"Sea level is a complicated problem," he continued. "Lots of processes can lead to sea-level rise, for example, geological processes like post-glacial rebound compounding the problem of climate change and its impacts on the coast. One thing that's useful about our study is that, for the East Coast, we've pinned down one part of the problem. And, since that problem unfolds over very long time scales, we can be confident predicting that component of sea-level rise centuries into the future. But, of course, that says nothing about the other parts of the sea-level rise problem, for example, due to ongoing ice melting and ocean warming."
His study is an attempt to bolster scientific knowledge about the factors involved, which should "help us understand how and why they will rise into the future, at a particular place, and for a particular time horizon," he said. "While these studies can't stem the rise of the tides, it can give us the best information possible so as to help us anticipate the impacts on our coasts."
To be sure, uncertainties remain. "We're still trying to understand just how much and just how fast sea levels will rise in the future," he said. Nevertheless, the news almost certainly will be bad. "There really are no good stories here," he said. "Under no physically plausible scenarios will global sea levels go down. They're certainly going to continue rising, very probably at accelerated rates, for decades and centuries into the future."
Reposted with permission from our media associate Nexus Media.
Britain's Prince William interviewed famed broadcaster David Attenborough on Tuesday at the World Economic Forum's annual meeting in Switzerland.
During the sit-down, the 92-year-old naturalist advised the world leaders and business elite gathered in Davos this week that we must respect and protect the natural world, adding that the future of its survival—as well as humanity's survival—is in our hands.
What's more, the accounting firm predicts that another 21 million electric cars will be on the road globally over the next decade due to growing market demand for clean transportation, government subsidies, as well as bans on fossil fuel cars.
By Matthew Savoca
Plastic pollution in the world's oceans has become a global environmental crisis. Many people have seen images that seem to capture it, such as beaches carpeted with plastic trash or a seahorse gripping a cotton swab with its tail.
Greenland is melting about four times faster than it was in 2003, a new study published Monday in the Proceedings of the National Academy of Sciences found, a discovery with frightening implications for the pace and extent of future sea level rise.
"We're going to see faster and faster sea level rise for the foreseeable future," study lead author and Ohio State University geodynamics professor Dr. Michael Bevis said in a press release. "Once you hit that tipping point, the only question is: How severe does it get?"
Finally, some good news about the otherwise terrible partial government shutdown. A federal judge ruled that the Trump administration cannot issue permits to conduct seismic testing during the government impasse.
The Justice Department sought to delay—or stay—a motion filed by a range of coastal cities, businesses and conservation organizations that are suing the Trump administration over offshore oil drilling, Reuters reported. The department argued that it did not have the resources it needed to work on the case due to the shutdown.
Most people have heard of the Amazon, South America's famed rainforest and hub of biological diversity. Less well known, though no less critical, is the Pantanal, the world's largest tropical wetland.
Like the Amazon, the Pantanal is ecologically important and imperiled. Located primarily in Brazil, it also stretches into neighboring Bolivia and Paraguay. Covering an area larger than England at more than 70,000 square miles, the massive wetland provides irreplaceable ecosystem services that include the regulation of floodwaters, nutrient renewal, river flow for navigability, groundwater recharge and carbon sequestration. The wetland also supports the economies of the four South American states it covers.
By Andrea Germanos
Organizers said 35,000 people marched through the streets of the German capital on Saturday to say they're "fed up" with industrial agriculture and call for a transformation to a system that instead supports the welfare of the environment, animals and rural farmers.
By Patrick Rogers
If you have ever considered making the switch to an environmentally friendly electric vehicle, don't drag your feet. Though EV prices are falling, and states are unveiling more and more public charging stations and plug-in-ready parking spots, the federal government is doing everything it can to slam the brakes on our progress away from gas-burning internal combustion engines. President Trump, likely pressured by his allies in the fossil fuel industry, has threatened to end the federal tax credits that have already helped put hundreds of thousands of EVs on the road—a move bound to harm not only our environment but our economy, too. After all, the manufacturing and sale of EVs, hybrids, and plug-in hybrids supported 197,000 jobs in 2017, according to the most recent U.S. Energy and Employment Report.