Tag Archives: Coast

Almost nine-tenths of the Earth’s coastlines are degraded by human activity

Our planet has a coast problem: only 15% of coastal areas worldwide remain intact, a new study finds.

Image via Pixabay.

Such results showcase the wide-scale impact human activity has on natural ecosystems, coastlines in particular. The findings also help pinpoint which areas of the coast need urgent rehabilitation and conservation work, potentially helping policymakers around the world secure a future with pristine beaches for future generations to enjoy.

Uncoasted

“Coastal regions contain high levels of biodiversity and are relied upon by millions of people for ecosystem services such as food and storm protection,” says Brooke Williams from UQ’s School of Earth and Environmental Sciences, who led the research. “Our results show that we need to act quickly and decisively if we hope to conserve those coastal regions that remain intact and restore those that are heavily degraded, especially if we’re going to mitigate the effects of climate change.

The study mapped the impact of human-driven pressure on coastal regions around the world in a bid to understand exactly which areas are already highly degraded, and which remain relatively intact. The findings have been compiled into a free-use dataset available here for any other researchers to analyze and use.

According to the findings, our effects on the Earth’s coasts are widespread and dramatic. All in all, only 15.5% of the planet’s coastal areas remain intact (as of 2013). Canada was the country with the single largest quantity of still-intact coastlines — and these aren’t exactly tropical beaches. Russia, Greenland, Chile, Australia, and the United States still had sizable stretches of intact coast, but less so than Canada.

The authors call such results “truly eye-opening”.

As far as ecosystems are concerned, those containing seagrasses, savannah, or coral reefs “had the highest levels of human pressure compared to other coastal ecosystems,” the authors report.

The findings are based on an analysis of two datasets: one focusing on human impacts on land, and the other focusing on a marine perspective.

Indeed, such figures do not bode well at all for anyone who wishes to see natural landscapes healthy and well-preserved. The data can help in this regard, pointing to areas where interventions are most needed and would produce the most benefit. With these findings in hand, the team hopes, policy-makers can start turning this degradation around, or at least slow it down.

The paper “Global rarity of intact coastal regions” has been published in the journal Conservation Biology.

Aquifer.

Largest freshwater aquifer of its kind found off the U.S. Northeast coast

A gigantic, relatively-fresh-water aquifer has been discovered just off the U.S. Northeast coast.

Aquifer.

Yellow crosses and the yellow dashed line show the inferred spatial extent of the low-salinity aquifer system.
Image credits Chloe Gustafson, Kerry Key, Rob L. Evans, (2019), Nature.

The aquifer is contained by the sediments of the seafloor and seems to be the largest of its kind (freshwater aquifer underneath a body of saltwater) that we’ve found so far. The aquifer stretches at least from the shore of Massachusetts to New Jersey, extending more or less continuously out about 50 miles to the edge of the continental shelf, a new study reports.

Thirsty?

“We knew there was fresh water down there in isolated places, but we did not know the extent or geometry,” said lead author Chloe Gustafson, a PhD candidate at Columbia University’s Lamont-Doherty Earth Observatory. “It could turn out to be an important resource in other parts of the world.”

The first clues that an aquifer rests in this area came in the 1970s when wells drilled off the coastline in search of oil sometimes hit fresh water. At the time, it was debated whether these were isolated pockets of water or a larger continuous body. About 20 years ago, study coauthor Kerry Key, now a Lamont-Doherty geophysicist, helped fossil fuel companies develop techniques to use electromagnetic imaging of the sub-seafloor to look for oil in this area. More recently, he decided to see if the same approach can be turned to spotting freshwater deposits in the area.

In 2015, he spent 10 days on the research vessel with Marcus G. Langseth and Rob L. Evans of Woods Hole Oceanographic Institution, taking measurements off the coast of southern New Jersey and the Massachusetts island of Martha’s Vineyard, where scattered drill holes had hit fresh-water-rich sediments. Their data indicated that these were not scattered pockets of water, but a more or less continuous structure extending from the shoreline far out through the continental shelf — in some areas as far as 75 miles. For the most part, the aquifer horizon spans from between 600 feet below the ocean floor to about 1,200 feet.

Based on the readings, the team is confident that the aquifer spans not just New Jersey and much of Massachusetts, but also the coasts of Rhode Island, Connecticut, and New York. All in all, they report, the aquifer holds an estimated 670 cubic miles of fresh water. So how did all this fresh water get there? The team was two hypotheses.

Aquifer section.

Conceptual model of offshore groundwater. Arrows denote groundwater flow paths.
Image credits Chloe Gustafson, Kerry Key, Rob L. Evans, (2019), Nature.

Some 15,000 to 20,000 years ago, toward the end of the last glacial age, most of the Earth’s fresh water was locked up as ice. In North America, these ice sheets extended through northern New Jersey, Long Island, and the New England coast. Since all of that water was solid ice, sea levels were much lower, exposing large surfaces of the continental shelf that today are submerged. As the climate warmed and the ice started melting, outflowing water formed huge river deltas on top of the shelf, and fresh water got trapped there in small pockets, eventually becoming submerged under the sea bed. This is the more traditional hypothesis as to how freshwater bodies can form beneath the ocean.

However, the team has reason to believe that the aquifer is still being fed by modern runoff from dry land. Rainfall and water infiltrating from other sources percolate through onshore sediment, Key explains, and is likely pumped towards the aquifer by the cyclical motions of the tide. This hypothesis is supported by the fact that the aquifer is generally freshest near the shore and saltier the further out you go — suggesting its water gradually mixes with that from the ocean.

This water is still less salty than ocean water. Fresh water usually contains less than 1 part per thousand of salt, and this is about the value found undersea near land; on the aquifer’s outer edges, it rises to 15 parts per thousand. Typical seawater is around 35 parts per thousand salt. As such, if water from the outer edge of the aquifer would be pumped out, it would need to be desalinated — but this would still be cheaper than processing seawater, according to Key.

“We probably don’t need to do that in this region, but if we can show there are large aquifers in other regions, that might potentially represent a resource,” he explains.

Key cites southern California, Australia, the Mideast, or Saharan Africa, as some of these regions, adding that the group hopes to expand its surveys there.

The paper “Aquifer systems extending far offshore on the U.S. Atlantic margin” has been published in the journal Scientific Reports.

Water.

Sea level change isn’t constant across the East Coast — because of long-past glaciers

A new study explains why different areas along the U.S. East Coast see significantly more sea level change than others.

Water.

Image credits Dimitris Vetsikas.

Seas and oceans across the globe are creeping ever so slowly upwards as climate change warms them up and melts glaciers big and small. However, local sea levels aren’t (surprisingly) the same everywhere — and this holds true for the U.S. East Coast as well. A new study published by researchers from the Woods Hole Oceanographic Institution (WHOI) comes to explain why.

Been under a lot of pressure lately

Over the last century, coastal communities near Cape Hatteras (North Carolina) and the Chesapeake Bay (Virginia) have seen about a foot and a half of sea level rise.  New York City and Miami, in contrast, have only seen roughly two-thirds of that rise (i.e. one foot) over the same period. Farther north in Portland, Maine, for example, sea levels only rose only about half a foot.

Which is weird, right? I mean, all the Earth’s oceans are linked together so, their water should be level, right? Not if you’re on a period of post-glacial rebound, says lead author Chris Piecuch.

Vast areas of land in the Northern Hemisphere, including Canada and parts of the Northeast U.S, were covered in massive glaciers during the last Ice Age, he explains. This effectively squashed the lands, pushing them down into the mantle (the crust is essentially a jigsaw puzzle of solid pieces floating on molten rock — see here). These ice sheets peaked in size and mass during the Last Glacial Maximum some 26,500 years ago, and then started melting to the state we see today. As they did so, the pressure they exerted on the ground also disappeared — and these areas started to rebound. Neighboring lands, meanwhile, started sinking, creating sort of a seesaw effect.

That effect continues to this day, Piecuch explains.

For the study, Piecuch and his team gathered tidal gauge measurements of sea levels in areas such as Norfolk Naval Station in Virginia and the Outer Banks in North Carolina. They also drew on GPS satellite data to see how much local landmasses had moved up and down over time, and looked to fossils recovered from salt marshes (which are a good indicator of past coastal sea levels). They combined all of this observational data with complex geophysical models to produce a more complete view of sea level changes since 1900 than ever before.

Post-glacial rebound, they found, accounted for most of the variation in sea level rise along the East Coast. Interestingly, however, when that factor was removed from the dataset, the team found that “sea level trends increased steadily from Maine all the way down to Florida.”

“The cause for that could involve more recent melting of glaciers and ice sheets, groundwater extraction and damming over the last century,” Piecuch says. “Those effects move ice and water mass around at Earth’s surface, and can impact the planet’s crust, gravity field and sea level.”

“Post-glacial rebound is definitely the most important process causing spatial differences in sea level rise on the U.S. East Coast over the last century. And since that process plays out over millennia, we’re confident projecting its influence centuries into the future. But regarding the mass redistribution piece of the puzzle, we’re less certain how that’s going to evolve into the future, which makes it much more difficult to predict sea level rise and its impact on coastal communities.”

The paper “Origin of spatial variation in US East Coast sea-level trends during 1900–2017” has been published in the journal Nature.

Powerful sound blasters can render tsunamis dead in the water, new study shows

Blasting high-powered acoustic waves at tsunamis could break their advance before reaching the shoreline, a new theoretical study has shown.

Tsunamis are one of the most dramatic natural phenomena we know of, and they’re equally destructive. These great onslaughts of water are powered by huge amounts of energy — on a level that only major landslides, volcanoes, earthquakes, nukes, or meteorite impacts can release. And when they reach a coastline, all that water in motion wipes infrastructure and buildings clean off.

[MUST READ] How tsunamis form and why they can be so dangerous

Traditionally, there are two elements coastal communities have relied on against tsunamis: seawalls and natural barriers. Seawalls are man-made structures that work on the principle of an unmoving object, resisting the wave’s kinetic energy through sheer mass. Natural barriers are coastal ecosystems, typically mangrove forests or coral reefs, that dissipate this energy over a wider area and prevent subsequent floods. Each approach has its own shortcomings however, such as high production and maintenance cost or the risk of being overwhelmed by a big enough tsunami.

Dr Usama Kadri from Cardiff University’s School of Mathematics thinks that the best defense is offence — as such, she proposes the use of acoustic-gravity waves (AGWs) against tsunamis before they reach coastlines.  Dr Kadri proposes that AWGs can be fired at incoming tsunamis to reduce their amplitude and disperse energy over a larger area. Ok that’s cool, but how does it work?

The tsunami whisperer

Waves are a product of the interaction between two fluids (air-water) and gravity. Friction between wind and the sea’s surface causes water molecules to move sideways and on top of one another, while gravity pulls them back down. Physically speaking, ‘waves’ are periodic wavetrains — and as such, they can be described by their period (length between two wave crests), amplitude (height), and frequency (speed).

One thing you can do with periodic waves is make them interfere constructively or destructively — you can ‘sum up’ two small waves to make a bigger one, or make them cancel out. Apart from a different source of energy, tsunamis are largely similar to regular waves, so they also interfere with other waves. Here’s where AGWs come in.

Think of AGWs as massive, sound-driven shock-waves. They occur naturally, move through water or rocks at the speed of sound, and can stretch for thousand of kilometers. Dr Kadri shows that they can be used to destructively interfere with tsunamis and reduce their amplitude before reaching the coast. Which would prevent a lot of deaths and property damages.

“Within the last two decades, tsunamis have been responsible for the loss of almost half a million lives, widespread long-lasting destruction, profound environmental effects and global financial crisis,” Dr Kadri writes in her paper. “Up until now, little attention has been paid to trying to mitigate tsunamis and the potential of acoustic-gravity waves remains largely unexplored.”

“The main tsunami properties that determine the size of impact at the shoreline are its wavelength and amplitude in the ocean. Here, we show that it is in principle possible to reduce the amplitude of a tsunami, and redistribute its energy over a larger space, through forcing it to interact with resonating acoustic–gravity waves.”

Her paper also shows that it’s possible to create advanced warning systems based on AGWs, which are generated with the tsunami and induce high pressures on the seabed. She also suggests harnessing these natural AGWs against tsunamis, essentially using nature’s own energy against itself.

The challenge now is to develop technology that can generate, modulate, and transmit AGWs with high enough accuracy to allow for interference with tsunamis. She admits that this won’t be easy to do, particularly because of the high energy required to put a dent in the waves.

The full paper “Tsunami mitigation by resonant triad interaction with acoustic–gravity waves” has been published in the journal Helyion.

More than 13 million Americans could be at risk from sea level rise by 2100

A new study analyzing sea level rise forecasts as well as population growth projections found that we’ve underestimated just how many people would be impacted by rising waters. Anywhere from 4.3 to 13.1 million people from the US alone will face the risk of inundation by 2100, according to their estimate.

Brackish sea water washes over the center line of a street in Charleston Oct. 1, 2015.
Image credits Stephen B. Morton/AP.

The team, with members from the University of Georgia and Stetson University in Florida used population trends and sea level rise estimates to establish a county-by-county risk assessment across the US. Their results suggest that previous research, based on current population numbers, underestimates the risk coastal states face.

An important implication of this is the estimated cost of adapting to sea level rise might be too low, since it doesn’t take population growth and the associated installation of more long-lasting, vulnerable infrastructure into account.

“There are 31 counties where more than 100,000 residents could be affected by 6 feet of sea level rise,” said study co-author Mathew E. Hauer, of the University of Georgia in a press release.

The southeastern U.S. coast is a hotspot for inundation risk related to sea level rise, the authors say. This is partly due to the high population growth that the area is experiencing. Over 10 percent of coastal populations in states such as Georgia and South Carolina will be affected by a global sea level increase of 1.8 meters (5.9 feet) by 2100. A similar rise would affect an estimated one million people in California and Louisiana each. Florida faces the most risk, with up to 6 million residents affected under the same scenario.

Densely populated counties in coastal areas, such as Broward or Miami-Dade Counties in Florida, San Mateo in California or Jefferson in Louisiana are expected to see more than 100,000 residents “potentially impacted” by a 0.9 meters (around 3 feet) rise in sea levels.

The study also identified three counties as having an “extreme exposure” to inundation: North Carolina’s Tyrrell and Hyde Counties, and Monroe County in Florida. Tyrell and Hyde Counties are home to abundant nature preserves on North Carolina’s Outer Banks, while Monroe County is located at the southwestern tip of Florida, encompassing a swath of Everglades National Park as well as the Florida Keys. People living in these areas will suffer “catastrophic impacts” by 2100 if steps aren’t taken to address the issue.

Image credits misterfarmer/pixabay

The authors also warn that the lack of protection for coastal residents could lead to a population migration on par with the “Great Migration” of southern African Americans after the first World War. They estimate that the cost of relocating all the people affected by sea rise by 2100 would exceed $14 trillion dollars.

“The impact projections are up to three times larger than current estimates, which significantly underestimate the effect of sea level rise in the United States,” Hauer added.

Compared to previous estimates, these are worrying numbers. The team’s estimates revolve around those 1.8 meters of sea rise used in their calculations. The study also doesn’t take factor in regional variations in the rate of sea level rise. But, while the consensus seems to be set around a 1 meter (3.6 feet) rise by 2100, there is growing concern around the stability of the Greenland and West Antarctic ice sheets in today’s warmer oceans. Faster melting of these ice sheets would rise the waterline significantly, possibly way above the 1.8 meter level the team set.

Ben Strauss told Mashable that the lack of regional variations in sea level rise would affect the results out to the year 2100, and the study also “assumes that people will be moving to the shore essentially just as briskly” in the latter half of the century as in 2020, despite the evident effects of sea level rise expected by 2070.

The full paper, titled “Millions projected to be at risk from sea-level rise in the continental United States” has been published online in the journal Nature Climate Change and can be read here.

Join the great Californian Trash Treasure Hunt, and help keep the ocean clean

Ok ok it’s not technically called that, but the California Costal Cleanup Day is definitely something you should check out this Saturday if you like finding cool stuff and wish your beach looked less….garbage-y.

For 31 years now, thousands of volunteers all over the world come together, put on the strongest pair of gloves they can find, and go scour the coast, lakes, rivers and their surroundings, picking up what we throw out the rest of the year.

Image via coastal.ca.gov

The Cleanup Day – put on by the California Coastal Commission – draws nearly 60,000 people each year. In Orange County alone, 7,053 volunteers picked up a staggering 64,037 pounds of trash and 3,636 pounds of recyclables last year. It’s quite an impressive event, even being hailed as Guinness World Record’s “largest garbage collection”.

Statewide, about 1.2 million pounds of trash and recyclables were removed from California’s beaches, lakes, and waterways last year. Volunteers included families, community groups, corporate sponsors and lone do-gooders hoping to help.

After each clean-up session, volunteers are given data cards to help keep track of and tally the “harvest”, with the data being fed to the Coastal Commission. Up to now, the most bountiful of all items found are cigarette buds, accounting for almost 40 percent of the debris picked up since the Day was first organised, they report.

Even if styrofoam, cigarette butts and plastic debris are collected by the truck-load each year, there have been a lot of unexpected finds among them. Last year’s more spectacular “spoils” included an E.T. doll, a partially burned bike, a fake mustache, a prom dress in and even a bottle of medical marijuana – with some of the health boosting herb still inside.

If you’re aiming to get more than your feet wet, you can join the efforts of Dana West Marina in Dana Point, where about 90 divers will be pulling up trash from the bottom of the harbor – however, you’ll need a diver’s certificate to be able to join.

 “We should find some interesting stuff,” said Kelly Rinderknecht, organizer of the underwater effort.

Other sites in Dana Point include: Ocean Institute/Dana Point Marine Protected Area; Dana Point Yacht Club on-the-water Kayak Clean Up; Doheny State Beach and San Juan Creek; Salt Creek/Strand Beach; Dana Point Harbor Cigarette Butt Round-Up; and Capistrano Beach.

The California Coastal Commission agency aims to enforce the California Coastal Act of 1976, which extended the commission’s authority to protect the California coastline. It also strives to educate the public about environmental conservation and getting them involved with coastal stewardship.

 

To volunteer, go to: coastal.ca.gov