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The coastal squeeze

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Globally, coastal areas are being squeezed between rising seas on one side and human development on the other.  The average distance from the high waterline to the first built-up area with human structures or paved roads is less than 400 yards around the world.  The narrower a coast, the sooner rising sea levels cause problems.

Narrow coasts have reduced ability to defend against storm surges and other weather events.  Construction close to the sea makes coastal areas extra vulnerable.  Narrow coasts are also bad news for biodiversity.  A study by the Royal Netherlands Institute for Sea Research investigated plant diversity in both the Netherlands and the United States.  They found that the wider the coast was, the greater the plant diversity.

In Florida and Georgia, whenever coastal zones reached a couple of kilometers in width, diversity increased rapidly.  In the Netherlands, only coastal areas at least 3.8 kilometers wide reached their maximum plant diversity, but such areas are rare.  Dutch sand dune areas are typically no more than a kilometer wide, leaving plant diversity at no more than half the possible level.

Limited biodiversity in narrow coastal strips can be somewhat boosted by nature management but would benefit much more by spatial planning.  In the Netherlands, a spot called The Sand Motor is where a gigantic amount of sand was deposited off the coast in 2011.  Since then, natural forces have spread it along the coast.  Such coastal expansion could increase biodiversity.  Biodiversity is not a luxury.  It makes for a better future for coastal defense, a healthy drinking water supply, and a better human food supply.

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Coastal squeeze is bad for biodiversity, and for us!

Photo, posted June 21, 2017, courtesy of Mark Bias via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Self-healing concrete

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Concrete is the most widely used building material on Earth.  It has a dangerous and costly flaw:  it cracks easily.  Cracks in concrete can lead to inconvenient damage or to catastrophic structural failures such as collapses of buildings, bridges, or highways.

Concrete is made by mixing crushed stone and sand with powdered clay and limestone and adding water.  The mixture hardens and once set becomes extremely strong.  However, natural forces like freeze-thaw cycles, drying shrinkage, and heavy loads can cause cracks.  Even very tiny cracks can allow liquids and gases to seep into embedded steel reinforcements causing corrosion and weakness. 

For over 30 years, researchers have investigated microbe-mediated self-healing concrete.  It involves introducing microbial healing agents into cracks and injecting nutrients for the healing agents to produce repair materials.  It is not a very practical solution.

Researchers at Texas A&M University have developed a technique inspired by the behavior of lichen systems. Their system, like lichen, uses a combination of cyanobacteria which turns air and sunlight into food, and filamentous fungi, which produces minerals that seal the cracks. 

In lab tests, the paired microbes were able to grow and produce crack-filling minerals even in challenging environments such as concrete.  If it is possible to produce concrete that can heal itself, it would significantly reduce maintenance costs, extend its longevity, and even protect lives through increased safety.

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Cracking the Code: Deciphering How Concrete Can Heal Itself

Photo, posted May 21, 2009, courtesy of DesignMag via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Restoring oil well sites with moss

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Researchers at the University of Waterloo in Canada have developed a method for restoring peatlands at tens of thousands of oil and gas exploration sites in Western Canada. 

A well pad is a prepared area used for drilling oil or gas wells, encompassing the site where drilling equipment, wellheads, and related facilities are located.  Preparing well pads involves burying native peatland vegetation under clay or sand, thereby eliminating the ability of the peatland to sequester carbon as well reducing available habitat for wildlife.

Restoring well sites has typically involved planting trees or grasses to eventually establish forests or grasslands.  The Waterloo method returns a well pad to its condition before drilling occurred and is part of ongoing efforts to restore peatlands, which are known to be even more effective for sequestering carbon than tropical forests.

The Waterloo technique involves lowering the surface of a decommissioned well site and transplanting native mosses onto it to effectively recreate a peatland.    They tested the technique to scale at an entire well pad and found that it results in sufficient water for the growth of peatland moss across large portions of the study site.

The results suggest that re-establishment of peatland vegetation on lowered well pads is possible.  The researchers plan to continue monitoring the ecosystem in the study’s well pads to confirm that the transplanted mosses will be self-sustaining over the coming decades.  They will focus on increasing the amount of water that flows from surrounding natural peatlands into the converted well pads to further optimize soil moisture. 

This work could represent an important milestone in ecological restoration.

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Restoring oil wells back to nature with moss

Photo, posted November 6, 2014, courtesy of Chris Boyer / Kestrel Aerial Services via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Redefining the perfect beach

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The iconic image of the “perfect” tropical beach is fine white sand, a few coconut palm trees, a gently sloping beach, and unobstructed views of the blue sea.  This image came about to a great extent from fascination with Polynesian scenery at the time of World War II.   And because of this imagery, beach resorts around the world have tried to achieve this look, often by reengineering and altering natural ecosystems to meet this artificial standard of perfection.

But natural tropical and subtropical beaches with their mangrove forests and seagrass meadows are complex ecosystems that support biodiversity, provide protection from storms, and capture carbon in significant amounts from the atmosphere.

With all this relandscaping of beaches, by the end of the 20th century, 35% of the world’s mangrove forests and 29% of its seagrasses were gone.  Mangroves sequester 10 times more carbon than mature tropical forests and sea grass can pull in up to 15 times as much.

In recent years, some resort developers are starting to embrace having beachscapes in their more natural states.  They are planting or preserving native vegetation and allowing sea grass to flourish.  The Six Senses Laamu resort in the Maldives, a major luxury tourist destination, was a trendsetter in this way. 

Coconut palms do little to prevent sand erosion, block wind, or even provide much shade.  In a warming world with increasingly powerful storms, they offer little protection for the world’s beaches.  They are not even native to the Caribbean, where they are now ubiquitous, having been introduced by Europeans.

Many resort developers are now rethinking the description of the perfect beach.

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Your Resort’s ‘Perfect’ Beach Is a Lie

Photo, posted March 2, 2011, courtesy of Breezy Baldwin via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sand mining and the environment

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Sand mining is the world’s largest mining endeavor.  It is responsible for 85% of all mineral extraction.  It is also the least regulated, possibly the most corrupt, and likely the most environmentally destructive.  Sand is the second-most exploited natural resource in the world after water.  Its global use has tripled in the past two decades.  More than 50 billion tons of sand is extracted from the environment each year.

Sand plays a critical role in much of human development around the world.  It is a key ingredient of concrete, asphalt, glass, and electronics.  It is relatively cheap and relatively easy to extract.  But we use enormous amounts of it.

Sand mining is a major threat to rivers and marine ecosystems.  It is linked to coastal erosion, habitat destruction, the spread of invasive species, and damage to fisheries. 

The harm from sand mining is only beginning to attract widespread attention.  A recent study by an international group of scientists published in the journal One Earth identifies        threats posed by sand mining.  Sand extraction in marine environments remains largely overlooked, despite sand and sediment dredging being the second most widespread human activity in coastal areas after fishing.

Sand is generally seen as an inert, abundant material, but it is an essential resource that shapes coastal and marine ecosystems, protects shorelines, and sustains both ecosystems and coastal communities.  Sand extraction near populated coastlines is particularly problematic as climate change makes coastlines increasingly fragile.

Like all other resources on our planet, even sand cannot be taken for granted.  It must be responsibly managed.

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The rising tide of sand mining: a growing threat to marine life

Photo, posted February 7, 2013, courtesy of Pamela Spaugy / U.S. Army Corps of Engineers via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rainfall and sea turtles

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There are seven species of sea turtles that inhabit the world’s oceans. Six of the seven sea turtle species – all of them except the flatback – are present in U.S. waters, and are listed as threatened or endangered under the Endangered Species Act. 

Sea turtles, which have been around for more than 100 million years, spend the majority of their lives in the ocean, but they do periodically come ashore to nest.  Female sea turtles lay their eggs in the sand and then return to the ocean.  Survival odds for sea turtle hatchlings are quite bleak.  In fact, only one out of every 1,000 makes it to adulthood. 

Research shows that both air and sand temperatures are critical for sea turtle hatchling development.  Cooler temperatures produce larger, heavier hatchlings with more males.  Hatchling size matters because larger hatchlings, which can move faster, are more likely to survive because they spend less time on risky beaches.  But rising temperatures might shorten incubation periods, and erratic rainfall can disrupt growth, potentially affecting survival.

A new international study by researchers from Florida Atlantic University and the University of Tübingen in Germany found that fluctuating rainfall patterns have a greater impact than changes in air temperature on sea turtle hatchling development. 

The results, which were recently published in the journal BMC Ecology and Evolution, reveal that the impact of rainfall varies between species.  As climate change shifts rainfall patterns, the impact on sea turtle nesting sites suggests that global conservation strategies for some species – like loggerhead and green sea turtles – likely need to be updated.

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Rain or Shine? How Rainfall Impacts Size of Sea Turtle Hatchlings

Sea Turtle

Photo, posted August 27, 2015, courtesy of USFWS/Orsulak via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Recycling cement

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Concrete is the second-most-used material on the planet.  Only water is used more.  Producing concrete is responsible for 7.5% of human-produced carbon dioxide emissions.  So, finding a cost-effective way to reduce these emissions is a major challenge in the face of ever-growing global demand for concrete.

Researchers at Cambridge University have found that used cement is an effective substitute for lime flux, which is an essential material used in steel recycling that results in a waste product called slag.  When lime is replaced with used cement, the end product instead is recycled cement that can be used to make new concrete.

The process does not add any significant costs to concrete or steel production and significantly reduces the emissions associated with both.

Concrete is made from sand, gravel, water, and cement.  Cement is made by a process called clinkering, in which limestone and other materials are heated to 2,600 degrees Fahrenheit.  The process converts the materials into cement but releases large amounts of CO2 as limestone decarbonates into lime. 

Cambridge researchers found that using cement clinker and iron oxide instead of lime works well in steel recycling.  Crushing old concrete and taking out the sand and stone results in a cement that is reactivated by the recycling furnace to produce a material with excellent properties. 

Recent tests by the Materials Processing Institute showed that recycled cement can be produced at scale in an electric arc furnace.  Ultimately, this method could produce zero emission cement if the electricity for the furnace comes from renewable sources.

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Cement recycling method could help solve one of the world’s biggest climate challenges

Photo, posted July 18, 2011, courtesy of Kenta Mabuchi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Groundwater loss

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Groundwater is the water found underground in the cracks and spaces in soil, sand, and rock.  It is held in aquifers and bubbles up naturally into springs, streams, and rivers, but also is pumped out for use by people.  Groundwater provides almost half the drinking water in the U.S. and is a main source of water for agriculture.

The world’s supply of groundwater is steadily declining.  The combination of climate change and human population growth is increasingly diminishing groundwater.

A study by the Desert Research Institute published in the journal Nature Communications has mapped the global permanent loss of aquifer storage capacity for the first time.  Computer modeling with advanced machine learning techniques has provided a detailed picture of the world’s groundwater situation.

The study found that global aquifer storage capacity is disappearing at a rate of 10 miles a year, about the size of 7,000 Great Pyramids of Giza.  The loss of groundwater storage is permanent, forever reducing the amount of water that can be captured and stored because the pumping of groundwater can cause the ground surface above to sink, collapsing the space where water can be stored.

About 75% of this subsidence is occurring over cropland and urban regions.  The United States, China, and Iran account for most of the global groundwater storage loss but many other places in the Middle East and Asia are experiencing significant groundwater withdrawal as well.

Most regions of the world do not have monitoring programs for groundwater pumping.  The study underscores the need to better understand this issue on a global scale and take appropriate action before it is too late.

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Scientists Map Loss of Groundwater Storage Around the World

Photo, posted August 7, 2015, courtesy of NRCS Oregon via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Lots of female turtles

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Green sea turtles were listed under the Endangered Species Act in 1978.  Since that time, there have been conservation measures put in place in many locations.  One such place is Florida, where restrictions on beachfront development and careful monitoring of turtle nests has helped to get hatchlings safely into the water.  A gill net ban in 1995 sharply reduced the number of young turtles killed by fishing gear.

All of this has resulted in what is described as an explosion in turtle populations in Florida.  Volunteers monitoring the 2023 nesting season on Florida’s beaches have counted more than 74,000 nests.  That beats the previous record – set in 2017 – by an incredible 40%.

Unfortunately, this does not represent a guaranteed great future for the species.  Sea turtles are particularly sensitive to the warming climate.  The sex of a baby sea turtle is not determined by DNA, but rather by the temperature of the sand in which its egg develops.  Cooler temperatures mean more males; warmer ones mean more females.

In recent years, the proportion of male green sea turtles has dwindled substantially.  In the past few seasons, between 87 percent and 100 percent of the hatchlings tested in Florida have been female.

In the short term, the skewed sex ratio might be a boon for the species.  Lots of females laying lots of eggs means lots of turtles.  Sea turtles don’t reach sexual maturity until their twenties or thirties.  So, for the next few decades, there are likely to be growing numbers of turtle nests.  But down the line, there is going to be a real problem.  Where will for all the female turtles find the mates to populate the species in the future?

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Florida Turtle Nests Are Recovering. When They Hatch, Expect Mostly Girls.

Photo, posted October 5, 2011, courtesy of Keenan Adams / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Storing Energy In Abandoned Mines | Earth Wise

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An international study led by researchers from Austria has developed a novel way to store energy by transporting sand into abandoned underground mines.  The technique is called Underground Gravity Energy Storage or UGES.

As the world deploys growing amounts of wind and solar energy, it is increasingly important to find ways to accessibly and efficiently store that energy to eliminate the inherent variability of the generation.  There are many ways to store energy on a short-term basis – most commonly in batteries – but cost-effective long-term storage is still in its early stages.

The UGES technique generates electricity by lowering sand into an underground mine thereby converting the potential energy of the sand into electricity by the same regenerative braking effect used in hybrid and electric cars.  The lowering sand operates a generator.   Storing energy is accomplished by lifting the sand from the mine with electric motors to an upper reservoir where it is ready for the next cycle.  By its nature, this storage technique has an indefinite duration, unlike batteries, for example, which lose energy to self-discharge.

The main components of UGES are the mineshaft, motor/generator, sand storage sites, and mining equipment.  The deeper and broader the mineshaft, the more power can be extracted from the plant, and the larger the mine, the more energy can be stored. Mines generally already have the basic infrastructure needed and are connected to the power grid.  The researchers estimate that there is global potential of 7 to 70 TWh of storage. Total global generating capacity is currently at the lower end of that range.

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Turning abandoned mines into batteries

Photo, posted October 21, 2020, courtesy of Christine Warner-Morin via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

New York Is Sinking | Earth Wise

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The rising seas represent a threat to coastal cities across the globe.  Increasing that threat is the fact that most global cities are slowly sinking as the earth beneath them settles and groundwater is removed.   Another factor that has seldom been considered is that in major metropolises, the weight of large, concrete-and-steel skyscrapers may be hastening the sinking.

A new study by the U.S. Geological Survey published in the journal Earth’s Future estimated the weight of every building in New York City – 1.085 million of them – which they determined to add up to 1.68 trillion pounds – and estimated the downward force of those structures across the city.

The study found that buildings have a greater effect in areas that are rich in clay compared with those areas where sand or bedrock predominate.  The softer the soil, the more compression there is from buildings.  It wasn’t a mistake to build large buildings in New York, but it is important to understand that doing so pushes down the ground more and more.

The study determined that New York is sinking by around 1 to 2 millimeters each year, although some areas are sinking much faster.  The researchers say that cities must plan for future sinking, which will exacerbate the impact of rising seas. Sea levels are rising 1 to 2 millimeter each year, so the subsidence caused by the weight of buildings is equivalent to moving a year ahead in time with regard to rising ocean levels.  This is not a cause for immediate panic, but it is important to understand that this ongoing process only increases the risk of inundation from flooding.

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New York City Sinking Under Weight of Skyscrapers

Photo, posted January 29, 2016, courtesy of Always Shooting via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Concrete And Carbon | Earth Wise

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After water, concrete is the world’s second most consumed material.  It is the cornerstone of modern infrastructure.  Its production accounts for 8% of global carbon dioxide emissions.  The carbon dioxide is a result of chemical reactions in its manufacture and from the energy required to fuel the reactions.

About half of the emissions associated with concrete come from burning fossil fuels to heat up the mixture of limestone and clay that ultimately becomes ordinary Portland cement.  These emissions could eventually be eliminated by using renewable-generated electricity to provide the necessary heat.  However, the other half of the emissions is inherent in the chemical process.

When the minerals are heated to temperatures above 2500 degrees Fahrenheit, a chemical reaction occurs producing a substance called clinker (which is mostly calcium silicates) and carbon dioxide.  The carbon dioxide escapes into the air.

Portland cement is then mixed with water, sand, and gravel to produce concrete.  The concrete is somewhat alkaline and naturally absorbs carbon dioxide albeit slowly.  Over time, these reactions weaken the concrete and corrode reinforcing rebar.

Researchers at MIT have discovered that the simple addition of sodium bicarbonate (aka baking soda) to the concrete mixture accelerates the early-stage mineralization of carbon dioxide, enough to make a real dent in concrete’s carbon footprint.  In addition, the resulting concrete sets much more quickly.  It forms a new composite phase that doubles the mechanical performance of early-stage concrete.

The goal is to provide much greener, and possibly even carbon-negative construction materials, turning concrete from being a problem to part of a solution.

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New additives could turn concrete into an effective carbon sink

Photo, posted April 4, 2009, courtesy of PSNH via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Self-Deicing Roads | Earth Wise

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Driving on snowy or icy roads can be pretty dangerous.  That is why roads are salted or coated with sand to provide traction in icy weather.  But excessive use of these substances is bad for the environment and sometimes a storm will blow in before the roads can be coated.

In a paper published in the American Chemical Society Journal ACS Omega, researchers in China describe a method of adding microcapsules filled with a chloride-free salt mixture to the asphalt with which roads are paved.  The idea is to provide the road itself with long-term snow melting capabilities.

The researchers prepared a sodium-acetate salt and combined it with a surfactant, silicon dioxide, sodium bicarbonate, and blast furnace slag, which is a waste product from power plants.  The substances were reduced to a fine powder and then coated with a polymer solution to form tiny microcapsules.  The microcapsules were then used to replace some of the standard mineral filler in asphalt.

Lab experiments showed that the special additive lowered the freezing point of water on the asphalt to -6 degrees Fahrenheit.   The researchers estimated that a 2-inch-thick layer of the anti-icing asphalt would be effective at melting snow for seven or eight years.  A real-world pilot test of the coating on a highway offramp showed that it melted snow that fell on the road whereas an uncoated road required snow removal operations.

According to the researchers, given the cost of materials used for the coating and its potential useful lifetime, it could be a practical and economic enhancement for wintertime snow and ice removal.  Maybe we’ll someday have roads that can fairly often deice themselves. 

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Keeping drivers safe with a road that can melt snow, ice on its own

Photo, posted April 8, 2007, courtesy of the Oregon Department of Transportation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Bengal Water Machine | Earth Wise

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Over the past three decades, the owners of 16 million small farms in the Bengal Basin of Bangladesh have been pumping shallow groundwater during dry seasons to irrigate rice paddies.  By lowering groundwater levels in this way during the dry season, the ability of leakage from rivers, lakes, and ponds to replenish the groundwater was greatly enhanced.   Capturing surface water not only improved the recovery of groundwater levels but only helped to reduce flooding during monsoons.

The net result of this enormous collective groundwater pumping by millions of farmers has been the creation of vast natural reservoirs underground that are comparable to what is contained by many of the world’s largest dams.   This system of sustaining irrigation has transformed what was previously a famine-prone country into a food-secure nation.

The details of this remarkable transformation have been laid out in a study by University College London recently published in the journal Science.  According to the study, over the course of 30 years, more than 75 cubic kilometers of fresh water was captured by this process, which is equivalent to the combined reservoirs of China’s Three Gorges Dam and the Hoover Dam in the U.S.

The authors of the study described the water cycling process as “The Bengal Water Machine” and argue that it can be a sustainable alternative to conventional approaches to seasonal river flow storage for irrigation, which typically involve dams and reservoirs.  Such approaches are difficult to implement in densely populated alluvial plains where sand, silt, and clay are laid down by annual floodwaters. 

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Millions of farmers “replumb” world’s largest delta

Photo, posted February 2, 2010, courtesy of Melanie Ko via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Trouble For The Outer Banks | Earth Wise

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The Outer Banks are a series of barrier islands off the coast of North Carolina that separate the Atlantic Ocean from the mainland.  They are a very popular tourist destination featuring open-sea beaches, state parks, shipwreck diving sites, and historic locations such as Roanoke Island, the site of England’s first settlement in the New World. There is also Kitty Hawk, the site of the Wright Brothers’ first flights.

The ribbon of islands is nearly 200 miles long.  Some of them are low and narrow and are only a few feet above sea level.  Many are especially vulnerable to Nor’easters in the winter and hurricanes in the summer.  The collision of warm Gulf Stream waters and the colder Labrador current helps to create dangerous shoals and some of the largest waves on the East Coast.

Over the years, developers have added billions of dollars’ worth of real estate to the Outer Banks.  Rising sea levels and increasingly frequent storms threaten the barrier islands of the Outer Banks.  Beach-front cottages have tumbled into the ocean for as long as people have built them in the Outer Banks but now they are falling at a greater rate and more and more are in danger.

The Department of Transportation has spent nearly $100 million dollars to keep NC12, the highway connecting the string of islands, open to traffic.  Three new bridges built to traverse inlets opened by storms and bypassing rapidly eroding shorelines raised the cost by another half a billion dollars.

There are many other measures such as pumping sand into eroded areas going on in the Outer Banks, but ultimately, all of the measures may not be enough to deal with rising sea levels and more powerful storms.

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Shifting Sands: Carolina’s Outer Banks Face a Precarious Future

Photo, posted August 31, 2011, courtesy of NCDOT Communications via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sand From Mining Waste | Earth Wise

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The natural resources people use the most are air and water.  It may come as a surprise that in third place is sand.  Sand is used to make glass, computer chips, toothpaste, cosmetics, food, wine, paper, paint, plastics, and more.  It is estimated that 50 billion tons of sand are used each year.

Concrete is 10% cement, 15% water, and 75% sand.  The concrete required to build a house takes on average 200 tons of sand, a hospital uses 3,000 tons, and a mile of a highway requires 15,000 tons.

One would think that there is no shortage of sand, but we are using it up faster than the planet can make it and the extraction of sand from seas, rivers, beaches, and quarries has negative impacts on the environment and surrounding communities.  For example, removing sand leads to erosion in riverbanks, significantly increasing the risk of flooding in some places.

A potential strategy to reduce the impact of extracting sand to meet society’s growing need for is also a strategy for helping to reduce the production of mineral mining waste, which is the largest waste stream on the planet.  Mining produces between 33 and 66 billion tons of waste material each year.

A new study by researchers in Switzerland and Australia looked at the potential for using mining waste as a source of so-called ore-sand.  Sand-like material left over from mining operations could be used for many current applications for sand.  Separating and repurposing these materials before they are added to the waste stream would not only reduce the volume of waste being generated by mining operations but would also create a responsible new source of sand.

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Solution to world’s largest waste stream: Make sand

Photo, posted October 22, 2005, courtesy of Alan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Rising Seas In The Maldives | Earth Wise

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The Republic of Maldives is an archipelago in the Indian Ocean, southwest of Sri Lanka and India and about 400 miles from the Asian mainland.  It is one of the world’s most geographically dispersed sovereign states, the smallest Asian country by land area, and, with a little over 500,000 inhabitants, the second least populous country in Asia.  With its spectacular scenic beauty, it is also a premier tourist attraction.

With more than 80% of its 1,190 coral islands standing less than 1 meter above sea level, the Maldives has the lowest terrain of any country in the world.  As a result, the Maldives is particularly vulnerable to the sea level rise associated with climate change.

Some studies predict a grim future for the Maldives as well as other low-lying islands.  One study concluded that the islands could become uninhabitable by 2050 as wave-driven flooding becomes more common and freshwater becomes limited.

The Maldives government has explored plans to purchase land on higher ground in other countries.  Planners are also working to enhance the resilience of the country’s current islands.   An example is Hulhumalé, a newly constructed artificial island northeast of the country’s capital, Malé.

Construction of Hulhumalé began in 1997 and it now covers 1.5 square miles, making it the fourth largest island in the Maldives.  Its population is now more than 50,000, with more than 200,000 expected to eventually move there.  The new island, built by pumping sand from the seafloor onto a coral platform, rises about 2 meters above sea level.  The extra height could make the new island a refuge for Maldivians driven off lower-lying islands by the rising seas.

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Preparing for Rising Seas in the Maldives

Photo, posted June 15, 2009, courtesy of Elena N via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Living On Trash | Earth Wise

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Litter is persistent and widespread in rivers worldwide.  The world’s major rivers and estuaries are hotspots for plastic waste.  Trash and microparticles wash down tributaries and build up before rivers enter oceans.

New research published in the journal Freshwater Biology has found that as this waste accumulates, aquatic river species like insects and snails are increasingly choosing to settle on plastic rather than on natural features like rocks and fallen branches.

Researchers from the University of Nottingham in the UK collected plastic waste from three rivers in eastern Britain along with rocks from the same rivers.  Their analysis of all the macroinvertebrates on the items’ surfaces found that the surfaces of plastic waste items had nearly four times the diversity of the small animals as did the rocks.  In addition, the more complex the plastic’s surface was, the higher the diversity.

The growing abundance of plastic waste coincides with a decline in natural habitat features in urban rivers.  This is a result of increasing amounts of sedimentation from development that blankets riverbeds in silt and sand, restricting the supply and movement of rocks, fallen tree branches, and aquatic plants.

Clearly litter can serve as a place for various species to colonize, but trash is not a good environment for them.  Trash can release toxic chemicals and entangle animals.  Microplastics pose risks for the animals if ingested.

Estimates are that between 1.15 and 2.41 million tons of plastic waste enter the ocean every year from rivers around the world.  Natural habitats have become rare in urban rivers.  River ecosystems built around piles of trash are not a good thing.

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As Plastic Pollution in Rivers Gets Worse, Species Are Increasingly Living on Litter

Photo, posted August 17, 2010, courtesy of Renee_McGurk via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Global Warming And Sea Turtle Births | Earth Wise

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Climate change is a serious threat to species whose sex is determined by temperature.  Among these are sea turtles.  Whether marine turtles are born male or female turns out to depend on the temperature of their nest during incubation.

Sea turtle nests need to be around 84.6 degrees Fahrenheit on average to produce a 50:50 sex ratio for embryos developing in eggs.  If temperatures are higher, embryos predominantly become female.  There is a transitional range of temperatures over which both males and females are produced.  Below that range, only males are produced; above that range, only females are produced.

According to recent research published in the journal Conservation Science and Practice, sand temperatures along the Red Sea exceeded the 84.6-degree threshold in all but one of the sites studied.  Some sites measured nearly 96 degrees.  The Red Sea region is home to five of the world’s seven species of sea turtles, including endangered green turtles and critically endangered hawksbill turtles.

Skewing the sex distribution of a species is a serious threat to the future survival of the population.

The Red Sea findings are similar to observations around the world.  In Florida, sea turtle hatchlings were born 100% female in seven out the past 10 years, and in the other three years, males only made up 10-20% of the brood.  In Australia’s Raine Island, the largest green turtle nesting ground in the Pacific Ocean, the ratio of female to male turtle hatchlings in 2018 was 116:1.

Marine turtles have been around since the late Triassic period and have adapted to previous climate shifts.  But the rapid pace of human-driven climate change is threatening the future survival of these creatures.

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Rising Temperatures Driving a Shift to All-Female Sea Turtle Populations

Photo, posted in October, 2005, courtesy of Frank_am_Main via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving The Arctic Permafrost | Earth Wise

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Permafrost is frozen ground – a combination of soil, rock, sand, and ice – that remains at or below freezing for at least two consecutive years.  Approximately 25% of the land in the Northern Hemisphere meets this criterion, the majority of which can be found in northern Russia, Canada, Alaska, Iceland, and Scandinavia.

But as a result of the changing climate, these permafrost soils in the Arctic are beginning to thaw.  As they thaw, large quantities of greenhouse gases could be released, further accelerating climate change.  

A new study recently published in the journal Scientific Reports explores an unconventional countermeasure: resettling massive herds of large herbivores.  According to researchers from the University of Hamburg in Germany, herds of horses, bison, and reindeer could be used to significantly slow the loss of permafrost soils. 

During Arctic winters, the air temperature is often much colder than the permafrost.  Thick layers of snow can insulate the ground from the frigid air, keeping the permafrost warm (relatively speaking). But when the snow cover is scattered and compressed by the hooves of grazing animals, the insulating effect is reduced, which intensifies the freezing of the permafrost.

If climate change continues unchecked, the research team expects permafrost temperatures to rise 3.8-degrees Celsius.  This would result in half of the world’s permafrost thawing by the year 2100.  But in contrast, researchers found that the permafrost would only warm by 2.1 degrees Celsius with the resettled animals.  This 44% reduction in permafrost temperature would preserve 80% of the existing permafrost by 2100.

Natural manipulations of ecosystems could have tremendous results. 

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How horses can save the permafrost

Photo, posted July 17, 2012, courtesy of Kitty Terwolbeck via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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