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New Orleans is sinking

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As climate change accelerates, rising sea levels are putting coastal communities at greater risk of flooding and storm surge. Driven by melting glaciers and warming oceans, global sea levels are rising at an increasing rate. For low-lying cities like New Orleans, even small increases can have serious consequences. And that risk is compounded by another factor: the land itself is sinking.

Much of New Orleans already sits at or below sea level, and parts of the city and its surrounding wetlands are gradually sinking. While most of the city remains stable, a new study by researchers from Tulane University suggests that sections of the region’s $15 billion post-Katrina flood protection system may require ongoing upgrades to keep pace with long-term subsidence.

The study, recently published in the journal Science Advances, used satellite data to track changes in ground elevation across Greater New Orleans between 2002-2020.  The researchers found that some areas – including neighborhoods, wetlands, and even concrete floodwalls – are sinking by more than an inch each year. In some spots, the land is dropping by nearly two inches annually.

Alarmingly, some of the concrete floodwalls and levees built to protect the city after Hurricane Katrina are themselves sinking. In a few cases, they are losing elevation faster than sea levels are rising, reducing their capacity to block storm surges.

The study highlights how satellite monitoring can play a critical role in guiding infrastructure maintenance and urban planning – not just in New Orleans – but in vulnerable coastal cities around the world.

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Vertical land motion in Greater New Orleans: Insights into underlying drivers and impact to flood protection infrastructure

Photo, posted September 22, 2010, courtesy of U.S. Army Corps of Engineers via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

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

Natural solutions for disappearing islands

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Atoll islands are made from sediment produced by corals, clams, snails, and varieties of algae that secrete carbonate.  Under the right conditions, over time, fragments of coral skeletons, shells, and other sediments made by marine life are piled up by waves.  Eventually, islands are formed – some large and some small.  Atoll islands are home to a diversity of human cultures and are important refuges for a quarter of the world’s seabirds as well as numerous nesting sea turtles and tropical plants.

Rising sea levels – the rate of which has more than doubled over the past 30 years – are a mounting challenge for atoll islands.  And by the end of this century, sea level is projected to rise between 11 and 40 inches, depending on the world’s actions with regard to greenhouse gas emissions.

The ability of atoll islands to persist depends on the health of their ecosystems and the extent to which their natural processes have been disrupted by human activity.  To protect the most vulnerable islands, some researchers now propose using nature-based solutions – like restoring and protecting coral reefs and native forests.

Reclaiming seabird habitat can help reefs persist and restore the resilience of atoll islands.  Seabird guano washes off islands and into reefs, providing nutrients that boost coral growth and fish populations. 

Nature-based solutions cannot help the most urbanized atoll islands.  These islands have already irreversibly lost their natural adaptive capacity.  For those places, engineered approaches such as concrete seawalls are needed.

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How Natural Solutions Can Help Islands Survive Sea Level Rise

Photo, posted July 3, 2014, courtesy of Roderick Eime / MG Media via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Nature: An important climate ally

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Nature is often seen as a victim of climate change, but it’s also one of the most powerful tools we have to fight it. Natural ecosystems, such as forests, wetlands, grasslands, oceans, and soils, absorb and store massive amounts of carbon dioxide. These ecosystems not only help reduce the concentration of greenhouse gases in the atmosphere, but they also regulate temperatures and provide buffers against extreme weather.

One of the most effective strategies for mitigating climate change is simply protecting and restoring these natural areas. For example, mangrove forests – those coastal wetlands filled with tangled, salt-tolerant trees – sequester carbon at high rates and help protect coastal communities from storm surges and rising seas.  Peatlands – another type of wetland – store more carbon than all the world’s forests combined – despite only covering 3% of Earth’s land surface.  Global restoration efforts are underway, from replanting mangroves in Southeast Asia to rewetting degraded peatlands in Europe.

Creating urban green spaces like parks and community gardens, restoring forests through native tree plantings, and adopting sustainable agricultural practices like cover cropping and agroforestry are all proven to be low-cost, high-impact climate solutions. 

While nature-based solutions are gaining recognition, they remain critically underfunded, according to a recent United Nations report.  Closing this gap is essential to unlocking nature’s  full climate potential.

Investing in nature isn’t just about preserving Earth’s natural beauty.  It’s a practical strategy for building a more resilient and sustainable future.

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Mangrove forests and rising seas

Financing Nature-based Solutions for a better future

Finding peatlands

The Importance Of Urban Green Spaces

Photo, posted October 23, 2011, courtesy of the Everglades National Park / NPS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rising seas are destroying buildings

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Alexandria is the second largest city in Egypt and is the largest city on the Mediterranean coast.  Its history goes back over 2,300 years and it was once home to a lighthouse that was among the Seven Wonders of the Ancient World and a Great Library that was the largest in the ancient world.  The modern city has more than 6 million residents but still has many historic buildings and ancient monuments.  But perhaps not for long.

Rising seas and intensifying storms are taking a toll on the ancient port city.  For centuries, Alexandria’s historic structures have endured earthquakes, storm surges, tsunamis, and more.  They are truly marvels of resilient engineering.  But now, climate change is undoing in decades what took millennia for humans to create.

Over the past two decades, the number of buildings collapsing in Alexandria has risen tenfold.   Buildings are collapsing from the bottom up as a rising water table weakens soil and erodes foundations.  Since 2001, Alexandria has seen 290 buildings collapse.  Comparing present-day satellite imagery with decades-old maps, the authors of a study by the Technical University of Munich have tracked the retreat of Alexandria’s shorelines to determine where seas have intruded into groundwater. The authors say that more than 7,000 buildings in Alexandria are at risk.  They call for building sand dunes and planting trees along the coast to block encroaching seawater.

The true cost of this gradual destruction goes far beyond bricks and mortar.  This is the gradual disappearance of historic coastal cities.  Alexandria is a warning for such cities around the world.

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In This Storied Egyptian City, Rising Seas are Causing Buildings to Crumble

Photo, posted September 11, 2012, courtesy of Sowr via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sharks and rays in a warming world

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Sharks and rays belong to a group of cartilaginous fish called elasmobranchs, which have been swimming in the world’s oceans for 450 million years. The resilient species have survived five mass extinction events, and are older than dinosaurs, trees, and Mount Everest. 

But despite their resilience, many species of sharks and rays today are threatened by human activities, including overfishing, habitat loss, and climate change.  In fact, according to a new study led by researchers from the University of Vienna in Austria, more than one third of the shark and ray species known today are severely under threat. 

The study, which was recently published in the journal Biology, found that higher carbon dioxide levels were having a negative effect on sharks and rays, ranging from impacts on the animals’ senses to changes in the skeleton during embryonic development.  An examination of fossil records found that higher CO2 levels had contributed to the extinction of individual shark and ray species in the past. 

But the study also found that global warming could be creating opportunities for sharks and rays.  Rising sea levels and higher temperatures have historically expanded shallow coastal habitats and warm waters, supporting species biodiversity.

But according to the research team, the rapid environmental changes, combined with the impacts from human activities, outpace the ability of sharks and rays to adapt, making it unlikely that they will benefit from global warming.

Protecting sharks and rays is crucial not only for their survival but also for maintaining entire ocean ecosystems. Without top predators, these ecosystems could collapse, impacting both marine life and the people and industries that depend on it.

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Sharks and rays benefit from global warming – but not from CO2 in the Oceans

Myths About Sharks and Rays

Photo, posted November 27, 2007, courtesy of Laszlo Ilyes via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Mangrove forests and rising seas

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Mangrove forests play a vital role in the health of our planet.  They protect coastal regions by acting as natural barriers against storms, erosion, and flooding. The intricate root systems of mangrove forests, which allow the trees to handle the daily rise and fall of tides, also serve as biodiversity hotspots, attracting fish and other species seeking food and shelter from predators.

But mangrove forests around the world are under increasing threat from deforestation, coastal development, and climate change.  In fact, according to a new study led by researchers from Northumbria University in England, the mangrove trees in the Maldives are actually drowning. 

The research, which was recently published in the journal Scientific Reports, found that sea levels around the Maldives rose more than 1.18 inches per year from 2017 to 2020.  An unusually intense climate phenomenon, known as the Indian Ocean Dipole, occurred toward the end of this period, causing warmer sea surface temperatures and an increase in sea level in the Western Indian Ocean. 

While mangrove forests can naturally keep pace with gradually rising seas, this rate of sea level rise was too fast.  The rising sea level meant that seawater effectively flooded mangrove forests, causing many trees to lose their resilience and die.  Some islands in the Maldives have lost more than half of their mangrove cover since 2020.

Since mangrove forests also store massive amounts of carbon, the research team fears that the loss of mangrove forests could release large amounts of carbon, further accelerating climate change.

The researchers warn that the findings in the Maldives could have implications for coastal ecosystems around the world.

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“Drowning” mangrove forests in Maldives signal global coastal threat

Photo, posted February 11, 2015, courtesy of Alessandro Caproni via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Limiting global warming

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A pressing question from the recently concluded 29th annual United Nations Climate Change Conference in Azerbaijan is how to transition away from fossil fuels and speed up climate mitigation in line with the 1.5 °C global warming target.

Keeping global average temperatures below 1.5 °C above pre-industrial levels is crucial to avoid the most severe impacts of climate change, including extreme weather, rising seas, biodiversity loss, and disruptions to food and water security. 

According to a new study by researchers from Stockholm University, Chalmers University of Technology, and Uppsala University in Sweden, it is still possible to limit global warming to 1.5 °C.  But the study found that the United States, the European Union, and 16 other countries will have to exceed their own current targets in order to achieve this global goal.  

The study, which was recently published in the journal Nature Communications, introduced an “additional carbon accountability” indicator, which quantifies countries’ responsibility for mitigation and carbon dioxide removal in addition to achieving their own targets.

The study identified 18 countries that should be accountable for increasing their ambitions to stay within their equal per capita share of the global carbon budget for 1.5 °C.  Additional carbon accountability is highest for the United States and China, and highest per capita for the United Arab Emirates, Russia, Saudi Arabia, and the U.S.

Failure to limit global warming risks catastrophic impacts of climate change.

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COP29: Possible to limit climate change to 1.5°C – if EU and 17 other countries go beyond their own targets

Photo, posted December 27, 2015, courtesy of Gerry Machen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon levies for shipping

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The global shipping industry is responsible for 90 percent of world trade.  The ships crossing the world’s oceans emit nearly 3% of the global greenhouse gas emissions caused by human activity that are contributing to climate change.  Among the effects of climate change are sea level rise, which is threatening the very existence of small island nations.

One such nation is Tuvalu, which is a group of islands in the South Pacific.  Tuvalu has a total landmass of just 10 square miles, and sea level there is rising 1.5 times faster than the global average.  Predictions are that within 50 to 100 years, low-lying islands like those of Tuvalu could be fully submerged by the ocean.

Representatives from six Pacific Island states and a growing number of Caribbean nations known as the 6Pac+ Alliance are urgently calling upon the International Marine Organization to enact a mandatory universal levy of $150 per ton of shipping emissions from large commercial vessels. 

Most marine vessels typically run on highly polluting heavy fuel oil.  Burning really filthy fuel is the cheapest way to cross the oceans.  There are alternatives including entirely carbon-free technologies, but they will be expensive to implement and utilize.  The cost of shipping would undoubtedly go up and be especially felt by small island nations and in developing countries where most food is imported.

The idea behind putting a price on ships’ carbon emissions is to both provide a financial incentive for the shipping industry to reduce its emissions and provide revenue for countries that incur costs from dealing with rising seas.

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Pacific and Caribbean Island Nations Call for the First Universal Carbon Levy on International Shipping Emissions

Photo, posted November 23, 2006, courtesy of Stefan Lins via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Artificial reefs

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The coral reefs that surround tropical islands are a refuge for a wide variety of marine life and also form a natural buffer against stormy seas.  The changing climate is bleaching coral reefs and breaking them down.  Extreme weather events are becoming more common and are threatening coastal communities with flooding and erosion.

Researchers at MIT are designing architected reefs – sustainable offshore structures that mimic the wave-buffering effects of natural reefs and can also provide habitats for fish and other marine life.

There are already artificial reefs in a number of places used to protect coastlines.  These are typically made from sunken ships, retired oil and gas platforms, and even assemblies of concrete, metal, car tires, and stones.  Generally, it takes quite a lot of material to form an effective barrier to waves.

The MIT group has developed a cylindrical structure surrounded by four rudder-like slats.  Their experiments have shown that when this structure stands in the way of a wave, it efficiently breaks the wave and creates turbulent jets that dissipate the energy in the wave.  The engineers calculated that the new design could reduce as much wave energy as existing artificial reefs but use 10 times less material.

Based on the initial experiments with lab-scale prototypes, these artificial reefs would reduce the energy of incoming waves by more than 95%.

Coral reefs are only found in tropical waters, whereas these artificial reefs don’t depend on temperature and could be placed along any coastline for protection.  In a time of rising seas and increasingly frequent storms, these artificial reefs may be just what coastlines need.

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Artificial reef designed by MIT engineers could protect marine life, reduce storm damage

Photo, posted December 9, 2010, courtesy of Phoenix Wolf-Ray via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Protecting coastal areas with tidal range electricity generation

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Tidal range electricity generation uses the water level difference between high and low tides to operate generator turbines.  The method requires the construction of barrages and sluices to capture water during high tides and then release it during generation at low tide.  Tidal range generation is predictable renewable energy driven by the gravitational pull of the moon and sun.

It is only a practical scheme in those places that have large tidal ranges.  The largest tidal range in the world is in the Bay of Fundy in Canada.  The second largest is the Severn Estuary, in the UK.  Tidal ranges are large in many places around Britain’s coasts. But they are also vulnerable to flooding and surges from rising seas.

A new study by Lancaster University in the UK has found that the environmental and economic benefits are huge because tidal range barrages can protect coastal areas from flooding and sea level rise. With two-way generation and pumping, the full range of existing tides can be maintained to protect and support low-lying intertidal areas such as saltmarshes and mudflats. High tides can be limited to existing levels simply by closing sluices and running turbines and low tide levels can be maintained by pumping.  The study determined that with modern technology and operating procedures, these so-called estuarine barrages may be the only practical way to protect vital coastal habitats.

Earlier work by the researchers found that tidal range projects under commercial consideration in the UK can produce about 5% of the country’s electricity use and additional projects are feasible for 4 or 5 times as much generation.

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How tidal range electricity generation can protect coastal areas from flooding

Photo, posted August 17, 2014, courtesy of Andrea via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Thousands of species threatened

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The International Union for the Conservation of Nature is an organization working in the field of nature conservation and sustainable use of natural resources.  The IUCN has been around for nearly 75 years and is the global authority on the status of the natural world and the measures needed to safeguard it.

In its latest accounting, the IUCN has determined that more than 44,000 species worldwide are threatened with extinction.  Among them, nearly 7,000 face an immediate threat from climate change.

The organization tracks 157,000 species to compile its Red List and found that climate change poses a growing threat to many kinds of wildlife. At particular risk are freshwater fish including Atlantic salmon, which are now classified as “Near Threatened.” 

In all, about 25% of freshwater fish are threatened with extinction.  This is in part driven by rising sea levels which causes saltwater to be driven up into rivers.  Some 41% of amphibians are threatened with extinction, in part due to more intense heat and drought.  Many populations of green turtles are at risk of extinction because of rising temperatures lowering hatch rates and rising sea levels flooding nests.

It isn’t just animals at risk.  For example, big leaf mahogany, one of the world’s most commercially sought-after timber trees, has moved from Vulnerable to Endangered on IUCN’s Red List.  Thousands of trees have been added to the Red List, many of which are timber species, and some are keystone species in forests.

Endangered and threatened species are often irreplaceable parts of ecosystems which provide humans with many services that only the natural world can.

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More Than 44,000 Species Now Threatened With Extinction

Photo, posted November 22, 2010, courtesy of E. Peter Steenstra/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Too hot for people

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The effort to mitigate the effects of climate change has a goal of keeping the global temperature increase below 1.5 degrees Celsius above preindustrial levels.  To date, the average global temperature has increased by more than 1 degree.  We hear about rising sea levels, powerful storms, and various other alterations in climate and weather patterns.  A new interdisciplinary study by three institutions looked at the impact of surpassing the 1.5-degree level upon people being able to withstand heat and humidity.

Humans can only withstand certain combinations of heat and humidity before their bodies begin to experience heat-related health problems such as heat stroke and heart attacks. 

In human history, temperatures and humidity that exceed human limits have been recorded only a limited number of times and only for a few hours at a time, in the Middle East and Southeast Asia.

According to the new study, if global temperatures increase by 2 degrees Celsius above preindustrial levels, the 2.2 billion residents of Pakistan and India’s Indus River Valley, the one billion people living in eastern China, and the 800 million residents of sub-Saharan Africa will annually experience many hours of heat surpassing human tolerance.

If the warming continues further to 3 degrees, heat and humidity levels that surpass human tolerance would affect the Eastern Seaboard and the middle of the US from Florida to New York and from Houston to Chicago.

The worst heat stress will occur in regions that are not wealthy and that are experiencing rapid population growth.  But even wealthy nations will not escape from the expansion of conditions that are too hot for people.

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Climate-driven extreme heat may make parts of Earth too hot for humans

Photo, posted June 28, 2018, courtesy of Ivan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rivers And Climate Change | Earth Wise

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Our planet is heating up.  Scientists have concluded that the changing climate is primarily the result of increased greenhouse gas emissions from human activities.  Some of the effects of global climate change include thawing permafrost, rising seas, intensifying storms and wildfires, and warming oceans.   

According to a new study led by researchers from Penn State University, rivers are warming and losing oxygen even faster than oceans.  The study, which was recently published in the journal Nature Climate Change, found that warming occurred in 87% and oxygen loss occurred in 70% of the nearly 800 rivers studied.

The research team projects that within the next 70 years some river systems, especially those in the American South, will experience such low oxygen levels that the rivers could “induce acute death” for some fish species and threaten the aquatic diversity of river ecosystems. 

The research team used artificial intelligence and deep learning to analyze water quality data from nearly 800 rivers across the U.S. and central Europe.  The researchers found that rivers are warming up and deoxygenating faster than oceans, which could have serious implications for both aquatic life and humans.

While climate change has led to warming and oxygen loss in oceans and lakes around the world, the researchers did not expect to find warming and deoxygenation in shallower, flowing rivers.  Since life in water depends on temperature and dissolved oxygen, the researchers hope this study serves as a wake up call.  Warming and deoxygenating rivers have significant implications for water quality and the health of aquatic ecosystems worldwide.

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Rivers are rapidly warming, losing oxygen; aquatic life at risk

Photo, posted June 2, 2017, courtesy of Francisco Anzola via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Global Aquaculture And Environmental Change | Earth Wise

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Blue foods are fish, invertebrates, algae, and aquatic plants that are captured or cultured in freshwater and marine ecosystems.  They include approximately 2,200 species of fish, shellfish, plants and algae as well as more than 500 species farmed in freshwater.  Blue foods play a central role in food and nutrition security for billions of people, and are a cornerstone of the livelihoods, economies, and cultures of many communities around the world.

But many of the world’s largest aquatic food producers are highly vulnerable to human-induced environmental change.  According to a new paper recently published in the journal Nature Sustainability, more than 90% of global blue food production is at risk from environmental changes, with top producers like the United States, Norway, and China facing the biggest threat.  Alarmingly, the research also found that some of the highest-risk countries in Asia, Latin America and Africa demonstrate the lowest capacity for adaptation. 

The paper is the first-ever global analysis of environmental stressors impacting the production quantity and safety of blue foods. A total of 17 anthropogenic stressors were surveyed, including rising seas and temperatures, ocean acidification, changes in rainfall, algal blooms, pollution, and pesticides. 

The research is one of seven scientific papers published by the Blue Food Assessment as part of a global effort to inform future aquatic food sustainability. 

The report calls for more transboundary collaboration and for a diversification of blue food production in high-risk countries to cope with the impact of environmental change. 

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Vulnerability of blue foods to human-induced environmental change

New research finds that more than 90% of global aquaculture faces substantial risk from environmental change

Photo, posted December 30, 2014, courtesy of NOAA’s National Ocean Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Airplane Turbulence And Climate Change | Earth Wise

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If you’ve ever been on an airplane, chances are pretty good that you’ve experienced turbulence.  As the busy summer travel season kicks off, travelers are being encouraged to brace themselves for a bumpier-than-usual ride. 

There has been a major increase in the number of severe turbulence cases on both domestic and international flights.  According to a new study by researchers from the University of Reading in the U.K., climate change is leading to this increase in turbulence, driving up costs (via wear and tear on aircrafts), and increasing the risks for passengers and flight attendants.  In the United States alone, turbulence costs the airline industry $150-$500 million annually. 

The study, which was recently published in the journal Geophysical Research Letters, found that warmer air, caused by carbon emissions, is creating bumpier flights around the world.  In fact, the study found that severe turbulence in the North Atlantic is up by 55% since 1979. 

The changing climate is affecting air travel in other ways as well.  A faster jet stream across the Atlantic is altering travel times.  Rising temperatures are reducing the weight that aircraft can carry.  Rising seas are threatening low-lying coastal airports around the world. 

But carbon emissions from aviation are also a significant driver of the climate crisis.  Air travel accounts for approximately 3% of global greenhouse gas emissions, and is one of the fastest growing sources of emissions. According to the International Civil Aviation Organization, emissions from international air travel are expected to triple by 2050.

The future is shaping up to be a bumpy ride.

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Climate crisis leading to more turbulence during flights, says study

Evidence for Large Increases in Clear-Air Turbulence Over the Past Four Decades

Climate Scientist Explains Increase In Airplane Turbulence

Airports and Rising Seas

Photo, posted May 9, 2018, courtesy of Steve Lynes 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

Glacial Loss In The Swiss Alps | Earth Wise

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In 2022, glaciers in the Swiss Alps melted more than in any year on record.   This is the latest piece of bad news for the country’s glaciers, which have lost more than half of their volume of ice since the 1930s.

The melting season for Switzerland’s snow and ice typically starts in May and ends in early October.  This year’s melting season caused glaciers in the Diablerets mountain group to thin by an average of 13 feet, which is 3 times the amount of thinning observed over the past decade.   The Tsanfleuron pass between two of the glaciers is now exposed as bare rock for the first time in several thousand years. Across Switzerland, glaciers lost about 6% of their remaining volume just this year.  The previous worst year for glaciers was 2003, when losses were nearly 4%. 

There was significant melting this year in part because of the small amount of snowfall over the winter.  That snow melted quickly, being sped up by the warming effect of dust from the Sahara Desert falling on the snow.  By early summer, there was no longer a protective blanket of snow on the glaciers, exposing them to summer heat.

The loss of glaciers is far more serious than the disappearance of aesthetically pleasing landscape features.   Glaciers act as reservoirs of water that persist through the summer months.  Melt from glaciers provides water to ecosystems and creates habitats for plants and animals.  Cold runoff from glaciers affects downstream water temperatures which have a major impact on insects, fish, and other creatures.  Globally, melting glaciers contribute more than 20% of the observed ongoing sea-level rise.

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Rocky Road for Swiss Glaciers

Photo, posted June 22, 2015, courtesy of Dennis Jarvis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sinking Cities | Earth Wise

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Sea levels across the globe are rising as a result of the changing climate.  Two factors are largely responsible: the melting of ice sheets in the polar regions and the fact that as the oceans get warmer, the water in them expands.  

Estimates are that by 2050, there will be over 800 million people living in 570 cities that will be at risk from rising sea levels.   The rising waters can drown neighborhoods, put people’s lives at risk, and wreck entire economies.  Unless global emissions can be reduced sufficiently, sea levels will continue to rise.

A new study, published in the journal Nature Sustainability by Nanyang Technical University in Singapore in collaboration with the University of New Mexico, ETH Zurich, and NASA’s Jet Propulsion Lab, has focused on yet another aspect of the threat to coastal cities.  They have found that many densely populated coastal cities worldwide are even more vulnerable to sea level rise because much of their land is sinking. 

The researchers processed satellite images of 48 cities from 2014 to 2020 using a system called Interferometric Synthetic Aperture Radar.  They found that land subsidence varied on a neighborhood and even individual block level but across all the cities studied, there was a median sinking speed of 6/10” a year.  Some places had land that is sinking at 1.7” per year.  Meanwhile, the global mean sea-level rise is about .15” per year.

The increasing prevalence of industrial processes such as the extraction of groundwater, and oil and gas, along with the rapid construction of buildings and other urban infrastructure are leading to the sinking of the urban areas. 

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Rapid land sinking leaves global cities vulnerable to rising seas

Photo, posted October 24, 2015, courtesy of Jeffrey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Mangrove Forests And Climate Change | Earth Wise

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Mangrove forests play a vital role in the health of our planet.  These coastal forests are the second most carbon rich ecosystems in the world.  A patch of mangrove forest the size of a soccer field can store more than 1,000 tons of carbon. It does this by capturing carbon from the air and storing it in leaves, branches, trunks, and roots.

Mangrove forests only grow at tropical and subtropical latitudes near the equator because they cannot withstand freezing temperatures.  These forests can be recognized by their dense tangle of prop roots that make the trees look like they are standing on stilts above the water.  These roots allow the trees to handle the daily rise and fall of tides.  Most mangroves get flooded at least twice a day.  The roots also slow the movement of tidal waters, which allows sediments to settle out of the water and build up on the muddy bottom.  Mangrove forests stabilize coastlines, reducing erosion from storms, currents, waves, and tides.

A new study by the University of Portsmouth in the UK looked at the effects of climate change on how carbon is stored in mangrove forests.  In mangrove ecosystems, a variety of organisms break down fallen wood.  These include fungi, beetle larvae, and termites.  Closer to the ocean, clams known as shipworms degrade organic material.

Climate change is disrupting these processes in at least two ways.  Rising sea levels are changing the way sediments build up and increased ocean acidity is dissolving the shells of marine organisms like shipworms.

Mangrove forests are crucial to mitigating climate change, and changes to the functioning of the carbon cycle of those ecosystems are a threat to their ability to perform that function.

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Study Reveals How Climate Change Can Significantly Impact Carbon-Rich Ecosystem

Photo, posted March 24, 2014, courtesy of Daniel Hartwig via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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