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Wind turbines and bats

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Collisions with wind turbines are one of the leading causes of bat mortality in North America and Europe.  Most bat fatalities are caused by bats colliding with the rotating blades of wind turbines.  Fatalities are highest during autumn migration and on nights with low wind speeds.

According to a recent study, land-based wind turbines kill as many as 880,000 bats a year and are wiping out so many threatened bats that some species may become endangered unless preventative action is taken.

The big challenge is that bat conservation experts and scientists don’t know how to stop or reduce turbine collisions.  They don’t really know why bats are interacting with turbines to the extent that they are.  Do turbines attract bats?  Do turbines’ bright lights or just their silhouettes stimulate an attraction response?

The U.S. Department of Energy has awarded $8 million to five research centers to develop strategies for deterring bats from wind turbines. 

One of these is Bat Conservation International, which is an organization whose mission is to accelerate research to address knowledge gaps in bat ecology and behavior and develop technologies and industry methods to reduce fatality of bats at wind farms.  Among the approaches to be tested is limiting the use of nighttime lighting on wind farms to make migrating bats less likely to fly through blades. 

Another team at Boise State University is designing ultrasonic noisemakers to scare off bats. 

In announcing the new program, the Department of Energy states that wind energy must be appropriately and responsibly sited, which includes the protection of wildlife and their habitats.

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Experts Seek to Spare Bats From Wind Turbine Collisions

Photo, posted January 10, 2013, courtesy of Tom Shockey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Record low Antarctic sea ice

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Antarctica’s winter came to a close in September and during that month, the continent reaches its maximum amount of sea ice that grows during the darkest and coldest months.  This year, that maximum occurred on September 10th and turned out to be the lowest on record.

The sea ice around Antarctica reached a maximum extent of 6.5 million square miles according to NASA researchers.  That was nearly 400,000 square miles below the previous record low set in 1986. 

There are several possible causes for the meager growth of Antarctic sea ice this year.  It may be a combination of several factors including El Niño, wind patterns, and warming ocean temperatures.  Recent research indicates that ocean heat is most likely playing an important role in slowing ice growth in the cold season and enhancing ice melting in the warm season.

The record-low ice extent so far this year is a continuation of a downward trend in Antarctic sea ice that has gone on since the ice reached a record high in 2014.  Prior to that year, the ice surrounding the southern continent was actually increasing slightly by about 1% every decade.

Meanwhile, Arctic sea ice reached its minimum extent in September and it was the sixth-lowest level in the satellite record.  Scientists track the seasonal and annual fluctuations of polar sea ice because they shape polar ecosystems and play a significant role in global climate.  Sea ice melting at both poles reinforces global warming because bright sea ice reflects most of the Sun’s energy back to space while open ocean water absorbs 90% of it.

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Antarctic Sea Ice Sees Record Low Growth  

Photo, posted June 30, 2023, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastics In The Air | Earth Wise

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Plastic pollution is a big deal.  There are plastics clogging up landfills and waterways and accumulating in the oceans, choking turtles and seabirds.  Annual production of plastics has grown from 2 million tons a year in 1950 to more than 450 million tons today.

As if plastic problems weren’t already big enough, it is becoming increasingly clear that there are growing amounts of microplastic particles in the air. Bits of plastic are lofted into the sky from seafoam bubbles and from spinning tires on highways.  The particles are so light that they can travel for thousands of miles, far from where they originate.

Studies in recent years documented the presence of plastic particles even in places like the Pyrenees in Europe and in federally protected areas of the US.  Other studies have measured the quantity of plastic in the air of various locations and have looked at the origins of the particles.

In the western US, over 80% of microplastics came from roads where vehicles kick up particles from tires and brakes.   In remote areas of the Pacific, there is less than a single particle of plastic per cubic meter of air.  In cities like London and Beijing, on the other hand, there can be several thousand particles per cubic meter.

Microplastics can act as airborne aerosols, like dust, salt, soot, volcanic ash, and other particles.  Aerosols play an important role in the formation of clouds and in temperature regulation on the earth.  At low concentrations, such as exist in most places, microplastic aerosols don’t have much of an effect.  But there are more in the atmosphere all the time and, at this point, scientists don’t really know what effect they will have.

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Microplastics Are Filling the Skies. Will They Affect the Climate?

Photo, posted August 28, 2014, courtesy of Alan Levine via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Decontaminating Drinking Water | Earth Wise

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At least two billion people around the world often drink water that is contaminated with disease-causing microbes.  Waterborne diseases are responsible for two million deaths each year, mostly among children under the age of five.

There are various ways to decontaminate water, including chemicals that can themselves produce toxic byproducts as well as using ultraviolet light, which takes fairly long to disinfect the water and requires a source of electricity. 

Scientists at Stanford University and the SLAC National Accelerator Laboratory have recently invented a low-cost, recyclable powder that kills thousands of waterborne bacteria every second when the water containing it is exposed to ordinary sunlight.  The discovery of this ultrafast disinfectant could be a tremendous benefit to the nearly 30% of the world’s population with no reliable access to safe drinking water.

The new disinfectant is a harmless metallic powder that works by absorbing both ultraviolet and high-energy visible light from the sun.  It consists of nano-sized flakes of aluminum oxide, molybdenum sulfide, copper, and iron oxide.  The key innovation is that when these four metallic ingredients are immersed in water, they all function together by reacting with the surrounding water and generating chemicals that quickly kill bacteria. The chemicals themselves don’t last long.  They quickly break down in the water leaving completely safe drinking water.

The nontoxic powder is recyclable.  It can be removed from water with a magnet.  It can also be reused at least 30 times.  Apart from its uses in less developed parts of the world, it could be valuable for hikers and backpackers who want to drink water from natural sources of unknown quality.

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New nontoxic powder uses sunlight to quickly disinfect contaminated drinking water

Photo, posted February 27, 2013, courtesy of Petras Gagilas via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Liquid Fuel From Sunshine | Earth Wise

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A key goal of artificial photosynthesis research is to be able to produce a useful liquid fuel using only carbon dioxide, water, and sunlight in a single step.  Such a so-called solar fuel would produce net zero carbon emissions and would be completely renewable.

Bioethanol has long been touted as a green alternative to fossil fuels, since it is made from plants rather than petroleum.  But producing it takes up agricultural land that could be used to grow food instead and there are emissions associated with many aspects of the process by which plant mass becomes fuel.

Researchers from the University of Cambridge in the UK have developed a so-called artificial leaf that produces ethanol or propanol – usable liquid fuels – in a single step.  They developed a copper and palladium-based catalyst that allows the artificial leaf to directly produce multicarbon complex chemicals.  Earlier versions of artificial leaves could make simple chemicals, such as syngas, which would then require additional processing to turn into high-density fuels.

The new device produces liquid fuel from carbon dioxide and water simply by shining sunlight on it.

At present, the artificial leaf is a proof-of-concept device that exhibits only modest efficiency.  The researchers are working to optimize the device’s light absorbers so that they can better make use of sunlight and to optimize the catalyst so that it can convert more of the sunlight into fuel.  In addition, the device needs to be scaled up so that it can produce large volumes of fuel.

All that being said, it is an important step towards people being able to do what plants have been doing for millions of years.

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Driving on sunshine: clean, usable liquid fuels made from solar power

Photo, posted March 23, 2015, courtesy of Astro via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Caterpillars And Light Pollution | Earth Wise

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Most of us are familiar with air pollution, water pollution, soil pollution, and even noise pollution.  But it turns out that light can be a pollutant as well, and it’s a consequence of industrial civilization.  In fact, nighttime light pollution now covers approximately 23% of the globe and over 80% of inhabited regions. 

Light pollution affects more than just our view of the stars.  For example, light pollution can alter our circadian rhythm, disrupting our sleep cycle.  In nature, light pollution can kill baby turtles by causing them to head inland instead of into the ocean, can cause birds to migrate during the wrong season, and can deter nighttime pollinators like bats.  And those are just a few of the examples.    

According to new research from scientists at Cornell University, moderate levels of artificial light at night – like a porch light – attract caterpillar predators and reduce the chance that caterpillars grow up to become moths. 

In the study, which was recently published in the journal Proceedings of the Royal Society B: Biological Sciences, the researchers placed 552 lifelike caterpillar replicas made of soft clay in a forest to measure predation rates compared to a control group.  They found that predation rates on clay caterpillars and the abundance of arthropod predators were significantly higher on the artificial light at night treatment plots.  In fact, of the 552 clay caterpillars deployed and glued to leaves to look authentic, 521 models were recovered and 249 of them- or 47.8% – showed predatory marks from arthropods during the summer-long nighttime study.

In addition to light pollution, caterpillars also face major threats from habitat loss, pollution, invasive species, and climate change.

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Artificial light at night aids caterpillar predators

Photo, posted July 23, 2020, courtesy of Judy Gallagher via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastic From Sunlight | Earth Wise

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Photosynthesis is the process that plants use to turn water, carbon dioxide, and energy from sunlight into plant biomass.  It provides humans and much of animal life with food.  Photosynthesis is also nature’s way of reducing the amount of carbon dioxide in the atmosphere.  The CO2 is not directly stored in plants but rather is combined into organic compounds.

Researchers across the globe are trying to find effective ways to mimic photosynthesis.  One version of artificial photosynthesis seeks to take carbon dioxide and combine it into organic compounds that can be used as raw materials for various kinds of manufacturing. 

A research team in Japan has found a way to synthesize fumaric acid from carbon dioxide using sunlight to power the process.  Fumaric acid is a chemical typically synthesized from petroleum and is used as a raw material for making biodegradable plastics such as polybutylene succinate. 

Much of artificial photosynthesis research is aimed at using solar energy to convert carbon dioxide directly into a fuel rather than a raw material.  Such solar fuels can be produced by a variety of means including thermochemical (using the sun’s heat to drive chemical reactions), photochemical (using the sun’s light to drive chemical reactions), and electrochemical (using solar-generated electricity to drive chemical reactions.)   These approaches generally involve the use of specialized catalysts to drive the desired chemical reactions. 

One way or another, what techniques for artificial photosynthesis have in common is trying to imitate what plant life on Earth has been doing for millions of years. 

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Artificial photosynthesis uses sunlight to make biodegradable plastic

Photo, posted June 14, 2017, courtesy of Alex Holyake via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fertilizing The Ocean | Earth Wise

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There are a variety of schemes for removing carbon dioxide from the atmosphere.  Some require advanced and generally not-very-well developed technology.  Others, such as planting vast numbers of trees, are nature-based but are daunting with respect to the scale to which they need to take place in order to be truly effective.

Researchers at the Pacific Northwest National Laboratory in Richland, Washington have been examining the scientific evidence for seeding the oceans with iron-rich engineered fertilizer in order to feed phytoplankton.  Phytoplankton are microscopic plants that are a key part of the ocean ecosystem.

Phytoplankton take up carbon dioxide as they grow.  In nature, nutrients from the land end up in the ocean through rivers and from blowing dust.  These nutrients fertilize the plankton.  The idea is to augment these existing processes to increase the growth of phytoplankton.  As they eventually die, they sink deep into the ocean, taking the excess carbon with them.


The researchers argue that engineered nanoparticles could provide highly controlled nutrition that is specifically tuned for different ocean environments.  Surface coatings could help the particles attach to plankton.  Some could be engineered with light-absorbing properties, allowing plankton to consume and use more carbon dioxide.

Analysis of over 100 published studies showed that numerous non-toxic, abundant, and easy-to-create metal-oxygen materials could safely enhance plankton growth.  According to the researchers, the proposed fertilization would simply speed up a natural process that already sequesters carbon in a form that could remove it from the atmosphere for thousands of years.  They argue that given the current trends in the climate, time is of the essence for taking action.

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Fertilizing the Ocean to Store Carbon Dioxide

Photo, posted August 2, 2007, courtesy of Kevin McCarthy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Getting Rid Of Hydrogen Sulfide | Earth Wise

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Hydrogen sulfide gas produces the characteristic smell of rotten eggs, sewers, stockyards, and landfills.  The petroleum industry produces thousands of tons of the stuff each year as a byproduct of the processes that remove sulfur from petroleum, natural gas, coal, and other products.  The industry faces substantial fines for emitting hydrogen sulfide, but remediation is expensive.

Researchers at Rice University have developed a method for turning hydrogen sulfide into hydrogen gas and sulfur in a single step.  Called plasmonic photocatalysis, it not only gets rid of an undesirable substance, it does so by producing valuable byproducts.

The established way of getting rid of hydrogen sulfide is called the Claus process.  It requires multiple steps, including some that require combustion chambers heated to 1,500 degrees Fahrenheit.  The end product is sulfur and water.

The Rice University process gets all of its energy from light.  A surface of grains of silicon dioxide is dotted with tiny gold nanoparticles.  These particles interact strongly with a specific wavelength of visible light and cause plasmonic reactions that create short-lived, high-energy electrons that drive the catalysis of hydrogen sulfide.  Given that the process requires only visible light and no external heating, it should be relatively straightforward to scale up using solar energy or very efficient LED lamps.

The new hydrogen sulfide remediation technology has been licensed by a Houston-based startup company with more than 60 employees whose founders include some of the Rice researchers.  The process may end up being efficient enough and cheap enough for cleaning up non-industrial sources of hydrogen sulfide such as sewers and animal waste.

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New catalyst can turn smelly hydrogen sulfide into a cash cow

Photo, posted July 8, 2021, courtesy of Doug Letterman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Windows To Cool Buildings | Earth Wise

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About 15% of global energy consumption is for cooling buildings.  Because of this, there is an ever- growing need for technologies that can more efficiently cool buildings.   Researchers at Notre Dame University have used advanced computing technology and artificial intelligence to design a transparent window coating that is able to lower the temperature inside buildings without using any energy.

The idea is to create a coating that blocks the sun’s ultraviolet and near-infrared light, which are parts of the solar spectrum that otherwise pass through glass and help to heat an enclosed room.  Cooling needs can be reduced further if the coating can radiate heat from the surface of the window so it can pass through the atmosphere into space.  Designing a coating that does both of those things simultaneously while transmitting visible light is difficult.  Coatings should not interfere with the view out the window.

The Notre Dame researchers used advanced computer modeling to create a so-called transparent radiative cooler that meets these goals.  The coating consists of alternating layers of common materials like silicon dioxide, silicon nitride, and aluminum oxide or titanium dioxide on top of a glass base and topped with a film of polydimethylsiloxane.  The computing method was able to optimize this structure far faster and better than conventional design techniques.

The researchers say that in hot, dry cities, the coating could potentially reduce cooling energy consumption by 31% compared with conventional windows.  The same materials could be used in other applications, such as car and truck windows.  In addition, the quantum computing-enabled optimization method used for this work could be used to design other composite materials.

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Clear window coating could cool buildings without using energy

Photo, posted September 6, 2015, courtesy of Robert Otmn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fuel From Coffee Grounds | Earth Wise

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The world drinks a lot of coffee.  Americans alone consume 400 million cups a day.  Each cup of coffee results in about half an ounce of coffee grounds.  Adding that up, this country produces over 6,000 tons of coffee grounds each day.  While coffee grounds are not particularly harmful, that is an awful lot of waste that mostly ends up in landfills or is incinerated.

Researchers at Aston University in the UK have developed a method of producing high-quality biodiesel fuel from coffee grounds.  Their study was published in the journal Renewable and Sustainable Energy Reviews.

The technique consists of growing a particular species of microalgae (Chlorella vulgaris) directly on spent coffee grounds.  The coffee grounds provide both the nutrients for the microalgae and a structure upon which it can grow.   Exposing the algae to light for 20 hours a day and dark for just four hours a day produced the best quality biodiesel.

Microalgae is well-known as a feedstock for biodiesel production.  Previously, it has been grown on materials like polyurethane foam or nylon which don’t provide any nutrients.   Using the coffee grounds as the substrate for growth means that no external nutrients are needed.

The resultant enhanced biodiesel produces minimal emissions and good engine performance and meets both US and European specifications.  This feedstock for producing biodiesel is ideal since it doesn’t require any competition with food crops and instead makes use of a widely available waste product.  The hope is that it may reduce the cutting down of palm trees to extract oil for biofuel.  In southeast Asia, this has been a major source of deforestation and increased greenhouse gas emissions.

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Aston University researchers ‘feed’ leftover coffee grounds to microalgae to produce low emission biodiesel

Photo, posted October 13, 2007, courtesy of David Joyce via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cleaning Up Urban Rivers With Nature’s Tools | Earth Wise

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Fifty years after the passage of the Clean Water Act, urban waterways across the United States are continuing their comeback and are showing increasing signs of life.  A strategy that is being adopted in many places is to use natural restoration techniques focused on bolstering plants and wildlife to improve water quality.

A nonprofit called the Upstream Alliance has focused on public access, clean water, and coastal resilience in the Delaware, Hudson, and Chesapeake watersheds.  Working with the Center for Aquatic Sciences and with support from the EPA and the National Fish and Wildlife Foundation, the alliance has been repopulating areas of an estuary of the Delaware River near Camden, New Jersey with wild celery grass, which is a plant vital to freshwater ecosystems.

In many places, scientists, nonprofits, academic institutions, and state agencies are focusing on organisms like bivalves (typically oysters and mussels) along with aquatic plants to help nature restore fragile ecosystems, improve water quality, and increase resilience.

Bivalves and aquatic vegetation improve water clarity by grounding suspended particles, which allows more light to penetrate.  These organisms also cycle nutrients both by absorbing them as food and by making them more available to other organisms.

Underwater restoration projects have been underway in New York Harbor for more than a decade, where the Billion Oyster Project has engaged 10,000 volunteers and 6,000 students. 

The hope is that bringing back bivalves and aquatic plants can create a lasting foundation for entire ecosystems.  It is restoring nature’s ability to keep itself clean.

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How Using Nature’s Tools Is Helping to Clean Up Urban Rivers

Photo, posted December 19, 2019, courtesy of Scott via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Colorful Solar Panels | Earth Wise

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More and more buildings and public spaces are incorporating solar panels and not only just on rooftops.  Some buildings are incorporating power-generating structures all over their facades.

Using solar panels in this way puts some design constraints on buildings because solar panels are typically a deep black color.  This is because solar panels need to absorb light and making them any other color decreases their ability to do so and generate power.  But the problem is that people don’t necessarily want a black building.

One alternative to traditional solar panel design is to use structural sources of color that include microscopic shapes that only reflect specific light frequencies, like the scales on butterfly wings.  But this approach generally leads to iridescence – which might not be what is wanted – and is often quite expensive to implement.

A team of researchers at a university in Shanghai has now demonstrated a way to give solar panels color that is easy and inexpensive to apply and that does not reduce their ability to produce energy efficiently.

The technique involves spraying a thin layer of a material called a photonic glass onto the surface of solar cells.  The photonic glass is made of a thin, disorderly layer of dielectric microscopic zinc sulfide spheres.  Even though most light can pass through the photonic glass, certain colors are reflected back, depending on the sizes of the spheres.  By varying that size, the researchers created solar panels that were blue, green, or purple with only a very small drop in solar panel efficiency.

The solar panels made this way maintained their color and performance under durability testing.  With this new technology, there may soon be colorful solar panels on our buildings.

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Colorful solar panels could make the technology more attractive

Photo, posted December 15, 2021, courtesy of Pete via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A Smart Window | Earth Wise

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Researchers at Oxford University have developed a new adaptable smart window technology that has the potential of reducing the energy usage of the average home by a third.

The technology uses a spectrally tunable low-emissivity coating that can control the amount of heat that comes into a room without affecting the quality of the light that enters.

The thermal energy from the sun’s infrared rays is absorbed by the glass and then is re-emitted as heat.  That heat can either be used to warm the room using transparent electrical heaters embedded in the glass or can be reflected away to cool the room.  The windows can change according to seasonal needs.

The researchers built a prototype using a material called an active chalcogenide-based phase change material.  When it is cold, the infrared rays from the sunlight are harvested and used to heat the building.  When it is warm, the new glass can switch state to reflect the heat and reduce the need for air conditioning.  The active phase change material is adjustable so that the amount of heat absorbed or reflected can be tuned for precise temperature control.  There is essentially no effect on visible light passing through the window.  Current low-emissivity glass for windows can reduce heat transfer, but its properties cannot be altered according to seasonal needs.

The researchers estimate that using windows fitted with the new prototype glass – including the energy required to control the film – would save 20 to 34% in energy usage annually compared to double-glazed windows found in many modern homes.

A spinout company from Oxford called Bodle Technologies is collaborating with two existing industrial partners to develop the technology further.

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New adaptable smart window coating could help heat or cool a home and save energy

Photo, posted April 26, 2008, courtesy of Lima Andruska via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change On Mount Everest | Earth Wise

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Climate change has shown up in the highest place on Earth.  The highest glacier on Mount Everest is rapidly retreating with rising temperatures.

New research by an international team led by the University of Maine and published in the journal Climate and Atmospheric Science has determined that the South Col Glacier atop Mount Everest has shrunk by half since the 1990s.   Its ice mass has thinned by an estimated 180 feet.

The glacier used to be covered by snow, which reflected the sun’s light and insulated the mass of ice under the snow.  But warmer temperatures, lower humidity, and more severe winds have eliminated the snow cover, fueling the decline of the glacier.

The study of the South Col Glacier highlights the critical balance created by snow-covered surfaces and exposes the potential for loss throughout high mountain glacier systems as snow cover is depleted by warming temperatures.  When even the highest glacier on Mount Everest is impacted, it is clear that no place is safe from the warming climate.

The human significance of this development is substantial.  More than 200 million people in Asia depend on meltwater from glaciers in the high mountains of the continent for their freshwater needs.  But now glaciers in the mountains are melting faster than they can be replenished by snowfall.

As for Mount Everest itself, future expeditions on the mountain will face new challenges as glacier melting causes more avalanches and climbers accustomed to digging into ice and snow will need to scale more exposed bedrock.  Climate predictions for the Himalaya in general all anticipate continued warming and continued loss of glacier mass.

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Climate Change Has Reached the Top of Mount Everest, Thinning Its Highest Glacier

Photo, posted October 27, 2011, courtesy of Goran Hogland via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Lighted Nets Protect Marine Wildlife | Earth Wise

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Gillnets are walls or curtains of netting that hang in the water to trap fish.  They are one of the most extensively used fishing gear in coastal regions throughout the world’s oceans.  While they are very effective at catching targeted fish species, they are not discriminating.  As a result, they carry significant risk of bycatch – the accidental capture of unwanted species as well as other interactions with various marine animals.

Researchers from The Wildlife Conservation Society, NOAA Fisheries, Arizona State University, and the National Fisheries and Aquaculture Institute of Mexico have recently published a study showing that using lighted gillnets reduced overall bycatch by 63%, including a 95% reduction in sharks, skates, and rays, and an 81% reduction in Humboldt squid. 

Gillnets often catch endangered, threatened, and protected species such as sharks, sea turtles, marine mammals, and seabirds, as well as unwanted species and non-marketable juvenile target fish species.  The bycatch animals are often dead or injured and are generally dumped overboard.

Illuminating gillnets with LED lights has emerged over the past decade as an effective tool to reduce bycatch of endangered sea turtles.  The new study is the first detailed examination of the effectiveness of illumination for other vulnerable species.

Gillnets are ubiquitous because they are inexpensive and catch everything that passes them.  Global populations of sharks, skates, and rays have declined as a result of bycatch and illegal fishing. The results of this study are encouraging because they provide a practical solution for increasing the selectivity of gillnets and avoiding bycatch. 

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Lighted Nets Dramatically Reduce Bycatch of Sharks and Other Wildlife While Making Fishing More Efficient

Photo, posted September 19, 2015, courtesy of Jim Bahn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Earth Is Dimming | Earth Wise

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According to a new study published in the journal Geophysical Research Letters, warming ocean waters have caused a drop in the brightness of the earth.

Researchers measure the earth’s albedo by observing the light reflected from earth that illuminates the surface of the moon as well as with satellite measurements. The earth reflects about 30% of the sunlight that shines on it.  The data shows that the earth now reflects about half a percent less light than it did 20 years ago, with most of the drop occurring in the last three years.  That number had been fairly constant for most of the past 20 years.

According to the researchers at the New Jersey Institute of Technology, New York University, and a Spanish astrophysical agency, the apparent cause of the albedo drop has been a reduction of bright, reflective low-lying clouds over the eastern Pacific Ocean in most recent years.  That is the same area off the west coasts of North and South America where increases in sea surface temperature have been observed because of the reversal of a climate condition called the Pacific Decadal Oscillation, which is likely a result of global climate change.

The dimming of the earth implies that more solar energy is being absorbed rather than reflected, which may contribute further to global warming.

These results are somewhat surprising.  Scientists had postulated that the warming of the earth could lead to more clouds and therefore a higher albedo – more reflection of the sun’s light.  If that were the case, it would help to moderate warming and balance the climate system.  These new results indicate that the opposite is true.

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The Earth Is Dimming Due To Climate Change

Photo, posted August 18, 2021, courtesy of Arek Socha/GPA Photo Archive via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Global Light Pollution

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Light pollution is excessive or obtrusive artificial light. It’s a consequence of industrial civilization.  Too much artificial light can cause a host of problems, including disrupting ecosystems, causing adverse health effects, and wasting energy. 

According to a new study led by researchers from the University of Exeter in the U.K., global light pollution has increased by at least 49% over 25 years.  But this figure only includes light visible via satellites.  Scientists estimate that the true increase may be significantly higher – up to 270% more globally. 

That’s because there is a hidden impact of LED technology that isn’t accounted for in the satellite data. LEDs emit more blue light than previous lighting technologies, but satellite sensors fail to pick up this blue light.   This leads to a large underestimate of global light pollution.

The researchers examined light pollution from 1992 to 2017.  They found persistently increasing light pollution in Asia, South America, Oceania and Africa.  In Europe, detected light increased until around 2010, after which it leveled off.  In North America, artificial light appears to be on the decline.  However, the researchers point out that the satellites inability to detect blue light of LEDs means that light pollution has likely actually increased in most locations.

Light pollution has widespread impacts on both animals and plants.  For example, light pollution can confuse the migratory patterns of animals and change predator-prey relationships.   It’s also been shown to cause trees to bud earlier in spring.      

While there’s no off switch for the planet, there are ways that we could reduce the amount of light drastically with little impact on our lives. 

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Rapid increase in global light pollution

Photo, posted November 2, 2008, courtesy of Timothy Tsui via Flickr.

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Understanding Geoengineering | Earth Wise

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The most recent report from the UN Intergovernmental Panel on Climate change includes discussion of a number of extreme and untested solutions to the climate crisis.  Among these are solar geoengineering – modifying clouds or spraying tiny reflective particles into the upper atmosphere in order to block some of the sun’s light and thereby cool the planet.  The underlying principles are relatively straightforward.

There have been various models that predict the extent to which solar geoengineering would lower the earth’s average temperature.  What hasn’t been modeled to any real extent is what other effects it would have.

The new report discusses the results of models that predict how temperatures would vary at different latitudes and how geoengineering would affect rainfall and snowfall.  According to the models, releasing sulfate aerosols into the upper atmosphere to block sunlight would lower average precipitation.  But every region would be affected differently.  Some regions would gain in an artificially cooler world, but others might, for example, suffer by no longer having suitable conditions to grow crops.

The drop in temperature would allow the planet’s carbon sinks (plants, soils, and oceans) to take up more carbon dioxide from the atmosphere.  However, as long as people continue to pollute, carbon dioxide would continue to make the oceans more acidic, causing significant harm to marine ecosystems.  Furthermore, solar geoengineering would have to be an ongoing process that would go on indefinitely and if it were to suddenly stop, it would lead to rapid warming.

The more we learn about geoengineering, the more it becomes clear that there would be many side effects as well as serious moral, political, and practical issues.  Society has to consider if all these things represent too much danger to allow us to seriously consider such a strategy.

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In the New UN Climate Report, a Better Understanding of Solar Geoengineering

Photo, posted September 9, 2012, courtesy of Kelly Nighan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Greenland Becoming Darker | Earth Wise

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According to research published by Dartmouth University, a weather pattern that pushes snowfall away from parts of Greenland’s ice sheet is causing the continent to become darker and warmer.

Reducing the amount of fresh, lighter-colored snow exposes older, darker snow on the surface of Greenland’s ice sheets.  Fresh snow is the brightest and whitest. The reflectivity of snow decreases fairly quickly as it ages. This decrease in albedo – or reflectivity – allows the ice sheet to absorb more heat and therefore melt more quickly. 

The research attributes the decrease in snowfall in Greenland to a phenomenon called atmospheric blocking in which persistent high-pressure systems hover over the ice sheet for up to weeks at a time.  Such systems have increased over Greenland since the mid-1990s.  They push snowstorms to the north, hold warmer air over Western Greenland, and reduce light-blocking cloud cover.

All of this contributes to Greenland melting faster and faster.  According to research cited in the study, the Greenland ice sheet has warmed by nearly 5 degrees Fahrenheit since 1982.  Overall, Greenland is experiencing the greatest melt and runoff rates in the last 450 years, at the minimum, and quite likely the greatest rates in the last 7,000 years.

The Greenland ice sheet is the second largest ice body in the world, after the Antarctic ice sheet.  It is 1,800 miles long and about 700 miles wide at its greatest width.  Its thickness is between 1.2 and 1.9 miles.  If the entire sheet were to melt, it would lead to a global sea level rise of 24 feet.  So, the darkening of Greenland is a source of great concern.

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Greenland Becoming Darker, Warmer as Snow Changes

Photo, posted April 3, 2012, courtesy of Francesco Paroni Sterbini via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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