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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

Wrong trees in the wrong places

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Temperatures in cities are rising around the world and urban heat stress is already a major problem.  Extensive surfaces of man-made materials absorb the sun’s energy, and lead to temperatures well above those in the surrounding countryside.  This is known as the urban heat island effect, and it can lead to greater energy use, higher air pollution levels, and a greater risk of heat-related illnesses, as well as death. 

Some cities have already started implementing mitigation strategies, with tree planting prominent among them.  Planting trees can cool the climate by absorbing carbon dioxide, providing shade, and releasing water vapor, which lowers air and surface temperatures. 

However, while trees can cool cities significantly during the day, new research from the University of Cambridge in the U.K. shows that tree canopies can also trap heat and raise temperatures at night. 

According to the study, which was recently published in the journal Communications Earth & Environment, planting the wrong species or the wrong combination of trees in suboptimal locations or arrangements can limit their benefits.

The researchers found that in temperate climates, trees can cool cities by up to 6°C during the day but can increase nighttime temperatures by 1.5°C.  Cities with open layouts in temperate and tropical climates benefit from a mix of evergreen and deciduous trees, enhancing cooling by 0.5°C more than in cities with only deciduous or evergreen trees. 

The researchers hope their findings will help urban planners choose the best combinations of trees and planting locations to combat urban heat stress.

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Wrong trees in the wrong place can make cities hotter at night, study reveals

Photo, posted October 29, 2017, courtesy of Lars Plougmann via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fireflies are in decline

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If you are seeing fewer fireflies each year, you’re not alone.  Like many insects, firefly populations are in decline.  A new study by researchers from the University of Kentucky, Bucknell University, Penn State University, and the USDA has shed some light on the precarious situation facing firefly populations across North America. 

The research team used a mix of field surveys from citizen scientists and advanced machine learning techniques to analyze more than 24,000 surveys from the Firefly Watch citizen science initiative.  The study, which was recently published in the journal Science of the Total Environment, identified the factors likely responsible for the declines in firefly populations. 

The research team found that fireflies are sensitive to various environmental factors, from short-term weather conditions to longer climatic trends.  Fireflies thrive in temperate and tropical climates.  As global temperatures rise, these conditions become less predictable and less hospitable.

Light pollution is another threat to fireflies.  Artificial light at night – from things like street lights and billboards – is particularly disruptive to fireflies as it interferes with their bioluminescent communication essential for mating.

Urban growth, including buildings, roads, and sidewalks, poses another significant threat to fireflies by overtaking their natural habitats and decreasing available breeding areas. 

Additionally, certain agricultural practices seem to contribute to the decline of fireflies. 

According to the research team, reducing light pollution, preserving natural habitats, and implementing wildlife-friendly agricultural practices are conservation measures that could help mitigate the decline of fireflies. 

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Fading lights: Comprehensive study unveils multiple threats to North America’s firefly populations

Photo, posted July 12, 2021, courtesy of Bruce Hallman/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Palm oil and water quality

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Palm oil is the world’s cheapest and most widely used vegetable oil.  In fact, more than 86 million tons of palm oil was consumed last year alone.  Even though few of us cook with it, palm oil can be found in approximately half of all packaged grocery items – everything from ice creams and pizzas to detergents and cosmetics. 

This massive global demand for palm oil is driving tropical deforestation around the world.  While many studies have shown how converting rainforests to oil palm plantations causes biodiversity loss, researchers from UMass Amherst are the first to demonstrate how these plantations also cause wide-ranging disturbances to nearby watersheds.

In the study, which was recently published in the journal Science of the Total Environment, the research team focused on the Kais River watershed of West Papua, a province in the far east of Indonesia.  Approximately 25% of the watershed has been turned into oil palm plantations. The watershed is also one of the oldest continually inhabited homes for different groups of Indigenous Papuans.

The researchers found that the conversion of tropical rainforest to oil palm plantation has increased precipitation, runoff, and soil moisture. Water quality in the watershed has also gotten dramatically worse: sedimentation has increased by 16.9%, nitrogen by 78.1%, and phosphorus by 144%.

The research team hopes regulators will work to limit the use of pesticides, conduct continuous water quality monitoring, and ensure that downstream communities have access to water quality information. 

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Oil Palm Plantations Are Driving Massive Downstream Impact to Watershed

Photo, posted December 13, 2008, courtesy of Fitri Agung via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate change and fish migration

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The warming climate is changing the distribution of fish species.  Researchers at the University of Adelaide in Australia have observed that tropical fish species are moving into temperate Australian waters.

The Eastern Australian Current is strengthening as the climate warms and larvae of tropical fish are getting caught in the current and moving into more temperate regions.  These larvae would not normally survive in the cooler Australian ocean water, but the warming current keeps the baby fish warm and increases their chances for survival.  The fish migration observed in the study is an ongoing process that has strengthened in the last few decades due to ocean warming.

The novel populations of tropical fish in these temperate ecosystems are not having much impact at the present time, but they may do so in the future.  The water is still cooler than the fishes’ natural environment and therefore they do not grow to their maximum size.  As a result, they don’t represent stiff competition for the native species – at least not yet.

As the ocean temperatures continue to rise, these tropical species will eventually grow to their full size and their diets will overlap more and more with those of temperate fish species.  Tropical herbivores tend to overgraze temperate kelp while the impact of tropical fish that eat invertebrates is less well understood.  Tropical fish with varied diets are the most successful invaders.  The ultimate effects on temperate ecosystems remain to be seen but survival may become difficult for the native fish in rapidly warming temperate ocean environments.

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Tropical fish are invading Australian ocean water

Photo, posted March 28, 2017, courtesy of Ryan McMinds via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Mercury in tuna

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Mercury is found throughout the ocean, and there is at least some of it in any fish one might eat. It is an element found naturally in the environment, but it is also a byproduct of manmade pollution. Generally speaking, bigger fish tend to have higher mercury levels than smaller ones, because they are higher up in the food chain. The more small fish those big fish eat, the more mercury builds up in their bodies.  Tuna aren’t the biggest fish in the ocean, but they are very common in many people’s diets.

Increased mercury levels are a result of human activities like burning coal and mining which release methylmercury into the air.  It then finds its way into the oceans in rainwater.  Methylmercury is a particularly toxic chemical that affects the nervous system.  Environmental protection policies in recent decades have helped to reduce mercury pollution.

However, a recent study by French researchers looked at the mercury levels in tuna over the past 50 years.  They found that the levels have basically not changed since 1971.  As a result, they are calling for more restrictive environmental policies to further lower mercury pollution levels.

The researchers explained that the lowering of mercury airborne levels to date has not necessarily been ineffective.  They theorized that the static levels in tuna may be caused by the upward mixing of “legacy” mercury from deeper ocean water into the shallower depths where tropical tuna swim and feed.  It could very well take decades to dramatically reduce ocean mercury levels. 

Meanwhile, mercury content in tuna varies considerably by tuna type and source and there are both better and worse choices out there.  Consumers should learn the facts.

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Mercury levels in tuna remain nearly unchanged since 1971, study says

Photo, posted November 7, 2015, courtesy of Mussi Katz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Seabirds rescuing coral reefs

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A new study by researchers at Lancaster University in the UK has found that the presence of seabirds on islands adjacent to tropical coral reefs can more than double the coral growth rates on those reefs.

The study found that when coral reefs grow faster, they can bounce back more quickly from bleaching events that occur when the seas become too warm.  The focus of the study was a type of coral called Acropora, which provides complex structures supporting fish populations and reef growth. 

The researchers found that Acropora around islands populated by seabirds recovered from bleaching events about 10 months faster than reefs located away from seabird colonies.  Speeding up coral recovery times could prove the difference between continuing to bounce back from bleaching events and dying off.

The seabirds are helping the coral reefs with their droppings.  The birds feed on fish in the open ocean far from islands and then return to the islands to roost.  They deposit nitrogen- and phosphorus-rich nutrients in the form of guano, some of which is washed off of the islands by rain and into the surrounding seas.  The nutrients fertilize corals and other marine species.

To determine whether the faster growth rates were really due to the bird-supplied nutrients, the researchers studied rat-infested islands that had no bird populations.  The study confirmed that it was the presence of seabirds that provided enhanced nutrients for the coral reefs.  In fact, a primary outcome of the study was to add further weight to the growing body of evidence of the ecological damage across ecosystems on land and sea from invasive rats on tropical islands.

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Feathered friends can become unlikely helpers for tropical coral reefs facing climate change threat

Photo, posted September 15, 2019, courtesy of Rickard Zerpe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rainforest Promises | Earth Wise

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The recent UN climate summit in Sharm el Sheikh, Egypt brought with it lots of pledges for action.   Among them was a promise from the three countries that are home to more than half of the world’s tropical rainforests to try to do something to protect them.

The ministers of Brazil, Indonesia, and the Democratic Republic of Congo signed an agreement pledging cooperation on sustainable management and conservation, restoration of critical ecosystems, and creation of economies that would ensure the health of both their people and their forests.

The plan has no financial backing of its own.  The countries are pledging to work together to establish a funding mechanism that could help to preserve the tropical forests that both help regulate the Earth’s climate and sustain a wide range of animals, plants, birds, and insects.

That such an agreement has come about at all is a result of the election of Luiz Lula da Silva as Brazilian president, replacing Jair Bolsonaro, who was famously an opponent of any and all environmental conservation or protections.  President Lula addressed the attendees of the climate summit promising that “Brazil is back.”   He described his country as having been in a cocoon for the past four years under his predecessor.  He declared that going forward, Brazil will be a force to combat climate change.  Given the importance of the Amazon rainforest, that is critical for the success of the world’s efforts.

Like all other issues on the table at the climate summit, the real challenge is not to come up with meaningful pledges on climate action, it is to be able to follow through on those pledges.  If past summits are any indication, that is not an easy task.

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Brazil, Indonesia and Congo Sign Rainforest Protection Pact

Photo, posted September 15, 2013, courtesy of Moises Silva Lima 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.

Training Corals To Tolerate Heat | Earth Wise

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When ocean water is too warm, corals expel the algae that lives in their tissues, which causes the coral to turn completely white.  This is called coral bleaching.   When this happens, the coral is not dead.  However, corals are dependent upon the symbiotic relationship with algae and if conditions don’t improve, they don’t let the algae back in and the corals will die.

According to the National Oceanic and Atmospheric Administration, between 2014 and 2017, around 75% of the world’s tropical coral reefs experienced heat stress severe enough to trigger bleaching.  For 30% of the world’s reefs, the heat stress was enough to kill the coral.

According to new research by the University of Miami published in the journal Coral Reefs, corals subjected to a stressful regimen of very warm water in the laboratory came to be more tolerant of high temperatures, offering a potential tool for preserving ailing coral reefs.

In the study, some corals were kept in water at a constant temperature of 82 degrees while others saw water temperatures fluctuating between 82 degrees and 88 degrees.  After 90 days of this treatment, the corals exposed to variable temperatures were able to tolerate high heat for longer periods before bleaching.  This training regime is akin to an athlete preparing for a race.

The findings suggest a possible approach for restoring coral reefs.  Nursery-raised corals that are “trained” to tolerate heat could be planted onto reefs endangered by warming waters.  Reefs populated by corals with boosted stamina to heat stress could have a greater chance of surviving the warming waters of the oceans.

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Some Corals Can Be Conditioned to Tolerate Heat, Study Finds

Photo, posted December 16, 2015, courtesy of Big Cypress National Preserve via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Tree Diversity | Earth Wise

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Scientists have estimated that there are more than 8 million species of plants and animals in existence.  Amazingly, only about 1.2 million of them have been identified and described so far and most of those are actually insects.  Millions of other organisms have yet to be discovered.

One would imagine that most of these unknown species are tiny things that are hard to spot or encounter.  But our ignorance of species even applies to trees, which are pretty easy to spot if you encounter them.

A new study involving more than 100 scientists across the globe has produced an estimate of the number of tree species on the Earth.  The new global estimate is that there are 73,000 tree species, which is about 14% more than previously thought.  Based on a combination of data from two global datasets, the study yielded a total of 64,100 documented tree species worldwide.  The researchers then used novel statistical methods to estimate the total number of unique tree species at biome, continental, and global scales, which includes species yet to be discovered and described by scientists.  Therefore, the estimate predicts that there are likely to be over 9,000 tree species still to be found.

Roughly 40% of the undiscovered tree species are likely to be in South America, which is the continent with the highest number of rare tree species and the highest number of continentally endemic tree species – meaning those found only on that continent.  Hot spots of undiscovered tree species are likely the tropical and subtropical moist forests of the Amazon basin and the Andes-Amazon interface.

Extensive knowledge of tree richness and diversity is key to preserving the stability and functioning of ecosystems.

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Number of Earth’s tree species estimated to be 14% higher than currently known, with some 9,200 species yet to be discovered

Photo, posted November 5, 2017, courtesy of Deensel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Bomb Cyclones | Earth Wise

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It seems like we are hearing about new weather phenomena pretty frequently these days.  One name that has popped up lately is “bomb cyclones.”  Bomb cyclones, it turns out, are storms that undergo “bombogenesis.”  What that means is a low-pressure area (in other words, a storm) that undergoes rapid strengthening and can be described as a weather bomb, or popularly, a bomb cyclone.

These things usually take place over remote tropical ocean areas but a really intense one struck the Pacific Northwest on October 24th.  The storm off the coast of Washington, with a barometric pressure reading equivalent to a category 4 hurricane, was the second extreme low-pressure storm in the North Pacific in a single week.  Both storms involved pressure drops of more than 24 millibars in 24 hours, making them bomb cyclones.

These storms brought high winds and extreme precipitation that doused wildfires and provided some relief to the extreme drought in Central and Northern California.  Along with these positive effects, however, the storms also caused power outages, flooding, landslides, and mud and debris that washed out roads.

The October 24-25 event brought 16.55 inches of rain to Mount Tamalpais in Marin County, California in a 48-hour period.  Sacramento got 5.44 inches of rain, breaking a 140-year-old record.  And the city had just broken another extreme weather record for the longest dry spell in history.

The storms directed streams of moisture from north of Hawaii toward the West Coast in long, narrow bands of moisture known as atmospheric rivers.  We are learning about all sorts of unfamiliar weather phenomena as extreme weather events become increasingly common.

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Extratropical Cyclones Drench West Coast

Photo, posted January 4, 2018, courtesy of NOAA/CIRA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Disappearing Mountaintop Glacier Ice | Earth Wise

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A newly released study has found that mountaintop glacier ice in the tropics of all four hemispheres has diminished dramatically over the past 50 years.  Among the findings of the study, published in the journal Global and Planetary Change, are that a glacier near Puncak Jaya, in Papua New Guinea, lost about 93% of its ice between 1980 and 2018.  Between 1986 and 2019, the area covered by glaciers on top of Mt. Kilimanjaro in Africa decreased by nearly 75%.

The study combined NASA satellite imagery with data from ice cores drilled during field expeditions on tropical glaciers around the world.  The combination of measurements demonstrated that climate change is causing these glaciers to disappear and that the ice loss has accelerated in recent years.

The study looked at glacier ice in Kilimanjaro in Tanzania, the Andes in Peru and Bolivia, the Tibetan Plateau and the Himalayas, and ice fields in Papua, New Guinea.  Collecting ice cores from these places provides information on the climate in these regions over the centuries and millennia.  As snow falls on a glacier each year, it is buried and compressed to form layers that preserve the chemistry of snow, pollutants from the atmosphere, and biological material such as plants and pollen.

Glaciers in the tropics respond more quickly to climate change because they exist in the warmest areas of the world and survive only at very high altitudes. For many of these tropical glaciers, it is too late to prevent their demise.  It is not too late to attempt the slow down the buildup of greenhouse gases in the atmosphere that is causing the planet to warm, but we don’t have unlimited time to act.

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Mountaintop glacier ice disappearing in tropics around the world

Photo, posted February 12, 2009, courtesy of Christoph Strassler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Palm Oil Replacement | Earth Wise

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In the 1990s, cardiovascular health issues associated with partially hydrogenated oils containing harmful trans fats became a focus of great concern.  As a result, food companies looked for substitutes and the alternative they identified was palm oil.  Its ability to remain solid at room temperature made it well suited for many food applications.  Unfortunately, that property stems from its high saturated fat content, which means it also increases the risk of coronary heart disease.

The widespread use of palm oil has also caused significant environmental problems.  Palm oil plantations have replaced millions of acres of tropical forests, destroying the habitat for numerous species and threatening biodiversity.

Other potential replacements for partially hydrogenated oils such as coconut oil tend to be more costly, limited in supply, and also high in saturated fats.

Food scientists at the University of Guelph in Ontario, Canada, recently demonstrated the use of enzymatic glycerolysis (EG) to turn liquid vegetable oils into solid fats.  Their process is able to produce solid fats with the textural and structural properties desired by consumers.

The process is fairly simple, relatively easy to scale up, and is amenable to smaller food production or even local production.  Using it would enable food producers to use all sorts of readily available vegetable oils that can be produced in parts of the world that are not necessarily tropical regions.

Palm oil use is not going to go away, but this work may point a way to help slow down the destruction of ecosystems and animal habitats as well lead to more sustainable and healthy food sources.

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U of G Food Scientists Find Palm Oil Alternative That’s Good for Human, Planet Health

Photo, posted February 21, 2010, courtesy of Craig Morey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring Tropical Forests | Earth Wise

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Tropical forests store more than half of the world’s above-ground carbon.  For this reason, deforestation is one of the greatest threats to global climate regulation.   Once forests are degraded through partial clearing and agricultural conversion, they are often perceived as no longer having much ecological value even though degraded forests still provide important ecosystem services despite no longer storing as much carbon.

As a result, once forests have been degraded, they tend to be seen as prime candidates for full conversion to agricultural plantations.   But this is not actually the case.

An international team of scientists, including researchers from Arizona State University’s Center for Global Discovery and Conservation Science, has provided the first long-term comparison of above-ground carbon recovery rates between naturally regenerating and actively restored forests in Southeast Asia.

First of all, the research shows that allowing forests to regenerate naturally results in significant amounts of restored above-ground carbon storage.  It is definitely worthwhile to allow forests to recover rather than giving up on them and putting the land to other uses.

But more importantly, the researchers found that forest areas that undergo active restoration recover their carbon-storing ability 50% faster than naturally recovering forests.

Restoration methods include planting native tree species and thinning vegetation around saplings to improve their chances of survival.   

These findings suggest that restoring tropical forests is a viable and highly scalable solution to regaining lost carbon stocks on land.  What is needed is sufficient incentive to engage in active forest restoration.  The current price of carbon is not sufficient to pay for restoration, but as the climate crisis intensifies, this is likely to change.

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Tempe to Hawaii: ASU professors teach Hawaiian youth about coral reef conservation

Photo, posted May 22, 2008, courtesy of Eric Chan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Mangrove Trees And Climate Change | Earth Wise

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Mangrove trees are small trees that grow in coastal saline or brackish water at tropical and subtropical latitudes.  Many mangrove trees can be identified by their dense tangle of prop roots.  These roots make the trees appear as if they are standing on stilts above the water.  The tangle of roots allows mangrove trees to handle the daily rise and fall of tides and to slow the movement of tidal waters.  

Mangrove forests provide many ecosystem services, including stabilizing the coastline by reducing erosion from storm surges, waves, and tides.  The intricate root system of mangrove trees are attractive to fish and other species seeking food and shelter from predators.  Mangrove forests also store large amounts of carbon.     

But according to a new study recently published in the journal Science, mangrove trees won’t survive sea level rise by 2050 if greenhouse gas emissions aren’t reduced.  

Using sediment data from 78 locations over the last 10,000 years, an international team of scientists led by Macquarie University in Australia estimated the chances of mangrove trees survival based on the projected rates of future sea-level rise.

When sea level rise rates exceeded 6 millimeters per year, which is similar to estimates under high-emissions scenarios for 2050, researchers found that mangrove trees were unlikely to keep pace with the rising water levels.  But when the annual increase was 5 millimeters or less – which is the projected low-emissions scenario this century – mangrove trees are much more likely to survive. 

These findings underscore the importance of reducing greenhouse gas emissions to mitigate rapid sea level rise.  The future of mangrove trees may depend on it.  

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Mangrove trees won’t survive sea-level rise by 2050 if emissions aren’t cut

Photo, posted December 17, 2012, courtesy of Edward Stojakovic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fighting Malaria With Gene-Drive Technology | Earth Wise

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Malaria continues to be a major health hazard throughout the tropical and subtropical regions of the world. There were 228 million cases of malaria in 2018 and over 400,000 deaths. 

Malaria is a mosquito-borne infectious disease spread by 40 of the world’s 3,500 mosquito species.  So, efforts to control mosquito populations are the primary strategy to eradicate malaria.

A team led by Imperial College London has created a genetic modification that distorts the sex ratio of a population of Anopheles gambiae mosquitoes using “gene drive” technology.  The modification works by using a DNA-cutting enzyme to destroy the X chromosome during the production of sperm, which leads to predominantly male offspring, since females require two X chromosomes.  The modification is coupled to a gene drive to allow it to spread through a population in a very effective way.  A gene drive is a genetic engineering technology that propagates a particular modification by assuring that a specific form of a gene (or allele) will be transmitted with far more than the natural 50% probability.

The result of this is that mosquitoes produce more male offspring, eventually leading to no females being born and a total collapse in the population. The mosquitoes studied are the main malaria vector in sub-Saharan Africa.  The hope is that mosquitoes carrying a sex-distorter gene drive would be released in the future, spreading the male bias with local malaria-carrying populations and causing them to collapse.  Only female mosquitoes bite and take blood meals.  If the gene drive technology works in the field, it could be a game-changer in the fight to eliminate malaria.

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Malaria mosquitoes eliminated in lab by creating all-male populations

Photo, posted June 20, 2014, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Forest Regrowth In The Amazon | Earth Wise

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The Amazon is the largest tropical rainforest in the world.  It covers an area approximately equal in size to the lower 48 states, and is home to an estimated 10% of the world’s biodiversity and 15% of its freshwater.  These so-called “lungs of the planet” provide many important global ecological services, including carbon storage, and regulating air quality and climate.

Deforestation in the Amazon exploded in the 1970s and remains one of its biggest threats today.  Since the 1970s, more than 20% of the Amazon rainforest has been cleared.  Cattle ranching, soy and palm plantations, logging, and climate change are some of the biggest drivers of deforestation.  

Now, according to a new study recently published in the journal Ecology, the regrowth of Amazonian forests following deforestation may happen more slowly than previously thought.  These findings could have significant impacts on climate change predictions as the ability of forest regrowth in the Amazon – so-called secondary forests – may have been overestimated.  The research, which was conducted in Bragança, Brazil and includes two decades of forest monitoring, reveals that climate change and the wider loss of forests could be hampering regrowth.    

After 60 years of regrowth, the research team found that secondary forests only held 40% of the carbon when compared with forests undisturbed by humans.  Secondary forests also take less carbon from the atmosphere during periods of drought, and climate change is increasing the number of drought-years in the Amazon.  (During their 20 years of monitoring, the researchers also found biodiversity levels in secondary forests were only 56% of those seen in undisturbed forests). 

More long-term studies are needed to better understand the impacts of reforestation efforts.  

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Amazon forest regrowth much slower than previously thought

Photo, posted September 6, 2009, courtesy of Nao Lizuka via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Mistaking Plastic For Food

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Green sea turtles are one of the world’s largest species of turtle, with some measuring close to four feet long and weighing up to nearly 300 pounds.  Their range extends throughout tropical and subtropical seas around the world, with the largest nesting populations found in Costa Rica and Australia. 

Green sea turtles get their name from the green layer of fat under their shell, as opposed to their shell itself, which can be brown, green, yellow, and/or black.  Scientists believe the green coloring of their fat is a result of their diet.  Unlike most other sea turtles, green sea turtles eat marine plants such as seaweed and seagrass.

But new research suggests that green sea turtles are also more likely to swallow plastic because it resembles their natural diet. The scientists from the University of Exeter and the Society for the Protection of Turtles who examined green sea turtles that washed up on beaches in Cyprus found they favored narrow lengths of plastic in natural colors (like green and black) as opposed to debris of other shapes and colors. 

Researchers were able to examine the full gastrointestinal tract of 19 green sea turtles.  They found pieces of plastic inside every one of them, with the number of pieces ranging from three to 183.  Smaller turtles tended to contain more plastic, possibly because they are less experienced or because diet choices change with age and size. 

Previous research has suggested that leatherback sea turtles also eat plastic that resembles their food: jellyfish. 

Researchers hope these findings will help motivate us to continue to work on reducing our overall plastic consumption and pollution.

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Green turtles eat plastic that looks like their food

Photo, posted September, 2007, courtesy of Brock Roseberry via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Economic Inequality

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A new study by Stanford University looked at the effects of climate change on global economic inequality.  The study found that the gap between the economic output of the world’s richest and poorest countries is larger today than it would have been without global warming.

The warming climate has enriched cooler countries like Norway and Sweden while dragging down economic growth in warm countries such as India and Nigeria.  The results of the study showed that most of the poorest countries on Earth are considerably poorer than they would have been in the absence of rising temperatures.  At the same time, the majority of rich countries are richer than they would have otherwise been.

Detailed analysis of 50 years of annual temperature and GDP measurements for 165 countries demonstrated that growth during warmer than average years has accelerated in cool nations and slowed in warm nations.  Historical data clearly show that crops are more productive, people are healthier, and they are more productive at work when temperatures are neither too hot nor too cold.  That means that in cold countries, a little bit of warming can help but the opposite is true in places that are already hot.

For most counties, whether global warming has helped or hurt economic growth is pretty certain.  Tropical countries in particular tend to have temperatures far outside the ideal for economic growth and they are already among the poorest countries.  It is less clear how warming has influenced growth in countries in the middle latitudes, such as here in the United States.  Some of the largest economies are near the perfect temperature for economic output but continued warming in the future is likely to push them away from the temperature optimum.

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Climate change has worsened global economic inequality

Photo, posted November 1, 2011, courtesy of CIAT via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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