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The warmer, greener Arctic and greenhouse gas

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About 15% of the Northern Hemisphere is covered by permafrost.  Permafrost is soil and sediment that has remained frozen for long periods of time, in some cases as much as 700,000 years.  It contains large amounts of dead biomass that has accumulated over millennia and hasn’t fully decomposed.  Therefore, permafrost is an immense carbon sink.

The Arctic is warming four times faster than the rest of the planet and, as a result, thawing permafrost is becoming a carbon source.  As warming continues, ice is melting, and vegetation is spreading.    A new study, published in Nature Climate Change, looked at the state of the Arctic and boreal north from the period 1990 until 2020.  The study found that although half of the Arctic region has been growing greener, only 12% of those green areas are actually taking up more carbon.  For one thing, the growth of forests means that there is more fuel for wildfires which are increasingly common.

A study of lakes in West Greenland found that thousands of crystal blue lakes have turned brown during record heat spells.  Runoff from melting permafrost made the lakes opaque killing off plankton that absorb carbon dioxide.  Meanwhile, plankton that release carbon dioxide multiplied.  So, these lakes went from being carbon sinks to being carbon sources.

As the northern latitudes warm, ice and permafrost are melting, vegetation is spreading, and the region is becoming a source of heat-trapping gas after having been a place where carbon has been locked away for thousands of years.  According to the Nature Climate Change study, roughly 40% of the Arctic is now a source of carbon dioxide.

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Warmer, Greener Arctic Becoming a Source of Heat-Trapping Gas

Photo, posted October 14, 2024, courtesy of Christoph Strässler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The green grab for land

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Solar and wind farms are spreading rapidly around the world.  Many economists believe that solar power has crossed the threshold where it is generally cheaper than other ways to make electricity and will become the dominant energy source in the next couple of decades.  As a result, both solar and wind farms are gobbling up more and more land around the world.  Estimates are that they will take up around 30,000 square miles by mid-century.

One concern is whether we are entering an era of trading food for energy.  Land conflicts seem inevitable since solar power operates best in unshaded areas with gentle winds and moderate temperatures, which are the same conditions favored by many crops.

China is installing more solar farms than the rest of the world combined.  Many of these are in the Gobi Desert, where there is no competing need for the land.  But some are in eastern China, in densely populated grain-growing areas.

There are a number of strategies that reduce the impact of solar farms on land use.  One approach is to put them on old industrial or brownfield sites that are otherwise unusable.  Another is floatovoltaics:  putting solar panels on the surface of lakes and reservoirs.  And then there is agrivoltaics, where solar panels are installed above crop fields or where livestock graze between or even beneath solar arrays.  China has more than 500 agrivoltaic projects that incorporate crops, livestock, aquafarming, greenhouses, and even tea plantations.

Green energy has both environmental and economic benefits to offer, but it must conserve nature and not excessively grab land needed for people, wildlife, and ecosystems.

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‘Green Grab’: Solar and Wind Boom Sparks Conflicts on Land Use

Photo, posted May 25, 2011, courtesy of Michael Mees via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The human footprint on Earth

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The Earth is a pretty big place, and it is easy to think that humans and their activities occupy very little of it.  But the impact of human activities on our planet continues to grow.  Recent satellite images from NASA’s Earth Observatory show the staggering extent of the human footprint on Earth.

Agriculture is a major part of it.  Farms and pastures take up almost half of the world’s habitable land – land not covered by ice or desert.  Greenhouses have recently proliferated tremendously and now cover 3.2 million acres, an area the size of Connecticut, and they even have effects on local climates.

More than half of the world’s population now lives in cities, which are expanding rapidly.  Enormous cities in Asia are changing the landscape in places like Thailand and Indonesia.  Apart from taking up lots of land, many of the world’s cities are immersed in clouds of air pollution that they generate.

Greenhouse gas emissions continue to grow, and temperatures continue to rise.  The effects of this on the planet are increasingly evident.  Seas are rising, ice is melting, glaciers shrink away, and wildfires continue to burn.  The massive wildfires in and around Los Angeles have made major changes in the local landscape.  Rising seas have flooded coastal wetlands and elsewhere, rivers and lakes have shrunk.

There are also human impacts visible from space that represent positive signs.  Large solar arrays supply the cheapest form of energy in most parts of the world and the number and size of solar installations are at a record high.   These solar installations provide some hope that global warming can be slowed.

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The Growing Human Footprint on Earth, as Seen from Space

Photo, posted July 28, 2012, courtesy of Beth Scupham via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Removing nanoplastics from water

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Plastic pollution is a growing problem for people and for the environment in multiple ways.  When plastics break down over time, they can form small particles called microplastics – bits smaller than sesame seeds – and these, in turn, can break down into even smaller pieces called nanoplastics.  They are too small to be seen with the naked eye and can enter the body’s cells and tissues.

Recent studies have shown that nanoplastics are increasingly showing up in bottled water.  In fact, measurements on several popular brands of bottled water found an average of nearly a quarter million tiny pieces of plastic in a single liter of bottled water.

The health effects of ingesting all of this plastic are not really known, but they are unlikely to be anything good.  Finding a way of avoiding this contamination of the beverages we drink is a pressing need.

Researchers at the University of Missouri have created a new liquid-based solution that eliminates more than 98% of microscopic plastic particles from water.  The method makes use of water-repelling solvents made from safe, non-toxic natural ingredients. A small amount of this designer solvent absorbs plastic particles from a large volume of water.

The solvent sits on the water’s surface.  When mixed with the water, it absorbs the plastic and eventually comes back to the surface carrying the plastic leaving behind clean, plastic -free water.

Ultimately, the hope is to scale up the process so it can be applied to increasingly large amounts of water – even lakes and, eventually, oceans.  There is work to be done, but it is a potential way to address an increasingly worrisome and pervasive form of pollution.

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Mizzou scientists achieve more than 98% efficiency removing nanoplastics from water

Photo, posted August 9, 2012, courtesy of Enid Martindale via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Potential for floating solar

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As installations of utility-scale solar power continue to expand around the world, there is the issue of where to put them.  They do take up considerable amounts of space and, in many places, available land is at a premium.

An alternative to taking up available land with solar panels is to deploy them on the surfaces of lakes and reservoirs.  A study by researchers at Bangor and Lancaster Universities in the UK calculated the potential electrical output for floating photovoltaic installation on nearly 68,000 lakes and reservoirs around the world.  The lakes and reservoirs selected were no more than 6 miles from a population center, were not in a protected area, and didn’t dry up and didn’t freeze for more than six months each year.  The calculations were based on covering just 10% of the surface area of the bodies of water.

The calculations were evaluated country-by-country.  Five countries could meet their entire electricity needs by floating installations including Papua New Guinea, Ethiopia, and Rwanda.  Many countries, mostly in Africa, South America, and Central Asia, could get between 40% and 70% of their electricity this way.  Most European countries could only meet a few percent of their electricity needs from floating solar, but even that could be significant. 

There are other benefits to floating solar apart from freeing up land.  The panels stay cooler, making them more efficient, and reservoirs lose less water through evaporation and the growth of algal blooms is reduced because there is less light reaching the water.

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Some countries could meet their total electricity needs from floating solar panels, research shows

Photo, posted November 25, 2015, courtesy of Smabs Sputzer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Forever chemicals in water

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So-called forever chemicals are pervasive in a wide range of products.  These are man-made substances called per- and polyfluoroalkyls or PFAS.  They get their unfortunate nickname because the chemical bonds in them are so strong that the compounds don’t break down for hundreds or even thousands of years.

PFAS compounds are used in makeup, dental floss, nonstick pans, food wrappers, pesticides, stain-resistant fabrics and carpets, firefighting foams, and more.  High level exposure to some of these chemicals has been linked to a variety of health problems include high cholesterol, liver and immune system damage, pregnancy problems, and kidney and testicular cancer.

A recent study published in the journal Nature Geoscience has found that PFAS chemicals are showing up in water around the world.  The study looked at more than 45,000 water samples and found that about 31% of ground water tested that wasn’t even near any obvious source of PFAS contamination had levels of the chemicals that are considered harmful to human health by the EPA.  About 16% of surface water samples – streams, rivers, ponds, and lakes – also not near any known source, had similar hazardous PFAS levels.

The EPA has now imposed strict new drinking water limits for six types of PFAS.  Going forward, water systems are required to monitor for these chemicals and remove them if they are found above allowable levels.  The new rules make the United States one of the strictest countries in the world in terms of regulating PFAS in water.

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EPA puts limits on ‘forever chemicals’ in drinking water

Photo, posted May 5, 2020, courtesy of Brandon Shaw via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Greenland is greening

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Despite their names, Iceland is very green, and Greenland is very icy.  But in Greenland, that is changing.  Temperatures in the world’s largest island are rising twice as fast as they are in the rest of the world and, as a result, the icy rocky landscape is turning increasingly green.

Satellite records reveal that over the last three decades Greenland has lost 11,000 square miles of ice, which is an area about the size of Massachusetts.  As the ice melts off, tundra and shrublands takes its place.  The ice melt moves sediment and silt and eventually wetlands and fenlands are formed.

Between the late 1980s and the late 2010s, the areas of Greenland covered by vegetation have more than doubled.  The new green areas cover roughly 33,000 square miles, which is an area the size of Maine.

Greenland’s dramatic changes are the result of the warming climate, but in turn, those changes are accelerating climate change.  Land covered with dark green vegetation absorbs more energy from the sun thereby warming the air whereas ice-covered landscapes reflect much of the sun’s energy back into space.  In addition, the rapidly expanding wetlands are a significant source of methane, which traps even more heat in the atmosphere.

Greenland is a poster child for the effects of climate change.  Its glaciers and icecaps are shrinking, glacier-fed lakes are expanding, permafrost lakes are draining, and rivers are transporting vast amounts of sediment and widening.  All of this is going on as its vegetation cover and species diversity is expanding.

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In Icy Greenland, Area Covered by Vegetation Has More Than Doubled in Size

Photo, posted September 20, 2019, courtesy of Amanda via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Little ice on the Great Lakes

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In an average year, the Great Lakes end up about 40% covered in ice.  But this is not an average year.  2023 was the warmest year on record and, in fact, the global temperature was more than 1.5 degrees above the pre-industrial average for the full year.  That hasn’t happened before.  As a result of the record-breaking warmth, as of mid-February, the average ice cover on the Great Lakes was only 5.9%.

Lake Erie and Lake Ontario tied their records for the lowest ice cover, which has been tracked since 1973.  Lake Huron, Lake Michigan, and Lake Superior are at historic lows.  Some parts of the Great Lakes have experienced the winter without any ice cover.

The warming air temperatures have led to rapid ice loss and warming summer temperatures.  According to experts, if the planet continues to warm, more than 200,000 lakes may no longer freeze every winter and 5,700 lakes may permanently lose ice cover by the end of the century.

Studying the Great Lakes is important because their ice melt can be a significant indicator of the progress of global warming.  Decreasing ice cover can affect hydropower generation, commercial shipping and fishing, and have environmental impacts such as the development of plankton blooms.

Since the 1970s, there has been a 5% decline in Great Lakes ice cover per decade.  Unfrozen lakes bring more rain than snow which has environmental, cultural, and societal impacts.  The Great Lakes hold 21% of the world’s freshwater supply and over 30 million people depend on them for drinking water.  They are also linked to over $3 trillion in gross domestic product.

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Great Lakes Winter Ice Cover Averaging Just 5.9%: NOAA

Photo, posted November 7, 2007, courtesy of Jim Sorbie via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Adirondack lakes becoming inhospitable for trout

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A combination of the warming climate and the phenomenon of lake browning are making the bottom of most lakes in New York’s Adirondack Mountains unlivable for cold water fish – such as trout, salmon, and whitefish – in the summer.

Lake browning occurs when dissolved organic matter from forests turns the water tea-brown.  Browning is the legacy of a century of acid rain and subsequently the fact that forest soils have suffered reduced capacity to absorb weak organic acids, leading to more dissolved plant matter flowing into lakes.  Climate change has increased the frequency of extreme precipitation events and the length of growing seasons, leading to more runoff of organic matter.

Browner water traps more of the sun’s heat at the top of the lake and blocks the sun’s rays from reaching deeper.  The result of the browning is lakes that are either too warm or too deoxygenated to support trout populations.

A study of 1,467 Adirondack lakes by Cornell University researchers found that only about 5% of them may continue to maintain water that is cold and oxygenated enough to support cold-water fish.

Deeper lakes fare much better because they have so much water that their oxygen is hard to deplete, but only 1% of all Adirondack lakes are deeper than 30 meters.  Another 4% are very clear because the influx of cold water outpaces the expansion of low-oxygen zones and limits the effects of browning.

The study urges the protection of as many lakes as possible from species invasions, nutrient and salt pollution, and other forms of environmental degradation. 

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Most Adirondack lakes will likely become unsuitable for trout

Photo, posted July 17, 2011, courtesy of Lida via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Attack of the giant goldfish

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Goldfish are just about the easiest pets to keep.  A species of carp native to East Asia, they have been bred to look pretty and are generally little more than home décor.  We keep them in little glass bowls and feed them mysterious flakes out of a container.  With these confined quarters and meager meals, they remain small, harmless creatures.  But released into the wild, it is a very different story.

People dump pet goldfish into lakes and ponds with some frequency.  Once they are in the wild, these humble creatures can grow to monstrous proportions.  They can eat nearly anything, including algae, aquatic plants, eggs, and invertebrates.  They can kill off native marine wildlife and damage or even destroy fragile and economically valuable ecosystems.

For a few years, Canadian researchers have been tracking invasive goldfish in Hamilton Harbour, at the western tip of Lake Ontario, about 35 miles southwest of Toronto.  That part of the lake has been decimated by industrial and urban development as well as by invasive species.

Goldfish were first spotted in the harbor in the 1960s, mostly died off in the 70s because of industrial contamination, but then recovered in the 2000s.  Goldfish can tolerate a wide range of water temperatures, reach sexual maturity quickly, and can reproduce several times in one season.  In resource-rich places, they can grow up to 16 inches long, making them too large a meal for many predators.

There are literally millions of goldfish in the Great Lakes and not only there.  Feral goldfish are a problem in Australia and in the United Kingdom.  Invasive species are a big problem, even if they start out small and cute.

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Once They Were Pets. Now Giant Goldfish Are Menacing the Great Lakes.

Photo, posted September 20, 2015, courtesy of Watts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Lakes Are Shrinking | Earth Wise

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A study by the University of Colorado Boulder has found that more than half of the world’s largest lakes have shrunk over the last three decades.  This is a very big problem because about one-quarter of the Earth’s population lives in the basin of a drying lake.  People depend on lakes for drinking water and irrigation and lakes are central to the survival of local ecosystems as well as migrating birds.  Lakes cover only about 3% of the planet, but they hold nearly 90% of the liquid surface freshwater.

The study used satellite observations from 1992 to 2020 to estimate the area and water levels of nearly 2,000 freshwater bodies.  These account for 96% of Earth’s total natural lake storage and 83% of that in man-made reservoirs.  About 53% of the world’s lakes have clearly shrunk, while only 22% have gained water.  The study estimates that about 160 trillion gallons of water has been lost over the 28-year period.  That’s about 17 times the maximum capacity of Lake Mead, the largest reservoir in the United States.

Many of the world’s most significant lakes have been shrinking. The dramatic declines in Lake Mead have been headline news for years.  The Caspian Sea, which is the world’s largest inland body of water – has long been declining.

The main causes of the decline in natural lakes are climate change and human consumption.  Reservoirs face an additional major problem of sediment buildup which reduces their storage capacity and diminishes their benefits of water supply, flood control, and hydropower.

Lake loss is a big problem.

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More than half of the world’s largest lakes are drying up

Photo, posted April 10, 2018, courtesy of Ninara via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastic In Lakes | Earth Wise

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We are always talking about the millions of tons of waste plastic that finds its way into the oceans and about the challenges of trying to remove it.  A new multinational study has found that the concentration of plastics and microplastics in some lakes is even worse than in the so-called garbage patches in the oceans and some of these lakes are even in remote places around the world

Scientists from institutes in multiple countries collected water samples from 38 lakes and reservoirs in 23 countries across six continents.  The samples were then all analyzed by the University of Milan to assess the presence of plastic particles more than a quarter millimeter in size.

The study found that two types of lakes are particularly vulnerable to plastic contamination:  lakes and reservoirs in densely populated and urbanized areas and large lakes with elevated deposition areas, long water-retention times, and high levels of human influence.

Lakes found to have the highest concentration of plastic included some of the main sources of drinking water for communities and were also important to local economies.  These included Lough Neagh in Northern Ireland, Lake Maggiore in Italy, and Lake Tahoe on the California/Nevada border.  Not all the lakes studied contained large amounts of plastic.  For example, Windermere, the largest lake in England, had very low concentrations of plastic in surface water.

This was the first global survey of the abundance and type of plastic pollution in lakes and reservoirs and the scale of freshwater plastic pollution is sobering indeed.  There is widespread concern that plastic debris is having harmful effects on aquatic species and ecosystem function and clearly is not limited to marine ecosystems.

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Plastic pollution is higher in some lakes than oceans

Photo, posted May 27, 2019, courtesy of Jonathan Cook-Fisher via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rain Gardens And Residential Pollution | Earth Wise

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Stormwater runoff has become the largest source of residential pollution for waterways.  As rainwater runs down roofs, over driveways and patios, and off other hard surfaces, it can pick up pollutants as it flows directly into streams, wetlands, lakes, and groundwater aquifers.  That water is typically routed directly through stormwater pipes and ditches with little filtering or treatment.  The main emphasis is on getting the water off of people‘s property as quickly and efficiently as possible to avoid flooding.

Many municipalities are dealing with the problem by installing rain gardens, which are a type of green infrastructure in commercial spaces that slow down and treat water before it enters streams, wetlands, and other bodies of waters.  When designed and installed properly with appropriate plants, rain gardens are like miniature water treatment facilities   Water gathers in the rain garden, soaks into the soil, and is taken up by plants.  The plants filter nutrients, sediments, and toxic materials from the runoff before excess water ever gets to waterways.

Homeowners are being encouraged to build their own rain gardens.  They need to familiarize themselves with how runoff from their roof, driveway, sidewalk, and roads is currently being routed and treated.  The idea is to try to incorporate that runoff into a rain garden design with sufficient area and infiltration rates.  The runoff would ultimately flow out from a safe, designated location into storm drains at a slower rate than from the previous impervious surfaces.  Homeowners would need to work with their local jurisdictions to find out the requirements for re-routing water in their area and make sure any modifications prevent erosion and protect nearby homes, roads, and other infrastructure.

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Rain gardens help keep pollutants out of waterways

Photo, posted March 3, 2017, courtesy of Jeremy Jeziorski / Oregon Convention Center via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Large Lakes In Decline | Earth Wise

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Globally, freshwater lakes and reservoirs hold 87% of the planet’s liquid freshwater, making them a valuable resource for both people and wildlife.  Despite their value, the long-term trends and changes to water levels of lakes have been largely unknown – until now.

According to a new assessment recently published in the journal Science, more than half of the largest lakes around the world are losing water.  Using satellite observations and climate data, the research team created a technique to measure changes in water levels in nearly 2,000 of the world’s biggest lakes and reservoirs, representing 95% of the total lake water storage on Earth.

The results are staggering.  According to the findings, 53% of Earth’s largest lakes and reservoirs now store significantly less water than they did in 1992.  The total amount of water lost is estimated to be 144.5 cubic miles, which is equivalent to the volume of 17 Lake Meads (the largest reservoir in the U.S.). 

Unsurprisingly, climate warming and human consumption were the main drivers of water loss from lakes, whereas sedimentation — the buildup of debris — was the biggest driver of water loss in reservoirs.  Roughly one-quarter of the world’s population – two billion people – live in the basin of a drying lake, indicating the urgent need for sustainable water resources management.

But the news is not entirely bleak.  According to the research team, the new method of tracking lake water storage trends can give water managers and communities insight into how to better protect this critical resource. 

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Satellites reveal widespread decline in global lake water storage

Photo, posted February 10, 2010, courtesy of Ninara via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Two Lost Lakes Return To California | Earth Wise

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The recent siege of powerful storms in California driven by a series of atmospheric rivers has had a significant effect on the severe drought that has plagued most of the state for many years.  Many of the state’s reservoirs are at the highest level they have been for decades.   The snowpack in the Sierras is well over 200% of its historical average.  Many parts of the state are no longer considered to be in drought conditions, and, in fact, flooding has been a serious problem in some areas.  This flooding has had some surprising results.

Two California lakes that drained a century ago have reappeared as a result of floodwaters from the recent storms.

Tulare Lake, in California’s Central Valley used to be fed by rain and snowmelt from the Sierras.  A system of dams and canals constructed in the early 20th century to support regional agriculture diverted water away from the lake.  It used to be the largest freshwater lake in the West but farmers ultimate planted crops in the dried lakebed.

The atmospheric river events in March inundated that farmland and once again there is water in Tulare Lake.

Owens Lake, on the eastern side of the Sierra Nevada, was long fed by mountain streams.  The 1913 construction of the Los Angeles Aqueduct redirected water to that city and desiccated the lake.   Floodwaters in March caused a partial collapse of the aqueduct and when the spill gates on the aqueduct were opened to drain the damaged areas, floodwaters poured in and partially refilled the lake.

California has suffered from drought for many years.  With its massive snowpack, as the weather warms, the state may face even more flooding.

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Two Long-Drained California Lakes Refilled by Floodwaters, Satellite Images Show

Photo, posted November 10, 2014, courtesy of CN via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Dangers Of Melting Glaciers | Earth Wise

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Some of most dramatic evidence that the Earth’s climate is warming is the retreat and even disappearance of mountain glaciers around the world.  2022 was the 35th year in a row that glaciers tracked by the World Glacier Monitoring Service lost rather than gained ice.  Glaciers gain mass through snowfall and lose mass through melting and sublimation (water evaporating directly from solid ice.)  Some glaciers that terminate in lakes or the ocean lose mass through iceberg calving.

In the warming climate, glaciers retreat and meltwater collects at the front of the glacier forming a lake.  Such lakes can suddenly burst and create a fast-flowing Glacier Lake Outburst Flood that can spread over a large distance from the original site – in some cases over 70 miles.  These floods can damage property, infrastructure, and agricultural land and can also be deadly.

The number of glacial lakes has grown rapidly since 1990 as a result of climate change.  According to research by an international team of scientists led by Newcastle University in the UK, the number of people living in glacial lake catchments has increased significantly.

According to the study, 15 million people live within 30 miles of a glacial lake.  The highest danger is in High Mountain Asia – which encompasses the Tibetan Plateau.  That area, which spans from Kyrgyzstan to parts of China, has 9.3 million people potentially at risk.  India and Pakistan have around 5 million exposed people.

Detailed analysis shows that it is not the areas with the largest number or most rapidly growing lakes that are most dangerous.  It is the number of people in proximity to the lakes and their ability to cope with potential floods.

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Glacial flooding threatens millions globally

Photo, posted February 12, 2022, courtesy of David Stanley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Agriculture Turning Wild Plants Into Weeds | Earth Wise

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We often hear about the importance of native plants in the environment and how invasive species can wreak havoc with ecosystems.   But it turns out that human activities can change the characteristics of native species and create unexpected new problems.

Common waterhemp is plant native to North America that typically grows near lakes and streams.  It never used to be any kind of problem, but in recent times it has become nearly impossible to eradicate from farms as a result of genetic adaptations triggered by modern agriculture.

A study led by researchers at the University of British Columbia looked at waterhemp samples from modern farms and neighboring wetlands and compared them with historical samples dating back as far as 1820 stored in various museums.

In recent times, mutations in genes related to drought tolerance, rapid growth, and resistance to herbicides have resulted in waterhemp that has become a pervasive weed on farms.  These genetic shifts, scarcely ever seen in historical samples, have made the plant thrive among human agricultural activities and enable it to outcompete crops.

Genetic analysis of the plants showed that herbicide-resistant mutations that were mostly absent from historical samples stand out as factors that allow waterhemp to prosper in agricultural settings. There are some plants in natural habitats that have herbicide-resistant mutations, but in many cases, these mutations are actually harmful to the plants in the wild.

Understanding how plant adaptations occur on relatively short timescales is increasingly important as farming and climate  change continue to drive rapid plant evolution.

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How intensive agriculture turned a wild plant into a pervasive weed

Photo, posted February 16, 2016, courtesy of Aqua Mechanical via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Harvesting Fresh Water From Ocean Air | Earth Wise

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Roughly three-quarters of the world population has access to a safely managed water source.  That means that one-in-four people do not have access to safe drinking water.  Even in the wealthy United States, persistent drought in the west is creating problems in places like Phoenix, Arizona.

Water is plentiful on Earth but more than 99% of it is unusable by humans and many other living things because it is saline, frozen, or inaccessible.  Only about 0.3% of our fresh water is found in the surface water of lakes, rivers, and swamps.

There is an almost limitless supply of fresh water in the form of water vapor above the oceans, but this source is untapped.  Researchers at the University of Illinois have been evaluating the feasibility of a hypothetical structure capable of capturing water vapor from above the ocean and condensing it into fresh water.

Existing ways to obtain fresh water like wastewater recycling, cloud seeding, and desalination have met only limited success and present various problems with regard to cost, environmental impact, and scalability.

The researchers have proposed hypothetical large offshore structures measuring 700 feet by 300 feet to capture water vapor that is continually evaporating from the ocean in subtropical regions.   Their modeling concluded that such structures could provide fresh water for large population centers in the subtropics.  Furthermore, climate projections show that the amount of water vapor over the oceans will only increase over time, providing even more fresh water supply.

This is only a theoretical study at this point, but the researchers believe it opens the door for novel infrastructure investments that could address global water scarcity.

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Researchers propose new structures to harvest untapped source of fresh water

Photo, posted June 28, 2009, courtesy of Nicolas Raymond via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Oxygen Loss In Lakes | Earth Wise

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Researchers from Cornell University and Rensselaer Polytechnic Institute have found that the continual warming in the world over the past 25 years has been reducing the amount of oxygen in many lakes.

Data from more than 400 lakes – mostly in the United States – shows that lakes with dissolved oxygen losses strongly outnumber those with gains.  Overall, the researchers found that the amount of low oxygen water is increasing by 0.9% to 1.7% per decade on average  and the volume of lake water lacking oxygen has increased by more than 50% from 25 years ago.

In the summer, lake surfaces may be about 70 degrees while the lake bottom may be about 40 degrees.  The colder water is denser than the warmer water which causes resistance to the layers mixing.  It is akin to having oil and vinegar in a cruet.  This is known as stratification.   The result is that oxygen from the atmosphere is prevented from replenishing dissolved oxygen in deep waters.  This is a normal seasonal phenomenon.

However, with winter ending sooner than it used to, seasonal stratification is starting earlier and ending later. As warming continues, it is likely that there will be an increasing number of oxygen-depleted lakes in the future.

Oxygen deprivation in water can lead to hypoxia (low oxygen) and even anoxia (no oxygen), which have negative consequences for fish and other species.  Reducing oxygen in lake water can lead to buildup of methane.   Nutrients from agricultural runoff, released from unsettled lake sediment, increase the likelihood of harmful algal blooms.

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Warming climate prompts harmful oxygen loss in lakes

Photo, posted June 23, 2010, courtesy of Alexander Acker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Moving Endangered Species | Earth Wise

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People have intentionally or accidentally introduced numerous invasive species to habitats around the world.  At the same time, the planet’s wildlife is in a steep decline.  A recent study estimated that the populations of over 5,000 vertebrate species have declined by an average of nearly 70% since 1970.  A United Nations report warns that human activity has threatened as many as a million species with extinction.

With all of this as a background, there is climate change that is altering the habitats of the world’s species – warming lakes and oceans, turning forests into grasslands, tundra into woodland, and melting glaciers.  In response to these changes, living things are rearranging themselves, migrating to more hospitable locations.  But many species are just not capable of finding more suitable habitats on their own.

Conservationists are now increasingly considering the use of assisted migration. In some cases, when a species’ critical habitat has been irreversibly altered or destroyed, agencies are establishing experimental populations outside of the species’ historical range.  Such actions are often deemed extreme but may be increasingly necessary.

However, clear-cut cases are relatively rare.  More likely, it is a more difficult judgement call as to whether assisted migration is a good idea or is possibly a threat to the ecosystem of the species’ new location.  The relative dearth of assisted migration experiments is less likely a result of legal barriers than it is a lack of scientific and societal consensus on the practice. Scientists are now trying to develop risk-analysis frameworks that various agencies can use in considering potential assisted migration experiments. 

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Last Resort: Moving Endangered Species in Order to Save Them

Photo, posted March 18, 2010, courtesy of Jean via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

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