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Airplanes and climate change

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The aviation industry is a powerful force in the global economy.  In fact, according to some estimates, the industry transports the equivalent of nearly half the world’s population every year.  But the world’s airports were largely designed for an older era – a cooler one.

As air warms, it becomes less dense, which makes it harder for airplanes to generate lift, which is the force that enables them to fly.

According to a new study by scientists from the University of Reading in the U.K., rising temperatures due to climate change may force aircraft at some airports to reduce passenger numbers in the coming decades.

The research team examined how warmer air affects aircraft performance during takeoff at 30 sites across Europe.  The study, which was recently published in the journal Aerospace, focused on the Airbus A320, which is a common aircraft used for short and medium-distance flights across Europe.

By the 2060s, the research team found that some airports with shorter runways may need to reduce their maximum take-off weight by the equivalent of approximately 10 passengers per flight during summer months.

Of the sites included in the study, Chios in Greece, Pantelleria and Rome Ciampino in Italy, and San Sebastian in Spain will be the four most affected popular tourist destinations.

Climate change is also making air travel increasingly turbulent, and the aviation industry itself remains a growing contributor to global greenhouse gas emissions. 

Taking meaningful action to curb greenhouse gas emissions, including those from the aviation industry, is one of the most crucial ways to mitigate global climate change.

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Holiday flights could carry fewer passengers as world warms

Photo, posted September 29, 2017, courtesy of Hugh Llewelyn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Mining extinct volcanoes

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Rare earth elements are a group of 17 elements that are used to improve the performance, efficiency, and durability of a wide range of products.  More than 200 products across a diverse set of applications make use of rare earth elements.  Although the amount of rare earth used in a particular product may not be very much of its weight, volume, or monetary value, it may often be necessary for the device even to function.  Rare earth elements react with other elements to form compounds that are essential because of their specific chemical behaviors. 

Rare earth elements are not actually rare; in fact, they are fairly common.  But they are mostly not found in their pure form and are generally difficult to refine.  China accounts for more than 90% of global production of rare earth elements and this represents a strategic problem for the rest of the world.

New research by scientists from the Australian National University has found that some extinct volcanoes, which have not erupted for thousands or even millions of years, may be rich sources of rare earth elements.  Furthermore, those elements may be easier to extract than the ones from other sources because the iron-rich magma that formed the volcanoes could be up to 100 times more efficient at concentrating rare-earths than magma found in active volcanoes today.

The clean tech industry uses rare earths for wind turbines, solar panels, and electric cars.  The demand for rare earths may grow fivefold by the end of this decade.  Relying on just one country for the world’s supply is a major concern.  There are ancient volcanoes all over the planet and they may represent a solution to a global problem.

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Extinct Volcanoes Could Be Source of Key Metals Needed for Clean Tech

Photo, posted June 6, 2020, courtesy of Dennis Jarvis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A structural battery

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The size and especially the weight of batteries is a critical factor for most things that use them.  Battery weight is a key limitation for computers and cell phones. It is even more of a limitation for electric cars, ships, or planes.

If the battery of a device or vehicle can also function as a load-bearing structure, its weight and energy consumption can be dramatically reduced.  This concept of a structural battery is sometimes called massless energy storage.  It has the potential to halve the weight of a laptop computer, make cell phones as thin as a credit card, and increase the range of an electric car by as much as 70%.

Researchers at Chalmers University in Sweden have been working on structural battery technology for many years.  Their first published results in 2018 showed how stiff, strong carbon fibers could be used for chemical storage of electrical energy.

Since then, they have been creating batteries with increasing energy density.  Their latest versions still have only a quarter of the capacity of today’s lithium-ion batteries. But if batteries can be part of the structure of a vehicle, for example, and can be made of lightweight materials like carbon fiber, then the overall weight of the vehicle can be greatly reduced and not nearly as much energy will be needed to power it.

The goal of the Chalmers research is to achieve battery performance that makes it possible to commercialize the technology.  There is a lot of engineering work to be done before these structural batteries can go from laboratory proofs of concept to real world use.  But the potential is quite promising.

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World’s strongest battery paves way for light, energy-efficient vehicles

Photo, posted August 8, 2024, courtesy of NOI Techpark via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Energy efficient cows

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Livestock production – primarily cows – produce nearly 15% of global greenhouse gas emissions, mostly in the form of methane emitted by burping caused by the way they process food.  A single cow produces roughly 200 pounds of methane gas per year and there are 1.5 billion heads of cattle in the world.

Researchers at Penn State University have found that supplementing the feed of high-producing dairy cows with the botanical extract capsicum oleoresin – a substance obtained from chili peppers – or a combination of that extract and clove oil resulted in the animals using feed energy more efficiently. 

Adding these substances – which are commonly called essential oils – to the cattle’s feed results in improved efficiency of energy utilization.  It is known that botanicals have the potential to modify fermentation in the cow’s largest stomach – called the rumen.

There have been previous studies for many years adding substances to dairy cow feed – such as seaweed, garlic, and oregano – in an effort to improve milk production and reduce environmental emissions from dairy farms.

The Penn State study was actually not specifically aimed at methane reduction but rather to better use the available energy from the feed to gain body weight.  However, the researchers found that the yield and intensity of methane from the cows in the study were decreased by 11% by the combination of capsicum oleoresin and clove oil.

Botanicals have shown a wide range of anti-microbial properties against bacteria, protozoa, and fungi, as well as being potential rumen modifiers in cattle.  The new study represents an interesting approach to improve the metabolism of dairy cows.

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Dairy cows fed botanicals-supplemented diets use energy more efficiently

Photo, posted April 9, 2012, courtesy of Aimee Brown / OSU via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Polar bears and the changing climate

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The changing climate poses a major threat to polar bear survival.  Polar bears, whose native range lies largely within the Arctic Circle, depend on sea ice for nearly all of their lifecycle functions.  Rising global temperatures are causing this sea ice to disappear.

With less sea ice, polar bears are forced to stay longer on land.  However, according to a new study led by researchers from Washington State University, more time stranded on land leads to a greater risk of polar bear starvation. 

During three summer weeks in Manitoba, Canada, 20 polar bears observed by researchers tried different strategies to maintain energy reserves.  But the research team found that nearly all of them lost weight – losing about 2.2 pounds per day on average.     

Some scientists have speculated that polar bears might be able to adapt to the changing climate by acting more like grizzly bears by either resting or eating terrestrial food.  But the polar bears tried versions of both strategies – with little success.

Polar bears can weigh nearly twice as much as grizzly bears.  To maintain this size, polar bears rely on the energy-rich fat of seals, which they best catch on ice.

In the study, which was recently published in Nature Communications, the researchers found that some polar bears laid down to conserve energy, while others searched on land for food.  But neither the activity nor the lack thereof paid off.  In fact, only one bear out of the 20 gained weight after stumbling across a dead marine mammal on land.

Polar bears across the Arctic are at risk of starvation as the ice-free period continues to grow.

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Polar bears unlikely to adapt to longer summers

Photo, posted November 16, 2015, courtesy of Anita Ritenour via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Electric Motors For Aviation | Earth Wise

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Aviation contributes about 3% of global greenhouse gas emissions.  Its carbon footprint is one of the more difficult ones to reduce.  Electrifying planes would shrink that footprint considerably, but it represents a significant technical challenge.  To date, only small all-electric planes have gotten off the ground.  The electric motors in those planes generate hundreds of kilowatts of power.  To power large planes, like commercial airliners, megawatt-scale motors are required.

A team of MIT engineers is developing a 1-megawatt motor that could be a key step towards electrifying commercial aircraft.  They have designed and tested major components of the motor and have calculated how the completed design could generate one megawatt of power at a weight and size competitive with existing small aircraft engines.

To be suitable for aircraft use, motors have to be compact and lightweight.  The more power electric motors generate, the bigger they are and the more heat they produce.  Cooling motors requires additional components that take up space and add significant weight.  The MIT motor design and associated power electronics are each about the size of a typical checked suitcase and weigh less than an adult passenger.

Once the MIT team can demonstrate an entire functional motor, the design could be used to power regional aircraft and could be the enabling element of hybrid-electric propulsion systems for jet aircraft.  Possible future configurations could make use of multiple one-megawatt motors powering multiple fans distributed along aircraft wings.

Electrification of aircraft is a slow but steady area of development and technologies such as that being developed at MIT could end up meeting the practical needs of the aircraft of the future.

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Megawatt electrical motor designed by MIT engineers could help electrify aviation

Photo, posted September 14, 2019, courtesy of Dylan Agbagni via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Airplane Turbulence And Climate Change | Earth Wise

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

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

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

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

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

The future is shaping up to be a bumpy ride.

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Climate crisis leading to more turbulence during flights, says study

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

Climate Scientist Explains Increase In Airplane Turbulence

Airports and Rising Seas

Photo, posted May 9, 2018, courtesy of Steve Lynes via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

New York Is Sinking | Earth Wise

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

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

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

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

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New York City Sinking Under Weight of Skyscrapers

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

Earth Wise is a production of WAMC Northeast Public Radio

Life In The Garbage Patch | Earth Wise

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A team of scientists has found thriving communities of coastal creatures living thousands of miles from their original homes and now ensconced on plastic debris in the Great Pacific Garbage Patch. 

A new study published in the journal Nature Ecology & Evolution reports that dozens of species of coastal invertebrate organisms – including tiny crabs and anemones – have been able to survive and reproduce on plastic garbage that has been floating in the ocean for years.

The Great Pacific Garbage Patch is an area in the ocean between California and Hawaii, larger than Texas, where plastic debris has been collected by the North Pacific Subtropical Gyre, one of five huge, spinning circular currents in the world’s oceans.  The patch is estimated to contain about 1.8 trillion pieces of plastic weighing an estimated 90,000 tons.  The Ocean Cleanup Initiative is dedicated to removing this immense accumulation of plastic, but it is an immense job.

Researchers discovered this new ecosystem after analyzing plastic samples collected by The Ocean Cleanup organization during its expeditions in the Pacific.  They were surprised to find 37 different invertebrate species that normally live in coastal water and only a dozen species that live in open waters.  These species have made their way from North America and have thrived.  So, the garbage patch has created a novel community that didn’t previously exist.

Debris from the Great Pacific Garbage patch constitutes the majority of debris arriving on Hawaiian beaches and reefs.  Hawaii’s fragile marine ecosystems have long been protected from invasive species because of the very long distances from North America or Asia.  With the coastal species now inhabiting the garbage patch, there is increased danger of colonization by them in Hawaii’s ecosystems.

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Coastal species persist on high seas on floating plastic debris

Photo, posted September 30, 2020, courtesy of Kees Torn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Humanity Weighs On The World | Earth Wise

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There are countless ways in which humankind has had disproportionate effects on our planet and most of those effects have been negative.  A recent study led by the Weizmann Institute of Science in Israel looked at the total combined weight of various groups of mammals on Earth.  The results are that human beings and our domesticated mammals are the overwhelming majority of the total mass of mammals.

We think of large land mammals – elephants, bears, bison, wildebeests, and so on – as adding up to a massive amount of animal matter.  The study determined that all wild land mammals put together add up to about 22 million metric tons. Wild marine mammals – such as dolphins and whales – add up to about 40 million tons in total.  These sound like pretty big numbers until we look at the human and human-created side of the equation.

The study found that humans weigh about 390 million metric tons, while domesticated mammals – like sheep, cows, and pigs as well as dogs and cats – weigh about 630 million metric tons combined.

All told, wild mammals account for only 6% of all mammals by weight.   People and their domesticated animals make up the other 94%.  This enormous imbalance is an indication of how profoundly humans have reshaped life on Earth.  House cats total twice the weight of African elephants and pigs add up to twice the weight of all wild land animals combined.

The conclusion to draw from the big picture here is that wild animals on Earth are not doing very well.  We already knew this from many other perspectives, but this census by weight presents a stark picture of the extent to which we have taken over the planet and its ecosystems.

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Total Weight of Wild Land Mammals Less Than One-Tenth Weight of All Humans

Photo, posted December 27, 2006, courtesy of Nigel Hoult via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Disappearing Glaciers | Earth Wise

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Glaciers are massive bodies of slowly moving ice.  Glaciers form on land, and represent the snows of centuries compressed over time.  They move slowly downward under the influence of their own weight and gravity. 

Most of the glaciers on the planet are found in the polar regions, including Antarctica, the Canadian Arctic, and Greenland.  Glaciers can also be found closer to the equator in mountain ranges, such as the Andes Mountain range in South America.  Glaciers are always changing, accumulating snow in the winter and losing ice to melting in the summer.  But in recent times, the melting has been outpacing the accumulation.

A new international study led by researchers at Carnegie Mellon University’s College of Engineering has produced new projections of glacier loss through the century under different emissions scenarios.  According to the projections, the world could lose as much as 41% of its total glacier mass this century – or as little as 26% – depending on climate change mitigation efforts. 

In a future with continued investments in fossil fuels (sometimes referred to as the “business as usual” scenario), more than 40% of the glacial mass will be gone by 2100, and more than 80% of glaciers by number could disappear.  Even in a best case scenario where the increase in global mean temperature is limited to 1.5° degrees Celsius relative to pre-industrial levels, more than 25% of glacial mass will be gone, and nearly 50% of glaciers by number will disappear.

Glaciers take a long time to respond to changes in climate.  A complete halt to emissions today would take anywhere from 30 to 100 years to be reflected in glacier mass loss rates.

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Team projects two out of three glaciers could be lost by 2100

Ice, Snow, and Glaciers and the Water Cycle

Photo, posted August 13, 2010, courtesy of Kimberly Vardeman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Race For EV Batteries | Earth Wise

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Lithium-ion batteries have been the power source for electric vehicles since 2008, when the Tesla Roadster was introduced.  They took over for nickel-metal hydride batteries that powered most hybrid electric cars such as the Prius.  Lithium-ion batteries store much more energy for a battery of a given weight, which leads to greater driving range.

But lithium-ion is not an ideal solution.  The batteries depend on critical materials that are obtained by hacking into mountains, utilizing scarce desert groundwater, and in some cases, making use of child labor. Many materials depend on countries with whom economic ties have complicated geopolitical consequences.

State and federal mandates and incentives are pushing auto companies to prioritize electric vehicles in their future plans.  The Inflation Reduction Act in particular provides credits and other incentives for both consumers and manufacturers to electrify. So, sources for EV batteries are a key issue.

The Department of Energy is funding 20 different companies with $2.8 billion to bolster the production and processing of critical minerals in the U.S.  The goal is to bring the electric vehicle supply chain onshore to the greatest extent possible.  Some of the work involves redesigning lithium-ion batteries to reduce or eliminate problematic materials such as cobalt.  Other efforts seek to find domestic sources of critical materials such as lithium without causing serious environmental problems.

Given all this, it is no surprise that academic and industrial researchers are also exploring a wide variety of alternative battery technologies. 

The future of transportation is electrification and the race for EV batteries is on.

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For U.S. Companies, the Race for the New EV Battery Is On

Photo, posted August 27, 2021, courtesy of Ron Frazier via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Birds Bees And Coffee | Earth Wise

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A new study by the University of Vermont in collaboration with researchers from three Latin American countries looked at the effects of birds and bees on coffee crops.  They found that coffee beans are bigger and more plentiful when birds and bees team up to protect and pollinate coffee plants.

The real-world study manipulated coffee plants across 30 farms by excluding birds and bees with a combination of large nets and small lace bags.  They looked at four scenarios:  bird activity alone (pest control), bee activity alone (pollination), no bird and bee activity at all, and a natural environment where birds and bees were free to pollinate and eat insects that otherwise damage coffee plants.

The study looked at fruit set, fruit weight, and fruit uniformity – important factors that determine the quality and price of the coffee crop.  The results were that the combined positive effects of birds and bees were greater than their individual effects.   Without birds and bees, the average coffee yield on the farms declined nearly 25%.  That is important information for the $26 billion coffee industry.

A surprising result of the study is that many birds providing pest control to coffee plants in Costa Rica had migrated thousands of miles from Canada and the U.S.

Previous studies looked at the benefits of natural factors separately and then added them up.  But the new study demonstrates that nature is an interacting system with both synergies and trade-offs.  Past assessments of individual ecological services may have underestimated the benefits biodiversity provides to agriculture and human wellbeing.  Ecosystems services are more valuable together than separately.

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The Secret to Better Coffee? The Birds and the Bees

Photo, posted March 2, 2012, courtesy of Caroline Gluck/Oxfam via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solid State Batteries For Cars | Earth Wise

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Today’s electric cars run on lithium-ion batteries, the same sort that power our phones, computers, and many other consumer electronic devices.  These batteries are far superior to the batteries of the past, offering long-life, high-energy density, and recyclable components.

Lithium-ion batteries do have their drawbacks.  They may be lighter than older battery technologies, but because the electrolytes in the batteries are liquid, they are still fairly heavy.  The huge number of them in an electric car adds up to a considerable amount of weight.  In addition, the flammability of the electrolytes can lead to explosions or fires if the batteries are damaged or exposed to extreme temperatures.

Solid-state batteries are an alternative technology that contain a solid electrolyte.  Such batteries are lighter, have higher energy density, offer more range, and recharge much more quickly than lithium-ion batteries. They have been used for years in some small devices like cardiac pacemakers, RFIDs, and some wearable devices.

For all these benefits, scaling up production to the level needed to be used in cars is an expensive and challenging endeavor.  The hope is that with sufficient effort, the result will be smaller, lighter battery packs for cars that can be charged in minutes and provide extended range.

Nissan Motor Company has recently announced that it is investing $17.6 billion over the next five years towards developing solid-state batteries for cars.  No doubt other companies will also be working on the technology.

Lithium-ion batteries have proven to be quite practical for powering vehicles.  But if solid-state batteries can meet the challenges of scaled up production, the lithium-ion era might end up being a relatively brief one.

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Nissan to Spend $18 Billion Developing a Cheaper, More Powerful EV Battery

Photo, posted November 13, 2018, courtesy of FirstEnergy Corp via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Reducing Emissions From Shipping And Aviation | Earth Wise

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The global marine shipping and aviation industries are each responsible for about 3% of greenhouse gas emissions.  These are relatively small numbers, but as other industries decarbonize, the contributions from shipping and aviation will loom larger and larger.

In October, both of these industries made commitments to reach net zero emissions by 2050.  How can they do it?  We don’t really have the details of the technologies to be used, and neither do these industries.  But there are ideas being considered.

For both ships and planes, the solution for short-distance trips can be electrification.  Electric planes are in the works for short distances.  Battery-powered container ships are also under development.  But the electrification of longer international and intercontinental routes for both industries is very difficult.  The size and weight of batteries needed for long hauls are major challenges to overcome.

The low-carbon solution slowly being deployed in aviation is sustainable aviation fuel made from renewable sources. Longer term, green hydrogen fuel for planes may be a solution.  For shipping, hydrogen may play an even larger role.  As in the other potential uses for hydrogen, the essential requirement is to be able to produce hydrogen in a way that does not emit greenhouse gases.

There are multiple ways to move towards the decarbonization of both aviation and shipping.  Which will turn out to be the most practical and successful is not yet known.  What is essential is for both industries to follow through on their commitments to research, develop, and deploy zero-carbon solutions.  They appear to have embraced the vision for the future.  Now comes the hard work of achieving that vision.

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Shipping & Aviation Plan To Go Net Zero. How?

Photo, posted August 8, 2014, courtesy of Tomas Del Coro via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Marine Heatwaves And Fish | Earth Wise

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Marine heatwaves are periods of abnormally high temperatures in the ocean that can trigger devastating impacts on ecosystems, including coral bleaching, toxic algal blooms, and mass mortality events.  Marine heatwaves can occur in any ocean and in any season.  They are defined based on the differences between actual and expected temperatures for the location and time of year.     

According to several studies, even under moderate climate warming scenarios, oceans will experience more frequent and longer-lasting marine heatwaves in the years to come.

Researchers from the University of British Columbia’s Institute for the Oceans and Fisheries in Canada have found that extremely hot years will wipe out hundreds of thousands of tons of fish globally this century.  These losses are in addition to the projected decreases to fish stocks from long-term climate change. 

Under a worst-case scenario where no action is taken to curb greenhouse gas emissions, the research team’s model predicts a 6% drop in the amount of potential catches per year.  In addition, the biomass (or amount of fish by weight) is projected to decrease in 77% of exploited species due to the extreme temperatures.

As a result of climate change and these extreme heat events, the research team projected that fisheries’ revenues would decrease by an average of 3% globally, and employment would fall by 2% globally – a loss of likely millions of jobs.

The research team says active fisheries management is critical.  Catch quotas, for example, need to be adjusted in years when fish stocks are suffering from marine heat events.  In severe cases, the fisheries may need to be shuttered in order to allow fish stocks to rebuild.  

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Fevers are plaguing the oceans — and climate change is making them worse

Marine heatwaves could wipe out an extra six per cent of a country’s fish catches, costing millions their jobs

Photo, posted October 11, 2016, courtesy of Kahunapule Michael Johnson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar Cell Greenhouses | Earth Wise

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A recent study at North Carolina State University has shown that it can be feasible to use see-through solar panels in greenhouses to generate electricity.  The idea is to use semi-transparent solar panels on greenhouses that allow some of the light to get in for the plants to grow while making the greenhouses energy neutral or even allowing them to generate more power than they use.

The question is how the semi-transparent solar panels might affect greenhouse crops.  To investigate this issue, researchers grew crops of red leaf lettuce from seed to full maturity under a standard set of growing conditions – temperature, water, fertilizer, and CO2 concentration – but varied the light they get. 

A control group was exposed to the full spectrum of white light while three experimental groups were exposed to light through different types of filters that absorbed the particular wavelengths of light that would be absorbed by different types of semitransparent solar cells.

The researchers paid close attention to characteristics of the lettuce that are important to growers, grocers, and consumers:  general appearance, leaf number, leaf size, and weight.  The results were that the lettuce produced using all three kinds of filtered light was essentially identical to that produced in the control group.    Further research is underway looking at how harvesting various wavelengths of light affects biological processes for lettuces, tomatoes, and other crops.

Getting growers to use solar-powered greenhouses would be very difficult if doing so would result in a loss of productivity.  But given these experimental results, it appears as though the decision will boil down to a simple economic argument about whether the investment in new greenhouse technology would be offset by energy production and its resultant savings.

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Study Finds Plants Would Grow Well in Solar Cell Greenhouses

Photo, posted April 8, 2008, courtesy of Brian Boucheron via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Other Ways To Cut Vehicle Emissions

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It is pretty clear that the way to drastically reduce vehicle greenhouse gas emissions is to switch as many vehicles as possible to electric power.  As a result, more and more localities are putting in place policies that encourage electrification.

While there is no doubt that electrification is the long-term solution to vehicle emissions, a recent study by MIT and the Ford Motor Company found that, in the short term, there are some places in the US where electric cars are not the best way to reduce emissions.

The study looked at a variety of factors that affect the relative performance of vehicles.  These include the role of low temperatures in reducing battery performance, regional differences in the average number of miles driven annually, and significant differences in the way electricity is generated in different parts of the US.

The results showed that electric vehicles definitely provide the greatest impact in reducing greenhouse gas emissions for most of the country – and particularly on both coasts and in the south – but that there are some places in the upper Midwest where the greatest reduction would be achieved by the use of lightweight gasoline-powered vehicles.

In places like parts of Wisconsin and Michigan, it is mostly rural, there are cold winters, and electricity is predominantly generated by coal-powered plants.  In these places, if gas-powered lightweight cars were to be used, the overall benefit would be greater than that of electric cars.  Unfortunately, there are no high-volume lightweight gasoline-powered mid-sized cars on the market in the US.  Ironically, the only cars of that class using lightweight aluminum construction are Teslas.

While electric cars are truly the long-term solution, the study does demonstrate the benefits of reducing the weight of vehicles.

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What’s the best way to cut vehicle greenhouse-gas emissions?

Photo, posted February 9, 2018, courtesy of Dave Field via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Plant-Based Jet Fuels

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The global aviation industry uses a whole lot of fuel:  more than 5 million barrels a day.  It is an incredibly energy-intensive industry and almost all of its energy comes from petroleum-based fuels.

While other large energy sectors such as electric power, ground transportation and commercial buildings have well-defined pathways to adopting renewable energy sources, the aviation industry does not have such a straightforward way to make a transition to sustainability.  Electrifying planes using batteries or fuel cells is very challenging for a number of reasons, notably the weight restrictions on aircraft.  So liquid biofuels as replacements for petroleum-based fuels remain the most promising approach.

A new study at the Lawrence Berkeley National Laboratory concludes that sustainable plant-based biofuels could provide a competitive alternative to conventional petroleum fuels if current development and scale-up initiatives are successful.

Multidisciplinary teams based at the Department of Energy’s Joint BioEnergy Institute are focused on optimizing each stage of the bio-jet fuel production process.  This includes bioengineering ideal source plants and developing methods for efficiently isolating the carbohydrates in non-food biomass that bacteria can digest and bioconvert into fuel molecules.

The critical issue is cost.  The theoretical cost of bio-jet fuel has come down dramatically in recent years but is still around $16 a gallon.  The cost of standard jet fuel is about $2.50 a gallon.  So, the real challenge is bridging that gap.

Reducing the cost of the fuel could come both from the material and process improvements that are underway as well as by finding ways to turn the leftover lignin residuals from the bioconversion process into valuable chemicals. 

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Bright Skies for Plant-Based Jet Fuels

Photo, posted March 28, 2009, courtesy of Yasuhiro Chatani via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Examining Sea Level Rise

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It’s no secret that sea levels along the East Coast of the United States are rising.  But what’s less known is that the water isn’t rising at the same rate everywhere.  As the climate continues to change, some cities may remain dry while others struggle to keep water out. 

During the 20th century, sea levels rose about 18 inches near Cape Hatteras in North Carolina and along the Chesapeake Bay in Virginia.  During that same time period, New York City and Miami experienced a 12 inch sea level rise, while the waters near Portland, Maine only rose 6 inches.  According to a study recently published in the journal Nature, there’s an explanation for this. 

The variation is a result of a phenomenon called “post-glacial rebound.”  During the last ice age, huge sheets of ice once covered land areas in the Northern Hemisphere, including parts of the Northeast U.S.  The weight of the ice weighted down the land like a boulder on a trampoline.  At the same time, peripheral lands such as the U.S. mid-Atlantic coast rose up.  As the ice melted, the previously weighted-down regions rebounded while the peripheral lands began to sink.  While these ice sheets disappeared some 7,000 years ago, this see-sawing of post-glacial rebound continues to this day. 

Researchers combined data from GPS satellites, tide gauges, and fossils in sediment with complex geophysical models to produce this comprehensive view of sea level change since 1900.  While post-glacial rebound accounts for most of the sea level variation along the East Coast, researchers noted that when that factor is stripped away, “sea level trends increased steadily from Maine all the way down to Florida.”

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Why is sea level rising faster in some places along the US East Coast than others?

Photo, posted August 24, 2014, courtesy of Bill Dickinson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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