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Green grout for stabilizing buildings

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We are all familiar with the grout that is used for tiles in our homes. We are less familiar with grout that is used to stabilize the soil beneath buildings.  Grouting is a process of ground improvement by injecting materials that can fill voids and cracks, strengthen and increase the bearing capacity of soil, and reduce permeability.

Traditional grouting methods have environmental downsides.  Most often, silica-based chemical grouts are used, and they are produced through energy-intensive processes that contribute substantially to carbon dioxide emissions.  As is the case for all materials and practices of the construction industry, developing sustainable, low-emission alternatives to conventional grouting materials has become an important priority.

Researchers from the Shibaura Institute of Technology in Japan have developed an innovative new grout material called Colloidal Silica Recovered from Geothermal Fluids.  This grout material enhances soil stabilization and simultaneously reduces the environmental impact of geothermal energy harvesting.

Geothermal energy production generates large amounts of silica-rich waste fluids which creates challenges for its maintenance and disposal.  The new grout repurposes this waste material thereby transforming an industrial byproduct into a valuable construction material.

The new grout material is particularly valuable in earthquake-prone regions, where soil stabilization is essential in preventing structural damage during seismic events.  In addition, the grout’s superior water-sealing properties makes it ideal for underground construction projects like tunnels, subways, and basements.  The new grout in an important step for the construction industry’s efforts to achieve carbon neutrality.

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From Waste to Wonder: Revolutionary Green Grout for Sustainable Construction Practices

Photo, posted July 8, 2011, courtesy of MTA Construction & Development Mega Projects via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Trapping carbon with rocks

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Many experts say that combating global warming will require both drastically reducing the use of fossil fuels and permanently removing billions of tons of CO2 already in the atmosphere.  Developing practical, large-scale technologies for carbon removal is a significant challenge.

There is a nearly inexhaustible supply of minerals that are capable of removing carbon dioxide from the atmosphere, but they don’t do it quickly enough to make a significant dent in the ever-growing supply in the atmosphere.  In nature, silicate minerals react with water and atmospheric CO2 to form minerals in the process called weathering.  But this chemical reaction can take hundreds or even thousands of years.

Researchers at Stanford University have developed a new process for converting slow-weathering silicates into much more reactive minerals that capture and store carbon quickly.  The new approach resembles a centuries-old technique for making cement.  They combine calcium oxide and another common mineral containing magnesium and silicate ions in a furnace.   The result are new materials that, when exposed to water, quickly trap carbon from the atmosphere.

In their experiments, the carbonation process took weeks to months to occur, thousands of times faster than natural weathering.

The idea would be to spread these materials over large land areas to remove CO2 from the air.  Meaningful use for trapping carbon would require annual production of millions of tons.  But the same kiln designs used to make cement could produce the needed materials using abundant minerals found in many places.  In fact, the required minerals are often common leftover materials – or tailings – from mining.

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Scientists discover low-cost way to trap carbon using common rocks

Photo courtesy of Renhour48 via Wikimedia.

Earth Wise is a production of WAMC Northeast Public Radio

Thawing permafrost in the Arctic

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Permafrost covers about a quarter of the landmass in the Northern Hemisphere.  It stores vast quantities of organic carbon in the form of dead plant matter.  As long as it stays frozen, it is no threat to the climate.  But as permafrost thaws, microorganisms start breaking down that plant matter and large amounts of carbon are released into the atmosphere in the form of carbon dioxide and methane.

Scientists estimate that there could be two and a half times as much carbon trapped in Arctic permafrost as there is in the atmosphere today.

Thawing permafrost poses various risks to the Arctic environment and the livelihoods of its people.  According to a new study led by researchers from the University of Vienna in Austria, Umeå University in Sweden, and the Technical University of Denmark, thawing permafrost threatens the way of life of up to three million people.

To identify these risks, the research team studied four Arctic regions in Norway, Greenland, Canada, and Russia between 2017 and 2023.  The research, which was recently published in the journal Communications Earth and Environment, identified five key hazards posed by the thawing permafrost: infrastructure failure, disruption of mobility and supply, decreased water quality, challenges for food security, and exposure to diseases and contaminants.

These are present developments – not future dangers.  Global scientific cooperation, policy interventions, and investment in research are critical to mitigate the impact of thawing permafrost and address the broader consequences it brings.

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A transdisciplinary, comparative analysis reveals key risks from Arctic permafrost thaw

Thawing permafrost threatens up to three million people in Arctic regions

Photo, posted February 9, 2017, courtesy of Benjamin Jones / USGS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Storing carbon in buildings

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According to a new study by researchers at the University of California, Davis and Stanford University, construction materials used in buildings have the potential to lock away billions of tons of carbon dioxide.  The study, published in Science, shows that storing CO2 in buildings could be a major contributor to efforts to reduce greenhouse gas emissions.

Overall efforts in carbon sequestration take carbon dioxide – either as it’s being produced or once it’s already in the atmosphere – and store it away.  Storing it might involve injecting it into underground caverns or deep in the ocean.  Alternatively, storing it might involve converting it into a stable form using chemical reactions.  These various strategies involve both practical challenges and potential environmental risks.

The new study suggests that many materials that are already produced in large quantities have the potential to store carbon dioxide.  These include concrete, asphalt, plastics, wood, and brick.  More than 30 billion tons of these materials are produced worldwide every year.

Ways to accomplish carbon storage include adding biochar into concrete, using artificial rocks loaded with carbon as concrete and asphalt aggregates, plastic and asphalt binders based on biomass instead of petroleum, and including biomass fiber into bricks. 

The largest potential is using carbonated aggregates to make concrete.  Concrete is by far the world’s most popular building material with more than 20 billion tons being produced each year.

The feedstocks for these ways to store carbon in building materials are mostly low-value waste materials, so the economics of implementing these carbon sequestering strategies are likely to be quite favorable.

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Storing Carbon in Buildings Could Help Address Climate Change

Photo, posted October 19, 2022, courtesy of Alexandre Prevot via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Tourism and greenhouse gas emissions

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Tourism is a major contributor to global greenhouse gas emissions, accounting for about 9% of the global total.  Over the past 15 years, its emissions have grown more than twice as fast as those of the rest of the global economy.

Unless the tourism industry finds ways to slow down its growing emissions, those emissions will continue to increase by 3 to 4% each year, meaning that they will double every 20 years.  The major drivers behind tourism’s growing emissions have been slow improvements in tourism-related technologies coupled with the rapid growth in demand.

Transportation is tourism’s main source of greenhouse gas emissions.  Planes and cars generate the most carbon dioxide but there are contributions from tour buses, boat rides, ferries, and trains as well.  The increasing demand for international travel has been the largest contributor to the growth of tourism-related emissions.  But just as people’s homes generate emissions from energy use, so do hotels and other lodging used on vacations.

The United States, China, and India are responsible for 60% of the total increase in tourism’s carbon footprint.  Generally speaking, it is the world’s wealthiest nations that have the most tourists exploring the world.

Researchers from Australia’s University of Queensland recommended several measures to slow the growth of tourism’s carbon emissions.  These include reducing long-haul flights, imposing carbon dioxide taxes, setting carbon budgets, and the use of alternative transportation fuels.  At the local level, tourism businesses making use of renewable energy sources and electric vehicles would help.

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Tourism leads the pack in growing carbon emissions

Photo, posted September 14, 2014, courtesy of Gary Campbell-Hall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The UN Carbon Market

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The UN climate conference in November approved an official market for large-scale trading of carbon credits.  This will allow industrial countries to help meet their emission reduction targets set by the Paris Climate Agreement by paying other nations to protect and restore forests and carbon-rich peatlands.

The first major participant in this multi-billion-dollar enterprise is Indonesia.  That country is home to the world’s third largest expanse of tropical rainforests and more than a third of the world’s carbon-storing peatlands.  Indonesia’s government plans to raise up to $65 billion by 2028 by selling carbon credits accrued by restoring and protecting its forests and peatlands.

The problem with carbon trading is that it can be filled with loopholes ranging from inaccurate carbon accounting to outright fraud.  Carbon trading with both individual companies and other countries can result in double- and even triple-counting of the same carbon.

For example, carbon credits are assigned when forests earmarked for agricultural or other development are preserved instead of being felled.  But what if that forest destruction wasn’t going to happen even without selling carbon credits? 

There are organizations in the business of verifying carbon accounting, but independent analysis of their methodologies has revealed serious shortcomings, and in many cases, the verifications have been deemed to be worthless.

There are real problems with carbon accounting and setting correct baselines for the carbon emission reductions associated with carbon credits.  Nevertheless, the existence of a global carbon market can be an important tool in the world’s efforts to mitigate the effects of climate change.

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Will UN Carbon Market Work? Indonesia Will Provide First Test

Photo, posted June 12, 2017, courtesy of Runa S. Lindebjerg via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Planting trees in Europe

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Planting lots of trees is one of many strategies being pursued to combat climate change.  Trees are storehouses of carbon from the atmosphere and planting more of them helps remove carbon dioxide.  But trees do more than that.  Trees are natural air conditioners in cities.

Trees significantly cool urban environments by providing shade and via a process called evapotranspiration by which they release water vapor into the air, which provides cooling.  This helps mitigate the urban heat island effect. Areas under trees in cities can be as much as 25 degrees cooler than in unshaded areas covered in asphalt.

The city of Paris has laid out a plan to help the city prepare for increasing amounts of extreme heat.  The goal is to replace 60,000 parking spaces across the city with trees by the end of this decade.  The plan to rip up parking spaces is part of a greater aim to create more than 700 acres of green space by 2030.  The Paris plan also includes creating more car-free zones and installing reflective roofs on 1,000 public buildings.  Nearly 80% of the buildings in Paris have zinc roofs – an affordable, corrosion-resistant and pretty much inflammable innovation of the 19th century.  However, these roofs can heat up to 194 degrees on a summer day, transferring heat into largely uninsulated top-floor garrets below.

Elsewhere in Europe, Danish lawmakers have agreed on a plan to rewild 10% of the country’s farmland and plant one billion trees.   According to the Danish government, this plan would bring about the biggest change to the Danish landscape in over 100 years.

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To Cope with Extreme Heat, Paris Will Swap Parking Spaces for Trees

Photo, posted April 11, 2014, courtesy of Val H. via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Regrowing forests naturally

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Deforestation is one of the major causes of climate change and restoring and enhancing forests is a major activity around the world as a way to mitigate its effects.  There are high-profile initiatives to plant millions of trees, but these projects are often ill-conceived and poorly managed.

One of the most dramatic failures was the planting of over a million mangrove seedlings on the Filipino island of Luzon back in 2012.  A study 8 years later found that fewer than 2 percent of the trees had survived.  The rest died or were washed away.

The causes of failure in tree planting programs include planting of trees that become vulnerable to disease, competing demands for land, changing climate, planting in areas not previously forested, and a lack of aftercare including watering seedlings.

A multinational study recently published in Nature has found that forests could regrow naturally on more than 800,000 square miles of land around the tropics without the need for planting trees by hand.  This is an area larger than Mexico.

The researchers mapped areas where forests would be likely to regrow – areas where soils are healthy and where there is already forest nearby to supply seeds.  In some places, lands are so degraded that it is necessary to plant trees by hand, but this is costly and prone to failure.  Forests that regrow naturally tend to fare better and make better habitats for wildlife.

The effect of regrown forests on the climate would be very substantial.  If these forests were allowed to grow for three decades, they would absorb enough carbon to offset 50 years of emissions by Australia, the home of the lead researcher of the study. 

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Tropical Forests Could Regrow Naturally on Area the Size of Mexico

Photo, posted February 16, 2018, courtesy of Jason Houston / USAID via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Capturing hot carbon dioxide

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Decarbonizing industries like steel and cement is a difficult challenge.  Both involve emitting large amounts of carbon dioxide both from burning fossil fuels and from intrinsic chemical reactions taking place.  A potential solution is to capture the carbon dioxide emissions and either use them or store them away.  But this sort of carbon capture is not easy and can be quite expensive.

The most common method for capturing carbon dioxide emissions from industrial plants uses chemicals called liquid amines which absorb the gas.  But the chemical reaction by which this occurs only works well at temperatures between 100 and 140 degrees Fahrenheit.  Cement manufacturing and steelmaking plants produce exhaust that exceeds 400 degrees and other industrial processes produce exhaust as hot as 930 degrees.

Costly infrastructure is necessary to cool down these exhaust streams so that amine-based carbon capture technology can work. 

Chemists at the University of California, Berkeley, have developed a porous material – a type of metal-organic framework – that can act like a sponge to capture CO2 at temperatures close to those of many industrial exhaust streams.  The molecular metal hydride structures have demonstrated rapid, reversible, high-capacity capture of carbon dioxide that can be accomplished at high temperatures.

Removing carbon dioxide from industrial and power plant emissions is a key strategy for reducing greenhouse gases that are warming the Earth and altering the global climate.  The captured CO2 can be used to produce value-added chemicals or can be stored underground or chemically-reacted into stable substances.

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Breakthrough in capturing ‘hot’ CO2 from industrial exhaust

Photo, posted March 3, 2010, courtesy of Eli Duke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Mangrove forests and rising seas

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

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

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

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

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

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

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“Drowning” mangrove forests in Maldives signal global coastal threat

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

Earth Wise is a production of WAMC Northeast Public Radio

The bloated carbon footprint of LNG

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According to the U.S. Department of Energy, the United States is the world’s largest producer of natural gas.  In fact, natural gas supplies approximately one third of the United States’ primary energy consumption, most of which is used to heat buildings and to generate electricity.  While most natural gas is delivered in its gaseous form in this country, the demand for natural gas in international markets has given rise to the use of natural gas in a liquified form. 

Liquified natural gas (LNG) is natural gas that has been cooled to a liquid state, at about -260° Fahrenheit, for easier storage and transportation.  The volume of natural gas in its liquid state is about 600 times smaller than its volume in its gaseous state, which makes it possible to transport it to places pipelines do not reach.

Liquified natural gas is considered a clean fossil fuel because burning it produces less emissions than coal and oil.  However, according to a new study by researchers from Cornell University, LNG imported from the U.S. actually has a larger climate impact than any other fossil fuel—including coal – once processing and shipping are taken into account. 

The study, which was recently published in the journal Energy Science & Engineering, found that LNG leaves a greenhouse gas footprint that is 33% worse than coal when emissions are analyzed over a 20-year time frame. 

According to the research team, there is no need for LNG as an interim energy source because the transition requires massive infrastructure expenditures.  Instead, those financial resources should be used to “build a fossil-fuel-free future as rapidly as possible.”

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Liquefied natural gas carbon footprint is worse than coal

Photo, posted November 17, 2017, courtesy of Colin Baird via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Canadian wildfires and global emissions

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The wildfires that burned vast amounts of Canada’s boreal forests in 2023 produced enormous amounts of smoke that found its way into American cities, working its way down the eastern seaboard and even producing unsafe air in Florida.

Researchers at Cal Tech and the Jet Propulsion Laboratory analyzed the carbon emissions associated with these fires last year and found that they were greater than those of all but three countries:  China, the US, and India.

Boreal forests have historically been a natural defense against climate change by storing carbon in trees rather than adding carbon dioxide to the atmosphere.  The fires in Canada, fueled by hot and dry weather, were extraordinary when compared with historical records.  But such fires are likely to be increasingly common as the climate continues to warm.

However, the hot and dry weather that fueled the 2023 fires was exceptional in many ways, involving early snow melt and so-called flash droughts.  This year’s fires in Canada are still bigger than average, but so far have not been as destructive as last year’s. 

Canada has been warming at about twice the global rate.  The extreme temperatures last summer were a major factor in the fueling of the fires, which burned an area almost the size of Florida.

Forests absorb about a quarter of global carbon emissions, but the increasing frequency and intensity of fires are calling into question their ability to continue to do so.  Parts of the Canadian forests are not regrowing after fires as they have in the past, partly because blazes burn trees so frequently and intensely.

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Canada’s Wildfires Were a Top Global Emitter Last Year, Study Says

Photo, posted June 8, 2023, courtesy of the Metropolitan Transportation Authority via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Ecofriendly Glass

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Glass has been used for thousands of years to make everything from windows to bottles to microscope slides.  For all that time, most glass has been in the form of soda lime silicate glass, which is made by melting quartz sand with carbon-based ingredients – soda ash and limestone – at high melting temperatures of about 2600 degrees Fahrenheit.

The process results in substantial carbon emissions.  Worldwide, glass manufacturing produces over 86 million tons of carbon dioxide per year.  Most of that comes from burning fuel to reach the high temperatures needed to make the glass, but about a quarter of it comes from the decomposition of the carbon-based materials used.

Researchers at Penn State University have developed an entirely new type of glass that represents an alternative to soda lime glass.  The glass – that they call LionGlass – eliminates the use of carbonate batch materials and has a melting temperature 700 degrees lower than traditional glass.   The new material has the potential to cut the carbon footprint of glass manufacturing in half.  It is also 10 times more crack-resistant than ordinary glass, which would enable light weighting of glass products, lowering the emissions associated with transporting glass and glass products.

Recently, Penn state has entered into a partnership with the Italian company Bormioli, one of the world’s leading glass manufacturers that specializes in high-end packaging for fragrances, cosmetics, and tableware.  By focusing on a smaller, high-end market, the focus can be on fine-tuning the glass and determining the feasibility of scaling it up further for other uses.

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Ecofriendly glass invented at Penn State secures partner for product development

Photo, posted December 26, 2005, courtesy of Lachlan Hardy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Better wood for storing carbon

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Scientists have discovered a new type of wood that is highly efficient at storing carbon.  A comprehensive survey of the microscopic structure of the wood from many species of trees revealed that there is a type of wood that is neither softwood, such as pine and conifers, or hardwood, such as oak, ash, and birch.

The scientists from Cambridge University and Jagiellonian University in Poland analyzed some of the world’s most iconic trees using electron microscopy to survey their microscopic structure.

They found that tulip trees, which are related to magnolias and can grow over 100 feet tall, have a unique type of wood.  The trees, which diverged from magnolias far back to a time when atmospheric CO2 concentrations were low, grow very tall and very quickly.  These features were an adaptation to those conditions and result in the ability to store larger concentrations of carbon to compensate based on their microstructure.  The elementary units of wood are known as macrofibrils, and tulip trees have much larger macrofibrils than hardwoods but smaller than those of softwoods.  This unusual intermediate structure makes the trees highly effective at carbon storage.

Based on the research, it may be the case that tulip trees will end up being useful for carbon capture plantations – tree plantings specifically for the purpose of mitigating the effects of climate change.  Some east Asian countries are already using various tulip tree species in plantations for locking in carbon.  This was based on their large size and rapid growth, but it turns out that their novel wood structure may be the most compelling reason to use them.

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Scientists discover entirely new wood type that could be highly efficient at carbon storage

Photo, posted March 3, 2021, courtesy of Thomas Quine via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wildfires and carbon storage

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Forests are known to be a key natural solution to the increasing amounts of carbon dioxide in the atmosphere.  For this reason, there are widespread efforts to plant more trees around the world and to prevent increasing deforestation for development and agriculture.  But a new study has highlighted the fact that wildfires in the western US are degrading the potential for forests to help curb climate change.

The study has established a baseline for how much carbon is currently stored in Western forests, how that amount is changing, and how fires and droughts are affecting the ability of the forests to mitigate climate change.

The study made use of survey data collected by the US Forest Service to estimate how much carbon is stored in 19 ecoregions across the West.  These ecoregions range from hot and dry areas in the Southwest to the wet and cool regions of the Pacific Northwest.

The study reveals that the carbon stored in living trees declined across much of the Western US between 2005 and 2019.  Carbon stored in dead trees and woody debris increased.  These things do not provide long-term carbon storage.  Instead, they release it back into the atmosphere through decomposition or combustion in forest fires.

The increasing frequency and intensity of wildfires, especially since 2020, indicate that the decline in live carbon stored in the forests will become increasingly pronounced.  The result, according to the study’s authors, is that we cannot rely on increasing carbon storage in Western US forests.  It may be possible to increase the stability of carbon storage in the forests with mechanical thinning and prescribed burning, but the carbon carrying capacity of those forests is not likely to be what is needed.

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Forest carbon storage has declined across much of the Western US, likely due to drought and fire

Photo, posted July 25, 2021, courtesy of Felton Davis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The carbon cost of wind farms

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Opponents of electric vehicles and renewable energy often try to make arguments to the effect that the carbon footprint associated with producing electric cars, solar panels, and wind turbines negates their advantages over legacy technologies that involve burning fossil fuels.  These arguments have been soundly refuted for the case of electric vehicles but there have been fewer studies related to other green technologies.

A new peer-reviewed study by engineers at the Te Herenga Waka Victoria University in Wellington, New Zealand, has analyzed the carbon emissions associated with wind farm operation.

The main result is that after operating for less than two years, a wind farm can offset the carbon emissions generated across its entire 30-year lifespan.   The study takes into account everything from the manufacturing of individual turbine parts, to transporting them and installing them into place, to decommissioning the entire wind farm at its life’s end.  The environmental impacts of the installation and transportation phases are important, accounting for about 10% of the overall emissions.

The decommissioning phase is also important.  The study recommended the development of a recycling process for end-of-life turbine blades.  Currently, such blades are disposed of in landfills, but a recycling process could reduce emissions.

The manufacturing of wind turbines is the primary contributor to the carbon and energy consumption footprints and continues to be the subject of efforts to be improved.

There are other aspects of wind farms that are subject to criticism including physical impacts on the local environment and various social, wildlife and economic impacts.  But with respect to carbon emissions, wind farms are a winning strategy.

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Wind Farms can Offset Their Emissions Within Two Years, New Study Shows

Photo, posted April 2, 2017, courtesy of Ian Dick via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Thawing permafrost:  Is it a ticking timebomb?

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Permafrost covers about a quarter of the landmass in the Northern Hemisphere.  It stores vast quantities of organic carbon in the form of dead plant matter.  As long as it stays frozen, it is no threat to the climate.  But as it thaws, microorganisms start breaking down that plant matter and large amounts of carbon are released into the atmosphere in the form of carbon dioxide and methane.

This process has often been described as a ticking timebomb for the climate.  The theory is that once global warming reaches a certain level, the process will become self-amplifying setting off a catastrophic amount of warming.  If that level was reached, it would be a tipping point in the changing climate.

An international research team from the Alfred Wegener Institute in Germany has extensively researched this hypothesis.  Their conclusion is that within the permafrost, there are multiple geological, hydrological, and physical processes that are self-amplifying and, in some cases, irreversible.  However, these processes act only locally or regionally.  There is no evidence that some particular threshold in global warming could affect all permafrost and accelerate its thawing on a global level.

This research does not mean that Arctic permafrost is nothing to worry about.  In fact, there are ways in which it is more worrisome.  Because the permafrost is very heterogenous – meaning it is very different in different places – there will be numerous small, local tipping points that will be exceeded at different times and at different levels of warming.  All of this will proceed in step with global warming, contributing to the overall worsening situation.  There is no warming level below which permafrost thawing is not a problem.

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Thawing permafrost: Not a climate tipping element, but nevertheless far-reaching impacts

Photo, posted January 24, 2014, courtesy of Brandt Meixell / USGS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Benefits of electric school buses

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There are about half a million school buses in use in the U.S.  A large number of them are older, highly polluting diesel buses.  There are well-established health and climate benefits of switching from diesel vehicles to electric vehicles but making the switch is expensive.  Diesel buses generally cost between $65,000 to $120,000, depending on the type and configuration.  Electric buses cost about $250,000 each.

The substantial cost makes it a difficult decision for local, state, and federal officials, particularly since the actual magnitude of the benefits is not well known.

A new study by researchers at Harvard’s T.H. Chan School of Public Health has quantified these benefits.  According to the study, replacing each bus may yield up to $247,600 in climate and health benefits. These benefits derive from fewer greenhouse gas emissions and from reduced rates of adult mortality and childhood asthma. 

The study compared the amounts of carbon dioxide emitted from diesel bus tailpipes to the emissions associated with generating electricity for the buses and producing their batteries.  It also compared how these respective emissions contribute to fine particulate air pollution, which is linked to adult mortality and the onset of childhood asthma.  The study concluded that particularly in dense urban settings, the savings incurred from electrifying older school buses easily outweigh the costs of replacing them.

An important question not tackled in the study is how electric school buses impact children’s exposure to in-cabin air pollution while riding the bus.  This issue could further inform policy decisions.

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Electric school buses may yield significant health and climate benefits, cost savings

Photo, posted May 9, 2008, courtesy of Christine H. via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cloud brightening

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Solar geoengineering is a type of climate intervention:  deliberate actions designed to affect the climate.  There are several ways to try to reduce the amount of sunlight reaching the surface of the earth and all of them are controversial.  Perhaps the least controversial approach is cloud brightening.

The idea is based on something called the Twomey effect, which is that large numbers of small droplets in the atmosphere reflect more sunlight than small numbers of large droplets.  Spraying vast quantities of minuscule aerosols into the sky, thereby forming many small droplets, could change the reflective properties of clouds.  If clouds are more reflective, then less sunlight reaches the surface, and the temperature goes down.

This form of geoengineering is thought to be less risky because it can be performed on a localized basis and can use relatively benign materials such as sea salt. 

In early April, scientists from the University of Washington started testing a device that sprays tiny sea-salt particles into the air from the deck of a decommissioned aircraft carrier in Alameda, California.  The test was simply to see whether the machine propelled a mist of suitable size.

Within two weeks, Alameda officials ordered a stop to the experiment, citing potential health and environmental risks.  After a month-long investigation, Alameda ruled that the experiment does not generate a measurable risk to health, wildlife, or the environment.

But before more ambitious experiments take place, there are potential side effects of cloud brightening that need to be studied.  It may turn out to be a useful tool in fighting global warming, but in any case, such technology should not be viewed as a substitute for moving away from fossil fuels.

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A Test of Cloud-Brightening Machines Poses No Health Risk, Officials Say

Photo, posted September 8, 2011, courtesy of Justin Ladia via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The largest carbon removal plant

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Direct air capture (DAC) is process that removes carbon dioxide out of the air and stores it away where it can no longer trap heat in the atmosphere.  It is intended to be a way of getting rid of the greenhouse gases that have built up in the atmosphere.  In principle, it’s a great idea.  In practice, it is a huge challenge.

In 2017, a company called Climeworks became the first company to take carbon dioxide out of the air and sell it as a product for use in carbonated drinks and in greenhouses.  In 2021, the company opened a DAC plant called Orca in Iceland that captures CO2 and permanently stores it underground.  Clients like Microsoft pay Climeworks for doing this as a way of offsetting their own emissions.

Recently, Climeworks has started operating a new plant called Mammoth – also in Iceland – that will be able to capture about 10 times more carbon dioxide than Orca.  Iceland is a prime location for DAC technology because its abundant geothermal energy makes powering it cheap and environmentally friendly.

Mammoth, when fully operational, will remove about 36,000 tons of carbon dioxide a year, the largest DAC system in the world.  But there is a long, long way to go.  Microsoft alone emits nearly 13 million tons of carbon dioxide a year.

There are multiple DAC projects in development including several in the United States being funded by the Bipartisan Infrastructure Law.  The four DAC hubs being developed under the program are each supposed to have the capacity to capture at least a million metric tons of CO2 a year.

Whether DAC can make a real difference remains to be seen.

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The world’s largest carbon removal plant is here, and bigger ones are on the way

Photo credit: Climeworks

Earth Wise is a production of WAMC Northeast Public Radio

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