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Are today’s refrigerants safe?

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Refrigeration is based on heat transfer mediums that absorb heat from the area being cooled and transfer it to the outside environment.

The earliest refrigerants were dangerous substances like ammonia.  In the 1930s, chlorofluorocarbons (CFCs) like Freon became the standard refrigerant for use in refrigeration systems and even in aerosol cans.  When these substances were found to be depleting the earth’s ozone layer, the Montreal Protocol dictated their phaseout and by the mid-1990s, CFCs were largely replaced by hydrofluorocarbons (HFCs).

HFCs don’t deplete the ozone layer, but they were eventually determined to be potent greenhouse gases, thousands of times more planet-warming than carbon dioxide.   As a result, the global phaseout of HFCs began in 2016, and have been increasingly replaced by hydrofluoroolefins (HFOs), which are considered a more environmentally-friendly alternative to all their predecessors.

Trying to not be surprised by additional unpleasant discoveries about refrigerants, researchers are studying the potential environmental impacts of HFOs.  Researchers at the University of New South Wales in Australia have found that HFOs can break down in the atmosphere and that some small amounts of the resultant products are in fact fluoroforms, which are the HFC with the greatest global warming potential and can stay in the atmosphere for up to 200 years.

That only a small amount of HFC gets into the atmosphere is good, but nevertheless it reveals that the consequences of replacing widely-used chemicals are not a simple matter to determine.

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Are our refrigerants safe? The lingering questions about the chemicals keeping us cool

Photo, posted July 19, 2021, courtesy of Vernon Air Conditioning via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wrong trees in the wrong places

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

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

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

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

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

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

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

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

Earth Wise is a production of WAMC Northeast Public Radio

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

Cooling cities

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As the climate warms, city dwellers tend to suffer from extreme heat more than people in rural areas because of the urban heat island effect. Extensive surfaces of man-made materials like concrete, asphalt, and brick absorb the sun’s energy and lead to temperatures well above those in the surrounding countryside.

Cities can take countermeasures that include creating urban green spaces full of plants that cool the surrounding air and the use of cool roofs that reflect the sun’s energy back into space.  Local governments in many cities provide incentives for planting more trees.  But more could be accomplished by encouraging the use of cool roofs.

The heat island effect has been well-known for a long time, but scientists are only recently learning what interventions are most effective. A recent study modeled two days of extreme heat in London in 2018 and compared the potential effects of cool roofs, green roofs, roof-top solar panels, and ground level vegetation. They found that cool roofs are the most effective way to lower temperatures and would have reduced London temperatures by 2 degrees on average and as much as 3.6 degrees in some places.

Cool roofs are created by swapping out dark, heat-absorbing roofing materials with reflective materials or simply by painting roofs white. Los Angeles is the first major city to require that all new residential construction includes a cool roof. 

Apart from the effectiveness of passive cooling techniques, using them also reduces the reliance upon air conditioning to protect people from heat.  Air conditioners themselves contribute considerable amounts of heat to urban environments.

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The surprisingly simple way cities could save people from extreme heat

Photo, posted February 21, 2024, courtesy of Warren LeMay 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

Sequoias in Britain

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Giant sequoias are the most massive trees on earth.  They can grow as tall as nearly 300 feet and have trunk diameters from 20 to 26 feet.  They are also among the oldest living organisms on Earth; some of them are well over 3,000 years old.  The trees are native to the western slopes of the Sierra Nevada mountain range in California.

Lengthy droughts and wildfires have been pushing giant sequoias in California into decline.  Up to 20% of all large giant sequoias in California died in wildfires in 2020 and 2021.  There are estimated to be only about 80,000 remaining in the native groves in the Sierra Nevada.  These old-growth forests are very much in jeopardy and represent rare ecosystems of considerable ecological and historical value.

Giant sequoias have been planted in many places around the world.  They were introduced to country estates in Britain during the 19th century.  They were seen as symbols of wealth and power.  Over time, they have been widely planted in parks and woodlands.   As a result, there are now half a million giant sequoias growing in Britain and they are thriving there.

The British sequoias are rather young by sequoia standards, so they are relatively squat in stature.  The tallest of them measures about 180 feet.  But recent research, published in the journal Royal Society Science, found that in Britain’s cool and mild climate, the trees are growing nearly as fast as they do in California. 

The British sequoias are probably more important for their aesthetic and historical interest than their impact on the environment, but it is good to know they are there.

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Under Threat in Their Native California, Giant Sequoias Are Thriving in Britain

Photo, posted November 4, 2010, courtesy of John Buie via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Why are bees making less honey?

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Scientists have been sounding the alarm on the global struggle of pollinators for a long time.  According to the United Nations, nearly 35% of the invertebrate pollinator species, such as bees and butterflies, are facing extinction. And since 75% of the world’s food crops depend on pollination to some extent, the decline of pollinators poses a major threat to global food security.

Honey bees are among the struggling pollinators.  Honey bee colonies in the United States have experienced annual population declines since 2006.  But in addition to there being fewer bees, the bees that remain are also making less honey.  In fact, honey yields in the United States have been declining since the 1990s. 

A new study by researchers from Penn State University has solved some of the mystery.  Using five decades of data across the United States, the research team analyzed the factors that could be affecting the number of flowers growing in different regions, which, in turn, affects the amount of honey produced by bees. 

In the study, which was recently published in the journal Environmental Research, the scientists found that climate conditions and soil productivity were two of the biggest factors in estimating honey yields.  States in both warm and cool regions produced higher honey yields when they had productive soils.  These two factors set a baseline production level of honey, while herbicide use, weather, and land use changes influenced how much honey was produced in a given year. 

The study’s findings  provide valuable insights that should help beekeepers, growers, and land managers better support honey bees.

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Why are bees making less honey? Study reveals clues in five decades of data

Photo, posted August 30, 2021, courtesy of Brandon O’Connor / NRCS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

What did the record warmth of 2023 mean?

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2023 was the warmest year in the 174 years of global temperature record-keeping.  According to some analyses, it may have been the warmest year in the past 125,000 years.

There were incredible heatwaves in Arizona and Argentina.  There were relentless wildfires across Canada.  The wintertime ice coverage in the seas surrounding Antarctica was at unprecedented lows

The global temperatures in 2023 did not just beat prior records; they smashed them.  Every month from June through November set all-time monthly temperature records. The US Northeast saw springlike temperatures at the end of the year.  The high temperature in Buffalo, New York on Christmas Day was 58 degrees.

Climate scientists have been predicting the warming trend that has been ongoing over the past several decades.  Indeed, computational models for 2023 called for a warm year.  Various models had a variety of projected temperatures and 2023’s heat was still broadly within the range of what was projected, although certainly at the high end.

The question is whether last year was an indicator that the planet’s warming is accelerating faster than we expect or that it just was a particularly warm year because of cyclical factors such as the El Niño that appeared last spring.

One theory that is being explored is that various types of industrial pollution have previously actually served to cool the atmosphere over time and as those sources are reduced for public health reasons, the warming effects of greenhouse gases have accelerated.

Currently, there is no consensus about why it seems to be getting warmer even faster than many climate models predict.  What there is no doubt about is that it is not a good thing.

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Earth Was Due for Another Year of Record Warmth. But This Warm?

Photo, posted June 8, 2023, courtesy of Anthony Quintano via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The importance of Alaska’s National Forests

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The world’s forests play a crucial role in taking carbon out of the atmosphere and mitigating the effects of climate change.  An analysis of U.S. national forests shows that two southern Alaskan forests are key to meeting climate and biodiversity goals.

The Tongass Forest in Alaska is America’s largest national forest, encompassing 16.7 million acres.  Alaska’s Chugach Forest is the country’s second largest at just under 7 million acres.  These two forests are not only the largest national forests, they are also the most intact. 

A study by researchers at the Oregon State University College of Forestry looked at 152 national forests and compared them in terms of carbon density and accumulation, total biomass carbon stocks, habitat for eagles, bears, and wolves, and landscape integrity – which is the extent of modification by human activity.  According to the study, almost 31% of all high-landscape-integrity area found in national forests is in the Tongass and Chugach forests.  The Tongass alone represents over 25%.

These forests are cool and wet.  Their carbon stocks are only minimally affected by wildfire, unlike many other forests in the lower 48 states.  Given the size and stability of the two forests, protecting them is a high priority for making it possible to meet global goals relating to climate and diversity of species.

Ecosystems remove about 30% of all the carbon dioxide humans put into the atmosphere and intact forests with high carbon density do most of that work.  Protecting Alaska’s forests is crucial.

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Southern Alaska’s national forests key to meeting climate, conservation goals, OSU study shows

Photo, posted August 4, 2014, courtesy of Jeff Canon via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Summers are getting hotter

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Climate scientists have warned for decades that a seemingly small change in the global average temperature can lead to large changes in extreme heat.  So far, the world has warmed by 1.2 degrees Celsius (or 2.2 degrees Fahrenheit) and that has been enough to cause big changes in summer heat.

This past summer was the hottest on record.  The heat fueled deadly wildfires across the Mediterranean.  Record highs caused Chinese cities to suspend outdoor work.  Weeks of triple-digit temperatures in the U.S. southwest led to heat-related hospitalizations and deaths.

But not every recent summer has been hotter everywhere.  Even this summer saw average or even colder than average temperatures in some places.  But the distribution of summer temperatures across the Northern Hemisphere has shifted dramatically in recent decades.

Less than 1% of summers in the middle of the 20th century were extremely hot for their location.  Over the past decade, more than a quarter of summers were extremely hot for their location.

Between 1950 and 1980, about a third of summers across the hemisphere were near average in temperature; a third were considered cold; a third were hot.  Only a few summers in a few places were either extremely cold or extremely hot.  Over the past decade, the vast majority of summers have either been hot or extremely hot.

We experience summer weather in the location where we spend our time, and it is entirely possible that our own experience may have been unremarkable.  We may even have had a cool, rainy summer.  But on a global scale, summers are getting hotter and hotter and making it harder to ignore what is happening to our planet.

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It’s Not Your Imagination. Summers Are Getting Hotter.

Photo, posted August 21, 2022, courtesy of Bonnie Moreland via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Hottest Summer | Earth Wise

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It was a very rainy and relatively cool summer in much of New England as well as in New York’s Capital Region, where Earth Wise originates.  Despite that fact, according to NASA scientists, the summer of 2023 was the Earth’s hottest since global record keeping began in 1880.

The months of June, July, and August taken together were .41 degrees Fahrenheit warmer than any other summer on record as well as being 2.1 degrees warmer than the average summer between 1951 and 1980.

The record summer heat was marked by heatwaves in South America, Japan, Europe, and the US.  The heat exacerbated wildfires in Canada that dumped smoke across much of the northern tier of our country and also led to severe rainfall in Europe.  All sorts of temperature records were set in places across the globe.

According to NASA, exceptionally high sea surface temperatures, fueled in part by the reemergence of El Niño in the Pacific, were a major factor in the summer’s record warmth.

The record-breaking heat of this summer continues a long-term trend of warming.  Scientists around the world have been tracking the warming that is driven primarily by human-caused greenhouse gas emissions.  The combination of this background warming and the marine heatwaves set the stage for new temperature records.  The El Niño was enough to tip the scales. 

In the current environment, heat waves will last longer, be hotter, and be more punishing.  The atmosphere can hold more water producing hot and humid conditions that are harder for the human body to endure.

Scientists are expecting the biggest impacts of El Niño in the early parts of next year.  We can expect to see extreme weather of many kinds over the next year.

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NASA Announces Summer 2023 Hottest on Record

Photo, posted June 8, 2023, courtesy of Anthony Quintano via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Saving Florida’s Corals | Earth Wise

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When corals are exposed to extended periods of excess heat, they are subject to bleaching, which occurs when they expel the algae that live within their structure.  Bleaching can lead to coral death.

This summer, temperatures in the Florida Keys crossed the bleaching threshold in mid-June and remained above it for extended periods of time.  This cumulative heat exposure leads to widespread bleaching and significant die-offs.  The last major mass bleaching event in the Florida Keys occurred in 2014 and 2015.

The Coral Restoration Foundation has been receiving reports ranging from partial bleaching to mass coral mortality throughout the keys.  Several coral restoration sites in the lower Keys have been totally lost already.

The National Oceanic and Atmospheric Administration and its state agency, university, and non-profit partners have initiated actions to try to save Florida’s corals.

They have halted all restoration-related planting and are evacuating some of their nursery-grown stock to climate-controlled labs.  They are considering interventions such as shading coral nurseries or even high-value reef sites.  They are also considering feeding nursery and wild corals until the waters cool off enough for algae to return.

Modeling indicates that there is a 70-100% chance that the extreme heat in the North Atlantic will persist through September-October.  NOAA and its partners will continue to do what they can to save Florida’s Coral Reef for the marine and human communities that depend on them.

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NOAA and partners race to rescue remaining Florida corals from historic ocean heat wave

Photo, posted April 19, 2012, courtesy of U.S. Fish and Wildlife Service Southeast Region via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Shrinking Birds | Earth Wise

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A new study by researchers at Yale University looks at the way bird morphology is changing in response to the warming climate.  As temperatures rise, birds’ bodies are growing smaller, but their wings are growing longer.

In the study, published in the Proceedings of the National Academy of Sciences, the scientists analyzed two independently collected datasets containing 40 years of morphology changes in 129 bird species comprising 52 migratory species in North America and 77 South American species.

In both datasets, similar changes were observed over the 40-year period.  The overall trend makes sense given that being smaller and having longer wings both would help birds to stay cool in warmer weather.  What was less obvious was that the changes to the birds were much greater among the smallest bird species.

One possible explanation is that smaller species tend to reproduce on a shorter time scale and therefore evolve more quickly.  However, the study found no link between generation length and the changes in body size.

Another possible explanation is that smaller species tend to have larger populations, which means there is a greater chance of having individuals with desirable new traits that can get passed on.  But the scientists found no link between population size and shifts in body size either.

At this point, it is unclear why smaller birds are shrinking more.  More research is needed to figure out why larger birds are slower to adapt to climate change.  In general, larger species of animals have an increased risk of extinction.  This new research suggests that larger body size exacerbates extinction risk by limiting the ability for birds to adapt to the changes we are making to the climate.

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Birds Are Shrinking as the Climate Warms — and Small Birds Are Shrinking Faster

Photo, posted October 30, 2018, courtesy of N. Lewis / National Park Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Geothermal Energy Storage | Earth Wise

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About 12% of the energy consumed by humanity is used to heat and cool homes and businesses.  A study by researchers at Lawrence Berkeley National Laboratory and Princeton University looked at a novel approach to making use of underground water to maintain comfortable temperatures and reduce consumption of natural gas and electricity.

The idea is to use aquifer thermal energy storage (known as ATES) to provide both heat in the winter and cooling in the summer.  The concept leverages the heat-absorbing property of water and natural geological features.  The idea is to pump up water from existing underground reservoirs and heat it at the surface using environmental heat or even excess energy from solar or wind generation.  Then the warm water is pumped back down. It stays warm for a long time – even months – because the earth is a good insulator.  When the water is pumped back up in the winter, it is much hotter than the ambient air and can be used to supply heat to buildings.

Alternately, water can be pumped up and cooled in the winter and then put back down underground and stored until cooling is needed in the summer months.

This technology has not been used much in the US, but it is gaining recognition internationally, particularly in the Netherlands.  It can perform very well in areas with large seasonal fluctuations.

The research study used modeling and various simulations to estimate how much energy ATES could save on the US grid.  The results showed that adding ATES to the grid could reduce consumption of petroleum products for heating and  cooling by up to 40%.  The system could also help prevent blackouts by reducing high power demand during extreme weather events.

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Underground Water Could be the Solution to Green Heating and Cooling

Photo, posted February 19, 2012, courtesy of Sanjay via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Windows To Cool Buildings | Earth Wise

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

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

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

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

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Clear window coating could cool buildings without using energy

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

Earth Wise is a production of WAMC Northeast Public Radio

A Smart Window | Earth Wise

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

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

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

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

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

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

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

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

Earth Wise is a production of WAMC Northeast Public Radio.

January Climate Report Card | Earth Wise

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January was the sixth-warmest January in the 143 years of global climate record keeping.  The global land and ocean surface temperature was 1.6 degrees Fahrenheit above the 20th century average.

Meanwhile, the United States had its coolest January since 2014, although the month still ranked nearly a degree above the long-term average across the nation.  This January was also the driest January in eight years and was one of the top- 15 driest Januarys on record.  That being said, there was the so-called Bomb Cyclone late in the month that dumped 1-2 feet of snow and brought blizzard conditions along the eastern seaboard and set a one-day snowfall record in Boston.

Global conditions and regional and local conditions can be very different.  In the big picture, January was the 46th consecutive January and the 445th consecutive month with temperatures above the 20th century average.

And while the US had a fairly cool January, South America saw its second-warmest January on record, Asia had its fourth warmest, and Oceania had its seventh warmest.

Apart from temperatures, Antarctic sea ice coverage was the second smallest January extent in 44 years.  Arctic ice was 208,000 square miles below the 1981-2010 average, although it was the largest since 2009.

Even as the global climate warms, local and regional climate conditions will continue to have unique and variable characteristics over the course of time.  Every time there’s a bout of cold weather, it isn’t time to stop being concerned about climate change.

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January 2022 was Earth’s 6th warmest on record

Photo, posted January 6, 2013, courtesy of Christopher Michel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Roof | Earth Wise

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Scientists at the Lawrence Berkeley Laboratory have developed an all-season smart roof coating that can keep homes warm during the winter and cool during the summer, and the coating does not consume any gas or electricity.

Existing cool roof systems consist of reflective coatings, membranes, shingles, or tile that lower house temperatures by reflecting sunlight as well as emitting some of the absorbed solar heat away from the roof as infrared radiation.  The problem with such systems is that they continue to radiate heat during the winter, which actually drives up heating costs.

The new material is called a temperature-adaptive radiative coating or TARC.  It enables energy savings by automatically turning off the radiative cooling in the winter.  TARC reflects about 75% of sunlight year-round, but its thermal emittance is high when the temperature is warm – promoting heat loss to the sky – but decreases in cooler weather, helping to retain the heat in a building.

The researchers produced thin-film TARC material that looks like Scotch tape that could be affixed to a surface like a rooftop.  They applied the material to a balcony alongside a sample of commercial dark roof material and a sample of commercial white roof material.

In experiments simulating 15 different climate zones across the US, they found that the TARC material outperforms existing roof coatings for energy savings in 12 out of the 15 zones, particularly in regions with wide temperature variations between day and night, such as in the San Francisco Bay Area, or between winter and summer, such as New York City.

The researchers believe that installing TARC coatings on roofs would save the average U.S. household about 10% in utility costs.

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New Smart-Roof Coating Enables Year-Round Energy Savings

Photo, posted May 18, 2017, courtesy of Damian Gadal via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Understanding Geoengineering | Earth Wise

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

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

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

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

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

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

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

Earth Wise is a production of WAMC Northeast Public Radio.

Strategies To Cool Off Cities | Earth Wise

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Heatwaves in cities are becoming increasingly common and increasingly intense.  The warming climate is a big factor, but it is the nature of our cities that really drives up temperatures.  Solar radiation stored throughout the day on asphalt and buildings is released slowly during the night, which generates significant heat stress.

A study carried out by a major Barcelona university and published in the journal Urban Climate looked at the effectiveness of various ways to mitigate the heating effects in cities.  In particular, the study examined the effects of the use of white roofs on buildings and the expansion of urban green areas with daily irrigation in the Barcelona metropolitan area.  It simulated various scenarios incorporating combinations of these two mitigation strategies.

The strategy with the greatest impact was a combination of the use of both white roofs and the addition of six urban parks, which is a target set by the Barcelona Urban Master Plan.  This scenario resulted in an average temperature reduction of 2.25 degrees Fahrenheit.  The maximum reduction occurs during the mid-afternoon with a reduction of 7 degrees and the combination still provides more than 3 degrees of reduction at 9 pm.  Reducing temperatures this way also results in a reduction in energy consumption, with 26% less spending on air conditioning.

The 2-pronged strategy combines the benefits of reducing the temperature at night due to more urban green areas with the reduction of daytime heat due to both the increased reflectivity of white roofs as well as the irrigation of the green areas.

The study demonstrates how modeling efforts can help urban planners to counteract the impacts of heatwaves, which are likely to increase with climate change and intensification of urbanization.

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White roofs and more green areas would mitigate the effects of heat waves in cities

Photo, posted January 16, 2011, courtesy of Sean MacEntee via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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