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Planting trees to cool the planet

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Planting lots of trees is one of many strategies being pursued to combat climate change. Forests absorb carbon dioxide, provide shade, and help regulate temperatures. They also support biodiversity and improve air and water quality.

According to a new study by researchers from the University of California – Riverside, restoring forests to their pre-industrial extent could reduce global average temperatures by 0.34 degrees Celsius. That’s equivalent to about 25% of the warming the Earth has already experienced.

The study models restoring 4.6 million square miles of forest.  While previous studies have focused on the role trees play in removing carbon, this research adds that trees also alter atmospheric chemistry in ways that boost their cooling impact.

Trees release natural chemicals called BVOCs – biogenic volatile organic compounds – which interact in the atmosphere to form particles that reflect sunlight and promote cloud formation. These effects enhance the cooling impact of forests, especially in climate models that take these chemical reactions into account.

But not all reforestation is created equal. The benefits of reforestation vary by region, with tropical forests offering stronger cooling and fewer drawbacks.  Importantly, the researchers emphasize that meaningful climate benefits don’t require restoring every lost forest. Small, localized efforts can still shift regional climates.

While forest restoration can meaningfully aid climate efforts, the researchers stress that it must complement – not replace – fossil fuel reductions.

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Does planting trees really help cool the planet?

Photo, posted May 20, 2005, courtesy of Ben Britten via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Redefining the perfect beach

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The iconic image of the “perfect” tropical beach is fine white sand, a few coconut palm trees, a gently sloping beach, and unobstructed views of the blue sea.  This image came about to a great extent from fascination with Polynesian scenery at the time of World War II.   And because of this imagery, beach resorts around the world have tried to achieve this look, often by reengineering and altering natural ecosystems to meet this artificial standard of perfection.

But natural tropical and subtropical beaches with their mangrove forests and seagrass meadows are complex ecosystems that support biodiversity, provide protection from storms, and capture carbon in significant amounts from the atmosphere.

With all this relandscaping of beaches, by the end of the 20th century, 35% of the world’s mangrove forests and 29% of its seagrasses were gone.  Mangroves sequester 10 times more carbon than mature tropical forests and sea grass can pull in up to 15 times as much.

In recent years, some resort developers are starting to embrace having beachscapes in their more natural states.  They are planting or preserving native vegetation and allowing sea grass to flourish.  The Six Senses Laamu resort in the Maldives, a major luxury tourist destination, was a trendsetter in this way. 

Coconut palms do little to prevent sand erosion, block wind, or even provide much shade.  In a warming world with increasingly powerful storms, they offer little protection for the world’s beaches.  They are not even native to the Caribbean, where they are now ubiquitous, having been introduced by Europeans.

Many resort developers are now rethinking the description of the perfect beach.

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Your Resort’s ‘Perfect’ Beach Is a Lie

Photo, posted March 2, 2011, courtesy of Breezy Baldwin via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Amphibians and climate change

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Amphibians are a group of vertebrate animals that include frogs, toads, and salamanders. They are unique for their ability to live both in water and on land during different stages of life. Amphibians play a crucial role in ecosystems, often serving as both predators and prey in food webs.

Amphibians are the world’s most at-risk vertebrates, with more than 40% of species listed as threatened.  They are cold-blooded creatures and rely on external sources to regulate their body temperature.  But needing to regulate their body heat this way makes amphibians particularly vulnerable to temperature change in their habitats. 

Researchers from the University of New South Wales in Australia can now predict the heat tolerance of 60% of the world’s amphibian species.  This new tool will allow scientists to better identify which amphibian species and habitats will be most impacted by climate change.  

The study’s landmark findings, which were recently published in the journal Nature, found that 2% of amphibian species are already exposed to overheating in shaded terrestrial conditions.  According to the research team, a 4°C global temperature increase could push 7.5% of amphibian species beyond their physiological limits. 

Local amphibian extinctions can trigger ecological repercussions, including reshuffling community compositions, eroding genetic diversity, and impacting the food chain and overall ecosystem health.

The researchers highlight the importance of vegetation and water bodies in protecting amphibians during heat waves, and emphasize the need to provide adequate water and shade during future conservation efforts. 

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The pot is already boiling for 2% of the world’s amphibians: new study

Photo, posted October 8, 2011, courtesy of Dave Huth 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

Strawberries and climate change

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The demand for strawberries continues to climb around the world.  According to data from World Population Review, China remains the global leader in strawberry production, a spot it’s held since 1994.  Last year, China produced 3.3 million tons of strawberries, followed by the United States at 1.05 million tons, Egypt at 597,000 tons, and Mexico at 557,000 tons.

While strawberries are grown coast to coast in the U.S., California and Florida are the top two strawberry-producing states due to their favorable climate conditions.  In fact, California produces more than 90% of the domestic strawberry crop.  But Florida plays a key role in domestic strawberry production as well by growing the majority of the winter crop. 

A new study by researchers from the University of Waterloo in Canada has examined the effect of climate change on California’s strawberry crop.  According to the research team, strawberries could be fewer and more expensive because of the higher temperatures caused by climate change.  The report, which was recently published in the journal Sustainability, found that a 3° Fahrenheit rise in temperature could reduce strawberry yields by up to 40%.

According to the researchers, the impact of climate change on strawberry production could be mitigated by implementing certain sustainable farming practices.  These include optimizing irrigation to ensure adequate water supply during heat waves and using shading plants and shade structures to mitigate heat stress.

Understanding how rising temperatures affect crop yields should encourage farmers and governments to develop sustainable agriculture responses to global warming.

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Influence of Regional Temperature Anomalies on Strawberry Yield: A Study Using Multivariate Copula Analysis

Strawberry Production by Country 2024

Researchers predict fewer, pricier strawberries as temperatures warm

Photo, posted June 3, 2007, courtesy of David Slack via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

How to make cities cooler

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In cities, the air, surface, and soil temperatures are almost always warmer than in rural areas. This is known as the urban heat island effect.  Urban heat islands occur when cities replace natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat.

Urban planners around the world have been researching ways to reduce the effects of heat in cities.  For example, trees, green roofs, and vegetation can help reduce urban heat island effects by shading building surfaces, deflecting radiation from the sun, and releasing moisture into the atmosphere.

A new study led by researchers from the University of Surrey in the U.K. has analyzed how well various green spaces and waterways are able to cool down cities.  The study, which was recently published in the journal The Innovation, found that wetlands, parks, and even botanical gardens are among the best ways to keep cities cool.   

In fact, the researchers found that botanical gardens can cool city air by a whopping 9°F during heatwaves on average.  Wetlands can cool city air by 8.5°F on average, followed by rain gardens at 8.1°F, green walls at 7.4°F, street trees at 6.8°F, city farms at 6.3°F, city parks at 5.8°F, and reservoirs and playgrounds at 5.2°F. 

The researchers also found that cities can unlock even greater benefits by connecting green spaces into green corridors.  Greening projects can also help remove carbon emissions and prevent flooding.

The research team hopes its findings will help urban planners design more resilient cities. 

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Wetlands, parks and even botanical gardens among the best ways to cool cities during heatwaves

Photo, posted April 25, 2022, courtesy of Catherine Poh Huay Tan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Controlled Environment Agriculture | Earth Wise

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The term “controlled environment agriculture” (or CEA) refers to any number of systems embodying a technology-based approach to farming.  CEA can range from simple shade structures to greenhouses to full indoor or vertical farms.  At the most advanced level, CEA systems are fully automated, closed loop systems with controlled lighting, water, and ventilation.   Many systems make use of hydroponics rather than traditional soil.

The goal of CEA systems is to provide optimum growing conditions for crops and prevent disease and pest damage. 

A recent study by the University of Surrey in the UK sought to understand the impact of using CEA systems to grow lettuce, which is a high-value crop that is often grown in such systems.

The study found that, on average, CEA methods produce double the crop yields compared to field-based agriculture.  They also found that the cultivation time of CEA yields was, on average, 40 days.  This compares with an average cultivation time of 60-120 days for field-based agriculture.  More specifically, production of lettuce using CEA was 50% faster in the summer and up to 300% faster in the winter.

Climate change presents many difficult challenges to society, not the least of which is its threat to food security.  Controlled environment agriculture could allow cultivation of crops in harsh environments and in the face of changing climates.  Quantifying the benefits CEA can have on yield and growth provides important information for advancing our understanding of where and when this technology can bring the most value to society. 

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Using artificial methods for growing crops could help solve global food security

Photo, posted February 24, 2013, courtesy of Cindy Kurman / Kurman Photography via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Community Solar On The Rise | Earth Wise

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Community solar is a way for people who can’t put solar on their own roofs to still take advantage of its benefits.  Whether they can’t afford to install their own panels, have too much shade on their roof, or don’t even own a home, community solar is another way to participate in green energy.

Community solar – also called “shared solar” or “solar gardens” – is a kind of development in which consumers can subscribe to a large solar installation in their area and receive credits on their monthly utility bills for their share of the solar electricity produced.

The large majority of community solar installations are in six states:  Colorado, Illinois, Massachusetts, Minnesota, New Jersey, and New York.  After substantial growth in community solar in 2022, New York now is the national leader, thanks to initiatives by the state government and the nonprofit sector.  Some programs focus on giving low-income households access to solar.  As of last fall, New York had over 728 community solar projects online.

One should understand that electrons are indistinguishable.  The power generated by a community solar installation is not piped directly to subscribers’ homes.  It just goes into the grid.  Subscribers get credit for their share of the power, but that is essentially a matter of bookkeeping, not physics.

The federal government now has $7 billion that can be used for community solar as part of the Greenhouse Gas Reduction Fund within the Inflation Reduction Act enacted last August.  The EPA plans to award up to 60 grants to assist projects deploying residential and community solar.  Research firm Wood Mackenzie forecasts the community solar market will double by 2027.

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Community Solar Is About to Get a Surge in Federal Funding. So What Is Community Solar?

Photo, posted November 18, 2008, courtesy of the Oregon Department of Transportation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Importance Of City Trees | Earth Wise

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It is well known that green spaces can improve the quality of life and create a better climate in cities.  City trees and vegetation can help reduce urban heat island effects by shading buildings and roads, deflecting radiation from the sun, and releasing moisture into the atmosphere.  City trees and green spaces have also been proven to increase property values, promote wildlife and plant diversity, reduce noise pollution, and improve human health.  But how important are trees and vegetation for producing cleaner air in cities?

According to a new study led by researchers at the University of Gothenburg in Sweden, trees do contribute to cleaner air in cities, but the degree to which they do so varies greatly between different locations. 

The research team measured air pollutants across seven urban settings in the city of Gothenburg, and compared them with pollutants on the leaves of deciduous trees.  The researchers chose to focus on polycyclic aromatic hydrocarbons (PAHs), which are pollutants generated primarily during the incomplete combustion of organic materials, like coal, oil, and wood.

The results revealed that the pollutants in leaves did increase over time.  The researchers were able to show a clear correlation between the level of air pollutants and the concentration of pollutants in leaves. 

But at the same time, the researchers discovered that pollution levels varied greatly between measurement sites.  For example, the levels of PAHs were seven times higher at the most polluted site (the city’s main bus station) than they were at a location on the periphery of the city.

The research team hopes its findings will be used to help guide the planning of future urban landscapes.

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Trees are important for cleaner air in cities

Photo, posted November 5, 2021, courtesy of Maria Eklind via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar Canopies | Earth Wise

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There are plenty of solar panels on residential rooftops but there are also increasing numbers of arrays of them on croplands, arid lands, and grasslands. Large solar arrays are mostly built in open spaces like these rather than in developed areas.  The reason is that it is cheaper to build on undeveloped land than on rooftops or construct covered parking lots.

However, building on undeveloped land is not necessarily the smartest idea.   Undeveloped land is a dwindling resource that is needed for many different things:  growing food, sheltering wildlife, storing and purifying water, preventing erosion, and sequestering carbon. 

Putting solar panels on parking lots has the appeal that they are abundant, close to electricity customers, and are on land that already has been stripped of much of its biological value.

Putting a solar canopy over a parking lot can produce large amounts of electricity and has the added benefit that it would provide shade for cars.  For example, a typical Walmart supercenter might have a five-acre parking lot, which is enough to support a 3-megawatt solar array.  If Walmart put solar canopies on all of its 3,500+ super centers, it would provide 11 gigawatts of solar power – as much as a dozen large coal-fired power plants.

Solar canopies are still pretty uncommon, but some examples are ones at four DC Metro rail stations, one at JFK Airport, and a large one at the Rutgers University Piscataway campus.

Building parking lot solar canopies is much more expensive than putting solar arrays on open space, but they do eventually pay for themselves. Despite active opposition by utility and fossil fuel interests, solar canopies may eventually be a common sight.

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Why Putting Solar Canopies on Parking Lots Is a Smart Green Move

Photo, posted January 10, 2020, courtesy of Tony Webster via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Living Walls | Earth Wise

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Green roofs are popular in many European countries.  A green roof is a layer of vegetation planted over a waterproofing system installed on a flat or slightly sloped roof.  Such roofs provide shade, remove heat from the air, and reduce temperatures of the roof surface, reducing energy use in the building and diminishing the urban heat-island effect.

A recent study by the University of Plymouth in the UK looked at the effectiveness of living walls – essentially the equivalent of a green roof located on the wall of a building.

The study looked at the effect of retrofitting an existing masonry wall with an exterior living wall façade consisting of a flexible felt fabric sheet system with pockets holding soil in which plants could grow.

Five weeks of measurements demonstrated that the amount of heat lost through the retrofitted wall was 31.4% lower than that of the original structure.  They also found that daytime temperatures within the newly covered section remained more stable than the area with exposed masonry, so that less energy was required to heat that area.

The concept of living walls is fairly new but could be valuable in temperate climates such as Great Britain.  Buildings in the UK account for 17% of greenhouse gas emissions and space heating accounts for 60% of all the energy used in buildings.  So, improving the thermal performance of buildings would have a significant effect on reducing energy use and therefore emissions.

So-called green infrastructure, including green roofs and living walls, provides a nature-based solution that can help tackle climate change, air pollution, and other modern urban problems.

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Living walls can reduce heat lost from buildings by over 30%, study shows

Photo, posted June 19, 2011, courtesy of Linda Hartley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Coffee And Climate Change | Earth Wise

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Over 2.25 billion cups of coffee are consumed in the world each day.  Americans spend $80 billion dollars a year on coffee.  Coffee in grown across 12.5 million largely smallholder farms in more than 50 countries.  In other words, coffee is a big deal.

Like many things, coffee is subject to the effects of climate change.  Many coffee-producing regions are experiencing changing climate conditions, which don’t only affect the yield and sustainability of the crop but have an impact on taste, aroma, and even dietary quality.  Coffee drinkers care very much about these things.

New research at Tufts University and Montana State University looked at how coffee quality can be affected by shifts in environmental factors associated with climate change.  The researchers looked at the effects of 10 prevalent environmental factors and management conditions associated with climate change and climate adaptation.

The most consistent trends were that farms at higher altitudes were associated with better coffee flavor and aroma, while too much light exposure was associated with a decrease in coffee quality.   They also found that coffee quality is also susceptible to changes due to water stress and increases in temperature and carbon dioxide levels.

They evaluated current efforts to mitigate these effects, including shade management, selection of climate resistant coffee plants and pest management. The hope is that if we can understand the science of the changes to the environment, it will help farmers and other stakeholders to better manage coffee production in the face of increasing challenges.   It will take a concerted effort to maintain coffee quality as the climate continues to change.

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Coffee and the Effects of Climate Change

Photo, posted May 22, 2009, courtesy of Olle Svensson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Potential For Solar Canals In California | Earth Wise

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California’s network of almost 4,000 miles of aqueducts is the world’s largest water conveyance system.  It serves the state’s Central Valley which produces a quarter of America’s food.  About 20% of the nation’s groundwater demand is pumped from Central Valley aquifers.

A recent study by the University of California Santa Cruz and UC Merced has determined that covering these aqueducts with solar panels could be an economically feasible way to advance both renewable energy and water conservation.  California’s aqueducts might more properly be called canals because they are located at ground level.  

The concept of solar canals has been gaining increasing interest around the world as the changing climate leads to more droughts in many regions.  Placing solar panels above the canals can shade them to help prevent water loss through evaporation.  In addition, some types of solar panels can work better situated over canals because the cooler environment improves their operation.  In addition to the increased solar panel output and the water evaporation savings, shade from solar panels could help control the growth of aquatic weeds, which are a costly canal maintenance issue.

Spanning canals with solar panels can be accomplished either by using steel trusses or suspension cables, either of which is more expensive to build than ordinary ground-mounted solar panel supports.  But the research study showed how the benefits of solar canals combine to outweigh the added costs for cable-supported installations.

Apart from the economic benefits of a solar canal system, producing solar energy in the canal system could eliminate the use of 15-20 diesel-powered irrigation pumps, helping to reduce air pollution in a region with some of the nation’s worst air quality.

Solar canals could be a real winner.

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New analysis shows potential for ‘solar canals’ in California

Photo, posted July 23, 2015, courtesy of Lance Cheung / USDA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Planting Trees and Climate Change | Earth Wise

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Forests are among the most important natural carbon sinks.  Trees remove carbon from the air and store it in their trunks, branches, and leaves, and transfer part of it into the soil.  But in some regions, these natural carbon sinks are starting to weaken due to deforestation, forest degradation, and the impacts of climate change.  This problem has led some climate mitigation projects to focus on increasing the overall number of trees on the planet. 

But, according to a paper recently published in the journal Science, “we can’t plant our way out of climate change.”  That’s the simple message from Restoration Ecologist Karen Holl and University of São Paulo Professor Pedro Brancalion to anyone who thinks planting one trillion trees will reverse the effects of climate change.  They say planting more trees is only one piece of the puzzle.  Any initiatives like 1t.org or the Trillion Tree Campaign must be done carefully and be accompanied by commitments to long-term management.

Tree plantings can provide many environmental benefits, including improving water quality, biodiversity, and increasing shade.  But trees can sometimes have undesirable impacts, such as harming native species and ecosystems or reducing water availability, depending on where and how the trees are planted.

The authors suggest four principles that should guide forest enhancement initiatives: reduce forest clearing and degradation, balance ecological and social goals, view tree plantings as one part of a multifaceted solution, and plan, coordinate and monitor the work. 

While tree plantings can clearly be part of the solution, slowing the pace of climate change requires a comprehensive approach that must start with burning less fossil fuels.

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Challenges in tree-planting programs

Planting trees is no panacea for climate change

Photo, posted December 1, 2019, courtesy of Akuppa John Wigham via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Cooling Down Urban Heat Islands

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Researchers have known about and studied the urban heat island effect for quite some time.  Since large cities began to emerge in the 19th century, it has been understood that various aspects of the urban environment lead to warmer temperatures than the surrounding countryside.

Researchers led by a group at Portland State University in Oregon have been utilizing a new way of studying the urban heat island effect.  They have used citizen science volunteers in 24 cities around the world to map temperatures in the cities at ground level in great detail using mobile sensors attached to slow-moving vehicles.  Previous studies have used data from satellite or stationary sensors.  They have learned that the urban heat island effect is more complicated, more varied, and subtler than the earlier data indicated.

They found that there are six things that affect urban heat. Three are living — the volume of the tree canopy, the height of the tree canopy, and the ground level vegetation. Three are human-built — the volume of buildings, the difference in building heights, and the coloring of the buildings.

Buildings can have both negative and positive effects. Tall buildings that cast shade actually lower relative afternoon temperatures, while densely packed shorter buildings, like the big-box stores in suburban areas, lead to hotter afternoon temperatures. The studies show that increasing the difference in building heights in an area creates more air circulation, which has a cooling effect.

The study also showed that urban heat is a social justice issue.  Lower-income neighborhoods largely barren of trees have considerably higher temperatures than more affluent, tree-shaded areas.

Such detailed research can be used to guide decisions in urban planning with regard to trees, building heights, and the color and type of surfaces in our urban spaces.

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Can We Turn Down the Temperature on Urban Heat Islands?

Photo, posted July 21, 2009, courtesy of Daniel Dionne via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sunlight As A Cash Crop

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It isn’t so easy to be a farmer these days.  Farming has always involved long hours, hard work and the uncertainties of weather and yield.  The 21st Century has added new and unique challenges such as increasingly unpredictable weather, insect infestation and disease, and low commodity prices.  Add in sudden tariffs and farmers struggle even more to make ends meet.  The default rate for farmers’ loans is the the highest in at least nine years.

One thing that remains reliable for farmers is the sun.  It rises in the morning and goes down at night.  The sun can be trusted, unlike politicians, rain, or commodity prices.  These days, many farmers are taking advantage of the dependability of the sun to make money from a new cash crop: solar energy.

The trend is spreading.  North Carolina has been a leading solar energy state for several years and a 2017 report found that solar energy generates 30% of the income of many farms.  Typical annual rent payments for farmland by solar companies range from $500 to $1,400 per acre in North Carolina.

A growing list of states have clean energy mandates targeting 100% use of renewable energy.   These mandates provide incentives for farmers that make installing solar a financially smart decision and falling prices for solar installations make it an even better deal.

Solar works well when co-located on a farm and can be built in ways that minimizes impact.  It is quiet, uses almost no water, doesn’t pollute, and if it is decommissioned, the land can go back to its previous use.  If the solar facilities are raised up, the same land can be used to graze livestock or grow shade-tolerant crops.

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Harvesting the sun is the new cash crop

Photo, posted December 25, 2017, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Trees And The Future Of Cities

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The shade of a single tree is a welcome source of relief on a hot summer day.  But even a relatively small patch of woods can have a profound cooling effect.  A new study at the University of Wisconsin-Madison looks at the role trees play in keeping towns and cities cool.

According to the study, the right amount of tree cover can lower daytime temperatures in the summer by as much as 10 degrees.  The effects are noticeable from neighborhood to neighborhood and even on a block-by-block basis.

Cities are well-known to be hot spots due to the urban heat islanding effect.  Using trees to keep temperatures more comfortable in cities can make a big difference for the people who live and work there.

The man-made structures of cities – roads, sidewalks, and buildings – absorb heat from the sun during the day and slowly release it at night.  Trees, on the other hand, not only shade those structures from the sun, but they also transpire -or release water in the air through their leaves – which helps to cool things down.

According to the study, to get maximum cooling benefits, tree canopies must exceed forty percent, meaning that city blocks need to be nearly halfway covered by tree branches and leaves.  To get the biggest bang for the buck, cities should start planting more trees in areas that are already near the forty percent threshold.  But

trees can’t just be in parks.  They need to be in places where people are active.

If we want the places where we live to be more comfortable and resilient in a warming world, we need to plant more trees.

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Study suggests trees are crucial to the future of our cities

Photo, posted May 26, 2012, courtesy of Mislav Marohnic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Making Cities Cooler

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Cities are particularly miserable during heatwaves.   With lots of concrete and asphalt surfaces, they soak up lots of heat and re-radiate it.  Lots of tall buildings block cooling breezes.  Factor in car exhaust and heat from air conditioners and it all adds up to the urban heat island effect.  Cities can be several degrees warmer during the day and as much as 20 degrees warmer at night.  All of this extra heat is not just a comfort issue, it is a serious health problem.

[Read more…] about Making Cities Cooler

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