green spaces

Cooling cities

September 2, 2024 By EarthWise Leave a Comment

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

How to make cities cooler

March 26, 2024 By EarthWise Leave a Comment

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

Sponging up a river

March 20, 2024 By EarthWise Leave a Comment

During the first week of February, an atmospheric river dumped enormous amounts of rain on Southern California. Over the course of four days, Los Angeles received 9 inches of rain. The average annual rainfall in the city is only 14 inches.

But Los Angeles was not the site of a flooding disaster because the city has spent years preparing for this type of deluge by becoming a “sponge city.” By installing lots of green spaces and shallow basins with porous soil, Los Angeles was able to soak up 8.6 billion gallons of water during the storm, enough to meet the water needs of 100,000 people for a year.

Cities covered with impermeable concrete sidewalks and paved areas make storm-related flooding worse because they are unable to absorb water. Instead, the water flows into drains and overwhelms infrastructure.

Natural materials like dirt and plants take in water from storms and can filter it into underground aquifer that cities can then tap into, especially during droughts. Adding green spaces to cities has many other benefits beyond the ability to absorb large amounts of rainwater.

The so-called sponge-city movement is catching on in many other places. Philadelphia is revamping its water systems in a 25-year project that includes green spaces to absorb stormwater runoff. In China, the government has spent more than a decade adding spongy elements to dozens of cities around the country.

Sponge cities are part of a broader effort to combine modern engineering techniques with natural systems. This is known as green-gray infrastructure. Nature knows what it is doing when it comes to flood control as well as to pollution control.

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‘Spongy’ LA Soaked Up Tons of Water From Atmospheric River

Photo, posted December 28, 2011, courtesy of Ron Reiring via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Golf courses gone wild

March 18, 2024 By EarthWise Leave a Comment

Golf courses are a significant burden on the environment. The US has 16,000 golf courses which use 1.5 billion gallons of water a day and are treated with 100,000 tons of nitrogen, phosphorus, and potassium each year. In recent years, the golf industry has taken steps to lighten its environmental toll by using less water, introducing pollinator-friendly plants, and decreasing pesticide and fertilizer use. The US has more golf courses than any other country, accounting for 42% of all courses worldwide.

There is really an oversupply of golf courses and, as a result, more golf courses have closed than have opened since 2006. Most closed golf courses end up in the hands of commercial or residential developers, but some of them are allowed to return to nature.

For this to happen, there has to be a willing seller and, more importantly, a conservation-minded buyer who can afford both to purchase the land and to restore it to a natural state. There have been 28 former golf courses transformed into public green spaces between 2010 and the end of 2022. But that number seems to be growing.

In 2023, the former Cedar View Golf Course on the eastern shore of Cayuga Lake in upstate New York was bought by the Finger Lakes Land Trust. In California, places like Santa Barbara, Marin County, and even Palm Springs have all undertaken the transformation of former golf courses into public parklands.

Rewilding a golf course is undoubtedly a disappointment to local golfers, but it can bring big benefits to animals, plants, and people.

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After Shutting Down, These Golf Courses Went Wild

Photo, posted October 19, 2016, courtesy of Cabo Girao via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate A Winner In The Elections | Earth Wise

December 22, 2022 By EarthWise Leave a Comment

The dominant issues in midterm elections in November were the economy and abortion rights, but at the same time there were also ballot initiatives in various cities and states across the country related to climate. What some describe as the ‘silent surprise’ of the election was that these initiatives generally passed and, in some cases, by large majorities.

The most significant of these ballot measures was in New York, where two-thirds of voters passed the largest environmental bond measure in state history. The measure funds up to $4.2 billion for environmental improvement projects including increasing flood resiliency, reducing greenhouse gas emissions, electrifying school buses, and creating more green and open spaces.

The Clean Water, Clean Air, and Green Jobs Environmental Bond Act provides up to $1.5 billion for projects aimed at climate change mitigation. Another $1.1 billion is targeted for flood risk reduction and waterway restoration. $650 million goes for water quality and infrastructure improvement.

Rhode Island voters passed a green bonds act that will allow the state to invest in climate resiliency at the municipal level, as well as local recreation, open space protection, brownfields remediation, and forest and habitat restoration.

Other climate-related ballot measures passed in Boulder, Colorado and in El Paso, Texas. There were however a few climate measures that lost. Proposition 30 in California that would have taxed very high-income residents to encourage sale of electric vehicles failed. So did Arizona Proposition 310, which would have increased sales taxes by 0.1% to fund fire districts.

But overall, it was a good election for the climate.

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Voters pass historic climate initiatives in ‘silent surprise’ of US midterms

Photo, posted September 24, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Importance Of City Trees | Earth Wise

January 28, 2022 By EarthWise Leave a Comment

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.

Perennials To Attract Pollinators | Earth Wise

November 26, 2021 By EarthWise Leave a Comment

There has been a decline in the abundance of insect and other animal pollinators in many ecosystems worldwide that began being observed at the end of the 20th century. Pollinators and their health have become growing concerns for the public and many states have enacted legislation related to pollinator decline.

In many places, the pollinator decline has largely been driven by a loss of flowering plants in the landscape, the primary source of food for the pollinators. A new study by Penn State researchers looked at the attractiveness to pollinators of various species of perennial flowering plants that people can plant in their gardens and other landscapes.

It turns out that there is considerable variation in how attractive different flowering plants are to pollinators. Greenspaces such as parks and gardens have the potential to support very rich pollinator communities, even including rare or vulnerable species.

People generally select ornamental plants because of their appearance and growth habit, not because of their pollinator attraction.

The Penn State study looked at a variety of perennials and identified the most attractive plant cultivars, which can attract 4 times the number of pollinator species than the least attractive plants studied.

The most appealing plant is the ‘Blue Fortune’ giant hyssop. Other highly attractive plants are the anise hyssop, the ‘Black Adder’ Agastache, the Cat’s Meow and Walker’s Low Nepetas, and the Triloba and Herbstonne Rudbeckias.

Many of these plants produce large floral displays and the researchers suggest that they should be prioritized when planting a pollinator garden amongst other species with comparably small floral displays and lower attractiveness to pollinators.

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Photo, posted September 7, 2019, courtesy of KM via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Green Solutions To Storm Water Runoff

July 5, 2018 By EarthWise Leave a Comment

Philadelphia, America’s fifth largest city, has struggled with storm water runoff problems since the days of Benjamin Franklin. The city’s numerous streams that run into the Schuylkill and Delaware Rivers were eventually covered with brick arches or cemented into underground sewers. The network of underground-to-riverfront outfalls through increasingly-larger pipes is pretty much how all U.S. cities have been coping with storm water for over 200 years.