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City Greenery And Carbon Emissions | Earth Wise

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According to the United Nations, more than half of the world’s population currently lives in cities.  Projections show that the combination of urbanization and global population growth could add another 2.5 billion people to cities by 2050. 

Unsurprisingly, cities are a major contributor to climate change.  According to U.N. estimates, cities are responsible for 75% of global carbon dioxide emissions, with transportation and buildings being among the largest contributors. 

According to a new study of vegetation across New York City and some adjoining urban areas, photosynthesis by trees and grasses on many summer days absorbs all the carbon emissions produced by cars, trucks and buses, and then some.  In fact, on many summer days, the total carbon uptake in the region equaled up to 40% of a summer afternoon’s total emissions from all sources in the City. The results, which were recently published in the journal Environmental Research Letters, further highlights the critical importance of urban greenery.

Most previous studies have analyzed the carbon uptake of vegetation by looking at the contiguous tracts of green spaces, but this only comprises about 10% of metro areas.  Using detailed aerial radar imagery of New York City that mapped vegetation in unprecedented 6-inch grids, the researchers were able to include the other 90% of the metro area typically left out in most models. 

Since carbon uptake by vegetation only occurs during the growing season, green spaces in cities situated in warmer climates likely play a larger role in carbon uptake. 

As city populations swell around the world, every bit of urban greenery is critical in the fight against climate change. 

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New York City’s greenery absorbs a surprising amount of its carbon emissions

68% of the world population projected to live in urban areas by 2050, says UN

Photo, posted October 5, 2009, courtesy of David Orban via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

El Paso’s Water Future | Earth Wise

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El Paso, Texas is part of the Paso del Norte region, which includes Ciudad Juarez in Mexico and Las Cruces, New Mexico.  The population on both sides of the border is booming, approaching 3 million people.  The region’s primary water source is the Rio Grande River.  But that river is declining.

Rising temperatures and decreasing rainfall have led to diminishing flow in the river.  Eighty percent of the river’s flow has historically been diverted to agriculture, but the reduced flow of the Rio Grande has forced many farmers to reduce planting or change to less water-hungry crops.  The river is expected to continue to decrease its flow as time goes by.

The city of El Paso gets 40% of its water supply directly from the Rio Grande.  Urban water authorities in the region are scrambling to find ways to provide cities with alternative supplies of water.

El Paso now gets some of its water from a desalination plant, which is the world’s largest inland municipal desalination plant.  The water comes from brackish groundwater rather than from the sea.  The briny waste from the plant is piped to an injection well many miles way and is permanently stored 4,000 feet underground.

El Paso continues to seek new water sources and reduce its water use.  It gets much of its water from wells drilled in nearby aquifers.  It is working to make this use of groundwater more sustainable.  The city recycles used residential water through its so-called purple pipe system, which cleans up waste water and delivers it for non-potable use on golf courses and park lawns. 

Like many places in the increasingly dry west, El Paso’s water future is uncertain. 

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As Rio Grande Shrinks, El Paso Plans for Uncertain Water Future

Photo, posted April 29, 2018, courtesy of R. Baire via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Floating Solar | Earth Wise

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The largest floating solar array in Europe, 12,000 panels sitting on top of the Alqueva Reservoir in Portugal – will come online in July.  Installing floating solar arrays, which are sometimes called “floatovoltaics”, produce renewable energy while shielding significant expanses of water from the sun’s heat.  These dual benefits have led to floatovoltaic projects in multiple countries around the world.

The city of Cohoes, in New York’s Albany County, has proposed an 8,000-panel floating solar array on the city reservoir.  Federal funding of $3 million for the project was obtained by local Congressman Paul Tonko and, in May, utility National Grid donated $750,000 towards the project.  Engineering work will shortly be underway on the 3.2 megawatt grid of solar panels.

The city of Cohoes pumps its drinking water supplies from the Mohawk River into the 10-acre, manmade reservoir.  The surface of the water is the largest undeveloped open space in the city.  Such reservoirs constitute prime sites for solar arrays since the space cannot be used for other purposes.  In addition, covering the water’s surface with the solar panels greatly reduces evaporation and helps to inhibit the growth of algae.

There are currently only 14 floating solar arrays in the U.S. and all of those are privately owned.  The Cohoes municipal array will be the first of its kind.  There are nearly 500 reservoirs in New York State and 24,000 nationwide that could be sites for floating arrays.   Drought-stricken Western reservoirs like Lake Mead and Lake Powell could be ideal locations of solar arrays.  Those reservoirs lose huge amounts of water to evaporation.  There are estimates that floating arrays could provide as much as 10% of the nation’s electrical needs.

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National Grid gives Cohoes $750,000 for floating solar array project

Photo, posted August 25, 2010, courtesy of Martin Abegglen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Car-Free Zone In Berlin | Earth Wise

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The regional parliament in Berlin is considering the creation of a car-free zone in the German capital as a result of a petition from a local advocacy group.  The group – called the People’s Decision for Auto-Free Berlin – collected 50,000 signatures, which was enough to require the Berlin Senate to take up the issue.

The city ban would apply to the space ringed by the S-Bahn train line, which circles the city center.  Known as the Ringbahn, the area enclosed was already established as a low-emission zone in 2008.  It is 34 square miles in area, larger than Manhattan.  The ban would restrict vehicle use to trucks, taxis, emergency vehicles, and limited car-sharing programs.

In Berlin, a combination of regular trains, ample bike lanes, and a robust network of public buses makes getting around without a car more practical than in many other major cities.  In fact, automobiles account for only 17% of trips inside of the Ringbahn.

Even so, there is still a lot of car traffic in the city center.  Advocates for the plan believe it would lead to a city with cleaner air and more livable spaces for its citizens.

If the Berlin Senate rejects the measure, the advocacy group will seek to collect 175,000 signatures, which would force the Senate to consider the matter for a second time.  If it is rejected again, it would automatically go to a referendum in 2023.

In Europe, it appears that the revolution in transportation may not just be one about electric vehicles, but in some places may be toward the removal of vehicles in general.

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Berlin Looks to Create Car-Free Zone Larger Than Manhattan

Photo, posted March 30, 2019, courtesy of Falco Ermert 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.

Clean Energy In Rochester | Earth Wise

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New York’s largest community choice clean energy program has been activated in the City of Rochester.   The program, offered by Rochester Community Power, offers 57,000 residences and small businesses access to clean energy from hydropower and wind sources.  It requires customers to opt out rather than enroll in order to provide clean energy to the greatest number of people.

Rochester Community Power is the city’s local community choice aggregation (CCA) program that leverages the collective buying power of participating residents to purchase renewable electricity and negotiate better terms for energy supply contracts.

The program will supply customers with more than 300 million kWh of renewable energy each year, which will avoid the emission of about 250,000 tons of carbon dioxide.  Rochester plans to add a community solar program next year which will provide additional clean energy opportunities, including offering guaranteed savings to thousands of participants in its Home Energy Assistance Program.

The project will be managed by Joule Assets, which is a provider of energy reduction market analysis, tools, and financing. Joule Assets, as program administrator for the Rochester program, managed the competitive bidding process that secured a fixed rate for electricity for the next two years, shielding participating residences and businesses from volatile market prices.

Community choice aggregation programs are local, not-for-profit public agencies that are an alternative to investor-owned utilities.  They give municipalities the ability to make decisions about the procurement, sourcing, and rates for energy for its residents.

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New York activates its largest opt-out 100% renewable energy program

Photo, posted June 25, 2011, courtesy of Paulo Valdivieso via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Floating Solar In New York’s Capital Region | Earth Wise

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We have previously talked about installing solar arrays on the surface of bodies of water.  The idea is especially attractive in places like Japan where land resources are scarce.  There are several floating solar installations in the UK and the idea is starting to catch on elsewhere as well.

It is quite possible that the largest municipally owned floating solar array may get built in the city of Cohoes in New York’s Capital Region if a project under consideration for federal funding moves forward.

The proposal is for an installation of 8,000 solar panels to cover about 2/3 of the 10-acre Cohoes reservoir.  Cohoes has wanted to erect a solar installation to generate power for its buildings but needed to find suitable vacant land.  The 10-acre manmade reservoir could be an excellent location for a floating solar array.

Cohoes would be the first community in the US to build and own a floating array on a manmade reservoir and could serve as a model for municipalities across the nation.  Such a project makes additional use of land that is already municipal property.  According to the city, the 3.2-megawatt array would generate over 4 million kilowatt hours of electricity per year, saving the city $300-350,000 annually.

Cohoes is seeking $4.59 million in federal funding to support the project and has the support of U.S. Representative Paul Tonko for possible inclusion in the 2022 federal budget. 

Apart from generating electricity, putting solar panels on the surface of a reservoir reduces evaporation, lowers algae growth, and actually improves solar panel performance because of the cooling effect of the water.

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Cohoes reservoir could be a floating solar power pioneer

Photo courtesy of Michael Coghlan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Street Trees And Depression | Earth Wise

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According to a study published in the journal Jama Network Open last fall, the COVID-19 pandemic has tripled the rate of depression in U.S. adults in all demographic groups. 

Previous studies have demonstrated that greenspaces in urban areas can have a positive effect on those people experiencing mental ill health. But most of those studies used self-reporting measures, which makes it difficult to compare results and draw conclusions.

As a result, an interdisciplinary research team from three research organizations in Germany tried to improve upon the work by involving an objective indicator: prescriptions of antidepressants.  To figure out whether greenspaces – in this case street trees – could positively influence mental health, the researchers focused on how the number of street trees and their proximity to homes correlated to the number of prescribed antidepressants.

After analyzing data from nearly 10,000 people living in Leipzig, Germany, and combining the findings with data on city street trees, researchers were able to identify an association between antidepressant prescriptions and the number of street trees.  The results were controlled for other factors known to be associated with depression, such as employment, gender, age, and body weight.

Having more trees within 100 meters of the home was associated with a reduced risk of being prescribed antidepressants.  The association was especially strong for groups of people deprived of street trees. 

Street trees in urban cities can not only serve as a nature-based solution for good mental health, but they can also contribute to climate change mitigation and biodiversity conservation.

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Street trees close to the home may reduce the risk of depression

Photo, posted August 17, 2011, courtesy of Aleksandr Zykov via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Lifestyle And Carbon Footprint | Earth Wise

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Many studies have shown, to no great surprise, that affluent lifestyles lead to larger carbon footprints. Households in Switzerland enjoy a high standard of living and a team of researchers there has been studying the consumption and travel habits of Swiss citizens to better understand the impact of various factors on carbon footprint. Key factors include household composition and income, and whether the households are in the city or the countryside – even though, in the end, people’s lifestyles do not differ greatly from one environment to another. 

A team of researchers at EPFL’s School of Architecture, Civil and Environmental Engineering analyzed data from Switzerland’s household budget survey for 2008, 2011 and 2014.  They combined that data with an environmentally extended input-output analysis to assess households’ carbon footprints by measuring their direct and indirect emissions.

Overall, households in the countryside have larger carbon footprints than those in the city, mainly because they travel more and use more energy in their homes. But urban households have larger carbon footprints than their rural counterparts when it comes to food, clothing, cultural activities and air travel.  

A household’s composition directly influences its carbon footprint. A two-person household has the largest per-capita carbon footprint, and it falls as the size of the family grows since many of the same resources are shared by more people. 

Income levels play an important role.  People consume without much thought because they can afford to and enjoy doing it. But there is a trend towards people becoming more conscious of their levels of consumption and trying to be more responsible in Switzerland.  Overall consumption has actually declined over the years studied.  

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Our carbon footprint is highly impacted by how we live

Photo, posted December 19, 2017, courtesy of Alexander Kozik via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Urban Agriculture And Sustainability Goals

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In 2016, the City Council of Phoenix, Arizona adopted eight Environmental Sustainability goals for 2050 that lay out the desired long term requirements in order to become a Sustainable Desert City.  Recently, a group of researchers from Arizona State University assessed how urban agriculture can help Phoenix, a desert city of 1.6 million people, meet those sustainability goals.  

Using public records and high-resolution satellite imagery, researchers analyzed the potential benefits of growing crops in three types of urban areas in Phoenix: vacant lots, rooftops, and building facades.  The study, which was supported by the National Science Foundation and the USDA, estimated that there are 28 square miles (or 5.4% of city space) available for urban agriculture.  The data-driven analysis found that 71% of the available areas for urban agriculture would come from existing buildings as opposed to vacant lots. 

All this available space for urban agriculture in Phoenix could supply the city with nearly 183,000 tons of fresh produce annually, which would allow for the delivery of fresh fruits and vegetables to all of the city’s existing food deserts. In fact, the city’s own urban-agriculture output could meet 90% of the fresh produce demand that currently exists in Phoenix. 

In addition to producing food, rooftop agriculture could also reduce the energy use in buildings by 3% per building per year, and displace more than 55,000 tons of CO2 annually.  The use of vacant lots could increase the total Phoenix green space by 17%, and reduce the number of areas lacking green space by 60%.   

This study demonstrates the many different ways that urban agriculture can benefit a city. 

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Urban agriculture can push the sustainability

Photo, posted May 10, 2011, courtesy of Stephen Zank via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Bee Friendly Amsterdam

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Scientists around the world have been sounding the alarm for years about the decline of bees and other pollinators that are crucial to the growth of crops.   One place where this trend has been bucked is in Amsterdam.  The diversity of wild bee and honeybee species in the Dutch capital has actually increased by 45% since 2000.

The city attributes this success to creating bee-friendly environments including the installation of so-called insect hotels.  There has also been a ban on the use of chemical pesticides on public land.

Four years ago, Amsterdam set a goal to convert half of all public green spaces to native plants including species that produce flowers and fruits that provide nourishment for bees.  Developers in Amsterdam are encouraged to install green roofs on new buildings which reduce reliance on heating and cooling systems and also create habitat for wildlife.

Residents can request to have a 16-inch strip of pavement adjacent to their homes removed in order to plant shrubs, flowers or climbing vines.  When a new highway was built in the area in 2015, local activists planted wildflowers along the sides of the road that otherwise would have been left with only gravel or grass.  This practice has spread to other major routes and along dikes and railways and is referred to as the Honey Highway.

All of these efforts seem to be having a positive effect.  An initial survey was conducted in 2000 to establish a baseline.  A 2015 survey of pollinators found 21 bee species not previously documented in the city.  The rest of the Netherlands has not done as well, and the Dutch government has recently introduced a pollinator strategy to revive bees, butterflies and other insects crucial to the country’s food crop.

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Bees are dying at an alarming rate. Amsterdam may have the answer.

Photo, posted December 28, 2006, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Urban Streams Are Breeding Superbugs

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City streams are subjected to a constant onslaught of synthetic chemicals found in pharmaceuticals and personal care products. Wastewater treatment facilities are not designed to filter out these compounds. Instead, they flow into surface waters where they impact aquatic organisms like microbes – which perform key ecosystem services like removing excess nutrients and breaking down leaf litter.

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Green Solutions To Storm Water Runoff

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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.

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The Delhi Air Pollution Crisis

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Delhi, the capital city of India, has always been a city bursting at the seams.  With over 19 million people, heavy industry, growing numbers of vehicles, and choking amounts of road dust, Delhi suffers from some of the worst air pollution in the world.  It is a situation the country has been struggling with for years.

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Green Steam

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Many of the world’s biggest cities have miles of underground pipes built decades ago that provide district energy.   District energy systems use a central plant to produce steam, hot water or chilled water that is then piped underground to individual buildings for space heating, domestic hot water heating and air conditioning. As a result, individual buildings served by a district energy system don’t need their own boilers or furnaces, chillers or air conditioners.

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