EarthTalk…Questions and Answers About Our Environment

Dear EarthTalk: What are the health and environmental benefits of planting more trees in urban areas?        ~ B. Marsden, Buffalo, NY

Planting more trees in urban areas has numerous health and environmental benefits. Trees are essential to human health, and they provide environmental benefits by reducing air pollution, conserving energy, mitigating the urban heat island effect, and reducing stormwater runoff. According to the Arbor Day Foundation, a single mature tree can absorb up to 48 pounds of carbon dioxide (CO2) annually and release enough oxygen for two people to breathe comfortably all year.

Trees reduce air pollution, conserve energy, mitigate the urban heat island effect & reduce stormwater runoff. Credit: Roddy Scheer,

Trees play a crucial role in improving air quality in urban areas. A study by the U.S. Forest Service found that trees in urban areas remove 711,000 metric tons of air pollution annually, saving the United States $6.8 billion in air quality-related health care costs. Trees absorb pollutants such as sulfur dioxide, nitrogen dioxide and ozone, which can cause respiratory problems and other health issues. Trees also absorb fine particulate matter (PM2.5), which is associated with asthma, heart attacks, and premature death.

Urban forests also help reduce the urban heat island effect, which is when urban areas are significantly warmer than rural areas due to human activity and infrastructure. Trees provide shade, which helps to reduce surface temperatures, and they also release water vapor through transpiration, which cools the air around them. According to a study published in the journal Landscape and Urban Planning, increasing tree canopy cover in cities can help reduce temperatures by up to two degrees Celsius.

In addition to their health benefits, trees also provide environmental benefits by reducing energy consumption. Trees provide shade, which reduces the amount of energy needed to cool buildings in the summer. According to federal researchers, properly placed trees can reduce a building’s air conditioning needs by up to 30 percent. Trees also act as windbreaks, which can reduce heating costs in the winter, helping to achieve up to a 50 percent decrease in annual heating costs. In fact, just three properly sited trees could save homeowners up to $250/year overall.

Trees are also essential in managing stormwater runoff. When it rains, stormwater runoff can cause flooding, erosion and water pollution. Trees absorb rainwater through their roots and help to reduce the amount of runoff. The U.S. Environmental Protection Agency calculates that a single mature tree can absorb up to 100 gallons of water per day.

Furthermore, planting more trees in urban areas can improve mental health and well-being. Studies have shown that exposure to nature and green spaces can reduce stress, anxiety and depression. A study published in the Journal of Environmental Psychology found that people who live in areas with more trees and green spaces report better mental health than those who live in areas with less greenery.

We also need trees to absorb all that excess CO2 we have spewed into the atmosphere that is causing global warming. Trees have always been essential to the survival of humans and other organisms, but maybe never so much as the present given the existential threat posed by human-induced climate change.


Dear EarthTalk: Is it really bad for the planet to upgrade my phone every two years?    ~ A.J., Darien, CT

Smartphones have certainly become ubiquitous, with some 85 percent of Americans and 67 percent of adults worldwide possessing one. Manufacturers sell almost 1.5 billion of them per year. And every year these manufacturers come out with upgraded models to lure customers into trading in their old models to get the latest technology at their fingertips. According to the Consumer Electronic Association the average lifespan of a smartphone is 4.7 years, but the average American user replaces their smartphone within three years. This can be, in part, attributed to planned obsolescence by manufacturers. As new smartphones are manufactured, new software updates accompany them; these updates can lead to older phones becoming unusable if they do not have the capacity to accommodate the new software.

Keeping a smartphone for more than two years could yield dividends for the environment. Credit:

Regarding pollution created by the industry, 95 percent of emissions come from the production phase. A culture that requires constant replacements results in ongoing growth of manufacturing emissions. In addition, continuously replacing phones creates e-waste in the form of the phones themselves. In 2019, 50 million tons of waste came from smartphones which constitute about 10 percent of e-waste globally.

One way to combat e-waste is to recycle. However, according to the World Economic Forum, only about 20 percent of global e-waste is recycled. The Basel Action Network used radio tracking to verify where shipments of e-waste were sent. They found that nearly 40 percent of e-waste from the United States was exported illegally to developing nations where it was unsafely processed or even burned in the open air.

There are steps manufacturers can take to alleviate the environmental burden, one being to introduce “repairable” phones. Currently manufacturers hamper smartphone repair with very high repair prices and restricting third parties from having access to the needed parts. Europe is leading the charge on embracing a circular economy surrounding smartphones that encourages repairs, refurbishments and upgrades instead of replacement. Various European countries have instituted programs to address the problem. France maintains a publicly accessible phone repairability index to help consumers there make smart choices about their smartphone purchases. Meanwhile, Sweden and Austria both offer financial incentives for device repairs to encourage fixing instead of junking old smartphones and other electronics.

Whether or not such programs exist in your neck of the woods, you can be part of the solution by simply waiting longer to upgrade your phone, which will help reduce the demand on production while lowering your environmental footprint. While it may not seem like much at first glance, keeping your phone for an extra year can reduce your lifetime device usage by 25 percent. When it is finally time to get a new phone, an eco-conscious consumer can turn to companies like Fairphone and SHIFT that offer easily changeable parts and support software upgrades throughout the phone’s lifespan.


Dear EarthTalk: What is former president Jimmy Carter’s environmental legacy?   ~ A.J., via email

Standing at the presidential lectern, in front of what looked like a series of oversized plastic deckchairs, Jimmy Carter prophesied that “[a] generation from now, this solar heater can be a curiosity, a museum piece, an example of a road not taken, or it can be a small part of one of the greatest and most exciting adventures ever undertaken by the American people.” The year was 1979, and then-President Carter was talking about the environmental imperative of weaning America from its dependency on non-renewable energy, much of which was being imported from abroad.

During his presidency, Carter amassed an impressive number of conservation achievements. He more than doubled the area conserved under the National Parks System and added 104 million acres to Alaska’s protected land areas—over 57 million of which were named ‘wilderness’ zones and safeguarded under the highest level of federal protection. More Than Just Parks, an organization for the protection of nature conservation, named this “the single greatest protection of public lands in our nation’s history.”

Jimmy Carter’s protection of vast swaths of Alaska before leaving office will remain one of the greatest conservation moves by any president in U.S. history.

In the first year of his presidency, Carter signed the Surface Mining Control and Reclamation Act which banned mining in national parks. Previously, as Georgia’s governor, he vetoed the building of a dam on the Flint River, which would have flooded scenic valleys and threatened native Cahaba Lily and Shoal Bass which thrived on its banks. As President, he would go on to veto 16 similar water reclamation projects. The wins Carter scored for the environment have helped him go down as one of the greenest presidents in history. But after a series of eco-unfriendly presidents, what remains of his environmental legacy today?

For one, the solar panels that held such symbolic weight have indeed become “museum pieces” after his successor in the White House, Ronald Reagan, dismantled them in 1986. The panels are shared between the Smithsonian Museum, the Carter Library and the Science and Technology Museum in China. Carter’s panels, along with his mission to move America’s energy consumption to 20 percent renewables by 2000, have been significantly downgraded.

Since Carter left office in 1980, his Alaskan conservation work has also come under threat. A Trump-era trading of public lands granted permission for a commercial road to be built across the Izembek National Wildlife Refuge, one of the zones protected under Carter’s extension of the national park system during his presidency. With petitions from Carter and other environmentalists, the decision has since been overturned. The incident remains, however, a pressing reminder of the fragility of conservation wins.

“He showed us what it means to be a public servant, with emphasis on servant,” Joe Biden said, and as Carter’s legacy ages, and the climate crisis continues to rage, it will be interesting to see how his environmental advocacy continues to influence U.S. leaders. The green legacy of Jimmy Carter is vast and important but, like the American landscapes he championed, it is in need of protection.


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