Lawn Maintenance & Climate Change
Provided by Jiahn Son of Princeton University
In America, over 40 million acres of land are covered by lawn, or, more specifically, turf grass. While lawns can function as “carbon sinks,” soaking up carbon dioxide from the atmosphere, this benefit is often outweighed by the heavy carbon cost associated with the maintenance of these lawns. Rather than alleviating climate change, lawns may be contributing to it. The main culprits are lawn equipment, specifically gas powered leaf blowers and lawn mowers, and synthetic fertilizers. Ultimately, Americans should consider alternatives for the technological and chemical ways they are treating their lawns, and even consider the potential of changing the structure of their lawn entirely.
Most lawn equipment is gasoline powered, typically being one of two types: two-stroke or four-stroke engines. To fuel this equipment, it takes about 800 million gallons of gasoline annually, with 17 million additional gallons spilled in the process. Two-stroke engines pose a unique environmental hazard because they do not have an independent lubricant system, so fuel and oil are mixed. Due to this, about 30 percent of the fuel does not combust completely, thus releasing toxic gases into the air. A 2014 study examined the VOC (combination of harmful gases) emissions of two stroke scooters, and it was found that the levels of emissions were 124 times higher from an idling scooter than from a car or truck. Four stroke engines are also used in some equipment, and while they are slightly more environmentally efficient, in total, they are also harmful. A four stroke lawnmower operating for one hour equates to a vehicle traveling for 500 miles.
According to a study done by Quiet Communities, this equipment was responsible for the release of 26.7 million tons of pollutants in 2011. Furthermore, in the same year, another study demonstrated that a consumer grade leaf blower releases more hydrocarbons than a pick up truck or a sedan. EPA data has found that gas-powered lawn mowers make up five percent of total air pollution in the United States, amounting to even more in urban areas. A sobering warning issued by the California Air Resources Board in 2017 reported the following:
“By 2020, gas-powered leaf blowers, lawn mowers, and similar equipment in the state could produce more ozone pollution than all the millions of cars in California combined.”
Although this equipment is often overlooked as a significant source of pollutant, lawn equipment poses a clear environmental hazard, especially given how large the lawn care industry remains in America.
As an alternative to two stroke or four stroke engines, homeowners can opt instead for electric engines. In the past, electric mowers and leaf blowers were eschewed because of a higher cost and limited battery life. Today, however, there are more affordable, long lasting options for homeowners. On average, a good quality electric mower will cost more money, but over the span of 10 ten years, the cost will even out due to fuel and maintenance. Electric mowers are lower maintenance and easier storage, and they don’t have a cord. Although they are not nearly as price accessible or well suited for extra large lawns, the environmental benefits are immense. Electric mowers produce no emissions.
If an electric mower is inaccessible, people can choose to make smaller adjustments to their mowing habits, which limit the release of pollutants over the long term:
• Cut down on how often you mow--go from once a week to once every two weeks, for instance
• This change will improve the health of the lawn, as long grass blades improve overall moisture retention of the soil, and will thus reduce the amount of water needed to maintain the lawn
• Upgrade your gas can
• Older cans can cause more spillage, and harmful emissions may be escaping from holes or the sprouts of these cans
• Mow in the evening
• During the day, ozone forms more easily. However, mowing the evening gives these chemicals time to disappear overnight, as they lack sunlight
• Reduce the amount of landscaping power tools you use
• While mowers and blowers are significant contributors, hedge trimmers, weed whackers, chippers, sheeders, and similar equipment also play a major factor
To attain lush, fertile, green lawns, homeowners will use nitrogen based fertilizers, approximately 3 million tons a year. These contribute to climate change due the manufacturing process and their use on lawns. David Wolfe, a professor of plant and soil ecology at Cornell noted that for every ton of nitrogen created to make this fertilizer, four or five tons of carbon are added to the atmosphere. Furthermore, the lawn does not need, or can hold, the amount of nitrogen in the fertilizer. Soil microbes will then turn this additional nitrogen into nitrous oxide gas, a greenhouse gas that has 300 times the heat-trapping ability of CO2. Once the level of nitrogen surpasses the point where the plants cannot use it, and after that, nitrogen emissions grow at an exponential rate. A 2012 study, using nitrogen isotope data, found that increased fertilizer use has directly caused a rise in atmospheric nitrogen oxide.
Furthermore, the nitrogen from the fertilizers can run off into local bodies of water, causing eutrophication, or the nutrient enrichment of water bodies. According to a study by the EPA, 40 to 60 percent of nitrogen ends up in surface and groundwater. Even worse, extreme weather and excessive rainfall caused by the effects of climate change in the coming decades could exacerbate the amount of runoff, polluting rivers and other waterways and turning them into “dead zones” via toxic algae blooms.
Although the greatest use of these fertilizers can be attributed to the agricultural industry, homeowners should work to minimize their own role as much as possible. Alternatives to synthetic fertilizers include:
• Use organic fertilizers
• While they still release nitrous oxide, the manufacturing process does not contribute to CO2 emissions.
• Let lawn clippings decompose on the lawn
• This will benefit the lawn, and also ensure that the clippings will not go to landfills, where they could break down and release methane.
• Improve the quality of your soil
• Pick grass that works well for your particular environment
• For example, there are cool-climate grasses, and warm climate grasses, grasses that are hardier than others, and grasses that can do well without sunlight
• Aerate your soil to open passages for air, water, nutrients, and soil life
• Check the pH of your soil, and, if it does not fall into the ideal pH range of 6.5-7.0 add lime to make it more neutral, or sulfur for more acidity
• Apply compost or topsoil to the top layer of your soil in early spring, about ¼ to ½ inch with a rake
• Start a natural compost system
• Don’t mow your lawn too often
• Allowing the grass to grow more gives it the opportunity to form a stronger root system
Deconstructing the Perfect Lawn
Lawns have the potential to act as a secret weapon against climate change. Dr. Carly Ziter studies the carbon-capturing ability of lawns, and she found the typical American lawn is more effective at capturing carbon than the untouched environment. This could be due to the unique ways that these lawns are cared for, like, for instance, mowing. However, Dr. Ziter cautioned that this study only compares the soil of lawns and natural ecosystems, not plants that may capture carbon aboveground, and the effectiveness of carbon-capturing soil could be offset by the emissions required to maintain it. As a result, it is not as much the unique qualities of the lawn itself that may work against climate change, but how we can leverage small green spaces, acting as fragmented ecosystems, especially in more urban environments.
To maximize the positive qualities of lawns and reduce the negatives, it may require a change in how Americans view lawns. For decades now, the ideal lawn has been a pristine swatch of bright grass. However, as explored earlier, it’s questionable if the aesthetic is worth the environmental cost. Instead of mowed turf, Americans can transform their lawns into frontiers of biodiversity and sustainability, by diversifying the face of lawns and allowing some freedom. As Dr. Ziter says:
“You don’t need to have a perfect lawn for it to be really beneficial. You don’t have to have an incredibly intensive management system. It’s O.K. to have things to be a little wild.”
Cornell University’s College of Agriculture & Life Sciences offers a useful program that instructs homeowners on how to transform their lawns, called Lawn Care: The Easiest Steps to an Attractive Environmental Asset. The general idea is to limit the amount of grass and the amount of maintenance associated with it. This organization and others recommend:
• Replacing grass with alternatives
• In drought prone areas, this may look like xeriscaping, which means replacing large areas of grass with native plants that do well in drought, such as succulents.
• Using more handscape materials, like rocks and gravel
• Using mulch
• Planting perennials, annuals, and groundcovers, such as mosses, ferns, and wildflowers
• Generally introducing more native plants to the landscape
• Shrubs and trees have high carbon capturing abilities
• Natural species improve the health of an environment by increasing biodiversity where monoculture makes it unstable
• Additionally, these plants help create a safe haven for endangered species, like butterflies and honey bees
• Leaving the lawn to its own devices
• This means less mowing and less irrigation
• Starting a garden
• As the agricultural complex has been exposed as a major contributor to climate change, homeowners can reclaim the benefits of fresh, nutrient rich foods by planting Climate Victory Gardens.
While some people may want to forgo lawn care entirely, and simply allow their lawns to grow completely wild, there are regulations against this in certain municipalities. As a result, residents should either opt for a tamer version of the wild lawn, or they can push for legislative change in their community by proving the benefits of these naturalized lawns to lawmakers. Most importantly, it’s critical to change the mindset, present in the minds of many Americans, that the best lawns are the ones that look the best kept. At Harvard, researchers have experimented with implementing more sustainable lawns that include different types of grasses and wildflowers. There, they have faced some backlash about the appearance of the lawns, but these landscapes require far less mowing and water than would the typical turf.
An additional policy change that some have pushed for is a ban on gasoline powered gardening tools. Already in Washington, D.C., a group of local residents was able to win a ban against gas-powered leaf blowers, citing hearing loss concerns. Their cause was also helped by a politician who championed their cause in the government. In California, many cities have put similar policies into place, and a statewide ban could be coming. However, there is controversy over the economic impact on small landscaping businesses and lower income residents, as they may be unable to afford the higher cost of electric equipment. Overarching policy bans are more feasible when there is technological momentum, as in some areas, gas-powered equipment is aging out of use, and when there is compelling health evidence for a ban. It may be a long time before structural policy change could be implemented everywhere, but for now, homeowners can choose to make their own changes.
The lawn industry and the American lawn are unlikely to be fundamentally shifted any time soon. People have come to pscyhologically appreciate the appeal of green turf. Despite this, it is still possible for homeowners to limit the negative environmental consequences associated with the maintenance of these spaces, and to make small concessions regarding appearance in exchange for a greener planet.