This fall the climate news sounded more dire than ever.  A panel of scientists concluded in the journal Nature that “we are in a state of planetary emergency,” that the world may have already crossed several climate tipping points that could cascade to make global heating unstoppable, and that “the reaction time to achieve net zero emissions is 30 years at best.”

The United Nations’ World Meteorological Organization reported that greenhouse gas emissions have reached a record high and are still surging upward, decreasing the likelihood that the world will be able to cut emissions in half by 2030, the target intended to limit global heating to 1.5C and prevent hundreds of millions of people from suffering intensified heat waves, droughts, floods and poverty.

At the same time, scientists worldwide have sounded the alarm of an unfolding “insect apocalypse.” The first-ever global scientific review of insect numbers, released in February 2019, found that the total insect mass has sharply declined in just a few decades, and that the current estimated losses of 2.5% per year could lead to the end of all insect life on earth within 100 years.

Pesticides, habitat loss to agriculture and urbanization, light pollution, and climate change are all suspected culprits. Some may ask why we humans should care, after decades of chemical warfare spent trying to eradicate bugs as pests.

“Insects are at the heart of every food web, they pollinate the large majority of plant species, keep the soil healthy, recycle nutrients, control pests, and much more,” Professor Dave Goulson of the University of Sussex in the UK told The Guardian recently.

“Love them or loathe them, we humans cannot survive without insects.” 

Against this backdrop of downright frightening ecological news, the autumn leaves fell. Left alone, they would provide a nutrient-rich blanket for the roots of their parent trees.

“Leaving the leaves where you can will provide organic material that is beneficial to the tree,” says Evanston’s Forestry Supervisor Michael Callahan.

“Any leaf material you can leave in place, or possibly compost for later if you wish to rake, is beneficial and helps reduce stress on the trees.”

Examples of this type of stress are drought and the extreme temperature fluctuations caused by climate change.

Why is it more important now than ever to protect trees from stress? 

Trees are humanity’s greatest defense against climate change, with magical powers to absorb and store heat-trapping carbon dioxide from the atmosphere; drink up stormwater; filter out air pollution; and generate fresh, clean oxygen through photosynthesis. In fact, one goal of Evanston’s Climate Action and Resilience Plan is to “preserve, restore, and expand Evanston’s urban canopy, natural areas, native vegetation and green space to maintain and increase carbon sequestration, improve stormwater runoff detention, improve air quality, energy efficiency and livability, and reduce adverse urban impacts on humans and key species such as birds and pollinators.”

When autumn leaves fall, insects recognize their winter home, for “leaf litter” to them is not trash but indispensable habitat. Many species of butterflies, bees, fireflies, moths, ants, ladybugs, beetles, flies, roly polies, snails, earthworms and millipedes all lay their eggs or hunker down for the winter in the leaves, soil surface, or inside the hollow stems of dried out plants, until longer daylight hours and warmer temperatures signal their re-emergence in the spring. Brown leaves may look dead to us, but they are packed with life.

The pollinators that will turn blossoms into our fruits, the butterflies that will sip nectar from our flowers, the moth larvae that birds will feed their chicks (6,000 caterpillars are needed to raise just one nest of chickadees!) – they are here and hibernating out of sight beneath our feet.

This begins to demonstrate what is wrong with leaf blowers:

1. Wind speeds of up to 200 miles per hour blast into oblivion all of the insect biodiversity nestled in the leaves and topsoil.

Then we or our landscaping crew haul away the leaves and any remaining life within as if they were garbage. On Nov. 18, 2019, the German government requested that its citizens stop using leaf blowers, saying they are “fatal to insects in the foliage.”

The government cited extreme concern about an “insect Armageddon” in Germany, where an October study confirmed 2017 findings that the country has lost 75% of its flying insects in protected areas in just 30 years.

When asked how to do fall lawn and garden cleanup in a way that preserves biodiversity, University of Illinois-Chicago insect professor Alan Molumby exhorts, “Stay inside! Drink coffee, watch cartoons, but don’t!” and explains that messier landscapes are essential. Even in England, where our concept of grass lawns originated, the government urges its citizens to avoid disturbing hibernating insects, and to mow less in summer to allow dandelions and clovers to bloom to supply nectar for dwindling bee populations, as part of its National Pollinator Strategy.

2. Leaf blowers eliminate the natural protective blanket of leaves over tree roots, leaving them exposed and bare, and depriving them of nutrients.

“In forests, leaves fall and decompose slowly over time, leading to a buildup of organic matter and a slow release of nutrients back to the tree,” says Meghan Midgley, Ph.D., a soil ecologist at the Morton Arboretum.

“When we mulch around trees or add compost or fertilizer to soils, we’re attempting to replicate this process,” she says. “Leaving the leaves simply skips this step in a way that is both economical (no need to get rid of leaves or purchase amendments) and ideal for the tree.”

3. Gasoline-powered leaf blowers belch out a staggering amount of air pollution with their inefficient two-stroke engines – far more than an automobile – at this time when scientists urge us to stop burning fossil fuels now to avert a climate disaster.

How much more?

A 2011 test by Edmunds’ found that “hydrocarbon emissions from a half-hour of yard work with the two-stroke leaf blower are about the same as a 3,900-mile drive from Texas to Alaska in a Raptor [a large Ford pickup truck].”

More recent tests of the top-selling blower by California’s state Air Resources Board (CARB) found somewhat less but estimated that one hour of use would still emit as much smog-forming pollution as driving a 2017 Toyota Camry 1,100 miles.

Remarkably, CARB reports that gas-powered lawn equipment in that state is set to outpace the smog-generating pollution from all the millions of cars in California combined.

“Two-stroke engines are that dirty,” writes James Fallows in The Atlantic. “Cars have become that clean.”

For this reason, phasing out gas- and propane-powered leaf blowers, lawn mowers and construction equipment is one goal of Evanston’s Climate Action and Resilience Plan.

In addition, CARB found that gas-powered blowers spew carbon monoxide, fine particulate matter and other toxic and cancer-causing air contaminants, including benzene, 1,3-butadiene, acetaldehyde and formaldehyde.

But it’s not just the engine exhaust that pollutes: each blower blasts up about five pounds per hour of fine particles of dust, animal feces, mold, fungi, pollen, heavy metals and pesticides into the air, where they are breathed into the lungs rather than lying dormant in the soil.

Who pays the health price for this fouling of the air?

Particulate pollution is inhaled by all of us, and it penetrates deep into lung tissue, increasing our risk of asthma and other respiratory ailments, lung disease and premature death from heart disease.

Landscaping workers are at greatest risk, since they often toil for hours per day in close proximity to blowers. In addition, “As always, groups that are especially sensitive to air pollution include children, whose immune systems are still immature and respiratory systems still developing,” says Susan Kaplan, a University of Illinois-Chicago public health professor and Evanston resident.

“Those with pre-existing illnesses, like asthma or heart disease, are also more vulnerable to health impacts of air pollution,” she adds.

“The Chicago area is already out of compliance with regulatory standards for ozone and fine particulate matter – linked with respiratory and other health impacts – so actions to avoid increasing them should be taken,” she urges.

4. The high-decibel, low-frequency drone of gas-powered leaf blowers can contribute to hearing damage.

It was this public health concern that helped persuade the city council of Washington, D.C., to vote to phase them out by the end of 2021.

The U.S. Centers for Disease Control and Prevention (CDC) reports that hearing loss is the third most common chronic health condition in the U.S., after finding in 2017 that one-quarter of Americans ages 20 to 69 who reported excellent hearing actually had damaged hearing, largely due to increasing levels of ambient urban noise.

“Hearing damage is cumulative,” writes James Fallows in The Atlantic. “When the tiny, sound-sensing hair-like cells, called stereocilia, in the inner ear are damaged – usually by extended exposure to sounds of 85 decibels or above – they are generally gone for good,” he reports.

“For the landscapers (and homeowners) who use gas-powered blowers – a foot away from their ears – the most powerful can produce sounds of 100 decibels or more.”

The low frequency of gas-powered blower engine noise makes the sound especially penetrating, affecting up to 15 times as many households at 75 decibels as a battery-powered blower with the same decibel rating, one study found.

CDC says continual exposure to noise can cause “stress, anxiety, depression, high blood pressure, heart disease, and many other health problems.”

“When I started out, I’d see people in their 60s with hearing problems,” Robert Meyers, an ENT specialist at the University of Illinois at Chicago, told The Atlantic. “Now I’m seeing them in their 40s. …

Each time I see these [landscape] crews, I think to myself: 10 years from now, they’ll be on the path to premature deafness.”

5. It wastes taxpayer money and fossil fuels to haul away leaves and yard waste. 

The City of Evanston pays just over $650,000 to a contractor each year to pick up and haul away our 2,800 tons of yard waste discarded in bins and bags – a cost that is only partly offset by the $225,000 residents pay for yard waste carts and stickers, says Evanston’s Environmental Services Coordinator Paul D’Agostino. The loads are driven about 50 miles to be dumped at Thelen Materials in Antioch, Ill., or at Midwest Organics in Wauconda, Ill.

Embracing plant debris as valuable habitat in the landscape, and simply leaving a brush pile for wildlife and leaf mulch for insects, could free up this $425,000 in the city budget for other needs, nourish trees in parks and homeowner gardens, and reduce the greenhouse gas emissions from diesel-fueled garbage trucks.

6. Using the gas-powered leaf blowers is illegal for much of the year in Evanston – and over 100 other U.S. cities. 

It may not be obvious from the sounds of summer … and spring and fall and winter … but Evanston City ordinance prohibits the use of gas-powered backpack leaf blowers from the first Friday of December through March 29, then again from May 16 through September 29.

Residents may report violations by calling 311 or 847-448-4311, and may document violations by photographing the blower in use and the license plate number of any landscaping trucks.

Calls are supposed to result in a $100 fine to the user but not necessarily to the property owner who hired them – a bad deal for landscaping crews.

So, what to do with the leaves instead? The only reason to remove them is to preserve our European grass lawns.

But even grass will benefit from a few leaves left to decompose in place and enrich the soil.

It all boils down to whether we, as stewards of our greenspaces, will tolerate a less tidy aesthetic to protect our environment and pollinators.

Will we suppress the urge or perceived societal pressure to scrub our outside spaces to the same standards as our kitchens? Evolving our expectation beyond unblemished lawns requires each of us to share, communicate, educate and reshape cultural ideals of what makes a desirable landscape and a good neighbor.

If you must tidy your yard: 

  • Rake leaves into rings around trees so they can insulate the roots and enrich the soil, as nature intended.
  • Instruct any hired lawn crews to do the same: If you pay them to blow the leaves, you can just as easily pay them to rake or sweep, and you will protect their health by requesting this change.
  • Rake extra leaves into flowerbeds, garden beds, and around shrubs. Their mulching power is supreme, preventing weed seeds from germinating and reducing the need to water in hot summer months. “If you have more than you wish to use directly as mulch, pile them under trees and shrubs and they will start to decay into precious leaf mold, which you can use in place of compost, add to your compost, or use as a mulch itself,” advises Tim Sonder of Edible Evanston.

As for this gardener and tree lover, I hoard leaves. Each fall I scour the alleys for bags, cart them home and blanket my garden beds with as thick a layer as the plants can handle, hoping that any remaining insect eggs and cocoons will hatch out next spring for built-in pollinators.

I admire our neighbors’ bur oak, basswood, sugar maple, and cottonwood leaves resting together with the elm, ash and hackberry leaves from my yard.

I layer leaves over areas I intend to plant next year to kill the grass and enrich the soil, and I pile a leaf mountain in the back corner to use for mulch around future plantings.

Except for the pile, most of the leaves degrade into rich topsoil by the following summer.

In spring thrushes, thrashers and other migratory birds stop by to forage for insects buried in the leaves.

In summer a good variety of bees, flies, and butterflies visit my native wildflowers and pollinate my vegetable garden, in spite of the insect declines.

No money spent, no fossil fuels burned, no jet engine noise, no pollution.

Allison Sloan is Co-Lead of Natural Habitat Evanston and leader of Second Sunday Tree Walks.


Quiet Communities,

Xerces Society for Invertebrate Conservation, Leave the Leaves!

National Wildlife Federation, This fall, remember to leaves the leaves on the ground.

Climate tipping points: too risky to bet against, Nature, November 27, 2019.

Climate-heating greenhouse gases reach new high, UN reports. The Guardian, November 25, 2019.

Plummeting insect numbers threaten ‘collapse of nature,’ The Guardian, February 10, 2019.

City of Evanston’s Climate Action and Resilience Plan

Leaf blowers contributing to insect Armageddon and should be avoided, German government warns, The Independent, November 18, 2019.

Flying insects disappearing from German skies, Nature, October 2017.

Leaf blower’s emissions dirtier than high-performance pickup truck’s, says Edmunds’