Earth Talk | July 2019

Research bears out the theory that a walk in the woods — otherwise known as “forest bathing” — can actually be good for your health and your mental outlook. Credit: Roddy Scheer,

Dear EarthTalk: What is so-called Forest Therapy? — Larry Schwarzwald, Page, AZ

Forest therapy uses immersion in nature to help soothe frayed nerves and restore a sense of mental well-being — and has even been shown to boost our immune systems and help us recover faster from physical maladies. The modern forest therapy movement is rooted in the Shinrin-yoku “forest bathing” practice developed in Japan in the 1980s that has since become a central part of preventative health care and healing in Japanese medicine.

“There are an infinite number of healing activities that can be incorporated into a walk in a forest or any other natural area,” reports the Association of Nature and Forest Therapy Guides and Programs (ANFT), which trains students to become certified forest therapists. “An activity is likely to be healing when it makes room for listening, for quiet and accepting presence, and for inquiry through all eight of the sensory modes we possess.”

Practitioners insist that forest therapy is rooted in science, citing dozens of research papers documenting the healing powers of something as simple as a stroll in the woods. According to ANFT, forest bathing seems to significantly mitigate the root cause of a multitude of ailments: stress. Given the role of stress in everything from headaches, high blood pressure, heart problems, diabetes, skin conditions, asthma, arthritis and other health problems, forest therapy could be an important part of staying or getting healthy.

“Levels of the stress hormone cortisol decreased in test subjects after a walk in the forest, when compared with a control group of subjects who engaged in walks within a laboratory setting,” adds ANFT. “Forest bathing catalyzes increased parasympathetic nervous system activity which prompts rest, conserves energy, and slows down the heart rate while increasing intestinal and gland activity.”

The research bears out the theory: the average concentration of salivary cortisol — a stress hormone — in people who gazed out at forest scenery for 20 minutes was 13.4 percent lower than those in urban settings. Meanwhile, leisurely forest walks were measurably better than urban walks at reducing cortisol levels and sympathetic nerve activity and decreasing blood pressure and heart rate. Meanwhile, other research shows we are better at creative problem-solving after time spent in the wilderness. Additionally, nature immersion has been linked to an increase in immunity boosting “killer T” cells, which the body uses to stave off infections and even possibly to fight the growth of cancer cells.

While anyone can take a hike through the woods and indulge in their own form of forest bathing, going with a guide can make the experience that much more meaningful. And you no longer have to go to Japan to find someone experienced in Shinrin-yoku. ANFT has trained more than 600 forest therapy guides working in 40 countries across six continents to date. Check out its map and directory to find one near you, whether you’re in North America, Western Europe, Southeast Asia, Australia or South America.

Contacts:,; ANFT,

The bionic leaf is a system for converting solar energy into liquid fuel developed by the labs of Daniel Nocera and Pamela Silver at Harvard. Credit: Jessica Polka, CreativeCommons.

Dear EarthTalk: What the heck is a “bionic leaf” and how does it help the planet? — William Friend, Billings, MT

Brainchild of Harvard biochemist Daniel Nocera, the “bionic leaf” is a small man-made solar collector that takes sunlight and water and turns it into any of a variety of usable fuels or fertilizers. Nocera’s first iteration, the so-called “artificial leaf,” was developed in 2011 at the Massachusetts Institute of Technology and could split water into oxygen and hydrogen when exposed to sunlight in a process similar to (and inspired by) Mother Nature’s photosynthesis.

Nocera soon thereafter moved his lab to Harvard and teamed up with Pamela Silver there to create the “bionic” version, which takes the concept further. There they fed the resulting hydrogen to an on-board catalyst, resulting in the generation of immediately useable downstream liquid “fuels” such as fertilizer for farms, isobutanol to run generators and engines, and PHB, a precursor for bio-plastic.

The team’s first version of the “bionic” leaf was about as efficient as natural photosynthesis. About 1 percent of the solar energy that flowed in came out as biomass dense enough to use as fuel. But their most recent version ups the ante considerably, clocking in at 10 times more efficient than Mother Nature’s fastest growing plants.

“If you think about it, photosynthesis is amazing,” Nocera tells the Harvard Gazette. “It takes sunlight, water and air — and then look at a tree. That’s exactly what we did, but we do it significantly better, because we turn all that energy into a fuel.”

When mass-produced, these tiny solar “carbon-negative” fuel factories could be inexpensive enough for everyday people to use to power their vehicles and run their lights and appliances. Farmers with a small on-site array of bionic leaves could create enough fertilizer for their own needs instead of buying container-loads of synthetic fertilizer produced at sprawling CO2-spewing factories and shipped for thousands of miles.

The widespread application of bionic leaves could be especially advantageous in developing countries (and remote areas in general) where access to conventional fuels and fertilizers is limited and expensive or non-existent. Nocera hopes his work can bring the poor of the world their “first 100 watts” of energy through one form or another of the technologies he is developing. A Harvard-funded pilot program putting bionic leaves to use in India is just getting off the ground and Nocera hopes to expand globally within the near future.

The vision is for retiring every fossil fuel out there and replacing them with solar fuels from your own “bionic” garden. Imagine a world with no more utility bills or lining up at the gas pump? “You can use just sunlight, air and water,” concludes Nocera, “and you can do it in your backyard.”

Contacts: Nocera Lab,; Silver Lab,; Harvard Gazette,

A few good scrubbies, some elbow grease and a little all-natural soap is all it takes for many household cleaning jobs. Credit: Marco Verch, FlickkrCC.

Dear EarthTalk: I’ve heard that many household cleaners contain toxic ingredients that can pollute my indoor environment. How do I avoid such chemicals and can you suggest any safer alternatives? — M. Sharp, Las Vegas, NV

It’s true that many common household cleaning products contain synthetic chemicals that can make the inhabitants of your home sick. The non-profit Environmental Working Group (EWG) looked into the ingredients lists of more than 2,000 cleaning supplies commonly available on store shelves across the country and found that hundreds of them contain substances linked to serious health problems.

“A large and growing body of evidence links frequent use of many ordinary cleaning supplies at home or on the job with development of asthma and other respiratory problems,” reports EWG. Furthermore, many cleaning products contain carcinogenic elements like 1,4-dioxane and formaldehyde. Still others can cause chemical burns, allergic reactions or other irritations upon exposure to the skin.

“Despite these health concerns, cleaning product labels often do not give consumers enough information about their ingredients to allow people to make informed decisions on which ones are safer and which ones might harm their health,” adds EWG. To fill the void, EWG launched its “Guide to Healthy Cleaning” to point consumers toward products made from natural ingredients that won’t make us sick.

This free online database provides short reviews and letter grades regarding the eco-friendliness of thousands of cleaning products. Among the dozens of products scoring an “A” grade are: Meliora’s Unscented Soap Flakes (general cleaning), Nature Clean Automatic Dishwasher Pacs (dishwasher detergent), Aura Cacia Arometherapy Mist (air freshening), MamaSuds Toilet Bombs (toilet bowl cleaner), Aspen Clean Kitchen Cleaner (kitchen disinfectant), Attitude Laundry Detergent (laundry soap) and BuggyLOVE Organic No-Wash Stain Remover (carpet and upholstery cleaner).

If you are a “do-it-yourselfer” you can make your own all-natural cleaning formulations for a small fraction of the cost of what you would pay for any manufactured name brand’s version of the same thing. National Geographic suggests that a 1:1 mix of distilled white vinegar and water in a spray bottle is all you need to clean stovetops, countertops, backsplashes, porcelain and ceramic tile, and that you can dissolve mineral deposits at the base of faucets by wrapping the offending areas in a vinegar-soaked rag for a few minutes and then wiping clean. Meanwhile, freshening indoor air without compromising indoor air quality is as simple as wringing out a towel soaked in vinegar and whirling it around the room.

If bad smells are coming up from the bowels of your sink, pour a 1:1 mix of baking soda and vinegar (about a quarter-cup of each) into the drain and then once the ensuing bubbles dissipate, flush with hot water. You can even avoid the nasty smell and chemical exposure inherent in using oven cleaning formulations by doing it yourself with an 8-hour, on-the-hour application of hot water and baking soda on oven splatter spots. It literally costs pennies to clean your house without any chemical exposure. With so many good all-natural, inexpensive options to choose from nowadays, why would anyone in their right mind pay the big bucks for name-brand, toxin-laden cleaners anymore?

Contacts: EWG,; Meliora’s,; MamaSuds,; Aura Cacia,; Nature Clean,; Aspen Clean,; BuggyLOVE,;  Attitude,

Marine biologists aren’t sure yet why so many gray whales are washing up dead on west coast beaches, but global warming is definitely a factor. Credit: Pexels.

Dear EarthTalk: Why are so many gray whales washing up dead on West Coast beaches this spring? — Bill W., Camden, ME

It’s definitely been a rough spring for Northern Pacific gray whales making their annual 5,500-mile trip from Mexico’s Baja California to the Alaskan arctic. Forty-eight of them, emaciated but otherwise showing no overt signs of any known disease, have “stranded” themselves along west coast beaches so far this spring, and researchers expect dozens more before the migration wraps up in June.

The last year when such large numbers of gray whales showed up dead along their migration route was 2000, but that year’s severe El Nino had sent lots of warm water into the Pacific and disrupted food webs accordingly. While a much more mild El Niño this time around probably has contributed some warmer water into the mix, other factors are definitely contributing to the increased strandings.

One optimistic view is that the whales’ very success in rebounding from near-extinction a century ago means more competition for finite amounts of food, leaving those individual whales less skilled at feeding themselves doomed to starvation. Unregulated commercial whaling had decimated Northern Pacific gray whales, with their population dwindling to just a few thousand individuals by the 1930s before an international ban on commercial whaling and other conservation measures kicked in to help spur their recovery. These days some 27,000 of them ply the Northern Pacific.

“The more whales you have, the more whales that are going to die,” NOAA Fisheries’ Michael Milstein tells Seattle-based news service Crosscut. “So, it’s not totally unexpected that we’d see an increasing trend in whale strandings.”

According to this theory, the whales may have rebounded to the point where they are bumping up against the Northern Pacific’s “carrying capacity” (defined as the maximum population size of a given species that the environment can sustain indefinitely given the availability of suitable food and habitat).

But there is likely still more to the story. Global warming has led to retreating polar ice and algae die-offs in the Arctic, key habitat where the whales go every summer to stock up on nutrients before their long commute back to Mexico. These changing conditions have also led to a decline in benthic amphipods, the tiny shrimp-like crustaceans that form the basis of the gray whales’ diet, which would explain why so many more of them are starving to death as they try to make the long journey north. And/or something could be wrong with (or contaminating) amphipods, in turn hurting gray whales.

Scientists worry that the troubled grays could be “canaries in the coalmine” for more widespread problems in marine ecosystems in the coming years, especially if this recent uptick in strandings is fundamentally tied to things wrong at the very bottom of the marine food chain.

“The same thing that’s affecting [gray whales] may affect other species in different ways,” adds Milstein, “if they either depend on the same food sources, or depend on food sources higher in the food web.”

Contacts: NOAA’s Gray Whale Info,; “Why are so many gray whales dying in WA?”; Michael Milstein,

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