Is your anxiety spiking along with the temperatures, fires and floods this summer? (I’m asking for a friend.) If we’re going to stay functional amid spiralling climate impacts, it seems like an important time to look at proven strategies to counter climate anxiety. So, like more and more people are doing lately, I called the doctor.

She told me to take a hike.

She wasn’t kidding and it wasn’t just good general advice. Dr. Melissa Lem has distilled the evidence for nature’s healing powers down to prescription-level precision: “Two hours a week, at least 20 minutes at a time,” she gently instructed.

You get big improvements in your levels of the stress hormone cortisol after 20 or 30 minutes, according to medical research. And there’s similar evidence for nature’s healing effects across a wide spectrum of problems. Health professionals across Canada are now writing prescriptions through a program called PaRx (who knew doctors were so deft with the double entendre?).

I reached Dr. Lem after a full day seeing patients but she showed no hint of fatigue. Quite the opposite — her enthusiasm for getting people into nature is infectious and she’s riding a wave of success. Barely three years ago, the PaRx program started as a side project with the BC Parks service and already doctors are bringing nature-based programs into hospitals in London, Ont., and schools in Nova Scotia. The Canadian Medical Association is on board and the World Health Organization has profiled the PaRx program globally. Within Canada, nature prescriptions are now being filled in all provinces by over 11,000 Canadian medical professionals.

Some patients even receive a free Parks Canada Discovery Pass on doctors’ orders. “Medical research now clearly shows the positive health benefits of connecting with nature,” said Minister Steven Guilbeault when the feds formalized a collaboration with PaRx. Canada’s environment and climate change minister called it “a breakthrough in how we treat mental and physical health challenges.”

If it is a “breakthrough,” it’s one of those peculiarly ancient ones. Indigenous spokespeople have been trying to impress the importance of connection to the land on settlers for a very long time. Hippocrates — he of the Hippocratic oath — was recommending time in his garden to patients well over 2,000 years ago. Japan’s Forest Agency has been recommending forest bathing, or shinrin-yoku, since the 1980s.

What’s new is the growing body of scientific evidence. Beyond that 20-minute point, we get an extraordinary range of health benefits. Dr. Lem ticks off a cornucopia of evidence: improvements in blood pressure, heart health, diabetes, recovery after illness. Mental health improves markedly. Time in nature helps with depression, attention disorders and anxiety. Better memory. More creativity. People of all ages become happier. Kids do better in school. The list goes on and on.

Dr. Lem started sifting through the research after her own encounter with what she calls “nature deficit.” In 2009, she moved back to Toronto following a stint running an emergency department in rural B.C., “I found myself way more stressed even though my job was way less stressful.” It makes sense when you think about evolution, she told me. “Our brains are wired for biodiversity.”

But she’s not one to rely on thought experiments. By temperament and training, she’s the type who doesn’t trust anything until someone’s done a randomized trial and the results have been replicated. Like so many medical professionals, she found the evidence undeniable. “We now call nature the fourth pillar of health,” she says, “along with sleep, diet and exercise.”

Most of us intuitively know that nature heals. But, as with so many things we know are good for us, the trick is in the doing. That’s even harder when it comes to ecological anxiety because the reaction isn’t always fight or flight, it can often be “freeze” — a kind of deer-in-the-headlights paralysis. Maybe doomscrolling or an entirely understandable urge towards distraction.

That’s one reason for the PaRx program, says Dr. Lem. Advice from a trusted health professional is proven to add motivation. And a written prescription is even more motivating.

And PaRx offers other strategies to overcome inertia as well. Scheduling is one deceptively simple tactic: That means entering it in your day planner (writing things down comes with its own evidence base). Schedule and prioritize green time like you would a doctor’s appointment or a dinner date.

Another strategy is to enlist others — co-workers, friends and family — which has also been shown to increase success at getting out into green spaces.

You’re probably not going to get out to a national park for several 20-minute sessions a week. And time in nature can sound awfully ableist and unattainable for city dwellers. There’s good news on that front, too.

“You don’t even have to walk,” says Dr. Lem. You can roll a wheelchair under a tree or sit on a bench in an urban green space. The health benefits of nature start to add up when you feel you've had a meaningful nature experience.

If there’s any concern that sitting on a park bench sounds more like a prescription for quietism than activism, Dr. Lem is living proof to the contrary. She’s a mother herself, has a medical practice and a role as an assistant professor at the UBC Medical School. All of which hasn’t stopped her from spearheading programs like PaRx and becoming president of the Canadian Association of Physicians for the Environment (CAPE).

At CAPE, Dr. Lem is a leading force behind campaigns against fossil fuel advertising and the dangers of natural gas while rallying health professionals to support federal regulations for a clean electricity system and a cap on oil and gas pollution.

Time in nature is “a gateway into bolder climate advocacy,” she’s discovered. Medical professionals start engaging on issues of broader planetary health. And, for all of us, the more we’re connected to nature, the evidence demonstrates more pro-environmental attitudes and behaviours.

If you want more about effective antidotes to climate anxiety, make sure you’re signed up for future newsletters. But you might also want to check out some back issues like Coping through climate change, where we looked at research out of Lakehead University and reviewed Britt Wray’s wonderfully helpful book, Generation Dread. Or click through to find out why a Tibetan meditation master recommends gratitude as the surprising antidote to climate despair.

In the meantime, you’ve got your doctor’s orders: go sit on a bench or get out on the land. Two hours a week, at least 20 minutes at a time.