I’m excited to welcome Leah Seligmann as The B Team’s new CEO. As a founding B Team Leader, I’ve known and worked with Leah for years and value her guidance, thoughtfulness and commitment to the issues that matter most to business leaders, policymakers and everyday people.

Leah and I share a conviction that it’s more important than ever to connect the health of the planet with the health of people — two crises now merging into a perfect storm. Combining the two is key to touching people’s hearts and minds and creating an environment for effective action.

This is our new “Inconvenient Truth” moment. In 2006, that film helped spark the global movement around climate change and planetary health. But we need to broaden our thinking about the health of the planet to include the health of the humans who inhabit it. Yes, we are drivers of climate change. But we are also its victims.

Consider the recent devastation in the southeastern United States. The death toll from Hurricane Helene has now climbed to over 250, making it the third-deadliest U.S. storm of the 21st century after Katrina (2005) and Maria (2017). Tragically yet inevitably, that toll will continue to rise. And we’re still learning about the scope of devastation in Florida from Hurricane Milton.

A new study in Nature estimates that the average hurricane and tropical storm generates 7,000 to 11,000 excess deaths over the 15 years following the actual storm. Part of that is due, the study notes, to the way the “heightened physical and mental stress” of experiencing the storms “may alter long-run health.” And of course, the long-term stress impacts physical and mental health even if it doesn’t lead to death. It’s all more evidence of the ways the health of our planet and the health of humans are so deeply connected.

And the health of the planet continues to worsen. Research shows that climate change is increasing the rainfall of hurricanes and making them more destructive. One study found that, since 1979, the intensity of hurricanes increased around 6% per decade, with storms now 25% more likely to hit the 111-mph mark to be considered a major hurricane.

Last year was also the hottest year on record, with other records being set for ocean heat, sea level rise, Antarctic sea ice loss and glacier retreat. But climate change isn’t just about the health of the planet. Healthcare systems around the world are also in crisis. What we’re now seeing is a direct collision between the healthcare crisis and the climate and nature crisis.

The numbers on chronic diseases are also record-breaking. Worldwide, an estimated 640 million people are living with cardiovascular disease, which is the leading cause of death globally. More than 530 million people are living with diabetes. In the United States, 129 million people have at least one major chronic disease, while in 2023, eight chronic conditions, including cardiovascular diseases, depression and diabetes, hit all-time highs.

Healthcare systems around the world are breaking under the burden of chronic diseases. In the United Kingdom, 9.7 million people — one in five people in the country — are currently waiting for tests or treatment by the National Health Service. Meanwhile, U.S. healthcare spending has gone from 5% of GDP in 1960 to 17%, and healthcare costs are projected to grow by 8% next year. Employers are also feeling the squeeze, with health insurance premiums increasing by 33% over the past five years.

That’s just part of the human backdrop against which climate change is unfolding. And as climate change records continue to be broken, we’re seeing more and more evidence of how the effects — extreme heat, wildfires, air pollution and more — disproportionately impact those with chronic diseases. As Isabella Cueto put it in Stat News, “Heat can set off flare-ups in a vast array of chronic health conditions…. All kinds of respiratory conditions, from asthma to COPD and pneumonia, are made worse by the lower-quality air.”

In fact, the health of the planet and the health of humans are so connected that it’s hard to tell where one begins and the other ends. Exposure to extreme heat has tripled in the last three decades and now affects around a quarter of the Earth’s population. Heat-related deaths climbed 117% in the last 25 years, with average mortality due to heat rising an average 3.6% per year over the same period. Our mental health is also at risk, with emergency room visits for mental health issues increasing on extreme heat days.

During the 2020 wildfires, doctors in Northern California reported a 43% increase in strokes and other cardiovascular issues, and hospital admissions went up by 12%. Studies have shown that wildfire-smoke exposure leads to an increased risk of heart attacks, strokes and pregnancy complications. It’s estimated that air pollution is responsible for over seven million deaths globally each year.

People with disabilities are also uniquely vulnerable to climate change, and are two to four times more likely to be injured or die in climate events like heat waves, hurricanes and floods.

In Austria, this connection between climate change and health is the basis for a lawsuit. A 43-year-old man named Mex Müllner is suing the government for violating his human rights by failing to do enough about the climate crisis. Müllner has multiple sclerosis, and, as with many MS patients, exposure to extreme heat can worsen neurological symptoms. “If people with disabilities have a problem, you can be quite sure that all the other people will have the same problem some few years later,” Müllner noted in a recent article by Zoë Schlanger in The Atlantic. “That’s the reason why I can go to the government and say, ‘Please do something.’”

As we continue taking action on climate and nature, we need to also do much more to strengthen the resilience of the people on our increasingly fragile planet.

For chronic diseases, we actually have a tool that could help to finally reverse the trendlines: behavior change. As the science shows, our five key daily behaviors — sleep, food, movement, stress management and connection — govern both our physical and mental health. Given that these behaviors account for as significant a share of health outcomes as medical care and our genes, behavior change can be a miracle drug for preventing disease and optimizing the treatment of disease. And now with AI and its power of hyper-personalization, behavior change can have an even greater impact on health outcomes.

We don’t have to accept the current trajectories on climate change and chronic diseases. Both are huge, interconnected challenges to solve.

Healthier people will be in a stronger position to make wise decisions for the long term and come up with creative and innovative solutions to the complex challenge of climate change. And any improvements in our shared capacity to mitigate climate change will have a measurable impact on people’s health.

So we need leaders to bring a renewed sense of urgency to both crises and raise awareness among their teams about how planetary health and human health are interconnected.

"The Catalyst" is The B Team’s monthly newsletter which showcases ways in which leaders are advocating a better way of doing business. Subscribe to receive updates.