The world has never been more united around the idea of health for all. More than 100 low- and middle-income countries have already taken steps toward it, advancing policies that better address the health needs of poor and vulnerable communities.

Yet, discussions on universal health often overlook one of its most serious threats: the climate crisis. Healthy humans need a healthy planet to survive and prosper.

Without urgent action, the climate crisis will undo decades of progress in global health. Rising temperatures, air pollution, which already causes approximately eight million deaths a year, diminishing supplies of clean water and rising food insecurity could create a perfect storm that rolls back advances in both health and development.

As temperatures rise, the geographic range of some diseases will expand, and transmission seasons will grow longer. A recent study found that more than two billion more people could be at risk for dengue fever in 2080.

Warming oceans are causing areas that were once too cold for certain bacteria to flourish, such as northern Europe and Alaska, to be more susceptible to outbreaks of diseases such as cholera. The World Bank has estimated that global warming of two to three degrees Celsius could increase the number of people at risk of malaria by up to five percent and diarrhea by up to 10 percent. And without concerted action, climate change could mean more than 100 million additional people living in poverty by 2030.

Extreme weather, such as hurricanes and cyclones, can also have disastrous effects on health. Each year, 22.5 million people are displaced by climate or weather-related disasters, a figure that is expected to rise as these types of events become more common. These ‘climate migrants’ may lose essential health services, leaving them more vulnerable to diseases. And losing their homes can take a serious toll on both mental and physical health.

Poor and vulnerable communities are more likely to suffer from the effects of climate crisis, which will further entrench inequalities. With more people becoming vulnerable to infectious and non-communicable diseases, greater effort and investments will be needed to ensure that lifesaving tools such as vaccines, bednets and effective treatments reach those most in need.

Urgent and collective action is the only option. The climate action and health communities must find common cause. The health sector must reduce its carbon footprint and increase efforts to make health systems more resilient and sustainable. Health systems must also be able to withstand climate shocks — such as drought, heat waves and extreme rainfall — and continue to have reliable energy supplies. Health can be a powerful motivator for climate action. Health and climate advocates, led by young people, must work together to prioritize urgent action to protect the health of people and planet. Delivering on the promise of health for all, including the health of our planet, depends on it.