MThe effects of climate change are all very large-scale, with heatwaves hitting entire continents. Floods that submerge vast areas of island countries and continental coastal areas. Other effects are less visible because they occur within the human body.
That doesn't make them any less dangerous.
Diseases related to immune health problems have been steadily increasing over the past few decades. Nasal allergies in children have more than doubled from 2012 to 2022. Fatal food allergies are also on the rise. The global prevalence of rheumatoid arthritis has skyrocketed by 14% since 1990. Young people are more susceptible to colorectal cancer.
To be sure, climate change is not the only culprit. Diets high in ultra-processed foods, lack of exercise, high levels of stress, and improved testing may all be contributing to higher disease rates. However, there is also strong evidence that the environment plays an important role in the rise of immune-mediated diseases, both at the biological and epidemiological levels. As I and a group of colleagues in the United States and Europe report in Frontiers in Science, stressors from climate change are causing immune dysregulation and contributing to the rise in immune-mediated diseases.
As a physician and a scientist, I believe that this immune disease epidemic must be treated at its roots. That includes tackling climate change.
Climate change upsets the human immune system in two important ways. It destroys the body's defenses and prevents them from rebuilding.
Consider the many irritants that climate change brings to communities around the world on a daily basis. Wildfires release dangerous amounts of tiny soot particles into the air. Floods often wash industrial chemicals into waterways, causing mold spores to germinate inside your home. An unusually warm spring stimulates the production of ragweed and other pollen. All these exposures damage structures that have evolved to protect humans from infection, such as the skin, the mucous membranes of the intestines and lungs.
How does climate change make it harder to build a strong immune system in the first place? Humans rely on a nutritious diet and a huge number of microorganisms to train and maintain a strong immune system. , requiring exposure to fungal, plant, and animal species. All of which are under threat from climate change. A warmer climate irreversibly changes ecosystems, forcing species to migrate or become extinct. For the remaining humans, less interaction with diverse species means less resilient immune systems.
Extreme weather events are also destroying crops and livestock in many parts of the world, leading to alarming increases in starvation and starvation. Even if crops grow, they may not be very nutritious. Staple foods such as wheat, corn, rice, and soybeans lose significant amounts of nutrients when exposed to high levels of carbon dioxide in the atmosphere. Malnutrition also impedes the development of a healthy immune system.
The effects of all these stressors are visible at the cellular level. Scientists have tracked the effects of many exposures through a series of chemical interactions that damage the body's protective barrier and upset the delicate balance of the immune system. In many cases, this actually activates the body's inflammatory response, keeping it turned on even when it should be turned off. This kind of persistent inflammation causes various diseases including cancer.
scientists understand why A growing number of people around the world are affected by immune-mediated diseases. The question now is whether something can be done about it.
Fortunately, the answer is a resounding yes.
In a paper published in Frontiers in Science, my colleagues and I outlined the global rise in immune-mediated diseases. We concluded that for every $1 he spends on mitigating climate change, he saves at least $3 in health care costs. That's an impressive return on investment, but it doesn't take into account the reduction in human suffering.
These improvements are not hypothetical. As policies change, the health benefits change with them. For example, in the 1980s and 1990s, U.S. air pollution efforts dramatically reduced particulate soot in Southern California, reducing asthma rates among local children by 20%. In Seoul, South Korea, clean air policies prevented 500,000 asthma-related hospitalizations in four years.
There is now an urgent need to implement these policies on a global scale.
My colleagues and I are calling for a renewed focus on balancing human and ecosystem needs to protect the health of both the planet and its people. We call for immediate global action to reduce greenhouse gas emissions from activities such as agriculture, waste management and transportation.
Addressing global immune health challenges will also require large-scale investments in food security and sustainable agriculture to improve access to nutritious food for all communities. By creating and protecting more green spaces and encouraging access to natural ecosystems such as national parks, policymakers can increase the public's exposure to a wide range of plants and animals, which also promotes strong immune systems. will be done.
Even housing policy can influence this crisis. Funding for people to harden their homes against extreme weather damage, eliminate mold, and improve indoor air quality will all help reduce exposure to immune stimulants.
In addition to bold policy changes, the United States and other governments need to fund more research focused on understanding the immune health challenges associated with climate change. This will require global investment in data collection and analysis and a concerted effort to assess the impact of mitigation and adaptation strategies on population health. New economic models are needed to better explain the health benefits of policies aimed at reducing greenhouse gas emissions. These should help further strengthen the case for these policies.
Above all, it is imperative that scientists, clinicians, journalists, politicians – anyone with a platform – continue to explain to the public that climate change is having a very real impact on the human body. is. These are not evenly spread around the world. Some communities and regions are more vulnerable than others. We must work together to fight this common threat.
The destructive forces of climate change are already manifesting in an epidemic of immune system health problems. Only by acting now can we prevent the worst damage.
Kari Nadeau, MD, is the John Locke Professor of Climate and Population Studies at Harvard T. H. Chan School of Public Health.
