Very brief summary of climate change's impact on health - Dr. Dora Anne Mills

Dora Anne Mills, MD, MPH, FAAP View from Maine

Very Brief Summary of Climate Change’s Impact on Health June 14, 2024

 

Several years ago, I lamented to my children that I yearned for the days when weather events were not a routine part of the national and international news. They looked at me quizzically, saying that they did not realize there had been such a time. It was one of those head-turning moments when I realized how much climate change had snuck up on us.

 

Ultimately, it will be the health impacts of climate change that will cause cataclysmic human loss to the point of extinction, or a convergence of resolve and science to solve and reverse climate change. What, then, are these health impacts?

 

Climate change is tightly intertwined with global pollution, human migration, biodiversity loss, land use, and resource scarcity. It is therefore very hard to tease out these different factors from one another. Below is a very brief summary of several health impacts that are quite directly related to climate change.

 

It is important to note that a factor contributing to the growth of fossil fuel use – and therefore climate change - is the doubling of human life expectancy in the last 100 years, after a stagnant or only slight progress for several centuries. Worldwide, life expectancy was 32 in 1900, now 71; in the U.S. it is 76. Ironically enough, this exemplary public health success is now contributing to fossil fuel use and other factors related to climate change.

 

Infectious Disease

Increase in air temperatures means we’re seeing insects and other vectors previously found in more southern climates. Increase in water temperatures and precipitation means we’re seeing more waterborne diseases (e.g. E. Coli, crypto) and infections associated algae blooms (e.g., cyanobacteria).

 

Other climate change-related causes of infection diseases are often more complicated and not so obvious. For instance, in some areas, climate change-related droughts or erosion trigger the overuse of fertilizers, which in turn causes excessive nutrient concentrations downstream, which then leads to vegetative alterations, that then alters the types of insects seen. In Central America, for instance, this cycle has led to increases in the types of mosquitoes that transmit malaria, and then malaria itself. Below are additional examples.

 

Zoonotic diseases (infections between animals and humans) are on the rise, in part due to the encroachment of humans into wildlife habitats as well as to rising temperatures causing the disruption and spread of some vectors (animals as well as human migration). Some examples:

•          Ebola from African fruit bats;

•          Hantavirus and plague seen in the Western US;

•          Spread of H5N1 and other types of influenza viruses, which are carried by migratory birds, whose routes are especially impacted by climate change.

Arthropod-borne diseases (infections transmitted by insects) are on the rise in New England as warmer shorter winters and longer summers are resulting in insect habitats to migrate northward, carrying infections, including newly-discovered ones.

•          Lyme disease and other tickborne diseases have increased exponentially in the last 30 years in New England.

•          Reports of infections transmitted by insects, esp. mosquitoes and ticks to the US CDC have more than doubled in the last 15 years, including Lyme, West Nile, Powassan, Zika, dengue, and even malaria.

 

Fungal infections are more common. Although normally found in soil, fungi generally can’t tolerate human body temperature. But they appear to be adapting to higher soil temps, and are then more likely to successfully infect humans. Examples include histoplasmosis and candida.

 

Waterborne diseases such as cholera, campylobacter, E. Coli, are on the rise. We already see increases in hospitalizations due to some of these after hurricanes. Others are increasing due to warmer water temperatures.

 

Poor Nutrition and Malnutrition

Climate change is extracting a toll on every part of food production: temperature increases, flooding, droughts, availability of arable land, disruptions of pollination, increase in pests, etc.

 

Disruptions of food production:

•          Climate change-related floods and droughts have resulted in dramatic losses of agriculture around the globe.

•          Climate change-related loss of pollinators results in lower consumption of fruit, veggies, nuts, and seeds that are otherwise important sources of nutrients such as vitamin A and folate.

•          Climate change-related depletion of fish (including from rising water temperatures and people overfishing) results in a reduction of a critical source of protein and nutrients.

 

Direct impacts of higher concentrations of CO2

We’re still learning about the effects of these changing conditions on the quality and quantity of food. An example is that higher CO2 concentrations result in lower amounts of iron, zinc, protein and other nutrients, which in turn causes poor nutrition.

 

Natural hazards

There are numerous direct impacts of weather changes that hit the headlines, e.g., people killed from floods, droughts, tornadoes, hurricanes, and wildfires. However, of all natural weather hazards, the deadliest are heat waves. For instance, in 2023 in the U.S., about 2,300 people died with heat listed as a cause of death. In 2022 in Europe, 61,672 were estimated to have died in the summer heat waves. These numbers far outweigh the tragic but much smaller (and increasing) annual U.S. tolls from flooding (88), tornadoes (71), hurricanes (45), lightning (37), and wildfires (16) during the period 1992-2021 (NOAA).

 

Non-communicable diseases

•          Air, water, and land pollution are all exacerbated by climate change:

o   air pollution due to increases in ozone (caused by increases in heat) and particulate matter (wildfires and dust storm);

o   water pollution due to rising and warmer water levels; and

o   land pollution due to droughts, desertification (due to droughts), erosion (due to floods), increase use of fertilizers.

Pollution is now among the leading global contributing factors to the biggest causes of deaths around the world - heart disease, cancer, stroke, and emphysema.

•          With climate change-related reduction in available protein, the replacement of dietary protein with carbohydrates can impact health, including leading to more type 2 diabetes.

•          With rising sea levels, the salinity of ground water has increased, and this can be a factor leading to more hypertension, including that associated with pregnancy.

 

Displacement and conflict

•          Climate change is a major driver of displacement e.g., migration, due to rising sea levels, failing crops, scarce resources, and extreme weather.

•          These same factors are associated with political conflicts around the globe.

 

Mental health

With an increasing number of people impacted by climate change’s direct weather hazards, forced migration, malnutrition, and other catastrophes, many feel these events are causing general increases in post-traumatic stress disorder (PTSD) and overall anxiety levels.

 

What is Needed?

•          We need urgent, deep, and sustained reductions in greenhouse gas emissions so that all communities achieve net-zero emissions as rapidly as possible.

•          We need to prioritize planetary health. Some of the health impacts of climate change were not predicted just a few years ago. There are likely many more in the future we are currently unaware of. We need to study the health of our planet in ways that combine public health with expertise found in land use planning, ecology, energy science, agriculture, and meteorology.

•          We need good governance at all levels – international, federal, state, local, within organizations and employers – that acknowledges climate change, that pursues scientifically-based policies, and that funds or otherwise supports funding for education and research on climate change.

•          We need an all-hazards approach so everyone is ready for anything. This means all of us are ready to function in and mitigate conditions in a wide variety of emergencies.

 

Disparities. All of these strategies need to also recognize that climate change disproportionately impacts the health of people living in poverty, the very young, those who are pregnant, and older people. Therefore, prevention and mitigation measures need to especially protect these populations, since by doing so, all will be able to thrive, in the vein of the New England adage, “a rising tide floats all boats”.

 

Personal Observations. I’ve been fortunate to travel the last couple of years to Morocco, Tanzania, Turkey, and Greece. Everywhere the impacts of climate change were striking, and people talked about it without any prompting. In all of these countries, I heard about crippling

heat waves, destructive wildfires, unpredictable weather patterns, and agriculturally-devastating droughts and floods. Some of these impacts were very visible, including driving on flooded roads during what is normally the dry season, and seeing how drastically the snows and glaciers of Mt. Kilimanjaro have shrunk since I was last there in the 1990s.

 

However, I also saw some signs of hope. Perched in the Atlas Mountains, I looked down across Morocco’s desert to see the Noor-Ouarzazate solar power complex, the world’s largest concentrated solar power plant. I saw Morocco’s high-speed electric rail system speed by us, transporting people between their major cities. Across all of these countries I saw solar and wind farms, including Tilos, a virtually carbon-neutral Greek island.

 

The irony of making these observations while traveling - an activity that heavily uses fossil fuels

-  is well-noted. The good news is that we found sustainability woven into the fabric of the tourist industry in these countries, including carbon offsets for the flights, reductions in plastic use, water being heated by solar panels, electrification of transportation, and many more adaptations.

 

If these countries, some of which have endured significant financial hardships and crises the last few years, can grow the political will to invest in green energy, then I hope the U.S. can do much more. And it is urgently needed – for the health and survival of everyone.

Resources:

•           Planetary health: protecting human health on a rapidly changing planet, 2017, Samuel Myers https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32846-5/ppt

•           The Imperative for Climate Action to Protect Health, 2019, Andy Haines and Kristie Ebi https://www.nejm.org/doi/full/10.1056/NEJMra1807873

•           NIH: Climate Change and Health Strategic Framework https://www.nih.gov/sites/default/files/research-training/initiatives/climate-change/nih- climate-change-framework.pdf

•           UN Sustainable Development Goals for Climate Change: https://www.un.org/sustainabledevelopment/climate-change/