8 billion people: four ways climate change and population growth combine to threaten public health, with global consequences

8 billion people: four ways climate change and population growth combine to threaten public health, with global consequences

(The Conversation is an independent, non-profit source for news, analysis, and commentary from academic experts.)

(Conversation) As a population and environmental health scientist, there are questions that deeply worry me.

Will we have enough food for a growing world population? How will we take care of more people in the next pandemic? What will heat do to millions of people with high blood pressure? Will countries launch wars because of the increasing drought?

All of these risks have three things in common: health, climate change and a growing population that the United Nations expects to reach 8 billion people around November 15, 2022 – double the population just 48 years ago.

In my 40-year career, working first in the Amazon rainforest and the Centers for Disease Control and Prevention, and then in academia, I’ve faced many threats to public health, but none as stubborn and rampant as climate change.

Among the many adverse health effects associated with climate, the following four factors represent the greatest public health concerns for a growing population.

Infectious diseases

Researchers have found that more than half of human infectious diseases could be exacerbated by climate change.

Floods, for example, can affect water quality and habitats where dangerous bacteria and vectors such as mosquitoes can breed and transmit infectious diseases to people.

Dengue fever, a painful mosquito-borne viral disease that infects approximately 100 million people annually, is becoming more common in warm, humid environments. R0, or the basic reproduction number — a measure of how quickly it spreads — increased about 12% from the 1950s to average in 2012-2021, according to the 2022 Lancet Countdown Report. Malaria season expanded 31% in highland regions of Latin America and about 14% In the highlands of Africa with rising temperatures during the same period.

Floods can also spread water-borne organisms that cause hepatitis and diarrheal diseases, such as cholera, particularly when large numbers of people are displaced by disasters and live in areas with poor water quality for drinking or washing.

Dehydration can also degrade the quality of drinking water. As a result, more rodent populations are entering human communities in search of food, increasing the potential for hantavirus spread.

intense heat

Another serious health risk is high temperatures.

Excess heat can exacerbate existing health problems, such as cardiovascular and respiratory diseases. And when heat stress turns into heatstroke, it can damage the heart, brain, and kidneys and become fatal.

Today, about 30% of the world’s population experiences fatal heat stress each year. The Intergovernmental Panel on Climate Change estimates that the proportion will rise to at least 48% and reach 76% by the end of this century.

In addition to the lives lost, heat exposure was projected to result in a loss of 470 billion potential man-hours globally in 2021, with associated income losses of up to US$669 billion. As populations grow and temperatures rise, more people will rely on air conditioning that runs on fossil fuels, further contributing to climate change.

Food and water security

Heat also affects the food and water security of a growing population.

A Lancet review found that high temperatures in 2021 shortened the growing season by an average of 9.3 days for maize, or maize, and six days for wheat compared to the 1981-2020 average. Meanwhile, ocean warming could kill shellfish and divert fisheries that coastal communities depend on. Heat waves in 2020 alone resulted in 98 million people facing food insecurity compared to the 1981-2010 average.

Rising temperatures also affect the fresh water supply through evaporation and shrinkage of the glaciers and mountain snows that have historically kept the water flowing during the summer months.

Water scarcity and drought will likely displace nearly 700 million people by 2030, according to United Nations estimates. Besides population growth and rising energy needs, it can also fuel geopolitical conflicts as countries face food shortages and compete for water.

poor air quality

Air pollution can be exacerbated by the drivers of climate change. Hot weather and the same fossil fuel gases that are warming the planet contribute to the formation of the ground-level ozone layer, which is a key component of smog. This can exacerbate allergies, asthma, and other respiratory problems, as well as cardiovascular disease.

Wildfires fueled by hot, dry landscapes increase the health risks of air pollution. Bushfire smoke is full of small particles that can travel deep into the lungs, causing heart and respiratory problems.

What can we do about this?

Many groups and medical experts are working to counter this series of negative climatic consequences for human health.

The US National Academy of Medicine has embarked on a major and ambitious challenge in climate change, human health, and equity to intensify research. At many academic institutions, including the University of Pittsburgh’s Department of Public Health, where I serve as dean, climate and health are included in research, education, and service.

Addressing the health burden on low- and middle-income countries is pivotal. Often, the most vulnerable people in these countries face the greatest damage from climate change without having the resources to protect their health and environment. Population growth can deepen these injustices.

Adaptation assessments can help countries at high risk prepare for the impacts of climate change. Development groups are also leading projects to expand the cultivation of crops that can thrive in drought conditions. The Pan American Health Organization, which focuses on the Caribbean, is an example of how countries are working to reduce infectious diseases and strengthen regional capacities to counter the impact of climate change.

Ultimately, reducing health risks will require reducing the greenhouse gas emissions that lead to climate change.

Countries around the world committed themselves in 1992 to reducing greenhouse gas emissions. Thirty years later, global emissions are beginning to level off, and societies around the world are increasingly suffering from severe heat waves, floods, and devastating droughts.

The United Nations Conference on Climate Change in November 2022 – which, in my opinion, does not focus sufficiently on health – can help draw attention to the main climate impacts that are detrimental to health. As United Nations Secretary-General António Guterres noted: As we celebrate our progress, “at the same time, it is a reminder of our shared responsibility to care for our planet and a moment to reflect on where we still fall short of our commitments to one another.”

Samantha Teutoni, Ph.D. Candidate at the University of Pittsburgh School of Public Health contributed to this article.

This article has been republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/8-billion-people-four-ways-climate-change-and-population-growth-combine-to-threaten-public-health-with-global-consequences-193077 .

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