Opinion: How can a warming planet support 8 billion people?

Opinion: How can a warming planet support 8 billion people?

There are issues that concern me deeply as a population health and environmental scientist.

Will we have enough food for a growing world population? How are we going to care for more people in the next pandemic? What will the heat do to millions of hypertensives? Will countries fight water wars because of increasing droughts?

These risks all have three things in common: health, climate change and a growing population that the United Nations predicts will exceed 8 billion people on November 15, 2022, double the population of 2020. barely 48 years old.

In my 40-year career, first in the Amazon rainforest and the Centers for Disease Control and Prevention, then in academia, I have encountered many public health threats, but none as intransigent and pervasive as climate change.

Among the multitude of climate-related adverse health effects, the following four represent the greatest public health concerns for a growing population.

Infectious diseases

Researchers have found that more than half of all human infectious diseases can be made worse by climate change.

Flooding, for example, can affect water quality and habitats where bacteria and dangerous vectors like mosquitoes can breed and transmit infectious diseases to humans.

Dengue fever, a painful mosquito-borne viral disease that affects around 100 million people a year, is becoming more common in hot, humid environments. Its R0, or basic reproduction number – a gauge of how quickly it spreads – increased by about 12% between the 1950s and the 2012-2021 average, according to the 2022 Lancet Countdown report. The malaria season has extended by 31% in the highlands of Latin America and by almost 14% in the highlands of Africa, as temperatures have increased over the same period.

Extreme heat

Rising temperatures are another serious health risk.

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

Today, approximately 30% of the world’s population is exposed to life-threatening heat stress each year. The Intergovernmental Panel on Climate Change estimates that this percentage will increase to at least 48% and up to 76% by the end of this century.

Food and water security

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

The Lancet review found that high temperatures in 2021 shortened the growing season by an average of about 9.3 days for maize or maize and six days for wheat compared to the 1981-2020 average . Warming oceans, meanwhile, can kill shellfish and displace the fisheries that coastal communities depend on. Heat waves in 2020 alone resulted in 98 million more people facing food insecurity than the 1981-2010 average.

Rising temperatures are also affecting the supply of fresh water through evaporation and the shrinking mountain glaciers and snowpack that historically allowed water to flow in the summer months.

Bad air quality

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

Wildfires fueled by hot, dry landscapes add to the health risk from air pollution. Wildfire smoke is loaded with tiny particles that can penetrate deep into the lungs, causing heart and respiratory problems.

What can we do about it?

Many medical groups and experts are working to counter this cascade of negative climate consequences on human health.

Addressing the health burden in low- and middle-income countries is essential. Often the most vulnerable people in these countries are the hardest hit by climate change without having the resources to protect their health and environment. Population growth can aggravate these inequities.

Adaptation assessments can help high-risk countries prepare for the effects of climate change. Development groups are also running projects to expand the cultivation of crops that can thrive in dry conditions. The Pan American Health Organization, which focuses on the Caribbean, is an example of how countries are working to reduce communicable diseases and advance regional capacity to counter the impact of climate change.

Ultimately, reducing health risks will require reducing greenhouse gas emissions that cause climate change.

Countries around the world made a commitment in 1992 to reduce greenhouse gas emissions. Thirty years later, global emissions are only beginning to level off and communities around the world are increasingly suffering from extreme heat waves and devastating floods and droughts.

The UN climate change talks, which in my view do not focus enough on health, can help draw attention to key climate impacts that harm health. As UN 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 the points where we still fail to meet our commitments to one another.”

Maureen Lichtveld is Dean of the School of Public Health at the University of Pittsburgh.
Samantha Totoni, Ph.D. candidate there, contributed to this article, which was first published by The Conversation.

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