There are questions that worry me profoundly as a population- and environmental-health scientist.
Will we have enough food for a growing global population? How will we take care of more people in the next pandemic? What will heat do to millions with hypertension? Will countries wage water wars because of increasing droughts?
These risks all have three things in common: health, climate change and a growing population that thewould pass eight billion people on 15 November, 2022 — double the population of just 48 years ago.
In my, first working in the Amazon rainforest and the Centers for Disease Control and Prevention, and then in academia, I have encountered many public health threats, but none so intransigent and pervasive as climate change.
Of the multitude of climate-related adverse health effects, the following four represent the greatest public health concerns for a growing population.
Researchers have found thatcan be worsened by climate change.
Flooding, for example, can affect water quality and the habitats where dangerous bacteria and vectors like mosquitoes can breed and transmit infectious diseases to people.
Dengue, a painful mosquito-borne viral disease that sickenspeople a year, becomes more common in warm, wet environments.
Its R0, or basic reproduction number — a gauge of how quickly it spreads —from the 1950s to the average in 2012-2021, according to the 2022 Lancet Countdown report.
Malaria’s season expanded by 31 per cent in highland areas of Latin America and nearly 14 per cent in Africa’s highlands as temperatures rose over the same period.
Flooding can also spread waterborne organisms that causeand , such as cholera, particularly when large numbers of people are displaced by disasters and living in areas with poor water quality for drinking or washing.
, too, can degrade drinking water quality. As a result, more rodent populations enter into human communities in search of food, increasing the .
Another serious health risk is rising temperatures.
Excessive heat can, such as and respiratory diseases. And when heat stress becomes , it can and become lethal.
Today, about 30 per cent of the global population is exposed to potentially deadly heat stress each year. The Intergovernmental Panel on Climate Change estimates that percentage will riseby the end of this century.
In addition to lives lost, heat exposure was projected to have resulted inglobally in 2021, with associated income losses totalling up to $669 billion.
As populations grow and heat rises, more people will be relying on air conditioning powered by fossil fuels, which.
Food and water security
Heat also affects food and water security for a growing population.
The Lancet review found that high temperatures in 2021by about 9.3 days on average for corn, or maize, and six days for wheat compared with the 1981-2020 average.
Warming oceans, meanwhile, can kill shellfish and shift. Heat waves in 2020 alone resulted in people facing food insecurity compared with the 1981-2010 average.
Rising temperatures also affect freshwater supplies through evaporation and by shrinkingand that historically have kept water flowing through the summer months.
Water scarcity and drought have the potential to displace almost, according to UN estimates. Combined with population growth and growing energy needs, they can also fuel geopolitical conflicts as countries face food shortages and compete for water.
Poor air quality
Air pollution can be. Hot weather and the same fossil fuel gases warming the planet , a key component of smog. That can exacerbate allergies, asthma and other respiratory problems, as well as cardiovascular disease.
Wildfires fuelled by hot, dry landscapes. Wildfire smoke is laden with tiny particles that can travel deep into the lungs, .
What can we do about it?
Many groups and medical experts are working to counter this cascade of negative climate consequences on human health.
The US National Academy of Medicine has embarked on an ambitiousto ramp up research.
At many academic institutions, including the University of Pittsburgh’s School of Public Health, where I am dean, climate and health are being embedded in research, teaching and service.
Addressing the health burden on low- and middle-income countries is pivotal. Often, thepeople in these countries without having the resources to protect their health and environment. Population growth can .
can help high-risk countries prepare for the effects of climate change. Development groups are also leading projects to that can thrive in dry conditions.
The, 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 the health risks will requirethat are driving climate change.
Countries worldwideto reduce greenhouse gas emissions. Thirty years later, global emissions are , and communities around the world are increasingly suffering extreme heat waves and devastating floods and droughts.
The, which in my view aren’t focusing enough on health, can help bring attention to key climate impacts that harm health.
As UN Secretary-General António Guterres noted: While we celebrate our advances, “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.”
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