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Climate Change and Human Health: Impacts, Inequities, and Innovations

Like COVID-19, the climate emergency hits the most vulnerable and marginalized people hardest.

In this special feature, we explore the surprising health effects of a warming world and the inequities that these effects expose.

We also look at some of the most promising technologies that could help protect our planet.

Climate change — stoked by rising concentrations of carbon dioxide, methane, and other greenhouse gases in the Earth’s atmosphere — will continue to increase the frequency and severity of extreme weather events, such as droughts, floods, and heatwaves.

The acute effects of these events, in terms of lost lives and livelihoods, are widely reported. But climate change is also likely to have substantial, long-term impacts on human health that are less likely to hit the headlines.

“Think about the effects of climate change — increases in temperature, intensified droughts and hurricanes, more rainfall and flooding, and a rise in sea level,” says Sarah Vogel, PhD, Senior vice president of Healthy Communities, at the Environmental Defense Fund.

These new or increased exposures lead to worsening health outcomes, such as heat stroke, heart and lung disease, food and water-borne diseases, and mental health stress.
Sarah Vogel, PhD

In 2014, the World Health Organization (WHO) estimated that climate change would cause around 250,000 additional deaths per year between 2030 and 2050.

The main climate-related causes of death that the WHO singled out included:

  • heat exposure in older people
  • diarrhea
  • malaria
  • childhood undernutrition

The WHO concluded that the burden of disease will fall mainly on children in low income countries. However, climate change is likely to affect the health of the most vulnerable in high income countries as well.

“These conditions can create or intensify exposures to hazards that impact human health, like extreme heat, poor air quality, reduced food and water quality, and displacement of populations of people,” she tells Medical News Today.

“These new or increased exposures lead to worsening health outcomes, such as heat stroke, heart and lung disease, food and water-borne diseases, and mental health stress.”

Heat Stress

In the closing years of the last decade, global mean surface temperatures had already risen by 1°C compared with pre-industrial levels.

Scientists report that, as a result, extreme heat events and their associated health effects and loss of life have become more common. A heatwave in Central Europe in 2004, for example, may have caused more than 70,000 additional deaths.

The frequency of heart attacks and other cardiovascular events increases during heatwaves, partly through higher temperatures, but also as a result of particulate pollution from wildfires.

Hotter, drier conditions are more likely to spark and spread the fires, which clog the atmosphere with tiny particles of soot that can carry on the wind for thousands of miles.

These particulates, in combination with high temperatures, exacerbate lung conditions such as asthma and chronic obstructive pulmonary disease (COPD), especially in older people.

In addition, air pollution and raised pollen counts in hot weather can worsen allergic conditions such as hay fever.

More surprisingly, there may be an association between extreme temperatures and kidney disease.

A study published in October 2021, for example, found that temperature increases may be responsible for 7.4 percent of hospitalizations for kidney disease in Brazil.

The authors report that this equated to more than 202,000 extra cases of kidney disease between 2000 and 2015.

Most of the cases are among children under 4 years of age, adults over 80 years of age, and women, they write.

In sweltering heat, dehydration as a result of excessive sweating is likely to put extra strain on the kidneys, which help to regulate blood pressure and maintain electrolyte levels.


The health effects outlined above are alarming, but the greatest impact of climate change on human health may come from outbreaks of infectious diseases.

Warm weather and changes in rainfall can trigger outbreaks of infections that are spread by insect vectors, such as mosquitoes, which transmit yellow fever and malaria.

Rising temperatures and increased precipitation can shift or broaden the geographical range of vectors and the diseases that they carry.

Climate change and habitat loss may also increase the likelihood that pathogens such as viruses will jump from wild animals into people and cause what are known as zoonotic infections.

Research suggests that degraded habitats harbor more of the viruses that can potentially affect humans. In addition, crop failures as a result of drought or flooding may induce hungry people to eat more “bushmeat” (wild mammals hunted for food), another potential source of viruses.


Industrialized countries are responsible for the vast majority of the increase in greenhouse gas concentrations in the atmosphere, but it’s less industrialized countries that are likely to suffer the worst consequences.

As a result of their location and relative lack of resources, some of the lowest income nations face the greatest risks from challenges such as drought, disease, and flooding.

Coastal and island nations such as Kiribati, a group of coral atolls in the central Pacific, are already living with the consequences of rising sea levels.

In Kiribati, seawater floods the land during storm surges, contaminating fresh water, destroying crops, and inundating homes.

As the polar ice caps melt, island nations like Kiribati may be the first to disappear beneath the waves. But according to the Intergovernmental Panel on Climate Change (IPCC), some of the world’s greatest coastal cities — including Jakarta, Bangkok, and New Orleans — may share their fate by the end of the century.

African nations also face substantial challenges as a result of climate change.

In Nigeria, for example, flooding in 2019 displaced around 1.9 million people.

Extreme weather events, changing patterns of infectious disease, food insecurity, declining access to safe drinking water and clean air all undermine our ability to live healthy lives.
Sarah Vogel, PhD

In addition, climate change has increased the burden of vector-borne diseases in the country, in particular malaria. This is partly because mosquitoes breed in the pools of stagnant water left behind by flooding.

At the other weather extreme, drought not only ruins crops and kills livestock in Nigeria and other sub-Saharan nations, but also provides ideal conditions for wildfires and dust storms, which worsen respiratory conditions.

A combination of lack of infrastructure, environmental degradation, and location exposes the inhabitants of some low income countries to the worst effects of climate change.

In the former French colony of Haiti in the Caribbean, for example, several factors conspire to increase residents’ vulnerability.

The island of Hispaniola, which Haiti shares with the Dominican Republic, lies in a “hurricane alley,” so severe storms already bring heavy rainfall and storm surges every year.

But climate change makes hurricanes more powerful and more dangerous. This is also bad news for countries such as the United States, in addition to countries such as Haiti that lack properly enforced building codes.

In low-lying areas, storm surges also contaminate aquifers — which provide fresh water for washing, drinking, and cooking.

The reality is that those communities and individuals who are already at greater risk for disease and death will be most vulnerable.

In addition, centuries of deforestation have left the country with only around 1.5 percent forest cover, which has exacerbated soil erosion and flooding.

In common with other low income nations, a large proportion of the population remains dependent on natural resources to feed themselves, for fuel, and to provide a livelihood.

So without appropriate financial and educational resources, such nations will continue to clear forests to graze their livestock and cut mangroves to make charcoal.

Impact on marginalized communities

The health impacts of climate change won’t fall equally on “rich and poor.” Rather, they'll exacerbate existing inequities.

“Extreme weather events, changing patterns of infectious disease, food insecurity, declining access to safe drinking water and clean air all undermine our ability to live healthy lives,” explains Vogel.

The impacts of these events aren’t evenly distributed, she tells Medical News Today.

“Instead, these changes magnify the [underlying] inequities that put low-wealth communities, communities of color, indigenous, and other marginalized communities around the world at much higher risk,” she says.

“The reality is that those communities and individuals who are already at greater risk for disease and death will be most vulnerable,” she concluded.

Hazards resulting from the increasing intensity and frequency of extreme weather events ... are already causing an average of more than 20 million people to leave their homes ... each year.
United Nations High Commissioner for Refugees (UNHCR)

People who labor outdoors in extreme heat are a case in point.

Doctors have warned of an epidemic of kidney disease as a result of heat stress in rural parts of countries in Central America, South America, the Middle East, Africa, and in India.

Only the most vulnerable, both economically and socially, are likely to take on outdoor employment in the sweltering conditions that increase a person’s risk of dehydration.

As conditions worsen as a result of a warming climate, such workers face a slew of challenges, including:

  • limited access to medical care or insurance
  • poor health infrastructure
  • little or no control over their working conditions
  • “piece-rate” pay, for example, by the weight of fruit they pick or sugarcane they cut, which incentivizes them to work long hours with no breaks

Indigenous communities are especially vulnerable to the warming climate.

Sámi reindeer herders in the far north of Europe, for example, are struggling to maintain their way of life as the Arctic warms 4 times as fast as the rest of the world. Temperature fluctuations have disrupted snow cover in the tundra to such an extent that their reindeer find it increasingly difficult to expose the lichen that they rely on for food.

Faced with intolerable heat, economic hardship, and other climate-related threats, millions of the world’s most vulnerable seek a better life elsewhere.

According to the United Nations High Commissioner for Refugees (UNHCR):

“Hazards resulting from the increasing intensity and frequency of extreme weather events, such as abnormally heavy rainfall, prolonged droughts, desertification, environmental degradation, or sea-level rise and cyclones are already causing an average of more than 20 million people to leave their homes and move to other areas in their countries each year.”

Racial justice

Of course, climate change doesn’t exclusively affect low income countries. In richer countries, minoritized communities, homeless people, people with existing health conditions, and those with limited access to healthcare are disproportionately affected by extreme weather.

In the United States, for example, People of Color are on average more vulnerable to flooding, wildfires, and other natural disasters, either as a result of residential segregation or relative poverty compared with their white counterparts. Communities of Color may be less able to protect their properties and have fewer resources to rebuild their lives after a climate-related disaster such as Hurricane Katrina.

At the recent COP26 climate summit in Glasgow in the United Kingdom, the New York Times Climate Hub hosted a discussion entitled “Why Climate Justice Means Racial Justice.”

A panel of speakers explored why “People of Color suffer more from the environmental impact of climate change, from zoonotic pandemics to air pollution.”

David Lammy, a British member of Parliament and shadow foreign secretary, who traces the roots of climate change to the ethos of colonialism:

“When I say that the climate emergency is colonialism’s natural conclusion, it is an understanding that at the heart of colonialism was an ‘extractive’ economy,” he said, meaning that natural resources were harvested or 'extracted' for export. ”At the heart of colonialism was fossil fuels. At the heart of colonialism was a disregard for black and brown people wherever they were found in the global south.”

Innovations for Climate Action

According to the IPCC, humans added 40 billion metric tons of carbon dioxide to the Earth’s atmosphere in 2020.

The IPCC predicts that to avoid the worst consequences of climate change we need to cut that figure to 0 by 2050. But how?

It will take multiple approaches — from electric cars to heat pumps — but here we focus on 3 of the most promising: carbon sequestration, green hydrogen from waste, and seaweed.

Carbon sequestration

Plants have been sequestering carbon for billions of years — extracting it from the atmosphere and storing it — but humans have put the process into reverse by burning fossil fuels, cutting down forests, and draining wetlands.

Scientists calculate that restoring ecosystems such as wetlands, minimizing agricultural emissions, reforestation, and preservation of existing forests, could sequester around 30 percent of the carbon needed to limit temperature rises to 1.5°C.

In Nigeria, the majority of landscapes are covered with concrete.
Idowu Ologeh, PhD

Planting trees is a major component of this drive for carbon sequestration.

“Carbon must be removed from the air and stored in trees or soil,” says Idowu Ologeh, PhD, a climate expert at Lead City University in Ibadan, Nigeria. “The topic is gradually getting the attention it deserves.”

She contrasts attitudes in Nigeria with those in New Delhi, India, where she’s currently based.

“There are trees everywhere, shade, leaves to enrich the soil, permeable soils for rainwater percolation — in Nigeria, the majority of landscapes are covered with concrete,” she says.

Tree planting may actually be counterproductive in some environments that reflect a lot of the sun’s energy, however. Compared with grass or snow, for example, trees are dark.

Modeling suggests that the best place to plant trees is in the tropics, where trees grow fastest. Planting them in snowy regions near the poles could have a net warming effect.

Preserving existing forests also has the potential to make a huge difference. Researchers estimate that in 2017, deforestation and other land-use changes emitted 4 billion metric tons of CO2 out of the total 41 billion metric tons from human activity.

Major carbon emitters such as the airline industry have seized on this untapped potential by offering their customers the option to “offset” their carbon emissions. The industries then pay third parties to plant trees, anywhere in the world or protect existing forests.

However, according to Greenpeace, this kind of “greenwashing” is unlikely to help in the long term.

The campaign group points out that it will take a newly planted tree up to 20 years to sequester the amount of CO2 promised by a typical offset scheme.

In addition, if planted in the wrong place, there’s a risk that the benefits could be wiped out in coming decades by droughts, wildfires, disease, or deforestation.

“Carbon ‘stored’ in trees or other ecosystems is not the same as fossil carbon left underground,” it concludes.

Carbon capture and storage

Renewable and nuclear energy can help achieve the goal of leaving fossil fuels in the ground, but industrial processes such as smelting iron are currently impossible without releasing CO2.

One option is to extract the gas from flues then store it underground, known as carbon capture and storage (CCS).

The basic technology is already available, but experts believe that to deliver it at the massive scale needed to meet the 1.5°C target in the Paris Agreement, there need to be further refinements. 

Similar technologies, known as direct air capture, can remove CO2 from the atmosphere, but the technical challenges are if anything even greater.

Because of the lower concentrations of the gas compared with industrial fuels, they would consume vast amounts of energy to extract sufficient quantities of carbon.

One of the most promising approaches to reducing emissions combines carbon-capture technology with plant-based energy production. This is known as bioenergy with CO2 capture and storage (BECCS).

Plants extract or “fix” the carbon from the atmosphere, which is then extracted during energy production and stored safely underground. So, in theory, this provides a way to generate energy with “net negative” carbon emissions.

However, BECCS can involve long, complex supply chains that create their own emissions.

For example, there are emissions associated with growing, harvesting, and transporting bioenergy crops. There are also emissions associated with capturing the CO2 and pumping it underground.

Finally, there are concerns related to changes in land use, such as higher food costs, loss of biodiversity, and increased use of water for irrigation.

“Nothing works in isolation,” Ologeh says. “You cannot be exercising to burn up calories and keep gaining more by [eating] ice creams.”

Green hydrogen

One way to reduce reliance on bioenergy crops may be to use waste material instead.

A new technology called SMO Solar uses locally available waste to generate “green hydrogen” that has no associated carbon emissions.

Yasmine Encelade, CEO of the startup behind the technology, which is based in Guadeloupe in the Caribbean, explained how it works at the New York Times Climate Hub.

Units would be relatively small and wouldn’t require an external power source, so even remote communities could use them to produce green hydrogen for sale to local people.

“We use local waste — so it can be wastewater sludge, it can be invasive biomass, like we have in the Caribbean with Sargassum today, it can be domestic waste plastics, so it’s a solution to recycle plastics — and we can turn out a profitable and valuable product,” she explains.

The technology uses solar energy to power a chemical process called pyrolysis. This heats biological matter to high temperatures in the absence of oxygen to produce carbon and hydrogen.

SMO Solar units would be relatively small and wouldn’t require an external power source, so even remote communities could use them to produce green hydrogen for sale to local people.

The technology locks up carbon from the waste in the form of activated carbon, carbon powder, and biochar (which is a soil improver).


One of the most surprising climate saviors to emerge in the past decade is seaweed.

Marine algae are not only suitable for generating green hydrogen (see above), but can also replace petroleum in the manufacture of products such as fertilizers, packaging materials, fabrics, and cosmetics.

Farmed seaweed grows fast, is cheap, and is easy to harvest. Better still, it provides another way to sequester carbon from the atmosphere.

According to Conservation International, coastal marine systems can absorb carbon up to 50 times faster than forests.

Research suggests that much of this carbon, in the form of organic matter, sinks in the deep ocean and remains locked up there.

One of the most surprising climate benefits of seaweed may be to reduce the amount of methane that livestock burp into the atmosphere.

The warming effect of methane from farm animals, particularly ruminants such as cattle, is equivalent to 7.1 metric gigatons of CO2, or 14.5 percent of all greenhouse gas emissions from human activity.

Adding small amounts of seaweed to animal feed reduces these methane emissions and increases productivity.

One study found that forage containing 5 percent seaweed slashed the methane emissions of male beef cattle by 80 percent without affecting the taste or quality of their meat.

Political Will: The Missing Ingredient

Innovative technologies are all very well, but without the political will to implement them at scale, they'll fail to address the worst effects of climate change.

In democracies, political will is largely driven by how people vote at the ballot box. Without broad social support for the need to decarbonize entire economies, therefore — and pay the bills — even the best technologies won’t be enough.

The green parties are increasingly influential. But in the absence of tighter regulation, they’ll need to establish a way to reward polluting industries for removing carbon emissions.

We are doing too much of almost everything, and the world’s living systems cannot bear it.
Oliver Geden, PhD

“There are almost no business cases for carbon removal right now,” Oliver Geden, a Climate analyst at the German Institute International and Security Affairs, as told at Yale Environment360.

Currently, it costs nothing to blast CO2 into the atmosphere, so there’s no financial incentive to reduce emissions through technologies such as CCS. A price on emissions would help.

But according to the environmental campaigner George Monbiot, an economic system founded on continual growth in productivity will inevitably ravage a planet that has finite natural resources.

He argues that even “green growth,” fueled by innovations such as green hydrogen, is a mirage.

“We are doing too much of almost everything, and the world’s living systems cannot bear it,” as written in the Guardian.

Take Action

Everyone can play a small part in the global effort to reduce the worst effects of climate change - for example, by flying less, eating less meat and dairy, and driving an electric car.

Healthline has established the Stronger Scholarship in partnership with The Nature Conservancy to drive climate innovation and change. Readers can learn about this initiative and apply here.

There are of course numerous other ways to get involved by volunteering for — or donating to — nonprofit organizations, such as the Service Employees International Union, Clean Air Task Force, Carbon180, and Rainforest Foundation US.


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