Amid the escalating consequences as Planet Earth is running a fever, the U.N. climate talks on Sunday zeroed in on the far-reaching implications for human health, a focus for the first time at the annual summit.

From the dangers of heat stress and lung damage caused by wildfire smoke to the spread of disease-carrying mosquitoes into previously unaffected areas due to rising temperatures, the global community at COP28 delved into the unprecedented intersection of climate change and public health.

Under a brown haze over Dubai, the COP28 moved past two days of lofty rhetoric and calls for unity from top leaders to concerns on health issues like the deaths of at least 7 million people globally from air pollution each year and the spread of diseases like cholera and malaria as global warming upends weather systems.

World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus said it was high time for the U.N. Conference of Parties on Climate to hold its first health day in its 28th edition, saying the threats to health from climate change were "immediate and present."

"Although the climate crisis is a health crisis, it’s well overdue that 27 COPs have been and gone without a serious discussion of health," he said. "Undoubtedly, health is the most compelling reason for taking climate action."

After two days of speeches by dozens of presidents, prime ministers, royals and other top leaders – in the background and off-stage – participants were also turning attention to tough negotiations over the next nine days to push for more agreement on ways to cap global warming at 1.5 degrees Celsius (2.7 degrees Fahrenheit) since preindustrial times.

Saturday was capped off with the COP28 presidency announcing that 50 oil and gas companies had agreed to reach near-zero methane emissions and end routine flaring in their operations by 2030. They also pledged to reach "net zero" for their operational emissions by 2050.

On Sunday, U.N. Secretary-General Antonio Guterres said "the promises made clearly fall short of what is required."

Guterres called the methane emissions reductions "a step in the right direction." But he criticized the net zero pledge for excluding emissions from fossil fuel consumption – where the vast majority of the industry’s greenhouse gases come from – and said the announcement provided no clarity on how the companies planned to reach their goals.

"There must be no room for greenwashing," he said.

Temperature rises have worsened natural disasters like floods, heat waves and drought and caused many people to migrate to more temperate zones – in addition to the negative knock-on effects on human health.

John Kerry, the U.S. climate envoy, said it was "astonishing" to him that it’s taken so long for health to become a centerpiece of the climate discussion.

"Our bodies are ecosystems, and the world is an ecosystem," Kerry said. "If you poison our land and you poison our water and you poison our air, you poison our bodies."

He said his daughter Vanessa, who works with Tedros, "repeats to me frequently that we should not measure progress on the climate crisis just by degrees averted, but by the lives saved."

A COP28 declaration backed by some 120 countries stressed the link between health and climate change. It did not mention phasing out planet-warming fossil fuels but pledged to support efforts to curb healthcare sector pollution, which accounts for 5% of global emissions, according to the WHO head.

Diarmid Campbell-Lendrum, head of climate and health at WHO, said heat alone has put pressure on the body and led to higher infectious disease rates.

"Climate change doesn’t need to be on a death certificate for us to be confident that climate change is causing deaths," said Diarmid Campbell-Lendrum, WHO’s head of climate and health.

Climate-driven health threats threaten to undo decades of progress in public health.

From 2030, experts expect that just four of these threats – malnutrition, malaria, diarrhea and heat stress – will push global death tolls up by 250,000 per year, according to the WHO.

"Extreme weather events are becoming extreme health events," said Martin Edlund, CEO of global health nonprofit Malaria No More.

Here’s how climate change is harming people’s health across the world today and what countries might expect in the future.

Vector-borne diseases

Mosquitoes that carry viruses, including dengue, malaria, West Nile and Zika, are shifting into new parts of the world as warmer temperatures and heavy rains create more hospitable conditions for them to breed.

Reported dengue cases have grown from around half a million in 2000 to more than 5 million in 2019, according to the WHO.

Just this year, cases in Brazil are up 73% against the five-year average, said Edlund, with Bangladesh suffering a record dengue outbreak.

Climate change is also having an unpredictable impact on malaria, with 5 million more cases registered in 2022 than the previous year – reaching a total of 249 million, the WHO’s World Malaria Report found.

Floods in Pakistan last year, for example, led to a 400% increase in malaria cases in the country, the report said.

The disease has also spread into the highlands of Africa that previously had been cold for mosquitoes.

Two new malaria vaccines expected to be available next year offer some hope of combating the scourge.

Murky waters

Storms and flooding wrought by climate change are also allowing other infectious water-borne diseases to proliferate.

After decades of progress against cholera, an intestinal infection spread by contaminated food and water, case numbers are rising again, including in countries that had all but extirpated the disease.

Without treatment, cholera can kill within hours.

In 2022, 44 countries reported cholera cases, a 25% increase over 2021, according to the WHO, which noted the role played by cyclones, floods, and drought in cutting off access to clean water and helping bacteria to thrive.

Recent outbreaks have also been far deadlier, with fatality rates now at the highest recorded level in over a decade, the WHO said.

Research has found that Diarrhea also receives a boost from climate change, with increasingly erratic rainfall – resulting in either wet or dry conditions – yielding a higher risk.

Diarrhea is the world’s second leading cause of death among children under 5, after pneumonia, claiming the lives of more than half a million kids every year.

Extreme heat, smoky skies

Heat stress – one of the more obvious health impacts of global warming – is projected to impact hundreds of millions of people as temperatures continue to climb through the next few decades.

With the world already about 1.1 degrees Celsius (2 degrees Fahrenheit) warmer than the average preindustrial temperature, people in 2022 experienced about 86 days on an average of dangerously high temperatures, a report from the Lancet medical journal found last month.

If the world warms by 2 degrees Celsius above preindustrial levels, the report said, yearly heat deaths could more than quadruple.

A July study in the journal Nature Medicine estimated that some 61,000 people died during European heatwaves in the summer of 2022.

The heat has also made forests drier, fuelling extreme wildfires that have swept across large swathes of the world in recent years.

During the decade starting in 2010, over 2 billion people were exposed to at least one day per year of unhealthy air pollution from fire smoke, according to a September study in the journal Nature. That was up by 6.8% compared with the previous decade.

In the United States, wildfire air pollution now kills somewhere between 4,000 and 28,000 people annually, according to the American Thoracic Society.