Small changes to the climate can have wide-ranging effects on public health from asthma to heart problems to mosquito-borne diseases.

While climate change discussions often focus on what will happen in the future, changes to the atmosphere have already been taking a toll on people today.

“Health is the canary in the coal mine and we are the canaries,” Jeffrey Shaman, PhD, director of the climate and health program at the Columbia University Mailman School of Public Health, told Healthline.

Last week, the U.S. Global Change Research Program’s climate change report made public by the New York Times concluded that “it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”

The report also pointed to a host of factors likely to affect the United States, including changes to “water quality and availability, agricultural productivity, [and] human health.”

Shaman and other health experts have pointed to the ways in which extreme temperatures and other effects of climate change are impacting people today, from heat-related illnesses to cardiovascular events.

Here’s a look at the main ways we’re already feeling the effects of climate change.


Spiking temperatures can affect air quality since it raises the levels of pollutants and ozone in the air.

The World Health Organization (WHO) explains that due primarily to climate change over the past 130 years, the world has warmed by approximately 0.85 degrees Celsius.

As a result, these high temperatures can make air pollution a bigger problem for those with asthma.

In the United States, asthma rates have already been climbing, with more than 4 million additional people diagnosed with the condition from 2001 to 2009.

Approximately 18 million adults and 6 million children have from the condition, according to the U.S. Centers for Disease Control and Prevention (CDC).

While asthma can usually be managed with medication, it leads to 1.6 million emergency room visits every year and approximately 3,651 deaths.

It’s difficult to blame climate change for a specific number of asthma attacks, but the National Institutes of Health (NIH) has warned that changes to the climate will impact pollen, ground level ozone, and other pollutants that can “trigger a variety of reactions.

These include chest pains, coughing, throat irritation, and congestion.

The pollutants can also reduce lung function and cause inflammation of the lungs.

Heat-related illnesses

Dramatic heat waves and record-breaking temperatures have become more common in recent years. The authors of the climate change report found that 16 of the past 17 years were the hottest on record.

Higher temps mean more people at risk for potentially dangerous heat-related illnesses.

Earlier this year a spike in temperatures led airlines to ground planes in Phoenix over fears it was too hot to fly.

With these soaring temperatures humans are more at risk for heat-related illnesses like heat exhaustion, heat stroke, and heat cramps. In a single heat wave in Europe in 2003 an estimated 70,000 people died, according to the WHO.

Shaman pointed out that due to global warming, parts of the planet may quickly become so hot that it becomes nearly impossible for people to go outside.

“We have a gradient of temperature in our inner core to our skin. If you can’t keep skin temp cooler than core temperature,” it’s dangerous, he said.

Shaman said if heat and humidity reach a point where sweat can’t effectively cool us down, people will have to be indoors.

This would greatly impact outdoor industries such as agriculture and construction.

“The continued concern [is] that as the planet warms we’re going to reach the physiological limit of what humans can live in,” Shaman said.


One lesser-known consequence of climate change is seasonal allergies.

Increasing temperatures and rising levels of carbon dioxide in the air can have a significant effect on plants and pollen that cause common seasonal allergy symptoms.

Plants that cause hay fever in the spring, summer, and early fall will bloom and flourish for longer due to warming temperatures.

Shaman said in particular the ragweed plant, a mainstay of the fall allergy season, has been shown to produce more pollen when exposed to higher carbon dioxide levels.

The NIH points out these changes in the climate will result in “amplifying” the pollen and mold being released.

This means the pollen will cause worse allergy symptoms, so you may need to stock up on tissues and allergy medications.

Cardiovascular disease

The warming climate can result in conditions that can put strain on the cardiovascular system. This puts people at risk for stroke, heart attack, or other major cardiac events.

Wildfires in particular can put people at risk. An increase in extreme hot and dry weather in recent decades can exacerbate natural cycles of forest fires.

“Wildfires have increased over parts of the western United States and Alaska in recent decades and are projected to continue to increases as a result of climate change,” the climate change report authors wrote.

These fires can increase rates of cardiac events for people, even if they are miles away.

Dr. Richard Josephson, a cardiologist at University Hospitals Cleveland Medical Center, told Healthline in an earlier interview that the cardiovascular system can come under increased strain from particulates in smoke or haze from a forest fire.

“There are a variety of toxic chemicals in the smoke and small particulate air pollution in the smoke that are bad for the cardiovascular system,” Josephson said.

These tiny particulates put strain on the cardiovascular system, putting people at risk for major cardiac events.

“It can cause activation of the clotting system and constriction of blood vessels,” Josephson said.

Insect-borne disease

There are other public health factors that scientists are closely watching to see if they will impact public health.

The WHO states that insect- and other animal-borne diseases could be affected by climate change if the insects and animals move to new habitats in reaction to changing weather patterns.

“Changes in climate are likely to lengthen the transmission seasons of important vector-borne diseases and to alter their geographic range,” the WHO wrote. “For example, climate change is projected to widen significantly the area of China where the snail-borne disease schistosomiasis occurs.”

However, Shaman said even if mosquitoes or other insects change habitats in the United States, it may not lead to an increase in infections like malaria or Zika. This is because so many Americans don’t spend much time outdoors.

“Houston by all rights is a malaria zone,” Shaman explained. “Why don’t you get it? Well, because they paved over the swamps and drained them… [Residents] spend 99 percent of their times indoors.”

Valley fever

This uncommon disease is spread by spores that infect people after they are inhaled.

Often the spores are spread in hot, dry climates and kicked up by dust storms.

Usually these spores infect people in the dry, Southwestern region of the United States.

Some people have mild flu-like symptoms for a few days or weeks after infection. But about 5 to 10 percent of people who get valley fever develop serious or long-term complications in their lungs, according to the CDC.

Earlier this year, the National Oceanic and Atmospheric Association (NOAA) found that dust storms in the Southwest region of the U.S. have more than doubled over the past 30 years, going from approximately 20 storms per year in the 1990s to approximately 48 per year in the 2000s.

“We’ve known for some time that the Southwest U.S. is becoming drier,” Daniel Tong, a scientist at NOAA’s Air Resources Laboratory and George Mason University, said in a statement. “Dust storms in the region have more than doubled between the 1990s and the 2000s. And we see that valley fever is increasing in the same region.”

The team found that the increasing dust storms were linked to changes in the climate hundreds of miles away in the Pacific Ocean, where warmer temperatures in part of the ocean led to cool air that dried out the Southwestern soil.

While the team didn’t specifically blame global warming, climate change is expected to exacerbate droughts that can increase the number of dust storms and continue to affect the surface of the oceans.