Children suffer most acutely from the impacts of climate change, doctors say. Photo credit: Joe Raedle/Getty Images

For years, politically and financially motivated campaigns have wrapped climate science in a cloak of doubt. Scientists, initially caught off guard, eventually responded with a relentless barrage of peer-reviewed papers producing a collection of very specific findings that together have led to irrefutable evidence of the human fingerprints on climate change. In this three-part series, we look at the state of the science linking human-induced climate change to environmental, business and human impacts and whether the science has grown strong enough to be successful evidence in lawsuits holding fossil fuel producers accountable for those impacts.

By Amy Westervelt

Human impacts have always been an easy entry point to environmental issues, which otherwise might seem technical or remote.  It was the impact on children’s health and adults’ enjoyment of nature that helped spur adoption of the Clean Air Act and Clean Water Act. An oil spill fouling the beaches of Santa Barbara led to the creation of Earth Day and the founding of the Environmental Protection Agency in 1970. One of the EPA’s early regulations was to ban the use of the pesticide DDT in the U.S. when it was linked to cancer in humans and animals.

It has historically been more difficult to prove climate change’s human health impacts, but that is beginning to change.

A study published in The Lancet: Planetary Health earlier this month predicts that two in three Europeans will have their health impacted by climate change-related extreme weather by 2100, with extreme heat alone killing 150,000 people per year across Europe if emissions are not curbed. Physicians across the U.S. formed the Medical Society Consortium on Climate & Health earlier this year after watching the impacts of climate change harm their patients—ranging from longer allergy seasons to increases in parasitic and bacterial infections. The Consortium released a report in March citing multiple studies linking climate change to a variety of health impacts, including heat-related illness, worsening chronic illnesses, injuries and deaths from dangerous weather events, infectious diseases spread by mosquitoes and ticks, illnesses from contaminated food and water and mental health problems.

A comprehensive report by the U.S. Global Change Research Program in 2016 outlined all of these impacts, showing how closely each is tied to climate change. As the science improves, it is increasingly likely that remedies will be sought through the courts.

“Lawsuits alleging health impacts are likely to increasingly be part of litigation campaigns,” Jeffrey Gracer, principal at environmental law firm Sive, Paget & Riesel, said. “Framing climate change as a health issue connects the issue with our daily lives and emphasizes that the impacts are present-day, not something decades off in the future.”

“As the science advances the ability to demonstrate a causal connection between climate change and mortality or the prevalence of particular illnesses and disease vectors, litigation on those fronts also will advance.”

The Climate-Clean Air Connection

According to the Lancet Commission on Health and Climate Change, cutting carbon emissions would cut premature deaths from air pollution by 500,000 a year in 2030, 1.3 million in 2050 and 2.2 million in 2100, particularly in the heavily polluted cities of India and China. In the U.S., research indicates that benefits to human health could be worth 10 times the cost of cutting carbon emissions.

“We’ve focused a lot on coal combustion as a source of both carbon dioxide and air pollution,” said Dan Greenbaum, president of Health Effects Institute, a nonprofit research center focused on air pollution. “In cases where there’s a question of whether or not people want to take action on doing things around CO2 for climate change reasons, often when the facts are put together in a way that suggests that coal burning also has enormous near-term health impacts, that can be helpful in driving action.”

Health Effects Institute published a study last year with Tsinghua University, the Institute for Health Metrics and Evaluation (IHME), and the University of British Columbia, in which it attributed 40 percent of the health burden of air pollution in China—equivalent to approximately 370,000 annual premature deaths—to industrial coal burning.

Air pollution has decreased overall in the U.S. thanks to the Clean Air Act and to new technology like the scrubbers reducing pollutants from coal-fired power plants. Still, the American Lung Association’s 2017 State of the Air report concluded that four in 10 Americans  live in areas with unhealthy levels of ozone or particle pollution.

Incidence of asthma is also increasing. According to the Centers for Disease Control, the percentage of the U.S. population dealing with asthma increased from 7.1 percent in 2001 to 8.4 percent in 2010. In 2014, 6.3 million children in the U.S. had asthma. Some of that increase is due to the extended and intensified wildfire seasons largely fueled by climate change.

This year’s fire season in the West has been exacerbated by the exceptionally wet winter, which fed a bumper crop of grass that the fires have been using as fuel, and record-breaking heat this summer, according to Ken Pimlott, California state forester and the director of the California Department of Forestry and Fire Protection (known as Cal Fire).

Weeks worth of triple-digit temperatures have helped spawn up to 400 or 500 fires per week in California alone this summer.

“I’m going to use the word ‘astounded,’ ” Pimlott said. “We are really astounded at just how many fires there have been. In the past few years, we’ve had maybe 150 to 200 fires a week during the most intense part of the fire season.”

All of that comes with a health impact, predominantly related to the smoke. “That smoke endangers not just the immediate environment; it can be carried hundreds of miles away,” said Rachel Cleetus, lead economist with the Union of Concerned Scientists. “So when there are these fires in California we see smoke carried to Reno, Nevada and other places.”

Extreme Heat Gets More Extreme

A paper published in 2016 in Environmental Research Letters was the first to explicitly quantify the role of anthropogenic climate change in human mortality during extreme heat waves. Study authors took a variety of factors into account, including social status, individual behavior, the extent of urbanization (also known as the “heat island effect,” the fact that the concentration of buildings in cities tends to increase temperatures), and the influence of increased air pollution which may occur during hot periods.  

“Statistically we’re likely to see more human costs, and scientifically our ability to attribute human-caused climate change in quantitative ways is improving and we can do it pretty quickly,” Peter Frumhoff, a co-author of the heat-wave mortality study and director of science and policy for the Union of Concerned Scientists.

The evidence is only getting stronger. “Health data can be difficult to come across at a 30-year or longer time frame, but that’s the amount of data we need to determine a climate signal,” said Jenni Vanos, assistant professor of climate, atmospheric science & physical oceanography at the Scripps Institute at University of California at San Diego.

According to Vanos, we’re about to hit the motherlode of data: a 30-year data set from the National Morbidity and Mortality study, which started in 1987 (it takes a couple of years to crunch the numbers, so 2017 data won’t be available until 2019 or so).

“With that data, you can start to break it down and only look at certain age groups or only look at cause of death,” Vanos said. “So you can look at what the risk of death [cardiovascular death] was due to exposure to this temperature in this age group, and then start comparing age groups or income levels, and see where there are climate signals.”

Bad News Gets Worse

Climate change’s role in sea level rise has become increasingly conclusive, and it’s impossible to ignore the death toll linked to intense flooding as well. This year extreme floods in Peru, Sri Lanka, Jamaica, and the U.S. have claimed hundreds of lives, and the year isn’t over yet. These sorts of natural disasters represent a climate-change double-whammy with first the events  themselves and then the spread of illnesses like cholera that tends to follow them.  

Other diseases are getting a more direct boost from climate change. An outbreak of anthrax in northern Russia last year killed two people and put 90 in the hospital; it also spread to 2,300 caribou. The deadly spores had not been seen in the Arctic since 1941. Scientists discovered they were released into the atmosphere when melting permafrost exposed long-dead animals infected with the bacteria. Public health experts warn that we may see more deadly bacteria return from the annals of time.

“Global warming’s greatest threat may also be the smallest,” Dr. Jonathan Patz warned in his keynote speech at the National Academy of Sciences forum on climate change and infectious disease in 2013. The forum focused on many causes of disease, including fungi, bacteria, viruses and mold spores, as well as vectors like bats and mosquitoes. As weather patterns shift, so too does the behavior, lifespans and regions of infectious diseases and their carriers.

In 2015, the Lancet Commission published a report in which it warned that climate change could reverse the last 50 years’ worth of public health advances.

Conversation Starter

The Lancet Commission also suggested that focusing on human health could help steer the debate over climate change in a more productive direction.

“A public health perspective has the potential to unite all actors behind a common cause — the health and wellbeing of our families, communities, and countries,” its 2015 report stated. “These concepts are far more tangible and visceral than tons of atmospheric CO2, and are understood and prioritized across all populations.”

This is already clear to the doctors treating real patients impacted by climate change.

“The emblems of climate change have often been glaciers and polar bears, and while people might care about those things it’s also easy to think of them as far away and not really relevant to our daily lives,” Vanos said. “Instead, what about a sweltering little girl in her home during a heat wave because she doesn’t have air conditioning and can’t afford to have extra water on hand?”

According to Frumhoff, tapping into that concern could also spur a movement to hold  companies responsible for their roles in climate change.

“Those kinds of events, where you have extreme weather leading to mortality, as awful as they are, do trigger conversations about responsibility,” he said. “Initially the common response even for those who know about climate science and believe actions need to be taken to mitigate its impacts, was to say ‘I’m responsible – I fly, I drive more than I should,’ and so forth. But now that we have powerful evidence that companies not only have played a role but also have tried to deceive the public about it, it’s become more socially acceptable to consider their responsibility.”