andresr via Getty Images Children, the elderly and suffers of chronic diseases are among the most vulnerable to climate change-related health risks.

One morning in July 2011, Samantha Ahdoot’s 9-year-old son, Isaac, grabbed his clarinet, trekked up the hilly road to the bus stop and set off for another day at the band camp near his home in the suburbs of Washington, D.C.

Within an hour, Ahdoot’s phone rang: Isaac had collapsed and was en route to the emergency room on a stretcher. Her otherwise healthy son suffered heat exhaustion and dehydration from the blistering heat of a summer that regularly broke temperature records. July alone shattered two daytime high temperature records in just the D.C. area. Concerned, Ahdoot, a pediatrician, volunteered to be camp physician. As temperatures soared, she was forced to cut soccer games short and limit campers to swimming and indoor activities.

“That was the experience that first got me thinking about how our summers are getting hotter and what does that mean for children, their health and their safety,” Ahdoot, a doctor at Pediatric Associates of Alexandria, told The Huffington Post by phone on Tuesday. “Climate change isn’t about our grandchildren or great-grandchildren, just as it’s not about polar bears and penguins. Climate change is about people and their health today in 2017.”

On Wednesday, Ahdoot joined more than 434,000 practitioners ― more than half the medical professionals in the U.S. ― in a newly formed medical consortium warning the public about the effects climate change is already having on health. The Consortium on Climate & Health includes a dozen top medical associations covering fields ranging from allergies and asthma to internal medicine to psychiatry. In one of its first moves, the nonprofit coalition plans to lobby governors, mayors, manufacturers, Fortune 500 chief executives, the U.S. Chamber of Commerce and the Trump administration to invest in renewable energy and slash greenhouse gas emissions.

The group faces an uphill battle. President Donald Trump has made axing environmental regulations a top priority as the White House seeks to boost the economy. Already, his administration has lifted regulations to protect streams and waterways from toxic pollution, scrapped a rule requiring oil and gas drillers to report methane leaks and proposed gutting the Environmental Protection Agency’s budget. In January, the Centers for Disease Control and Prevention abruptly canceled a climate change summit just days before Trump was sworn in. Last week, EPA Administrator Scott Pruitt ignited a firestorm when he said on CNBC that he doesn’t believe carbon dioxide emissions cause global warming.

Yale University Most Americans believe in climate change, but few understand the scientific consensus behind it.

Even in red states, the vast majority of Americans disagree with the White House. Nearly 70 percent of Americans believe global warming is happening, and 53 percent understand that humans are to blame, according to 2016 survey data from the Yale Program on Climate Change Communication. Yet despite 71 percent of those surveyed saying they trust scientists’ conclusions on global warming, less than half realized that most scientists believe climate change is real.

That’s a problem. For years, oil companies, particularly Exxon Mobil Corporation, have funded groups that reject the overwhelming scientific consensus on the causes of climate change as part of disinformation campaigns modeled on efforts by tobacco companies and automakers to hide the health effects of smoking and leaded gasoline. In fact, study after study shows 97 percent or more of climate scientists who actively publish in peer-reviewed journals agree that increased greenhouse gases in the atmosphere are warming the planet. The surge in greenhouse gases such as carbon dioxide and methane irrefutably mirrors the dramatic upswing in industrial emissions, both of which track rising temperatures.

“At this point, physicians are really trying to speak out about their own observations and let everyone know it isn’t just climate scientists,” Mona Sarfaty, director of the new consortium and a professor at George Mason University, told HuffPost by phone. “Physicians ― who have a closer relationship with the public than scientists, generally ― are seeing this, and they feel concerned and feel a responsibility to speak directly to the American public.”

“To get 12 different major medical organizations coming together like this is rare,” she added. “It doesn’t happen often. It only happens when the stakes are really high.”

Consortium on Climate Health The health risks posed by climate change vary by region.

Just 1 in 4 Americans can name even one way in which climate change poses a risk to health, according to a 2014 poll. A report released Wednesday in conjunction with the consortium’s launch announcement outlines three types of maladies linked to global warming:

Direct harms, such as injuries and deaths due to increasingly violent weather, and asthma and other lung diseases exacerbated by extremely hot weather, wildfires or longer allergy seasons. Diseases spread through insects such as ticks and mosquitoes that carry infections like Lyme disease or Zika virus, and through contaminated water and food. Mental health effects, such as increases in depression and anxiety resulting from the damage climate change can do to society.

Stories of such ailments abound. One anecdote featured in the report detailed the spike in lung disease, asthma and pneumonia diagnoses after the 2008 Evans Road wildfire ripped through North Carolina during the state’s worst drought on record. Another described the medical chaos that followed the evacuation of Baton Rouge, Louisiana, last year as people fled their homes without medications after two days of torrential rains caused a “1,000-year” flood.

Last year, Ahdoot treated a 6-year-old boy for Lyme disease he caught while riding his bike in Chicago in November, when the city is typically too cold for ticks to survive.

It’s difficult to draw a direct line from manmade global warming to individual diagnoses or weather events. But refusing to cut greenhouse gases until evidence is as conclusive as the sky is blue is like waiting until a patient is on a ventilator to begin treatment, Ahdoot said.

“If doctors waited for absolute certainty, they’d never treat a single patient because there’s nothing that we do that’s based on certainty,” Ahdoot said. “There’s only best available evidence. That’s what doctors use to care for patients.”

“The best available information today, as determined by over 97 percent of climatologists and every legitimate scientific organization in the world,” she added, “is that rising greenhouse gases are warming our planet.”

CORRECTION: An earlier version of this article implied the consortium was made up entirely of physicians.