I love the summer. Growing up, it meant family vacations, beach days, block parties—really, what’s not to like? But for millions of Americans, the meaning of summer has been shifting. In many parts of the country, excitement for the upcoming season has turned into anxiety over the weather events—the extreme heat, hurricanes, drought, and wildfires—that have increasingly defined our summers in recent years.
These weather extremes are not natural. They are climate disasters. And as a report published today by my organization, Public Citizen, outlines, they are exactly the kind of catastrophes that Big Oil companies predicted their fossil fuel products would cause—at the same time that they were orchestrating fraudulent campaigns of climate denial to block solutions that would have alleviated these harms.
To put it bluntly, Big Oil is ruining summer.
Naturally, the most obvious threat is the heat. The last three summers have been the three hottest ever recorded. Since 1985, 80 percent of U.S. cities have experienced an increase in the number of days with a heat index of 90 degrees or higher. This trend has already extended into 2026, with record-smashing heat this spring across the western half of the country, including an average national temperature in March that was an astounding 9.35 degrees Fahrenheit hotter than the twentieth-century norm.
This escalation in extreme heat isn’t a coincidence. A climate attribution study of the March 2026 heat wave found that it would have been “virtually impossible” without climate change. Nationally, scientists have found that the climate crisis lengthened the average heat wave season in the U.S. from 23 days to 70 days over the last 60 years. Another scientific study concluded that last summer, the average American experienced at least one additional week’s worth of risky heat days due to climate change, while 32 U.S. cities (home to over 21 million people) experienced 30 or more additional risky heat days.
Scientists are increasingly able to determine the degree to which the emissions of particular oil and gas companies have contributed to particular heat waves. For example, a study published last fall in the prestigious journal Nature analyzed a number of major heat waves, including the extreme heat that hit the American Southwest in July 2023. The researchers found emissions from each of the biggest fossil fuel companies—ExxonMobil, Chevron, ConocoPhillips, Shell, and BP—made that lethal heat wave at least 10,000 times more likely to occur. They concluded that these events would have been virtually impossible without those emissions.
And it’s not just that these companies contributed to the oppressive heat that is now defining summer for so many of us—it’s that they knew full well what they were doing. For decades, Big Oil companies internally forecast exactly how their fossil fuel products would drive increasing heat, and how we would experience these changes. In 1996, for example, Exxon scientist DJ Devlin gave a presentation to the Global Climate Coalition, a group of fossil fuel companies that colluded to spread climate denial, reviewing the science connecting climate change with “suffering and death due to thermal extremes.” He discussed how the “elderly, sick, and very young” would be particularly vulnerable. And he explained the idea of threshold temperatures, referring to the point at which temperatures cross a critical limit “beyond which mortality rises significantly.”
While the “thermal extremes” of recent summers have been bad, they occurred during a La Niña, the cooling phase of the Pacific Ocean’s heat cycle. But this summer is going to be different. Scientists expect that in the coming months the Pacific Ocean will begin its warming cycle, or El Niño. And this El Niño is predicted to be particularly catastrophic—again, largely due to climate change.
Some studies have found that global warming may be leading to stronger El Niño events. More importantly, climate change means that this El Niño will build on a higher temperature baseline, which will have the effect of supercharging its impacts. That constitutes a dangerous cycle. As Defense Department meteorologist Eric Webb put it: “Due to the increasing concentration of greenhouse gases, the climate system cannot effectively exhaust the heat released in a major El Niño event before the next El Niño comes along and pushes the baseline upward again.”
And it’s not just heat that will be supercharged this summer. Climate change is also causing a severe intensification of droughts and wildfires across our country, turning summer in many areas into a season of water rationing, air quality alerts, or worse.
The U.S. already experienced its most intense spring drought ever this year, with the first three months of 2026 being the driest on record. Over 60 percent of the country is currently experiencing at least moderate drought. And in many regions, the situation is far more severe.
Ninety-nine percent of the Southeast is in drought, with over 60 percent in severe to exceptional drought. This has spurred record-breaking wildfires across the region—Georgia has already had eight times as many burned acres so far this year compared to the pace of the last five years. The Great Plains region is facing similar challenges. Nearly 90 percent of Nebraska is in drought, and the region has already experienced record-breaking spring wildfires that burned over a million acres of land across Nebraska, Kansas, and Oklahoma. And in the West, extended drought is reaching a tipping point, following the lowest snowpack levels in a century. Utah recently announced a state of emergency over its water crisis, with the entire state in severe drought and 22 of 29 counties experiencing extreme drought. Colorado, which also relies on snowpack, may soon follow.
These droughts, and their subsequent impacts on wildfires, are directly related to climate change. Climate scientist Kaitlyn Trudeau described the relationship this way: “Climate change is making the atmosphere thirstier. As it gets hotter, the amount of moisture that is pulled out of the landscape or sucked out of plants and soils also increases.” A 2023 study in the journal Environmental Research Letters found that almost 40 percent of the area burned by wildfires in the western United States over the last several decades can be attributed to the emissions of the world’s largest fossil fuel companies. Speaking of the connection between climate change and increasing dryness that is contributing to wildfire growth, the author of the study said, “I’ve never had such a strong correlation in my data before.”
Big Oil companies understood their role in enabling these climate effects decades ago. In 1981, Exxon scientist Henry Shaw wrote an internal memorandum to Exxon’s president of research and engineering explaining that it was “Exxon’s position” that a doubling in atmospheric carbon dioxide from the burning of fossil fuels would result in “major shifts in rainfall.” In 1982, the American Petroleum Institute commissioned a report warning that climate change would have “serious consequences for man’s comfort and survival since patterns of aridity and rainfall can change.” And in 1998, Shell confidentially predicted that if fossil fuels were not brought under control there would be “more droughts” that would “dramatically change” agricultural patterns and “disrupt eco-systems.” Shell even predicted that because of these changes, “conflicts would abound” and “civilization could prove a fragile thing.”
Then there are summer storms. Hurricane season began on June 1. The National Oceanic and Atmospheric Administration has predicted a worse than average hurricane season in the Pacific this year (combined with a below-normal season in the Atlantic, where El Niño generally suppresses the number of storms), forecasting between three and six hurricanes, including one to three major storms.
Although hurricanes are not new phenomena, climate change is increasing their severity in several ways. Higher sea surface temperatures make hurricanes more likely to intensify—in fact, over the past 40 years, three times as many storms within a few hundred miles of coasts have intensified rapidly due to warming of the oceans. Storms are also staying stronger farther inland than they did in the past, with warmer sea surface temperatures leading to a “slower decay” of storms by increasing the amount of moisture they can carry. They are generating more rainfall, as well. For every degree of warming, the atmosphere can hold 7 percent more water vapor that could fall as rain. For example, a study funded by the Energy Department looking at Hurricane Ida concluded that climate change was directly responsible for up to half a million people’s exposure to the storm’s floodwaters.
Coastal storms are also becoming more dangerous due to rising seas, whose levels have increased eight to nine inches since 1880, and may rise multiple feet during this century. A study of Hurricane Sandy estimated that sea level rise increased the likelihood of flooding in that storm by 300 percent.
Big Oil companies were fully aware that climate change would make coastal storms like these more dangerous. In 1989, Shell Oil Company produced a confidential planning document that predicted, based on “conventional and probably conservative” assumptions, that the continued burning of fossil fuels would cause “more violent weather,” including “more storms” and “more deluges.”
In fact, Big Oil companies demonstrated their understanding of and belief in these scientific conclusions by modifying their own infrastructure, often at significant expense, to prepare for the coming reality of worsening storms and rising sea levels. In the 1990s, engineers working for Shell, Exxon, and ConocoPhillips noted in design specifications for natural gas pipelines that there could be a “considerable increase of the frequency of storms as a result of climate change,” even specifying for one offshore natural gas platform that an “estimated rise in water level, due to global warming, of 0.5 meters may be assumed” for the project’s 25-year lifespan.
Even as these firms were taking action to protect their own assets from the climate harms they knew were coming, these same companies were engaging in massive disinformation campaigns to, as one fossil fuel coalition’s internal strategy document put it, “reposition global warming as theory (not fact).” In the words of former Senator Chuck Hagel, who championed anti-climate legislation when he was in Congress: “They lied.… It would have put the United States and the world on a whole different track, and today we would have been so much further ahead than we are. It’s cost this country, and it cost the world.”
One of these costs is the carefree summers of our past. Big Oil stole them from us. So over the next few months, if—or more likely when—you find yourself baking under the sun of a record-breaking heat wave that’s making it impossible to enjoy your favorite summer activities, or stuck inside because the air outdoors is dangerously smoky from wildfires near and far, keep in mind that this didn’t just happen. Our summers haven’t simply gotten worse. They have been made worse by specific companies that knew that what they were doing would ruin summer and went ahead and did it anyway. We shouldn’t let them get away with it.
