Republican presidential candidate Vivek Ramaswamy, a self-professed “unapologetic proponent of greater use of fossil fuels,” has repeatedly cited false or misleading statistics to downplay the risks of climate change.
A former biotech entrepreneur, Ramaswamy made headlines for his performance in the first Republican primary debate, including a moment when he said that because he was “the only person on the stage who isn’t bought and paid for,” he could say “the climate change agenda is a hoax.” He proceeded to claim that “more people are dying of bad climate change policies than they are of actual climate change.”
As we wrote at the time, there is evidence that climate change has already claimed lives, but no indication that climate change policies have killed people. And Ramaswamy does, in fact, have a financial interest in fossil fuels, including a $50 million stake in an investment firm whose flagship fund — DRLL — is primarily made up of oil and gas companies.
Since the debate, Ramaswamy has doubled-down on his climate change hoax claim. He has also frequently cited other climate-related statistics to make his case.
“Today, 8x as many people die of cold temperatures as warm ones,” Ramaswamy wrote on X, the platform formerly known on Twitter, in early September. “The climate disaster-related death rate is down by 98% in the last century & Earth is more covered with green surface area today because carbon is plant food.”
As we’ll explain, each of these statements may be technically accurate, but they omit important context and mislead about the very real risks of climate change.
“It’s classic what they call cherry-picking,” Texas A&M climate scientist Andrew Dessler told us of Ramaswamy’s claims. “You know, you go through a really big data set and you pick out the very small number of facts that tell you the opposite of what the whole dataset tells you.”
In an Aug. 29 interview with MSNBC’s Andrea Mitchell, Ramaswamy recited each of these so-called “hard facts,” but also added another, which is overtly false: that “carbon dioxide as a percentage of the atmosphere is still at a relative low through human history.” He reprised that incorrect claim a few days later at a town hall in Hampton, New Hampshire.
On several occasions, Ramaswamy has claimed to be an environmentalist and “a staunch advocate for clean air and clean water.” But in our review of his website and recent interviews, we found no mention of how he would protect the environment, other than by encouraging nuclear energy.
When running, nuclear power plants produce no air pollution, although they do generate radioactive waste and some designs have the potential to harm aquatic life by discharging heat into bodies of water. Fossil fuels are major contributors to air and water pollution, and burning more of them would not improve the environment.
Ramaswamy’s campaign did not respond to a request asking about how he would protect the air and water, or for more information about each of his four main climate change claims.
Carbon Dioxide Levels at Record High in Human History
Contrary to Ramaswamy’s claim that carbon dioxide levels are at a “relative low” in human history, measurements show that concentrations of the gas are now higher than they have been in more than 4 million years.
As the National Oceanic and Atmospheric Administration explained when CO2 levels peaked in 2022 at 421 parts per million, according to measurements taken at the Mauna Loa observatory, the CO2 concentration in the atmosphere is “now comparable to the Pliocene Climatic Optimum, between 4.1 and 4.5 million years ago, when they were close to, or above 400 ppm.”
The agency notes that at that time, temperatures were significantly warmer, forests blanketed the Arctic, and sea levels were some 16 to 82 feet higher than today.
Some human ancestors lived then, but it would be millions more years of evolution before modern humans would appear. Our species, Homo sapiens, goes back about 300,000 years. And human civilization as we know it — with larger populations supported by agriculture — has only existed for some 12,000 years.
“The reality is that CO2 levels today are higher than they’ve been in millions of years, so his claim is completely false,” University of Pennsylvania professor of earth and environmental science Michael Mann told us in an email. “Moreover,” he added, “the real threat isn’t the absolute level of CO2 or the absolute warmth anyway, it’s the rate of increase that we are seeing today that has no precedent.”
Carbon dioxide is the primary heat-trapping greenhouse gas that is causing global warming. Among other sources, it’s released when fossil fuels, such as coal, natural gas and oil, are burned. Data from ice cores show that before the Industrial Revolution, CO2 levels had hovered around 280 parts per million for thousands of years.
Temperature-Related Deaths
One of Ramaswamy’s go-to lines is that eight times more people die from the cold than from the heat. He often pairs the statistic with his statement, as he did on X, that “the right answer to all temperature-related deaths is *greater* access to fossil fuels.”
The figure, which appears to originally come from a 2021 Lancet Planetary Health paper, is largely correct. But the suggestion that climate change is therefore not a problem or will be a net positive in the future is not.
The notion that climate change might actually be a boon for global temperature deaths is a favorite of Bjorn Lomborg, a Danish political scientist who has a history of minimizing the risks of climate change.
Lomborg, notably, cited the Lancet Planetary Health paper in an April 2023 article in the conservative outlet National Review, in which he stated that “[c]old kills eight times as many” as heat. (He has since used the figure of nine times in a commentary published in a Canadian newspaper in August; he previously also mentioned the study in opinion pieces for the Wall Street Journal and the New York Post, the latter of which was fact-checked by our colleagues at Climate Feedback. In each case, Lomborg incorrectly referred to the study as being published in the Lancet — one of the most prestigious medical journals in the world — rather than a specialty journal from the same publishing group.)
The Lancet Planetary Health study used a statistical technique to estimate the number of excess deaths due to non-ideal temperatures between 2000 and 2019. It found that across the globe, deaths from colder-than-ideal temperatures were far more common than those from warmer-than-ideal temperatures. But Ramaswamy and Lomborg leave out the fact that the study itself cautions this may not always be the case.
“At a global level, the results indicate that global warming might slightly reduce net temperature-related deaths in the short term, although, in the long run, climate change is expected to increase the mortality burden,” the paper reads.
Shanshan Li, an associate professor of environmental change and global health at Monash University in Australia and the senior author of the study, told us that her results are “commonly misinterpreted by climate deniers.”
“It is true that in many temperate regions such as Europe cold-related deaths are generally far higher than heat-related mortality. This is mostly related to the definition of such excess mortality, usually made by comparing the observed temperatures to the value at which the mortality risk is the lowest, the minimum mortality temperature (MMT). The MMT is generally between the 75th and 95th percentiles of the temperature distribution, meaning that most of the days have temperatures lower than the MMT and generate cold-related excess deaths,” she explained.
“The fact that cold-related deaths are higher than heat-related ones does not automatically imply that decreases in the former will offset increases in the latter. Actually, the evidence seems to suggest that the opposite is true, especially under extreme climate change scenarios,” she added. “This is related to the fact that heat-related risks rise steeply for minimal increases in temperature above the MMT, while cold-related risks exhibit close-to-linear increases.”
It’s important to recognize that in such estimates of temperature-related mortality, the vast majority of people are not obviously dying of the heat or the cold. It’s a statistical excess death method that counts many cold-related deaths, for example, even at relatively comfortable temperatures such as 65 degrees, Dessler told us.
When counting deaths due to extreme temperatures, such as when heat or cold are found to be a cause of death, heat deaths already outnumber cold deaths in the U.S., according to government data. Climate change, of course, is expected to lead to more extreme heat deaths.
According to the latest assessment report from the Intergovernmental Panel on Climate Change in 2022, climate change “is projected to significantly increase population exposure to heatwaves … and heat-related morbidity and mortality.” With high confidence, the authors concluded that “[f]uture increases in heat-related deaths are expected to outweigh those related to cold.”
As Dessler has explained in two Substack posts, whether cold or heat deaths, as measured by the excess death method, outnumber the other in the future will vary depending on location, how much it warms, and how much adaptation occurs. Poorer places that are already hot are likely to fare the worst, underscoring the importance of equity issues when thinking about how to address climate change.
Even if in the short term there might be some benefits to climate change in terms of temperature-related deaths, scientists say it doesn’t mean global warming should be encouraged. As Li noted, the impacts of climate change are not only from temperature, but from floods, cyclones, air pollution from wildfire smoke and drought — and all of these have “serious health impacts.”
“We should consider the whole picture of the impacts of climate change,” she said.
Climate-Related Disaster Deaths
Another of Ramaswamy’s favorite talking points is that climate-related disaster deaths have declined by 98% in the last 100 years.
“The number of people who died of hurricanes, tornadoes, heat waves and other weather-related events in 1920 — for every 100 that died then, two die today,” Ramaswamy said in his MSNBC interview. “And the reason why is more plentiful, abundant fossil fuels and technology powered by fossil fuels.”
This statistic appears to come from data compiled in the International Disaster Database. It’s unclear where Ramaswamy picked it up, but Lomborg has highlighted it before, including in a 2020 paper, in which he classified disaster deaths as “climate-related” when they involved weather disasters “that could be affected by the changing climate.” This included floods, droughts, storms, wildfire and extreme temperatures. The Reason Foundation, a libertarian think tank, has also cited the statistic.
Ramaswamy is correct that far fewer people today die in climate-related disasters than a century ago. And over that time, society did burn a lot of fossil fuels. But it doesn’t logically follow, scientists say, that the world should keep burning fossil fuels.
“That I think is 100% wrong,” Dessler said, noting that now there are good alternatives in wind and solar.
“We know that fossil fuels have all of these other problems that renewable energy doesn’t have. And so for the future, there’s really no reason to continue burning fossil fuels,” he added.
Particle air pollution from fossil fuels, for example, is estimated to be responsible for as much as 18% of all global deaths in 2018 — a sum that dwarfs the losses from climate-related disasters. Burning more fossil fuels, of course, will also lead to more warming, exacerbating climate change.
We reviewed the figures reported from the International Disaster Database and found that much of the decline in disaster-related deaths over this period is due to fewer large famines, which were much more frequent in the first half of the last century and often killed hundreds of thousands or millions of people at a time. Such famines are much less common today. To a lesser extent, the decline is also driven by fewer fatalities in floods and storms.
Whether the ultimate reason for the decline in disaster-related deaths is fossil fuels per se is debatable. Kristie L. Ebi, an expert on the health risks of climate change at the University of Washington, told us it was more accurate to say the declines were due to things such as early warning systems, better infrastructure, and research funded by NOAA and the World Meteorological Organization.
Using data from the International Disaster Database, a report from the World Meteorological Association found that between 1970 and 2019, weather-related disasters increased about five-fold, likely due to climate change-driven extreme weather and better reporting — but deaths fell nearly threefold. The group credited this decline to improved early warning systems and disaster management.
Dessler felt it was reasonable to attribute the decline to cheap energy — but emphasized that Ramaswamy’s error was in suggesting this means society should continue to rely on fossil fuels.
“The decline in deaths is not due to fossil fuels, but due to the availability of cheap energy,” he noted in his fact-check of Ramaswamy on Substack. Fossil fuels happened to be what was available in the past, but they don’t need to be what we use in the future, he said.
Green Surface Area
Ramaswamy’s last — and hardly new — argument against climate change is correct on the specifics but suggestively misleads.
“The Earth is more covered with green surface area today than it was 100 years ago because carbon dioxide, it turns out, is plant food,” Ramaswamy said at the New Hampshire town hall. “So it kinda works that way. It was predictable.”
People opposed to addressing climate change have long used the “CO2 is plant food” or “global greening” lines to argue against taking action. Lomborg, notably, has repeated this idea recently.
Carbon dioxide, of course, is plant food. “Every plant uses a photosynthetic pathway to extract carbon dioxide from the atmosphere, break it into carbon and oxygen, and use the carbon to grow,” Ebi said.
A rising level of CO2 in the atmosphere due to human activities has allowed many plants to grow more than they otherwise would have. This has been documented in studies using satellites that measure leaf cover. According to a 2016 satellite study, increased CO2 was responsible for about 70% of the “greening” of the planet between 1982 and 2009.
This extra growth has helped slow global warming some and has had some positive effects on plants. But the implication that CO2 is an unmitigated good for plants or the planet is incorrect.
For one, most but not all plants tend to respond to increased levels of CO2 by growing more. This includes corn, a major food staple, and other so-called C4 plants. Second, CO2 is not the only thing that plants need to grow — and many of the changes expected with increased global warming are predicted to be harmful to plants and crops, including drought and higher temperatures.
Field experiments growing crops such as wheat and rice at double the concentration of CO2 have also found that the plants had less protein and B vitamins, and fewer micronutrients, Ebi noted. “So yes, those particular plants may be growing, but the nutrient density is declining,” she said.
“Higher carbon dioxide is affecting basically the internal physiology of plants,” she added. “It’s changing the balance of compounds within plants, not to the benefit of human health and well being.”
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