Human Emissions Drive U.S. Heat, Death, and Damage

The National Academies of Sciences, Engineering, and Medicine released a sweeping new report confirming that the evidence has only grown stronger: human-caused greenhouse gas emissions are endangering U.S. health, infrastructure, and ecosystems.

“This study was undertaken with the ultimate aim of informing the EPA, following its call for public comments, as it considers the status of the endangerment finding,” said Shirley Tilghman, professor of molecular biology and public affairs, emeritus, and former president of Princeton University, and chair of the committee that wrote the report. “We are hopeful that the evidence summarized here shows the strong base of scientific evidence available to inform sound decision-making.”

Reinforcing the Endangerment Finding

The EPA’s 2009 Endangerment Finding determined that greenhouse gases pose a threat to public health and welfare. The Academies’ 2025 report reaffirms that conclusion—and then goes further. Drawing on a decade and a half of new data, attribution science, and observational records, the committee found even clearer links between human emissions and the rising frequency and intensity of extreme heat, heavy precipitation, wildfires, sea-level rise, and ocean acidification.

The overarching conclusion: EPA’s 2009 finding was accurate, and is now reinforced by stronger evidence. The study underscores that every ton of carbon dioxide, methane, and other greenhouse gases released into the atmosphere adds to these risks.

Public Health on the Front Lines

The report highlights the growing health toll from climate-related impacts:

• Extreme heat has intensified across U.S. cities, driving higher rates of heat stress and mortality. Peer-reviewed analyses show more than 21,000 heat-related deaths in the U.S. since 1999.
• Air pollution is worsening as warmer conditions increase ground-level ozone formation and amplify the reach of wildfire smoke, which now affects populations thousands of miles from fire zones.
• Vector-borne diseases and allergens are spreading as longer warm seasons alter ecological ranges.
• Vulnerable groups—older adults, children, outdoor workers, and those with chronic illnesses—face disproportionate risk.

Adaptation measures such as cooling centers, early-warning systems, and resilient infrastructure are helping but cannot eliminate the underlying threat while emissions remain high.

The Cost to Welfare and Infrastructure

Beyond direct health impacts, the Academies warn of significant consequences for U.S. welfare:

• Agriculture faces declining yields from heat stress and unpredictable rainfall, undermining productivity and food security.
• Ecosystems are destabilizing as oceans warm and acidify, stressing fisheries and marine food webs. Harmful algal blooms and coastal inundation are already producing economic and social losses.
• Infrastructure is under strain from flooding, hurricanes, and wildfire damage. Energy systems in particular face growing risks, from grid instability under extreme heat to storm-related outages.

The committee noted that U.S. energy generation is shifting—coal’s share has fallen to roughly one-third of its 2007 peak while renewables are the fastest-growing source—but these changes don’t insulate infrastructure from climate exposure. Electricity demand is projected to rise sharply as data centers, electrified transport, and industry expand, increasing vulnerability to weather-driven disruptions.

Science Beyond Debate

The report places U.S. findings in a global context. The Intergovernmental Panel on Climate Change’s Sixth Assessment Report concluded it is unequivocal that human influence has warmed the atmosphere, ocean, and land. Today, atmospheric carbon dioxide concentrations are rising 100–200 times faster than natural increases following the last Ice Age—an unprecedented pace in Earth’s history.

The Academies emphasize that this is not just about projections. A measurable positive energy imbalance at Earth’s surface confirms that more heat is being trapped than emitted, committing the planet to additional warming. That imbalance means that even if emissions were halted today, further temperature increases and impacts are already “baked in.”

Implications for Policy and Business

For EPA, the timing of the report is significant. The agency is currently reviewing its Endangerment Finding in light of ongoing public comments and legal challenges. The Academies’ conclusion offers a clear scientific mandate: the threat is real, measurable, and worsening.

For businesses and local governments, the findings underscore the urgency of resilience and decarbonization planning. Companies face mounting operational and reputational risks from climate-related disruptions, as well as regulatory obligations on emissions disclosure and reduction. Facility managers and compliance teams are being forced to shift from incremental efficiency improvements to comprehensive strategies that account for physical, transition, and liability risks.

A Stronger Case, a Narrower Window

The message of the National Academies report is stark but clear. The scientific foundation for recognizing greenhouse gas emissions as a threat to public health and welfare has never been stronger. The question now is how quickly policies and corporate strategies align with that evidence.

The costs of delay—measured in human lives, economic disruption, and ecological loss—are rising with each year of inaction.