Ben Santer never imagined that 12 words could change the trajectory of his life and humanity’s understanding of what it was doing to the planet:
“The balance of evidence suggests a discernible human influence on global climate.”
He wrote that sentence as the lead author of a pivotal chapter in the 1995 report by the Intergovernmental Panel on Climate Change. It was cautious, qualified and still controversial. But in the decades since, the signal it pointed to has only grown clearer.
Now the data sources that made that discovery possible are under threat.
Under the Trump administration, publication of scientific reports is being frozen and some records risk being removed from public access. The White House has also moved to terminate a key contract with the firm responsible for producing the National Climate Assessment, casting doubt on the completion of the next scheduled report. Computer models and observational records Santer helped build are in the crosshairs.
“There’s real concern that the data may go away, that the satellites, measurements that have been collected for 40 plus years, may not continue,” Santer told a room of more than 100 science students and environmental researchers at Stanford University last month. He was there to deliver a lecture hosted by Students for a Sustainable Stanford and sponsored by the university’s Woods Institute for the Environment.
It’s not just a loss of institutional memory, he said. It’s the dismantling of the tools that proved what is happening to the environment over the last few decades and the causes.
“The evidentiary chain,” he warned, “may break.”
Backlash against findings
Santer spent 30 years at the Program for Climate Model Diagnosis and Intercomparison at Lawrence Livermore National Laboratory, analyzing satellite measurements and surface records, and matching them to computer simulations of the Earth’s atmosphere. He and his colleagues tested how variables like greenhouse gas emissions, solar activity and volcanic aerosols affected climate patterns. They then compared the predictions to real-world records from more than 40 years of Earth observation.
The warming they found in the lower atmosphere and simultaneous cooling higher up pointed to only a single scenario, one driven by human pollution. “Nature can’t explain what we’ve monitored and observed,” he said.
In 1995, the report he helped write did not claim certainty. The models were basic and the satellite history relatively short. The phrase “discernible human influence” reflected what could be responsibly concluded. Still, it triggered a political backlash and personal attacks, not because the science was unsound but because it implied accountability.
Santer, then a relatively new hire at Lawrence Livermore Lab, had trained at the Max Planck Institute for Meteorology in Germany, where he specialized in isolating the human signal in climate observations. He thought the work would speak for itself.
Instead, it put him under scrutiny. “I was investigated by Congress. There were calls for my dismissal with prejudice,” he said. “It was rumored that I was about to be indicted by the Hague International Court of Justice for, quote, falsification of international relevant scientific documents.”
He considered quitting. “It was a bad time.”
But mentors encouraged him to stay, to recognize the significance of what he helped establish. “If you’re a scientist, you have some responsibility to defend the hard-fought scientific understanding that you and your colleagues have reached,” he said. “What’s the point of being a scientist if you’re unwilling to stand behind the science?”
The current attacks on science emanate largely from the so-called Department of Government Efficiency, the extra-governmental but Trump-endorsed secretive group of technologists affiliated with billionaire Elon Musk. Since Trump’s recent inauguration, they have been rummaging through sensitive files of various federal agencies, altering and deleting data, and firing vast numbers of career civil servants with no notice or explanation, in apparent violation of several laws. While some dismissals are arbitrary, others target climate research, which the administration labels “alarmist” and “wasteful” — as if these adjectives could invalidate whole libraries of hard-won scientific knowledge about the natural world.
Signals from the noise
Santer’s approach relied on the subtle art of pattern recognition, identifying how warming or cooling moved through the atmosphere, over oceans and across latitudes. Greenhouse gases heat the planet unevenly. Warming concentrates in the troposphere, cooling in the stratosphere, with especially strong effects at the poles.
Scientists at the National Center for Atmospheric Research in Boulder, Colorado, simulated possible causes of global temperature shifts — solar cycles, volcanic eruptions, sulfate pollution, deforestation, fossil fuel combustion, ozone concentrations and many others — one variable at a time. They then checked those models against satellite and surface measurements going back to the late 1970s.
Only one explanation fit all the patterns at once: human activity.
Santer built on the accomplishments of other leaders in the field. Syukuro Manabe and colleagues at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Lab in Princeton, New Jersey, had pioneered the climate models that predicted this layered heating effect in the 1960s. Klaus Hasselmann, working in Germany, showed how to map observed temperature shifts onto distinct causal patterns, a technique known as detection and attribution. In 2021, Manabe and Hasselmann shared the Nobel Prize in physics for that insight.
As datasets grew larger and simulations more refined, new indicators piled up: Warming of ocean surface temperatures. Changes in cloud cover. Rising sea levels. Shrinking snowpack. Shifts in hurricane strength and timing. Each measured and modeled independently but all pointing in the same direction.
That convergence — multiple lines of evidence aligning with theory — is what the biologist E.O. Wilson called “consilience.” It is not the same thing as a guess. It is more like the scientific equivalent of corroboration. “Fingerprints” turned up in the tropopause (the atmospheric boundary between the troposphere and stratosphere), the oceans and cloud decks. Each told the same story.
But to the public, the search for consilience is often misread as confusion. Where scientists see a growing body of mutually supportive evidence, others see contradiction. The very thoroughness and openness of the process can look suspicious to outsiders, as if constantly revisiting the findings signals a lack of confidence rather than a commitment to accuracy. Politicians, corporate lobbyists and conspiracy theorists seize on minor revisions to cast doubt on the entire enterprise.
Santer was initially reluctant to enter the fray. “Since 1995, I was forced unwillingly to enter the public arena,” he said. “I’m a very private person. I’m happiest when I’m far away from the maddening crowd in the mountains, climbing with my son.” But he stepped forward because someone had to explain how the science worked and why it mattered.
Researchers, he said, must try to translate complex science “into plain English, to tell stories, to get people to care about the kind of world in which their kids will live and love and hopefully thrive.”
Santer has spent decades learning to communicate across that gap.
Life-and-death consequences
It has never been more urgent to tell these science-driven stories. The climate emergency is escalating and the infrastructure that monitors it is being dismantled.
Last week The New York Times reported that the National Weather Service, part of NOAA, had agreed with its employee union to reduce head count at field offices. That would result in “degraded” services, according to the agreement, with less frequent weather warnings and slower releases of weather balloons that help improve the accuracy of predictions. Rep. Zoe Lofgren, representing parts of the Peninsula and South Bay in the House, said the cuts were “endangering the agency’s lifesaving work.”
Ben Jealous, executive director of the Sierra Club, told The Guardian on April 15: “Efforts to delete, unpublish or in any way remove” NOAA data “jeopardize people’s ability to breathe clean air, drink clean water, and live safe and healthy lives.”
Among the systems being dismantled are support for Earth-monitoring satellites, laboratories and long-standing information repositories. The proposed budget would eliminate NOAA’s Office of Oceanic and Atmospheric Research, curtailing federal support for regional environmental monitoring and educational centers. The Office of Space Commerce, which helps manage commercial satellite traffic, also is facing deep cuts. Staff reductions have begun affecting the National Centers for Environmental Information, home to the world’s largest climate archive, going back more than 150 years. NOAA has also moved to sunset leases for critical facilities, including the Radar Operations Center in Oklahoma, which is essential to national forecasting systems.
Santer recently joined hundreds of other members of the U.S. National Academies of Sciences, Engineering, and Medicine in signing an open letter denouncing the broad attacks on the nation’s scientific infrastructure, which reads in part: “The voice of science must not be silenced. We all benefit from science, and we all stand to lose if the nation’s research enterprise is destroyed.”
This comes as political appointees have asserted the right to claw back billions of dollars in previously awarded environmental protection grants, attacked long-standing pollution regulations and slashed public lands management. The White House loudly equates “climate change” with left-wing ideology, and even systematically censors that and related terms on websites throughout the federal government.
Santer has lived through that kind of opposition once already. This time, the stakes are higher.
“I’m hopeful because I think everyone, irrespective of political persuasion, recognizes that we only have one planet here,” he told the assembled Stanford scholars, specifically addressing students in science and engineering who asked him about where to focus the next few decades of their careers. Seeing young people who want to devote their lives to solving global problems, he said, “makes me optimistic.”
While Santer officially stepped down four years ago, he said, he is “failing at Retirement 101” and has taken on a role as distinguished scholar in residence at Woods Hole Oceanographic Institution, as well as being a spokesperson against climate change denial.
Nearly every day, he visits an overlook near his home in southern Oregon. It faces Upper Klamath Lake, with mountains in the distance and ponderosa pine forests in between. He goes there to think, decompress and remember why he is still working to help the public understand the scientific method.
“I don’t want to give that stuff up without a fight,” he said. “There are many people on the other side who are destroyers. They can’t build. And that’s a fundamental distinction to me — the distinction between building and destroying.”
