Climate scientist rebukes environment minister for claiming scientific divergence on human-caused climate change

On the evening of May 25th, 2026, Chile's Environment Minister Francisca Toledo appeared on CNN Chile for an interview with journalist Mónica Rincón. When asked whether human activity plays a role in climate change, Toledo acknowledged that scientific data showed environmental variables were shifting, but when pressed on humanity's specific responsibility, she claimed there was "divergence" in the scientific community. Only after the journalist pushed back did she concede that "obviously humans have some contribution." The response prompted an immediate and forceful rebuttal from Gabriela Guevara Cue, a climate scientist at the Universidad de O'Higgins and a lead author for the upcoming seventh assessment report of the Intergovernmental Panel on Climate Change.

Guevara's critique was unsparing. She noted that while climate science is indeed complex, complexity does not translate to uncertainty about fundamental causation. The accumulated evidence from successive IPCC reports—synthesized by hundreds of world-class scientists and thousands of peer reviewers across all continents—shows with unmistakable clarity that warming has accelerated dramatically, driven overwhelmingly by human greenhouse gas emissions. The most recent IPCC assessment, released in 2021, was approved line by line by 195 governments, including Chile. Its opening statement used language the organization had never deployed before: "It is inequivocal that human influence has warmed the atmosphere, the oceans and the land." The word "inequivocal" represents the strongest possible formulation the IPCC has ever adopted. In previous reports, the language was "probable" or "extremely probable." The shift to "inequivocal" means there is no reasonable alternative interpretation. The numbers back this up. The IPCC's best estimate shows human activity caused 1.07 degrees Celsius of warming between 1850-1900 and 2010-2019, out of a total observed warming of 1.09 degrees Celsius. Natural factors—the sun and volcanic activity—account for between minus 0.1 and plus 0.1 degrees. In plain terms: without human activity, the planet would be at the same temperature it was 170 years ago. This is not "some contribution." This is nearly the entire warming.

Guevara cited a comprehensive analysis of 88,125 scientific papers on climate change that found more than 99.9 percent agreed on the human origin of climate change. Only 28 papers out of nearly 90,000 expressed skepticism. This consensus is comparable to the scientific agreement on plate tectonics or evolution. To claim there is "divergence" on this question, Guevara wrote, is equivalent to claiming there is disagreement about whether the Earth orbits the Sun.

What made Toledo's hedging particularly grave, in Guevara's view, was not merely the factual error but its source and timing. An environment minister should be able to state the scientific reality without hesitation, just as a health minister should be able to affirm that vaccines work. When the highest environmental authority in a country introduces doubt where none exists, the damage extends beyond rhetoric into the institutional realm. It weakens public policy, erodes the country's international credibility, and sends a dangerous signal: that scientific evidence is negotiable depending on political convenience. Guevara noted that this tactic—suggesting the debate remains open—has a known and troubling history. The tobacco industry used it for decades to delay cigarette regulation. Fossil fuel companies deployed it to obstruct climate action. The mechanism is always the same: not outright denial, but the suggestion that "two sides" exist where in reality they do not.

Guevara's criticism arrived in the context of broader policy moves that deepened the contradiction. In its first week, the Chilean government withdrew 43 environmental decrees from the Comptroller's office in their final stages of approval. These included air quality standards, emissions regulations, the creation of national parks, the designation of the Humboldt penguin as a natural monument, and key regulations needed to implement Chile's own Climate Change Framework Law and Biodiversity Service. Only six have been resubmitted. The rollback was significant enough that Science, the world's leading scientific journal, published two separate alerts within weeks—one warning that the withdrawal "represents a substantial setback for conservation" and another cautioning that it "endangers regulatory advances developed over multiple administrations." It is unusual for Science to issue two alerts about the same country in such a short span.

Meanwhile, Chile is losing glaciers at an alarming pace. The Echaurren Norte glacier has shed 65 percent of its surface since 1955. The Queulat glacier has lost an area equivalent to 16 football fields in just 18 years. Since 2010, the country has endured an unprecedented megadrought—the worst in five centuries. In 2025, Santiago received 57.5 percent less rain than normal. By 2100, glaciers will provide only half the water they do today. The wildfires of 2023 and 2024 rank among the most devastating in the nation's history. None of this is speculation. It is what is already happening. The Climate Change Framework Law that Toledo herself has championed was built on the same evidence she had just relativized. If that foundation is questioned by the ministry responsible for implementing it, while the decrees that make it operational are frozen, the contradiction becomes untenable.

Guevara emphasized that she was not motivated by personal dispute with the minister, but by professional obligation. Climate science is her field of work. She knows firsthand the rigor with which these conclusions are produced. And she carries an ethical imperative that researchers in this domain cannot evade: what they study are not abstractions but processes that impact the concrete lives of vulnerable communities and territories in disproportionate ways. That responsibility compels her to be direct when an authority commits a factual error of this magnitude, however uncomfortable the correction may be. In academic publishing, any scientist who claimed "divergence" on the human cause of climate change would be corrected by peer reviewers before the text reached print. The minister has no peer reviewers, but she carries something that imposes an equivalent—and perhaps greater—obligation: the responsibility of her office and the consequences her words carry for an entire nation's public policy.