Scientists uncover signs that Earth’s resilience to carbon emissions may be unraveling faster than climate models suggest.

A new study led by the International Institute for Applied Systems Analysis (IIASA) suggests that Earth’s carbon-climate system may be more vulnerable than previously believed. The research takes a comprehensive look at how the planet is reacting to human-driven environmental stress, offering a broader, systems-level perspective.

Published in Science of the Total Environment, the study was conducted by scientists from IIASA and Lviv Polytechnic National University in Ukraine. The team introduced an innovative method to evaluate how human activity is impacting Earth by converting carbon emissions into measurable indicators of “stress” and “strain.”

“Until now, the scientific community has mainly measured Earth’s condition in gigatons of carbon per year. That’s important, but it doesn’t show how Earth as a physical system responds to the growing pressure we’re putting on it,” explains lead author Matthias Jonas, a researcher in the IIASA Advancing Systems Analysis Program. “We wanted to see how the entire Earth system stretches and strains under that burden.”

One of the study’s key findings is the introduction of “stress power,” a concept that describes the rate at which human activity adds energy per unit volume to the Earth system. In 2021, stress power was estimated to fall between 12.8 and 15.5 pascals per year. Although this may seem negligible (roughly equal to the pressure of a light breeze), the cumulative effect across the planet’s land, oceans, and atmosphere suggests that this pressure could be shifting Earth out of its natural equilibrium. In a system undisturbed by human-caused climate change, both stress and strain would typically remain close to zero.

A Hidden Turning Point in Earth’s Response

The researchers also analyzed changes over time in Earth’s “delay time,” which describes how quickly the planet’s carbon system reacts to stress and identified a turning point between 1925 and 1945, suggesting that Earth’s system began shifting its response to stress much earlier than previously believed.

“This early turning point was unexpected,” says Jonas. “It suggests that Earth’s land and oceans may have started changing from their usual patterns as early as the first half of the 20th century. After that, instead of working as they used to, these systems were increasingly overwhelmed by human activities and eventually stopped absorbing CO₂ as effectively.”

This could mean countries need to act sooner than planned to cut greenhouse gas emissions.

“Meeting future emissions targets is important, but we also need to pay attention to how quickly Earth is becoming more fragile,” Jonas says. “Even if we hit our targets, the weakening of Earth’s natural systems could still leave us facing major disruptions sooner than expected. Earth’s shift to earlier fragility isn’t captured in climate models yet, but it needs to be.”

The team emphasizes the need for further research to quantify this shift and include their stress-strain approach in global climate modeling. They hope that by expanding how scientists track Earth’s condition from counting carbon alone to understanding how the planet physically reacts under pressure, the world can better prepare for the challenges ahead.

Reference: “Human-induced carbon stress power upon earth: integrated data set, rheological findings and consequences” by Matthias Jonas, Rostyslav Bun, Iryna Ryzha and Piotr Żebrowski, 27 June 2025, Science of The Total Environment.
DOI: 10.1016/j.scitotenv.2025.179922