Earth’s climate may not always change as gradually as a thermostat being turned up or down. Instead, the planet can remain locked in a relatively stable climate–carbon state for long periods before crossing a threshold and shifting into a fundamentally different regime. A new study suggests that these transitions were repeatedly associated with periods when the Phanerozoic biosphere—the complex web of life that has existed for roughly the past 539 million years—became especially vulnerable.
Published in Nature Communications, the research by I. Sudakow, C. Myers, A. Spiridonov and colleagues examines the relationship between long-term climate stability, the global carbon cycle and biological resilience. The findings point to a striking pattern in Earth history: biodiversity may be at greater risk not only during periods of extreme climate conditions, but also when the planet is moving rapidly between persistent climate–carbon regimes.
The Phanerozoic Eon includes the rise and diversification of complex marine and terrestrial ecosystems, as well as some of the most severe biological crises in the fossil record. During this immense interval, atmospheric carbon dioxide, oxygen levels, temperature, ocean chemistry and the distribution of continents changed repeatedly. Yet the researchers argue that these variables did not fluctuate randomly. Instead, Earth’s climate–carbon system appears to have occupied recognizable states, each maintained by interacting feedbacks among the atmosphere, oceans, rocks and living organisms.
The carbon cycle is central to this stability. Carbon dioxide is exchanged among the atmosphere, oceans, soils, sediments and rocks. Volcanic activity can release carbon dioxide, while chemical weathering, ocean sedimentation and the burial of organic carbon can remove it from the atmosphere over geological timescales. Life itself is part of the machinery: photosynthesis draws carbon dioxide down, organisms transfer carbon through food webs, and the eventual burial or decomposition of biological material influences how much carbon returns to the atmosphere.
These processes can create feedback loops that help keep the climate within a broad range. A warmer climate, for example, can accelerate some forms of chemical weathering, potentially increasing the removal of carbon dioxide and counteracting warming over long periods. Changes in ocean circulation, ice cover, vegetation and marine productivity can also alter the movement and storage of carbon. Such feedbacks may produce persistent regimes—long-lived combinations of atmospheric composition, temperature and carbon-cycle behavior.
The danger emerges when those stabilizing relationships weaken or when the system is pushed beyond a critical boundary. A transition between regimes can involve changes in the dominant feedbacks controlling climate and carbon storage. Once the system begins to reorganize, environmental conditions may shift in ways that are difficult for ecosystems to track. Temperature, ocean acidity, oxygen availability and habitat distribution can all change together, creating compound stress rather than a single isolated threat.
This distinction is important because ecosystems can sometimes withstand severe conditions if they develop gradually or remain geographically limited. A rapid transition, however, can outpace adaptation and migration. Species may face simultaneous losses of habitat, disrupted food webs and physiological stress. Marine organisms sensitive to ocean chemistry could be affected by acidification, while animals and plants on land may be squeezed between shifting temperature zones and changing precipitation patterns. The study’s central message is that biological vulnerability may peak during instability itself—the interval when Earth is leaving one persistent state and entering another.
By examining climate–carbon behavior across the Phanerozoic, the researchers connected these transitions with intervals of elevated biosphere vulnerability recorded in Earth’s geological history. The approach places past extinction and ecological disruption within a broader dynamical framework. Rather than viewing each crisis as an entirely separate event, the analysis suggests that many episodes of biological stress may share a common characteristic: the climate–carbon system was undergoing a major reorganization.
The results do not imply that every modern climate shift will produce an extinction on the scale of the largest events in the fossil record. Ancient transitions unfolded under conditions very different from those of today, and geological records are incomplete. However, the study offers a warning about how climate risk should be interpreted. A planet can appear relatively stable for a time while accumulating pressures that eventually trigger a nonlinear response. Once a threshold is crossed, environmental change may accelerate or move into a new pattern that is more difficult to reverse.
That perspective adds urgency to current concerns about human-driven carbon emissions. Modern society is rapidly altering atmospheric carbon dioxide concentrations, ocean chemistry and global temperatures over decades to centuries—a pace far faster than many natural geological processes. The new research does not provide a direct forecast of a specific future tipping point, but it reinforces the importance of studying Earth’s climate as a connected system rather than as a collection of independent variables. The fossil record suggests that the most dangerous moments for life may occur when long-standing climate–carbon relationships break down. Understanding those transitions could help scientists identify early warning signals and better assess the vulnerability of the biosphere in a rapidly changing world.
Subject of Research: The relationship between transitions in persistent Phanerozoic climate–carbon regimes and vulnerability of the biosphere.
Article Title: “Transitions between persistent climate–carbon regimes coincide with elevated Phanerozoic biosphere vulnerability.”
Article References: Sudakow, I., Myers, C., Spiridonov, A. et al. “Transitions between persistent climate–carbon regimes coincide with elevated Phanerozoic biosphere vulnerability.” Nature Communications 17, 7559 (2026). https://doi.org/10.1038/s41467-026-75655-9
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41467-026-75655-9
Keywords: Phanerozoic Eon, climate–carbon regimes, carbon cycle, biodiversity, biosphere vulnerability, mass extinction, climate transitions, Earth system, tipping points, paleoclimate
