In the dynamic arena of Earth’s climatic evolution, the role of volcanic activity has long been considered a pivotal driver of global temperature fluctuations. A recent groundbreaking study by Longman, Mills, and Merdith, published in Nature Communications in 2025, offers a compelling reassessment of the long-term climatic impacts of one of the most colossal volcanic episodes in Earth’s history: the Pangaean flood basalt eruptions. Their research challenges long-standing notions that the weathering of these vast basaltic provinces induced significant prolonged global cooling, reshaping our understanding of ancient climate regulation mechanisms.
The phenomenon under scrutiny involves flood basalts, immense lava flows that can stretch for hundreds of thousands of square kilometers and persist erupting for millions of years. These basaltic provinces, abundant in the supercontinent Pangaea’s late Paleozoic and early Mesozoic landscapes, have historically been linked to dramatic environmental transformations. Traditional hypotheses have posited that their weathering accelerated the drawdown of atmospheric carbon dioxide (CO2), thereby driving sustained global cooling periods that could have influenced mass extinctions and the rearrangement of ecosystems.
Longman and colleagues’ meticulous analysis integrates multidisciplinary geological records with refined geochemical modeling to quantify the scale and rate of chemical weathering of Pangaean flood basalts. Their findings indicate that while flood basalt weathering did contribute to CO2 sequestration, the magnitude and duration of its cooling effect on the global climate system were considerably less than previously estimated. This nuanced perspective urges a re-evaluation of proxy data interpretations and encourages skepticism toward simplifying complex Earth system feedbacks.
The research deploys state-of-the-art isotopic tracing techniques combined with sedimentary analysis to reconstruct paleo-weathering rates more accurately. Unlike prior studies that relied predominantly on bulk geochemical proxies, this approach disentangles multiple drivers influencing isotopic signatures, such as volcanic outgassing and continental erosion. The result is a refreshed understanding of how basalt weathering operated under the specific tectonic and atmospheric conditions of the late Paleozoic and early Mesozoic eras.
One central outcome of the study is the realization that the CO2 consumption by basalt weathering was somewhat counterbalanced by the concurrent volcanic CO2 emissions from active eruptive phases. This coeval balance maintained a relatively stable greenhouse gas concentration, moderating temperature swings rather than enforcing a steep long-term cooling trend. Such insights highlight the complex interplay between volcanic degassing and silicate weathering feedback loops and implicate other mechanisms, such as organic carbon burial or tectonically driven sea level changes, in shaping the climate trajectory.
Excavating deeper, the authors compare the weathering intensity of Pangaean flood basalts with more recent large igneous provinces (LIPs), such as the Siberian Traps and Deccan Traps, known for their links to catastrophic climate events. Their comparative analysis suggests a heterogeneous climatic influence governed by regional environmental factors, eruptive volume, and prevailing atmospheric compositions rather than a simplistic uniform effect. This context places constraints on utilizing flood basalt weathering as a universal climate driver and impels climate models to assimilate localized geochemical complexities.
In addition to climatological implications, the study delves into the geochemical cycling of elements mobilized by basalt weathering, such as calcium, magnesium, and silica, which interact with ocean chemistry and biological productivity. The researchers elucidate how these processes modulated seawater alkalinity and carbon cycling, indirectly influencing atmospheric CO2 levels and marine ecosystem dynamics over geological timescales. Such findings underscore the interconnectedness of terrestrial weathering processes and ocean-atmosphere chemistry in the Earth system.
This fresh perspective also carries profound repercussions for interpreting early Mesozoic environmental conditions. For decades, global cooling episodes have been invoked to explain shifts observed in fossil assemblages and sedimentary facies. With the diminished role of basalt weathering-induced cooling proposed here, paleoclimatologists and paleoecologists may need to reorient their hypotheses to emphasize alternative climatic or tectonic triggers, including changes in solar insolation, ocean circulation patterns, or the episodic release of methane from clathrate reservoirs.
The study harnesses a sophisticated coupled climate-geochemical model that integrates new kinetic parameters for basalt dissolution rates calibrated from field and laboratory data. This model simulates realistic CO2 fluxes and climate feedbacks over the tens-of-million-year lifespan of the flood basalt provinces. By running multiple sensitivity analyses, the authors robustly demonstrate the limited cooling potential, reflecting a system more resilient to perturbations from volcanic weathering than previously considered. This approach sets a new standard for future Earth system modeling endeavors.
Geological field investigations conducted in key Pangaean flood basalt localities provide invaluable ground truth for the researchers’ assertions. Sampling profiles and stratigraphic correlations reveal spatial heterogeneity in weathering profiles, partly controlled by age, mineralogy, and prevailing climatic regimes at the time. This spatial variability contributes additional complexity governing the net effect of basalt weathering on the global carbon cycle and by extension, climate, cautioning against oversimplified global extrapolations based on limited local data.
Importantly, the investigators highlight that short-term climate perturbations triggered by flood basalt volcanism—such as transient warming episodes caused by CO2 and sulfur gas emissions—may have overshadowed any subsequent slow cooling driven by weathering feedbacks. These pulse-like disturbances could have dominated the biotic and atmospheric response, complicating efforts to isolate subtle long-term trends registered in the geologic record. This insight invites renewed scrutiny into temporal resolution limits of paleoclimate proxies and their ability to detect overlapping climatic forcings.
Beyond the geological past, the study resonates with contemporary climate research debates. Understanding the efficacy and timescale of silicate weathering feedbacks remains crucial for predicting Earth’s future carbon cycle responses in a warming world. By elucidating the constrained climatic impact of flood basalt weathering over millions of years, this work cautions against overestimating natural carbon sinks and underscores the persistent influence of anthropogenic emissions on current climate trajectories.
Environmental scientists may find this research instrumental in refining carbon cycle models that underpin global climate change assessments. Its emphasis on coupled feedback mechanisms aligns with the growing consensus that Earth’s climate system behaves as a complex and non-linear entity, sensitive to multiple interacting forcings rather than dominated by a single process. This conceptual advance helps reconcile discrepancies between proxy reconstructions and model simulations of past climate states.
While the new findings do not negate the importance of large igneous provinces in Earth’s climatic history, they advocate for a more differentiated and comprehensive interpretation of their roles. Particularly, the study illuminates how the timing, duration, and geochemical conditions of flood basalt weathering episodes modulate their climatic signatures, reinforcing the need for multidisciplinary approaches combining fieldwork, geochemistry, and advanced modeling tools.
In contextualizing the present work within the broader scientific discourse, Longman and colleagues confront the prevailing paradigm that considered Pangaean flood basalt weathering a primary driver of long-term cooling. Their rigorous methodological framework and nuanced conclusions will likely reverberate across Earth system sciences, prompting reexaminations of past global crises and invigorating future research directions aimed at unraveling the intricate feedbacks that govern planetary climate dynamics.
Ultimately, this landmark study contributes a pivotal piece to the puzzle of Earth’s climatic evolution, demonstrating that volcanic weathering, while an important component of the carbon cycle, exerts only a limited long-term cooling influence following flood basalt episodes. By reframing our understanding of these ancient volcanic giants, it empowers scientists to ask deeper questions about the Earth’s resilience and vulnerabilities in the face of natural perturbations.
Subject of Research: Climatic impacts of flood basalt weathering during the Pangaean period and its influence on long-term global cooling.
Article Title: Limited long-term cooling effects of Pangaean flood basalt weathering.
Article References:
Longman, J., Mills, B.J.W. & Merdith, A.S. Limited long-term cooling effects of Pangaean flood basalt weathering. Nat Commun 16, 4813 (2025). https://doi.org/10.1038/s41467-025-59480-0
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