Genming Luo

Deep-time hyperthermal/transient warming events provide critical analogs for modern climatic warming and its impacts. However, all ancient hyperthermals documented to date have occurred under greenhouse climate states, limiting their relevance for understanding the trajectory of present-day climate change. Here, we present conodont oxygen isotope data and climate modeling for the Kasimovian–Gzhelian Thermal Maximum (KGTM) at ~304 Ma. This transient warming event is inferred to have been marked by a ~7.5 ± 1 °C rise in global mean surface temperature and an increase in atmospheric CO ₂ concentrations from ~ 300 -50 +100 to ~700 ± 100 ppm over ~175 kyr during the Late Paleozoic Ice Age. Carbon and mercury isotope records indicate large-scale carbon release and the development of photic-zone euxinia during the KGTM, coincident with a marine biocrisis. The KGTM was initiated by a modest carbon release and temperature increase potentially associated with enhanced volcanic activity at an orbital eccentricity maximum, which likely crossed a climatic tipping point and triggered massive carbon release and abrupt large-scale warming. These findings demonstrate that transient warming events and severe oceanic deterioration can be caused by a modest thermal perturbation within an icehouse climate state analogous to that of the modern Earth.

Millennial‐scale events of the last glaciation profoundly reorganized global climate, yet the terrestrial temperature response in East Asia remains debated due to the seasonal biases and calibration uncertainties inherent in biological proxies. To address this, we present a carbonate clumped isotope (Δ ₄₇ ) record from a central Chinese speleothem spanning the Last Glacial Maximum (LGM) and Heinrich Stadial 1 (HS1). Supported by petrographic and trace element evidence for negligible kinetic effects, our temperature record from the thermally buffered cave provides a robust reconstruction of mean annual temperature. We identify a ∼6°C cooling compared to the present during the LGM, intensified by an additional ∼2°C cooling during HS1. These results contradict warming signals found in precious study but align with iTraCE simulations, which attribute HS1 cooling to severe winter temperature drops partially offset by insolation‐driven summer warming. Our findings reconcile current proxy–model temperature discrepancies and improve the climatic interpretation of speleothem δ ¹⁸ O during Heinrich stadials.

The great phytoplanktonic shift from green to red plastid lineage dominance in the early Mesozoic marks a primary producer revolution in marine ecosystems, facilitating the rise of modern ecosystems and impacting global carbon cycling and energy flows. The causes driving this evolutionary transition have been attributed to the changes in essential nutrients and the environmental crises of the Permian–Triassic mass extinction. Nonetheless, the underlying mechanisms driving this transition remain poorly understood. Here, we integrated culture experiments, molecular and physiological analyses, big data analysis, and phylogenomic dating analyses to uncover how environmental stresses influence algal physiology, thereby altering their evolutionary trajectories. We find that environmental and endogenous reactive oxygen species (ROS) collaboratively shape phytoplanktonic responses. The structural characteristics of red lineage phytoplankton enhance resistance to environmental ROS, facilitating physiological strategies that minimize endogenous ROS accumulation, thereby driving more adaptive evolutionary trajectories under environmental stresses in the early Mesozoic. The alignment of the turnover in diversification dynamics between the two lineages with paleoenvironmental shifts that triggered increased ROS production supports the role of ROS in driving this evolutionary transition. Our findings highlight ROS as a key underlying factor driving phytoplankton evolution, providing predictive insights into major biota–environment coevolutions throughout Earth’s history.

《地球科学》(ISSN 1000-2383;CN42-1874/P) (原刊名《地球科学——中国地质大学学报》ISSN 1000-2383;CN42-1233/P)，创刊于1957年，是由教育部主管、中国地质大学主办的综合性地学学术理论期刊，月刊，2015年改名为《地球科学》,她以反映中国地质大学教学与科研最新的、高水平的基础地质、应用地质、资源与环境地质及地学工程技术研究成果为主要任务。

Methane (CH ₄ ) is a potent greenhouse gas but also an important carbon and energy substrate for some lake food webs. Understanding how CH ₄ incorporates into food webs is, therefore, crucial for unraveling CH ₄ cycling and its impacts on climate and ecosystems. However, CH ₄ -fueled lake food webs from pre-Holocene intervals, particularly during greenhouse climates in Earth history, have received relatively little attention. Here, we present a long-term record of CH ₄ -fueled pelagic food webs across the Cretaceous Oceanic Anoxic Event 1a (~120 Mya) that serves as a geological analog to future warming. We show an exceptionally strong expansion of both methanogens and CH ₄ -oxidizing bacteria (up to 87% of hopanoid-producing bacteria) during this Event. Grazing on CH ₄ -oxidizing bacteria by zooplankton (up to 47% of ciliate diets) within the chemocline transferred substantial CH ₄ -derived carbon to the higher trophic levels, representing an important CH ₄ sink in the water column. Our findings suggest that as Earth warms, microbial CH ₄ cycling could restructure food webs and fundamentally alter carbon and energy flows and trophic pathways in lake ecosystems.

The geobiological cycle of nitrogen is a coupling of the biogeochemical and geological cycles of nitrogen, which provides insights into the interactions between life and the environment and the evolution of Earth systems. The partial pressure of atmospheric nitrogen (p N₂) is a principal proxy for understanding the evolutionary history of the global geobiological cycle of nitrogen, and is also a potential biosignature of extraterrestrial life detection. Thus, it is of great significance to reconstruct the geological evolution of p N₂. In this article, the primary nitrogen reservoirs on Earth are summarized, and the processes, affecting factors and evolutionary stages of the nitrogen geobiological cycle are discussed from the perspective of nitrogen biogeochemical and geological cycles. On this basis, this article further reviews the current knowledge of the evolutionary history of p N₂ and its possible influencing factors. Finally, I raise some key issues that have to be addressed in the future.

The invisible microbes are the main components of the biosphere and proliferated in many mass extinctions of animals. Whether the proliferation of microbes was an accomplice or a savior of the mass extinction remains uncertain. Future work has to quantify the dual effects of microbes on the environment.