Toward a Cenozoic history of atmospheric CO.

The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions, degree of understanding, and even reconstructed values. In this study, we critically evaluated, categorized, and integrated available proxies to create a high-fidelity and transparently constructed atmospheric CO record spanning the past 66 million years.

Quantifying climate conditions for the formation of coals and evaporites.

Coals and evaporites are commonly used as qualitative indicators of wet and dry environments in deep-time climate studies, respectively. Here, we combine geological records with climate simulations to establish quantitative relationships of coals and evaporites with temperature and precipitation over the Phanerozoic. We show that coal records were associated with a median temperature of 25°C and precipitation of 1300 mm yr before 250 Ma.

Short-term paleogeographic reorganizations and climate events shaped diversification of North American freshwater gastropods over deep time.

What controls species diversity and diversification is one of the major questions in evolutionary biology and paleontology. Previous studies have addressed this issue based on various plant and animal groups, geographic regions, and time intervals. However, as most previous research focused on terrestrial or marine ecosystems, our understanding of the controls on diversification of biota (and particularly invertebrates) in freshwater environments in deep time is still limited.

Continental configuration controls ocean oxygenation during the Phanerozoic.

The early evolutionary and much of the extinction history of marine animals is thought to be driven by changes in dissolved oxygen concentrations ([O]) in the ocean. In turn, [O] is widely assumed to be dominated by the geological history of atmospheric oxygen (pO). Here, by contrast, we show by means of a series of Earth system model experiments how continental rearrangement during the Phanerozoic Eon drives profound variations in ocean oxygenation and induces a fundamental decoupling in time between upper-ocean and benthic [O].

Dataset of Phanerozoic continental climate and Köppen-Geiger climate classes.

This article describes a suite of global climate model output files that provide continental climatic conditions (monthly temperatures, precipitation, evaporation, precipitation minus evaporation balance, runoff) together with the calculated Köppen-Geiger climate classes and topography, for 28 evenly spaced time slices through the Phanerozoic (Cambrian to Quaternary, 540 Ma to 0 Ma). Climatic variables were simulated with the Fast Ocean Atmosphere Model (FOAM), using a recent set of open-access continental reconstructions with paleotopography and recent atmospheric CO and solar luminosity estimates. FOAM is a general circulation model frequently used in paleoclimate studies, especially in the Palaeozoic.

Drivers of diversification in freshwater gastropods vary over deep time.

Unravelling the drivers of species diversification through geological time is of crucial importance for our understanding of long-term evolutionary processes. Numerous studies have proposed different sets of biotic and abiotic controls of speciation and extinction rates, but typically they were inferred for a single, long geological time frame. However, whether the impact of biotic and abiotic controls on diversification changes over time is poorly understood.

Increase in marine provinciality over the last 250 million years governed more by climate change than plate tectonics.

Amidst long-term fluctuations of the abiotic environment, the degree to which life organizes into distinct biogeographic provinces (provinciality) can reveal the fundamental drivers of global biodiversity. Our understanding of present-day biogeography implies that changes in the distribution of continents across climatic zones have predictable effects on habitat distribution, dispersal barriers and the evolution of provinciality. To assess marine provinciality through the Phanerozoic, here we (a) simulate provinces based on palaeogeographic reconstructions and global climate models and (b) contrast them with empirically derived provinces that we define using network analysis of fossil occurrences.

Quantitative comparison of geological data and model simulations constrains early Cambrian geography and climate.

Marine ecosystems with a diverse range of animal groups became established during the early Cambrian (~541 to ~509 Ma). However, Earth's environmental parameters and palaeogeography in this interval of major macro-evolutionary change remain poorly constrained. Here, we test contrasting hypotheses of continental configuration and climate that have profound implications for interpreting Cambrian environmental proxies.

Elevated CO degassing rates prevented the return of Snowball Earth during the Phanerozoic.

The Cryogenian period (~720-635 Ma) is marked by extensive Snowball Earth glaciations. These have previously been linked to CO draw-down, but the severe cold climates of the Cryogenian have never been replicated during the Phanerozoic despite similar, and sometimes more dramatic changes to carbon sinks. Here we quantify the total CO input rate, both by measuring the global length of subduction zones in plate tectonic reconstructions, and by sea-level inversion.