Coupling of surface temperatures and atmospheric CO_2 concentrations during the Palaeozoic era

Atmospheric carbon dioxide concentrations seem to have been several times modern levels during much of the Palaeozoic era (543–248 million years ago), but decreased during the Carboniferous period to concentrations similar to that of today. Given that carbon dioxide is a greenhouse gas, it has been proposed that surface temperatures were significantly higher during the earlier portions of the Palaeozoic era. A reconstruction of tropical sea surface temperatures based on the δ^(18)O of carbonate fossils indicates, however, that the magnitude of temperature variability throughout this period was small, suggesting that global climate may be independent of variations in atmospheric carbon dioxide concentration. Here we present estimates of sea surface temperatures that were obtained from fossil brachiopod and mollusc shells using the 'carbonate clumped isotope' method—an approach that, unlike the δ^(18)O method, does not require independent estimates of the isotopic composition of the Palaeozoic ocean. Our results indicate that tropical sea surface temperatures were significantly higher than today during the Early Silurian period (443–423 Myr ago), when carbon dioxide concentrations are thought to have been relatively high, and were broadly similar to today during the Late Carboniferous period (314–300 Myr ago), when carbon dioxide concentrations are thought to have been similar to the present-day value. Our results are consistent with the proposal that increased atmospheric carbon dioxide concentrations drive or amplify increased global temperatures

Data Descriptor: A global multiproxy database for temperature reconstructions of the Common Era

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.(TABLE)Since the pioneering work of D'Arrigo and Jacoby1-3, as well as Mann et al. 4,5, temperature reconstructions of the Common Era have become a key component of climate assessments6-9. Such reconstructions depend strongly on the composition of the underlying network of climate proxies10, and it is therefore critical for the climate community to have access to a community-vetted, quality-controlled database of temperature-sensitive records stored in a self-describing format. The Past Global Changes (PAGES) 2k consortium, a self-organized, international group of experts, recently assembled such a database, and used it to reconstruct surface temperature over continental-scale regions11 (hereafter, ` PAGES2k-2013').This data descriptor presents version 2.0.0 of the PAGES2k proxy temperature database (Data Citation 1). It augments the PAGES2k-2013 collection of terrestrial records with marine records assembled by the Ocean2k working group at centennial12 and annual13 time scales. In addition to these previously published data compilations, this version includes substantially more records, extensive new metadata, and validation. Furthermore, the selection criteria for records included in this version are applied more uniformly and transparently across regions, resulting in a more cohesive data product.This data descriptor describes the contents of the database, the criteria for inclusion, and quantifies the relation of each record with instrumental temperature. In addition, the paleotemperature time series are summarized as composites to highlight the most salient decadal-to centennial-scale behaviour of the dataset and check mutual consistency between paleoclimate archives. We provide extensive Matlab code to probe the database-processing, filtering and aggregating it in various ways to investigate temperature variability over the Common Era. The unique approach to data stewardship and code-sharing employed here is designed to enable an unprecedented scale of investigation of the temperature history of the Common Era, by the scientific community and citizen-scientists alike

Beyond equilibrium climate sensitivity

ISSN:1752-0908ISSN:1752-089

The end-Permian mass extinction: A rapid volcanic CO2 and CH4 – climatic catastrophe

The end of the Permian was a time of crisis that culminated in the Earth's greatest mass extinction. There is much speculation as to the cause for this catastrophe. Here we provide a full suite of high-resolution and coeval geochemical results (trace and rare earth elements, carbon, oxygen, strontium and clumped isotopes) reflecting ambient seawater chemistry and water quality parameters leading up to the end-Permian crisis. Preserved brachiopod low-Mg calcite-based seawater chemistry, supplemented by data from various localities, documents a sequence of interrelated primary events such as coeval flows of Siberian Trap continental flood basalts and emission of carbon dioxide leading to warm and extreme Greenhouse conditions with sea surface temperatures (SST) of ~36 °C for the Late Permian. Although anoxia has been advanced as a cause for the mass extinction, most biotic and geochemical evidence suggest that it was briefly relevant during the early phase of the event and only in areas of upwelling, but not a general cause. Instead, we suggest that renewed and increased end-Permian Siberian Trap volcanic activity, about 2000 years prior to the extinction event, released massive amounts of carbon dioxide and coupled with thermogenic methane emissions triggered extremeglobal warming and increased continentalweathering. Eventually, these rapidly discharged greenhouse gas emissions, less than 1000 years before the event, ushered in a global Hothouse period leading to extreme tropical SSTs of ~39 °C and higher. Based on these sea surface temperatures, atmospheric CO2 concentrations were about 1400 ppmv and 3000 ppmv for the Late and end-Permian, respectively. Leading up to the mass extinction, there was a brief interruption of the global warming trend when SST dropped, concurrent with a slight, but significant recovery in biodiversity in thewestern Tethys. It is possible that emission of volcanic sulphate aerosols resulted in brief cooling just after the onset of intensified warming during the end of the Permian. After aerosol deposition, global warming resumed and the biotic decline proceeded, and was accompanied by suboxia, in places of the surface ocean which culminated in the greatest mass extinction in Earth histor

The end-Permian mass extinction : a rapid volcanic CO2 and CH4 – climatic catastrophe

The end of the Permian was a time of crisis that culminated in the Earth\u2019s greatest mass extinction. There is much speculation as to the cause for this catastrophe. We provide a full suite of high-resolution and coeval chemical results (trace and rare earth elements, carbon, oxygen, strontium and clumped isotopes) reflecting ambient seawater chemistry and water quality parameters leading up to the end \u2013 Permian crisis. Preserved brachiopod low-Mg calcite-based seawater chemistry, supplemented by data from various localities, documents a sequence of interrelated primary events such as coeval flows of Siberian Trap continental flood basalts and emission of carbon dioxide leading to warm and extreme Greenhouse conditions with sea surface temperatures (SST) of ~ 36\ub0C for the Late Permian, and followed by increased continental weathering. Although anoxia has been touted as a cause for the mass extinction, most biotic and geochemical evidence suggests that it was briefly relevant during the early phase of the event and in areas of upwelling, but not a cause of it. Instead, renewed and increased end of the Permian Siberian Trap volcanic activity, about 2,000 years prior to the event, released massive amounts of carbon dioxide and aided by methane emissions triggered extreme global warming and continental acid precipitation. Eventually, these rapidly discharged greenhouse gas emissions, less than 1,000 years before the event, ushered in a global Hothouse period leading to extreme tropical SSTs of ~ 39\ub0C and higher. Based on actual sea surface temperatures, atmospheric CO2 concentrations were about 1400 ppmv and 3000 ppmv for the Late and end \u2013 Permian, respectively. The most elevated atmospheric CO2 level, about 1,500 years before the end \u2013 Permian event, lead to increased acid precipitation and triggered massive continental weathering and soil erosion. Leading up to the mass extinction, there was a brief interruption of the global warming trend when SST dropped by about 5\ub0C concurrent with a slight but significant recovery in biodiversity in the western Tethys. It is postulated that emission of volcanic sulphate aerosols brought about the brief cooling just after the onset of intensified warming during the end of the Permian. With aerosol deposition, global warming resumed and the biotic decline proceeded, and was accompanied by collapse of the thermohaline circulation and suboxia, in places, of the surface ocean, destabilization of marine and terrestrial foodchains, in part through enhanced acid precipitation and continental weathering-erosion, and eventual ecosystem collapse accelerated by hypercapnia during the end of the Permian, culminating in the greatest mass extinction in Earth history

The end‐Permian mass extinction: A rapid volcanic CO2 and CH4‐climatic catastrophe

The end of the Permian was a time of crisis that culminated in the Earth's greatest mass extinction. There is much speculation as to the cause for this catastrophe. Here we provide a full suite of high-resolution and coeval geochemical results (trace and rare earth elements, carbon, oxygen, strontium and clumped isotopes) reflecting ambient seawater chemistry and water quality parameters leading up to the end‐Permian crisis. Preserved brachiopod low-Mg calcite-based seawater chemistry, supplemented by data from various localities, documents a sequence of interrelated primary events such as coeval flows of Siberian Trap continental flood basalts and emission of carbon dioxide leading to warm and extreme Greenhouse conditions with sea surface temperatures (SST) of ~36 °C for the Late Permian. Although anoxia has been advanced as a cause for the mass extinction, most biotic and geochemical evidence suggest that it was briefly relevant during the early phase of the event and only in areas of upwelling, but not a general cause. Instead, we suggest that renewed and increased end‐Permian Siberian Trap volcanic activity, about 2000 years prior to the extinction event, released massive amounts of carbon dioxide and coupled with thermogenic methane emissions triggered extremeglobal warming and increased continentalweathering. Eventually, these rapidly discharged greenhouse gas emissions, less than 1000 years before the event, ushered in a global Hothouse period leading to extreme tropical SSTs of ~39 °C and higher. Based on these sea surface temperatures, atmospheric CO2 concentrations were about 1400 ppmv and 3000 ppmv for the Late and end‐Permian, respectively. Leading up to the mass extinction, there was a brief interruption of the global warming trend when SST dropped, concurrent with a slight, but significant recovery in biodiversity in the western Tethys. It is possible that emission of volcanic sulfate aerosols resulted in brief cooling just after the onset of intensified warming during the end of the Permian. After aerosol deposition, global warming resumed and the biotic decline proceeded, and was accompanied by suboxia, in places of the surface ocean which culminated in the greatest mass extinction in Earth history