• Energy Research

Abstract The potential for explosive volcanism to affect the state of the El Niño-Southern Oscillation (ENSO) has been debated since the1980s. Several observational studies, largely based on tree rings, have since found support for a positive ENSO phase in the year following large eruptions. Models of different complexities also simulate such a response, detectable above the backdrop of internal variability – though they disagree on the underlying mechanisms. In contrast, recent coral data from the heart of the tropical Pacific suggest no uniform ENSO response to all eruptions over the last millennium. Here we leverage paleoclimate data assimilation to integrate the latest paleoclimate evidence into a consistent dynamical framework and re-appraise this relationship. Our analysis finds only a weak statistical association between volcanism and ENSO, suggestive of either no causal association, or of an insufficient number of large volcanic events over the past millennium to obtain reliable statistics. While currently available observations do not support the model-based inference that tropical eruptions promote an ENSO response, there are hints of a response to hemispherically asymmetric forcing, consistent with the "ITCZ shift" mechanism. We discuss the difficulties of conclusively establishing a volcanic influence on ENSO given the many degrees of freedom affecting the response, including eruption season, spatial characteristics of the forcing, and ENSO phase preconditioning.

AbstractThe progress of science is tied to the standardization of measurements, instruments, and data. This is especially true in the Big Data age, where analyzing large data volumes critically hinges on the data being standardized. Accordingly, the lack of community‐sanctioned data standards in paleoclimatology has largely precluded the benefits of Big Data advances in the field. Building upon recent efforts to standardize the format and terminology of paleoclimate data, this article describes the Paleoclimate Community reporTing Standard (PaCTS), a crowdsourced reporting standard for such data. PaCTS captures which information should be included when reporting paleoclimate data, with the goal of maximizing the reuse value of paleoclimate data sets, particularly for synthesis work and comparison to climate model simulations. Initiated by the LinkedEarth project, the process to elicit a reporting standard involved an international workshop in 2016, various forms of digital community engagement over the next few years, and grassroots working groups. Participants in this process identified important properties across paleoclimate archives, in addition to the reporting of uncertainties and chronologies; they also identified archive‐specific properties and distinguished reporting standards for new versus legacy data sets. This work shows that at least 135 respondents overwhelmingly support a drastic increase in the amount of metadata accompanying paleoclimate data sets. Since such goals are at odds with present practices, we discuss a transparent path toward implementing or revising these recommendations in the near future, using both bottom‐up and top‐down approaches.

AbstractReproducible 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.