Collaborative Research: P2C2--A Model/Proxy Synthesis of Walker Circulation Trends During the Last Millennium

点击翻译按钮获取中文摘要

The Pacific Walker circulation alters weather and climate extremes around the world, but its sensitivity to external climate forcings remains unknown. In particular, observational estimates of 20th century trends in the Walker circulation provide conflicting results, with some suggesting a strengthening and others a weakening or no trend, complicating the attribution of these trends to any specific forcing. Paleoclimate records can improve the detection and attribution of trends by providing longer-term context, but their use has been hindered by the lack of multi-proxy synthesis products and climate model simulations covering the last millennium. This project aims to create new quantitative reconstructions of multiple Walker circulation metrics using the recently constructed PAGES Iso2k database, and to evaluate the mechanisms for variability and trends in these metrics using the Community Earth System Model Last Millennium Ensemble (LME) and new simulations with its isotope-enabled complement (iLME). The research seeks to apply these new tools to answer one central question: What are the mechanisms underlying Walker circulation variability and trends from the Last Millennium through the 20th century, and what are the relative roles of external forcings and internal variability?The potential Broader Impacts (B.I.) includes strong science and educational aspects. Climate variability in the tropical Pacific affects societies and ecosystems; understanding long-term variability of the Walker circulation is thus critical for improving projections of the impacts of 21st century climate change. This scientifically-interdisciplinary research team is composed entirely of early-career researchers, two of whom are female. The project will support a graduate student and postdoctoral researcher. High school students from underrepresented demographics will be recruited for summer internships and mentoring through a program that targets diversity in STEM. Finally, the project will produce multi-proxy synthesis reconstructions of tropical Pacific climate variability and iLME ensemble members, all of which will be made available as resources to the wider scientific and civil communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.