Preprints
https://doi.org/10.5194/egusphere-2022-184
https://doi.org/10.5194/egusphere-2022-184
 
22 Apr 2022
22 Apr 2022
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

Reconstructing Holocene temperatures in time and space using paleoclimate data assimilation

Michael P. Erb1, Nicholas P. McKay1, Nathan Steiger2,3, Sylvia Dee4, Chris Hancock1, Ruza F. Ivanovic5, Lauren J. Gregoire5, and Paul Valdes6 Michael P. Erb et al.
  • 1School of Earth and Sustainability, Northern Arizona University, Flagstaff, AZ, USA
  • 2Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA
  • 3Institute of Earth Sciences, Hebrew University, Jerusalem, Israel
  • 4Department of Earth, Environmental, and Planetary Sciences, Rice University, Houston, TX, USA
  • 5School of Earth and Environment, University of Leeds, Leeds, UK
  • 6School of Geographical Sciences, University of Bristol, Bristol, UK

Abstract. Paleoclimatic records provide valuable information about Holocene climate, revealing aspects of climate variability for a multitude of sites around the world. However, such data also possess limitations. Proxy networks are spatially uneven, seasonally biased, uncertain in time, and present a variety of challenges when used in concert to illustrate the complex variations of past climate. Paleoclimatic data assimilation provides one approach to reconstructing past climate that can account for the diverse nature of proxy records while maintaining the physics-based covariance structures simulated by climate models. Here, we use paleoclimate data assimilation to create a spatially-complete reconstruction of temperature over the past 12,000 years using proxy data from the Temperature 12k database and output from transient climate model simulations. Following the last glacial period, the reconstruction shows Holocene temperatures warming to a peak near 6,400 years ago followed by a slow cooling toward the present day, supporting a preindustrial global mean surface temperature maximum during the mid-Holocene. Sensitivity tests show that if proxies have an overlooked summer bias, some apparent mid-Holocene warmth could actually represent summer trends rather than annual mean trends. Regardless, the potential effects of proxy seasonal biases are insufficient to align reconstructed global mean temperature with the warming trends seen in transient model simulations.

Michael P. Erb et al.

Status: open (until 17 Jun 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Michael P. Erb et al.

Data sets

Holocene temperature reconstruction using paleoclimate data assimilation Michael P. Erb, Nicholas P. McKay, Nathan Steiger, Sylvia Dee, Chris Hancock, Ruza F. Ivanovic, Lauren J. Gregoire, and Paul Valdes https://doi.org/10.5281/zenodo.6426332

Model code and software

Code for the Holocene reconstruction Michael P. Erb and Nathan Steiger https://github.com/Holocene-Reconstruction/Holocene-code

Michael P. Erb et al.

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Short summary
To look at climate over the past 12000 years, we reconstruct spatial temperature using natural climate archives and information from model simulations. We see mild global mean warm around 6000 years ago, which differs somewhat from past reconstructions. If more of our data represents summer values, this could explains some of the observed temperature change, but it still wouldn't explain the large difference between many reconstructions and climate models over this period.