20 Dec 2021
20 Dec 2021
Status: a revised version of this preprint is currently under review for the journal CP.

Holocene climates of the Iberian Peninsula: pollen-based reconstructions of changes in the west-east gradient of temperature and moisture

Mengmeng Liu1, Yicheng Shen2, Penelope González-Sampériz3, Graciela Gil-Romera3, Cajo J. F. ter Braak4, Iain Colin Prentice1, and Sandy P. Harrison2 Mengmeng Liu et al.
  • 1Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK
  • 2Geography & Environmental Science, Reading University, Whiteknights, Reading, RG6 6AH, UK
  • 3Instituto Pirenaico de Ecología-CSIC, Avda. Montañana 1005, 50059, Zaragoza, Spain
  • 4Biometris (Applied Mathematics and Applied Statistics Centre), Wageningen University & Research, 6708 PB Wageningen, The Netherlands

Abstract. The Iberian Peninsula is characterised by a steep west-east moisture gradient today, reflecting the dominance of maritime influences along the Atlantic coast and more Mediterranean-type climate further east. Holocene pollen records from the Peninsula suggest that this gradient was less steep during the early to mid-Holocene, possibly reflecting the impact of orbital changes on circulation and thus regional patterns in climate. Here we use 7121 pollen samples from 117 sites covering part or all of the last 12,000 years to reconstruct changes in seasonal temperature and in moisture across the Iberian Peninsula quantitatively. We show that there is an increasing trend in winter temperature at a regional scale, consistent with known changes in winter insolation. However, summer temperatures do not show the decreasing trend through the Holocene that would be expected if they were a direct response to insolation forcing. We show that summer temperature is strongly correlated with plant-available moisture (α), as measured by the ratio of actual evapotranspiration to equilibrium evapotranspiration, which declines through the Holocene. The reconstructions also confirm that the west-east gradient in moisture was considerably less steep than today during the early to mid-Holocene, indicating that atmospheric circulation changes (possibly driven by orbital changes) have been important determinants of the Holocene climate of the region.

Mengmeng Liu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-174', Anonymous Referee #1, 30 Dec 2021
    • AC1: 'Reply on RC1', Mengmeng Liu, 13 Jan 2022
  • RC2: 'Comment on cp-2021-174', Anonymous Referee #2, 07 Feb 2022
    • AC2: 'Reply on RC2', Mengmeng Liu, 22 Feb 2022

Mengmeng Liu et al.

Data sets

Pollen data and charcoal data of the Iberian Peninsula Sandy Harrison, Yicheng Shen, Luke Sweeney

Model code and software

Iberia paper code Mengmeng Liu

Mengmeng Liu et al.


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Short summary
We reconstructed the Holocene climates in Iberian Peninsula using a large pollen dataset and found that the west-east moisture gradient was much flatter than today. We also found that the winter was much colder, which can be expected from the low winter insolation during the Holocene. However, summer temperature didn’t follow the trend of summer insolation, instead, it was strongly correlated with moisture.