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Jesper Sjolte

Jesper Sjolte

Researcher

Jesper Sjolte

The influence of external forcing on subdecadal variability of regional surface temperature in CMIP5 simulations of the last millennium

Author

  • Thanh Le
  • Jesper Sjolte
  • Raimund Muscheler

Summary, in English

We use Granger causality to investigate the influences of external forcings on subdecadal variability of regional near-surface air temperature (SAT) in past millennium simulations (period 850–1850 A.D.) of the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Our results strengthen the conclusion for robust influence of volcanic forcing on SAT during preindustrial times of the last millennium. The SAT response to solar variations is detected in tropical and subtropical regions. In other regions, this response is weak. The impact of greenhouse gases (GHGs) radiative forcing to regional SAT is weak and uncertain. This is most probably due to the low amplitude of the variations in GHGs and hence weak GHGs forcing during the preindustrial millennium. The low agreement between models in simulating the impacts of solar variations on SAT in several regions suggests the different dynamical responses in these models, possibly associated with inaccurate parameterization of the processes related to solar forcing. Our analysis suggests that internal climate variability played a more significant role than external forcings in short-term SAT variability in the regions of the North Atlantic, the North Pacific, the Arctic, the Antarctic Peninsula, and its surrounding oceans. The possibility of long-term impacts of external forcings on SAT and the uncertainties that might be contained due to effects of internal climate modes other than El Niño–Southern Oscillation underscore the necessity for a more detailed understanding of the dynamical response of SAT to external forcings.

Department/s

  • Quaternary Sciences
  • MERGE: ModElling the Regional and Global Earth system
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2016-02-27

Language

English

Pages

1671-1682

Publication/Series

Journal of Geophysical Research: Atmospheres

Volume

121

Issue

4

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Climate Research

Status

Published

ISBN/ISSN/Other

  • ISSN: 2169-8996