Abstract
Abstract. We use geothermal reconstruction of the ground surface temperature (GST) history early obtained in the Middle Urals to determine the surface heat flux (SHF) history over the past 35 kyr. A new algorithm of GST–SHF transformation was applied to solve this problem. The timescale of geothermal reconstructions has been corrected by comparing the estimated heat flux and annual insolation at the latitude of 60° N. The consistency of SHF and insolation changes on the interval 35–6 kyr BP with the linear correlation coefficient R = 0.99 points to orbital factors as the main cause of climatic changes during the Pleistocene–Holocene transition. The amplitude of SHF variations is about 1.3% of the insolation change amplitude. The increase of carbon dioxide concentrations lagged by 2–3 kyr from the SHF increase and occurred synchronously with GST changes.
Highlights
The role of orbital factors in Pleistocene climatic variations has been studied for more than 100 years since the works of Joseph Adhemar, James Croll and Milutin Milankovitch
There is a lag between external radiative flux and temperature changes, which disappears if we consider the heat content or the surface heat flux changes
Differentiating Eq (11) with respect to z, we find the ground surface heat flux change q(0,t):
Summary
The role of orbital factors in Pleistocene climatic variations has been studied for more than 100 years since the works of Joseph Adhemar, James Croll and Milutin Milankovitch. Some investigators (Peixóto and Oort, 1984; Pielke, 2003; Douglass and Knox, 2012) criticized this approach They noted that temperature field is not an optimal parameter for climate attribution, for evaluation of climatic reaction on the external radiative forcing. Wang and Bras (1999) proposed the integral relation to estimate surface heat flux (SHF) changes from ground surface temperature (GST) variations. SHF history reconstructions based on borehole temperature data were made on timescales from several centuries to a millennium (Beltrami et al, 2002, 2006; Huang, 2006). Another approach was used in Majorowicz et al (2012). Palaeoclimatic interpretation of GST and SHF histories is based on a comparison of them with orbitally driven solar insolation and atmospheric carbon dioxide changes
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