800-kyr land temperature variations modulated by vegetation changes on Chinese Loess Plateau

Abstract

The complicity of long-term land surface temperature (LST) changes has been under investigated and less understood, hindering our understanding of the history and mechanism of terrestrial climate change. Here, we report the longest (800 thousand years) LSTs based on distributions of soil fossil bacterial glycerol dialkyl glycerol tetraethers preserved in well-dated loess-paleosol sequences at the center of the Chinese Loess Plateau. We have found a previously-unrecognized increasing early and prolonged warming pattern toward the northwestern plateau at the onset of the past seven deglaciations, corresponding to the decrease in vegetation coverage, suggesting underlying surface vegetation or lack of has played an important role in regulating LSTs, superimposed on the fundamental global glacial–interglacial changes. Our results support that LSTs in semi-humid and semi-arid regions with little vegetation will be more sensitive to the anticipated global temperature rise, while improving vegetation coverage would reduce LSTs and thus ecological impacts.

Atmospheric Dust Variations in the Ili Basin, Northwest China, During the Last Glacial Period as Revealed by a High Mountain Loess‐Paleosol Sequence

“…Sweeney and Mason () suggested that loess sediments were easily entrained and resuspended under the conditions of sparse vegetation. Total organic carbon (TOC) contents were used as an indicator of vegetation cover on the CLP (Lu et al, ), proposed to reflect vegetation cover history and biomass variations (Zhang & Liu, ). The total organic carbon‐inferred vegetation cover varied in parallel with the monsoon intensity indicators such as magnetic susceptibility (Lu et al, ).…”

“…Total organic carbon (TOC) contents were used as an indicator of vegetation cover on the CLP (Lu et al, ), proposed to reflect vegetation cover history and biomass variations (Zhang & Liu, ). The total organic carbon‐inferred vegetation cover varied in parallel with the monsoon intensity indicators such as magnetic susceptibility (Lu et al, ). Vegetation coverage increases with increasing precipitation in the arid and semiarid regions in particular (Cheng et al, ), and even the extreme precipitation processes will significantly promote growth of vegetation in the Ili River Valley (Zhu, ).…”

Ice formation on lake surfaces in winter causes warm-season bias of lacustrine brGDGT temperature estimates

“…The isomer ratio (IR) of 6-methyl was calculated following De Jonge et al (2014). The IIIa / IIa ratio was calculated as in Martin et al (2019), which is modified from Xiao et al (2016). The weighted average number of cyclopentane for the tetra-and pentamethylated brGDGTs (#Rings tetra , #Rings penta 5ME and #Rings penta 6ME ) were calculated according to Sinninghe Damsté (2016):…”

Speleothem‐Based Hydroclimate Reconstructions During the Penultimate Deglaciation in Northern China

“…Day and Henderson (2013) observed that the distribution coefficient of Mg (D Mg ) is temperature dependent, and there is a significant positive correlation between temperature and calcite Mg/Ca ratios, suggesting that temperature could be a potential factor contributing to the variation in the speleothem Mg/Ca ratio (Huang & Fairchild, 2001). The temperature increased during the penultimate deglaciation in Northern China (Lu et al, 2019), and Mg/Ca ratios would increase if temperature dominated the Mg/Ca ratio of the stalagmite. However, our Mg/Ca record decreased gradually from glacial to interglacial, in contrast to the temperature-dominated assumption, and therefore, temperature as being the dominant factor can be eliminated.…”