Elevational differences in Holocene thermal maximum revealed by quantitative temperature reconstructions at ~30° N on eastern Tibetan Plateau

Meteorological data indicate that the increase in temperature at high-elevation sites with the background of global warming is much higher than the global average. However, there are few studies trying to evaluate temperature changes in high elevational areas over longer time scales. Here, we use brGDGTs in a sediment core collected from Hongyuan Peatland (3503 m a.s.l.), to reconstruct an independently-dated, high-resolution (~100 years), quantitative record of mean annual temperature (MAT) over the past 13,300 yr BP on the eastern Tibetan Plateau. Our data, consisting with other quantitative local reconstructions, show a peak warmth in the middle Holocene (6100–5600 yr BP). Together with other published MAT records from ~30° N in China, we find that the timing of the Holocene Thermal Maximum (HTM) in high-elevation sites lagged that in low-elevation sites. We also find that the warming rate in early Holocene was faster at a higher elevation site, by comparing with another MAT reconstruction using the same archive and the same proxy. We hypothesize the delayed HTM at high-elevation areas was probably caused by the offset of remaining regional glaciers and/or snow cover on the Tibetan Plateau. The enhanced warming with elevation can be ascribed to snow albedo and latent heat release. Our new results may imply a faster high-elevation temperature rise with an on-going global warming, considering the disappearing regional glaciers on the Tibetan Plateau.