Abstract Insight in the spatial evolution of absolute land temperature is crucial for understanding the dynamics of East Asian Summer Monsoon (EASM) precipitation, which governs the water supply for over 20% of the global population. The spatiotemporal evolution of land surface temperatures in East Asia is however not well documented. Here, we use paleothermometry based on membrane lipids of soil bacteria, so‐called brGDGTs, to reconstruct growing season temperatures (i.e., temperatures above freezing) for seven sections across the Chinese Loess Plateau (CLP) over the last deglaciation. Our records show that the amplitude of warming over the past ∼40 thousand years (Kyr) increased with elevation, indicating the sensitivity of high‐elevation areas to ongoing warming. Notably, the onset of warming on the lower‐elevation, southeastern CLP precedes that in the higher‐elevation northwest by up to ∼23 Kyr. We propose that this spatial offset arises from variations in growing season length across the CLP, where a longer growing season at low elevation allows for a stronger influence of obliquity on integrated insolation, leading to an apparent early onset of warming in the brGDGT‐based temperature records. Conversely, on the northwestern CLP, precession dominates insolation variations due to the shorter growing season at higher elevation. Climate model outputs confirms the importance of growing season length on orbital‐scale temperature evolution, and thus spatial offsets in reconstructed warming patterns on the CLP.
Guo et al. (2026) studied this question.