Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years
Significance The variability of the Asian summer monsoon (ASM) is important for the functioning of ecological and societal systems at regional to continental scales, but the long-term evolution and interannual variability of this system is not well understood. Here, we present a stable isotope–based reconstruction of ASM variability covering 4680 BCE to 2011 CE. Superimposed on a gradual drying trend, a rapid drop in mean annual precipitation (>40%) toward persistently drier conditions occurred in ∼1675 BCE. This megadrought caused regional forest deterioration and enhanced aeolian activity affecting Chinese ecosystems. We argue that this abrupt aridification starting ∼2000 BCE triggered wa…
Spatial and temporal temperature trends on the Yunnan Plateau (Southwest China) during 1961-2004
Monthly mean (TEM), maximum (Tmax) and minimum (Tmin) surface air temperatures at 119 meteorological stations on the Yunnan Plateau (YP, Southwest China) were analysed for temporal trends and spatial variation patterns during the period 1961–2004. Linear trend analyses revealed that annual temperature over the YP increased at a rate of 0.3 °C/decade during the period 1961–2004, while warming trend of 0.33 °C/decade and 0.26 °C/decade was observed for winter and summer temperatures, respectively. Warming trends of nighttime minimum temperature are more pronounced than those of daytime maximum temperature, especially during winter season. Consequently, a decreasing trend of diurnal temperatur…
Late Holocene Asian summer monsoon variability reflected byδ18O in tree-rings from Tibetan junipers
[1] Recent warming in High Asia might have a strong impact on Asian summer monsoon variability with consequences for the hydrological cycle. Based on correlations between climate data, the tree-ring δ18O of high-elevation junipers is an indicator of August precipitation. Thus, our 800-year long annually resolved oxygen isotope series reflects long-term variations in summer monsoon activity on the southern Tibetan plateau. Summer precipitation was reduced during 13th–15th centuries and since the 19th century, whereas the Little Ice Age period (15th–19th century) was rather moist. The late 20th century was among the driest periods during the past 800 years, showing a tendency to slightly wett…
The influence of decision-making in tree ring-based climate reconstructions.
Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature reconstructions from a common network of regional tree-ring width datasets. Taken together as an ensemble, the Common Era reconstruction mean correlates with instrumental temperatures from 1794–2016 CE at 0.79 (p < 0.001), reveals summer cooling in the years following large volcanic eruptions, and exhibits strong warming since the 1980s. Differing in…
Past millennium hydroclimate variability from Corsican pine tree‐ring chronologies
Reduced Temperature Sensitivity of Maximum Latewood Density Formation in High-Elevation Corsican Pines under Recent Warming
Maximum latewood density (MXD) measurements from long-lived Black pines (Pinus nigra spp. laricio) growing at the upper treeline in Corsica are one of the few archives to reconstruct southern European summer temperatures at annual resolution back into medieval times. Here, we present a compilation of five MXD chronologies from Corsican pines that contain high-to-low frequency variability between 1168 and 2016 CE and correlate significantly (p <