Although global warming over the past century has been confirmed, the response of different regions to it is still uncertain. We developed a tree‐ring width chronology based on tree‐ring samples from juniper trees from the Xiqing Mountains in the northeast Tibetan Plateau, the central headwater area of the Yellow River. Using this tree‐ring chronology, the minimum winter half‐year (October–April) temperature for the research area was reconstructed for the past 425 years. The reconstruction shows that temperature variability was minimal over past four centuries prior to the warming that began in 1941. During the 50 years from 1941 to 1990, the minimum temperature of the winter half‐year increased 2.5 °C. This degree of warming relative to the past 400 years suggests that the eastern Tibetan Plateau is highly sensitive to global warming. Copyright © 2007 Royal Meteorological Society

Long‐term relative humidity change in central China has been rarely studied due to the shortness of instrumental records. In this study, we developed an annually resolved tree‐ring width chronology dating back to 1727 coefficient of efficiency (CE) with Chinese pine (Pinus tabulaeformis Carr.) samples from Mt. Shiren, central China. Relative humidity of current April–July (RH_AJ) was reconstructed for the region from 1801 to 2016 CE using a linear regression model, which explains 43.9% of the variance in the instrumental records from 1960 to 2016 CE. The reconstructed RH_AJ revealed that there were 33 extremely dry years, accounting for 15.28% of the past 216 years. The five driest years and the corresponding anomalies were 1835 (60.05%), 1955 (60.24%), 1929 (60.50%), 1907 (60.71%), and 1801 (60.83%). In agreement with the PDSI reconstruction for Mt. Shennong and the drought/flood series in Zhengzhou, the reconstructed RH_AJ captured common droughts in 1813–1814, 1847, 1876–1880, 1900, 1923–1945, 1960–1961, and wet periods in 1863–1872, 1882–1885, 1897–1898, 1954–1956, and 1983–1984. Spatial correlation analyses showed that the reconstructed RH_AJ for Mt. Shiren had significant positive correlations with vapour pressure, precipitation, and relative humidity of 850 hPa around the study area, which indicates that the reconstructed RH_AJ reflects regional humidity change in central China. To sum up, these results may be provide us with a better understanding of drought variation in central China.

Tree ring data from the southern boundary of Chinese Pine (Pinus tabulaeformis Carr.) distribution where is the southern warm temperate margin, the paper analyzes the response of climate factors along north–south direction to tree growth. The results show that temperature and precipitation in May–June and relative moisture from March to June are main limiting factors on trees growth; however, the temperature in the south of the mountains and the moisture in the north of the mountains have relatively greater influence on trees’ growth. Additionally, we also found that the regional scPDSI_MJ (that is scPDSI in May–June) was the most significant and stable factor limiting tree growth to be used for reconstruction. The reconstructed scPDSI_MJ revealed that there were 29 extremely dry years and 30 extremely wet years during 1801–2016, and it could represent the drought variation in central and eastern monsoon region. The variation exists in good agreement with the reconstructed PDSI for Mt. Shennong and the drought/wetness series in Zhengzhou. Further research found that the droughts of May–June in central China were mainly impacted by local temperature and moisture (including precipitation, soil moisture, potential evaporation and water pressure), and then by the northern Pacific Ocean and the northern Atlantic Ocean. These results may provide better understanding of May–June drought variation and service for agricultural production in central China.

The Tongbai Mountains are an ecologically sensitive region to climate change, where there lies a climatic transitional zone from a subtropical to a warm–temperate monsoon climate. The northern boundary of Pinus taiwanensis Hayata is here; thus, climate information is well recorded in its tree rings. Based on developed earlywood width (EWW), latewood width (LWW) and total ring width (RW) chronologies (time period: 1887–2014 year) of Pinus taiwanensis Hayata in the Tongbai Mountains in central China, this paper analyzed characteristics of these chronologies and correlations between these chronologies and climate factors. The correlation results showed that earlywood width chronology contains more climate information than latewood width chronology and total ring width chronology, and mean temperature and mean maximum temperature in May–June were the main limiting factors for radial growth of Pinus taiwanensis Hayata. The highest significant value in all correlation analyses is −0.669 (p < 0.05) between earlywood width chronology and May–June mean temperature (T_MJ) in the pre-mutation period (1958–2005) based on mutating in 2006. Thus, this paper reconstructed May–June mean temperature using earlywood width chronology from 1901 to 2005 (reliable period of earlywood width chronology is 1901–2014). The reconstructed May–June mean temperature experienced eight warmer periods and eight colder periods and also showed 2–3a cycle change over the past 105 years. The spatial correlation showed that the reconstructed series was representative of the May–June mean temperature variation in central and eastern China and significant positive/negative correlation with the sea surface temperature (SST) of the subtropical Pacific Ocean and the tropical Western Pacific Ocean and Indian Ocean from the previous October to the current June. This also indicated that May–June mean temperature periodic fluctuations might be related to the quasi-biennial oscillation (QBO) in the tropical Western Pacific Ocean and Indian Ocean. The results of this study have extended and supplemented the meteorological records of the Tongbai Mountains and have a guiding significance for forest tending and management in this area.