New paper finds a significant decreased temperature trend in China during 20th century

A new paper published in Palaeogeography, Palaeoclimatology, Palaeoecology reconstructs May-July maximum temperatures in China over the past 267 years and finds that there was a significant decrease in temperatures over the 20th century. According to the authors, the "Reconstruction exhibits a significant decreased trend in 20th century" and "The reconstructed [temperatures are] similar to several observed [temperature series] and the temperature index in north-central China, which indicated that the decrease in summer temperatures in the 20th century was a large scale phenomenon."

The paper adds to hundreds of peer-reviewed papers from around the globe finding non-hockey-sticks and no evidence of any unusual, unprecedented, or unnatural warming during the 20th century in comparison to warm periods in the past.

Fig. 7. 

Comparison between observed (grey line) and reconstructed (black line) May–July MMT [Mean Maximum Temperature] (1951–2012).  Added: Calibration of the proxy to observations 1951-2012 shows good agreement.

Fig. 8. 

Reconstruction of the average of May–July MMT [Mean Maximum Temperature] for Qianshan Mountain for the last 268 years (the smoothed line is an 11-year moving average). 

Added: Reconstruction exhibits a significant decreased trend in 20th century [excerpt from abstract]

Reconstructed May–July mean maximum temperature since 1745 AD based on tree-ring width of Pinus tabulaeformis in Qianshan Mountain, China

• Yu Liu^a, b, , , 
• Yanchao Wang^b, a, c, 
• Qiang Li^a, 
• Junyan Sun^a, 
• Huiming Song^a, c, 
• Qiufang Cai^a, 
• Yanhua Zhang^a, c, 
• Zhonglin Yuan^d, 
• Zhongyu Wang^d

• ^a The Stay Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China
• ^b School of Human Settlement and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049,China
• ^c Graduated University of the Chinese Academy of Science, Beijing 100049, China
• ^d Forestry Bureau of Qianshan Scenic Area Administrative Committee, Anshan 11041, China

Highlights

•

May–July maximum temperature (MMT) reconstructed for Qianshan, China using tree rings.

•

Reconstruction exhibits a significant decreased trend in 20th century.

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The MMT reconstruction is regionally representative.

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Abstract

A tree–ring–width chronology of Pinus tabulaeformis was developed from the Qianshan Mountain, Liaoning province, northeastern China. Based on the correlation between the ring width and instrumental data, a transfer function was designed and the May–July mean maximum temperature (MMT) from 1745 to 2012 was reconstructed. The reconstruction explains 42.7% of the instrumental variance during the calibration period (41.7% after adjusting for the loss of the degrees of freedom). The reconstructed MMT is similar to several observed MMT series and the temperature index in north-central China, which indicated that the decrease in summer temperatures in the 20th century was a large scale phenomenon. The reconstruction also showed that high MMT values corresponded to historical drought events in Liaoning. In addition, a spatial correlation analyses revealed that the MMT reconstruction is regionally representative. Significant 128.2-, 64.1-, 18.6-, 3.46-, 3.19-, 2.43-, 2.15- and 2.10-year cycles were detected in the reconstructed MMT series from Qianshan Mountain.