Climate change in China during the past 2000 years: An overview Ge Quansheng , Zheng Jingyun Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Email: [email protected] Outline 1 Introduction 2 Historical Documents as Proxy 3 Reconstructions and Analyses 4 Summary and Prospects 1. Introduction: E Asia2K Climate System Socio-economic System •typical East Asian •dense population and rapid monsoon climate economic development • significant seasonal and • be susceptible to global inter-annual and inter- warming and extreme decadal variability climate events Climate change study in the past 2ka in East Asian is both beneficial and advantageous. • various types of natural proxy • Plenty of historical documents Fig. Active regional working groups under as proxy the past 2ka theme (PAGES 2009) 2. Historical Documents as Proxy Type Period Amount Chinese classical 1,531 kinds, 137 BC~1470 AD documents 32,251 volumes More than 8,000 1471~1911 (The Ming Local gazettes books (部), 110, and Qing Dynasty) 000 volumes Memos to the About 120,000 1736~1911 emperor pieces Archives of the 1912~1949 20,000 volumes Republic of China More than 200 Private diaries 1550~ books (部) Chinese classical documents AD 833, North China plain: Extreme drought event was occurred, crops were shriveling, no yields, people were in hungry…. Fig. Example for Ancient Chinese writings Local gazettes The 28th year of the Daoguang reign (1848 AD), the 6th (lunar) month, strong wind and heavy rain, the Yangtze River overflowed; the 7th month, strong wind Fig. Gazettes of Yangzhou Prefecture and thunder storm, field published in 1874 AD and houses submerged. Memos to the emperor, Yu-Xue-Fen-Cun • Yu (雨, rainfall)—the infiltration depth into soil after each rainfall; Fig. Distribution of YXFC •Xue (雪, snowfall)—the snowfall and the amount of every reign depth after each snowfall; •Fen (分, Chinese length unit )— 0.32 cm approximately; •Cun (寸, Chinese length unit, =10 Fens) —3.2 cm approximately. Memos to the emperor, Yu-Xue-Fen-Cun On the Dec. 26 (11th day of the comment by eleventh month in lunar calendar), Emperor Zhengding Fu: Gaocheng county 3 Qianlong: “read cuns; Jinzhou county 2 cuns; Wuji it” county 2 cuns; Pingshan county 2 cuns. Fig. The first and last page (right to left) of the original 6-page memo reported by Gao Bin, Governor General of Zhili province 3. Reconstructions and analyses 3.1 Winter Half-year Temperature Variation in the past 2000a 3.2 Precipitation or Dry-wet Reconstructions • Variation • The past 1500a • Extreme events • Spatial patterns • The past 300a 3.3 Inter-comparison between independent reconstruction and uncertainty assessment on regional temperature reconstructions 3.1 Winter Half-year Temperature Variation in the past 2000a —— Methodology • 1 AD~1500 AD Relationship between Modern Spatial phenological phenomena Instrumental representativeness of and temperature change data each station The past and present phenology’s Temperature Seasonal Winter half-year latitude and date difference temperature of temperature in difference a single site East China 10a or 30a winter half- Phenological records in year temperature in East Chinese historical documents China in the past 3.1 Winter Half-year Temperature Variation in the past 2000a —— Methodology • 1501 AD~1740 AD Proxy indicator or temperature 10a winter half-year anomaly series in some sub- temperature in East China regions by other authors Spatial • 1741 AD~1950 AD representativeness Winter snow-days extracted Winter temperature from Yu-Xue-Fen-Cun in Hefei • 1951 AD~1999 AD The mean instrumental temperature data of twenty stations 3.1 Winter Half-year Temperature Variation in the past 2000a —— Results Fig. Winter half-year temperature anomaly in East China with 30a resolution in the past 2ka (below), and 10a resolution during 961~1110 and 1501~1999 (above). Curve is three-year running mean. 3.1 Winter Half-year Temperature Variation in the past 2000a —— Results 0~500s: with a cooling trend of -0.17℃/100a; around the 490s reached the lowest temperature level (about 1℃ colder than 1951~1980) 510s~1310s: with a warming trend of 0.04℃/100a; the 30a mean temperature of two warm peaks were generally 0.3~0.6℃higher than the present, while a maximum warming of 0.9℃ occurred in 1230s~1250s 1320s~1870s: with a rapid cooling rate of 0.10℃/100a; the 30a mean temperatures of four cold troughs were generally 0.6~0.9℃ colder with a maximum cooling of 1.1℃ during 1650s~1670s 1880s~1990s: rapidly warming to the 20th century; temperature increased dramatically for the most recent two decades whose mean temperature was 0.5℃ than 1951~1980 3.2 Precipitation or Dry-wet Reconstructions —— The Past 1500a Basic dataset Annual dry-wet grades derived from Chinese historical documents at 48 stations • Spatial coverage: East China (three sub-regions including North China, Jiang-Huai and Jiang-Nan) • Temporal coverage: 137 BC~2000 AD; but before 500 AD existed a lot of discontinuous records 3.2 Precipitation or Dry-wet Reconstructions —— The Past 1500a Dry-wet variation Fig. Precipitation change and its regional difference in East China during 500~2000 • Upper panel: Regional D-W index series (Blue dash: 0.01HZ FFT low-pass filter) • Lower panel: standard deviation (in 100a running) of the D-W index series starting from 500-599 3.2 Precipitation or Dry-wet Reconstructions —— The Past 1500a Dry-wet variation • Strong Multi-decadal to centennial changes and regional differences Region Whole East China North China Plain Jiang-Huai Jiang-Nan Dry-wet Wet Dry Wet Dry Wet Dry Wet Dry period -510s 520s-570s -510s 520s-580s -520s 530s-560s -530s 540s-570s 580s-630s 640s-700s 590s-620s 630s-700s 570s-640s 650s-690s 580s-850s 860s-920s 710s-750s 760s-900s 710s-750s 760s-900s 700s-760s 770s-820s 930s-970s 980s-1010s 910s-1000s 1010s-1240s 910s-990s 1000s-1280s 830s-990s 1000s-1230s 1020s-1060s 1070s-1130s Duration 1250s-1430s 1440s-1520s 1290s-1430s 1440s-1520s 1240s-1320s 1330s-1380s 1140s-1160s 1170s-1220s 1530s-1620s 1630s-1640s 1530s-1560s 1570s-1540s 1390s-1460s 1470s-1530s 1230s-1420s 1430s-1540s 1650s-1910s 1920s- 1650s-1910s 1920s- 1540s-1880s 1890s-1950s 1550s-1630s 1640s-1690s 1960s- 1700s- Tab. Dry-wet phases in East China and its 3 sub-regions in the past 1500a 3.2 Precipitation or Dry-wet Reconstructions —— The Past 1500a Dry-wet variation • The range of precipitation variability observed in the 20th century in East China can not fully represent that for the past 1500a. • The decadal pattern of warming with drought in North China from 1980s is likely to be the pattern of the natural climate variability. 570s-770s: 14 of 21 decades, dry Warm 930s-1310s: 27 of 39 decades, dry epoch: Totally, 41 of 60 (68%) decades, show dry 500s-560s: 4 of 7 decades, dry Cold 1320s-1890s: 21 of 58 decades, dry epoch: Totally, 25 of 65 (38%) decades, show dry 3.2 Precipitation or Dry-wet Reconstructions —— The Past 1500a Extreme events With precipitation anomaly of at least 1.645 times the standard deviation distancing the mean of the series Fig. Severe persistent drought (red bar) and flood (blue bar) events. Pink bar: three most severe droughts in the past 300a. 3.2 Precipitation or Dry-wet Reconstructions —— The Past 1500a Extreme events There occurred 16 severe, persistent droughts and 18 severe, persistent floods over East China during 501~2000. And the most severe sustained drought occurred in 1634~1644. Droughts were more frequent during the 12th ~14th century while floods were more frequent since the middle of the 17th century. The severity and duration of the most severe flood in the 20th century was comparable to that in the past 1500a. However, the severity and duration of the most severe drought in the 20th century can't compare with that in the history. 3.2 Precipitation or Dry-wet Reconstructions —— The Past 300a ② The Semi-arid ① The Middle-Lower Reaches of Region: including 3 Yellow River: including 17 sites representative sites and dividing into 4 sub-regions. ③ The Middle-Lower Reaches of Yangtze River: including 5 representative sites ④ The East China: including North China and the Middle-Lower Reaches of Yangtze River 3.2 Precipitation or Dry-wet Reconstructions —— The Past 300a ① The Middle-Lower Reaches of Yellow River Yu-Xue-Fen-Cun Snowfall depth Infiltration depth Snowfall and depth Principle of ＋Physical model equation for each site water balance of infiltration Precipitation of Precipitation of each snowfall each rainfall Monthly ~ seasonal ~ annual precipitation at each site or sub-region or the whole region 3.2 Precipitation or Dry-wet Reconstructions —— The Past 300a ② Semi-arid Region Yu-Xue-Fen-Cun Infiltration depth Rainfall Date Soil infiltration experiment Precipitation of each rainfall Criteria: at least 6 rainy days in a 25-day period; less than 10 days continuous rainless days The length, initial/final date of rainy season at each site 3.2 Precipitation or Dry-wet Reconstructions —— The Past 300a ③ The Middle-Lower Reaches of Yangtze River Yu-Xue-Fen-Cun Rainfall date and rain-days Criteria of Meiyu period: Identified by the • from May to August, there are at least six instrumental data rainy days during any continuous 10 days; during 1951-2000 • Meiyu period is starting (ending) over the whole region only if those at 4 of the 5 sites are starting (ending). Conversion equation The length, starting/ending data of Meiyu period over MLRYR Rainfall of Meiyu period over MLRYR 3.2 Precipitation or Dry-wet Reconstructions —— The Past 300a (a) Hebei region 800 Hebei region region 200 Spring 600 100 400 (b) Jinnan region Jinnan region 800 0 Summer 900 700 600 500 300 400 100 Weihe region(c) Weihe region Autumn 800 200 600 100 400 0 Winter (d) Shandong region 1200 100 Shandong region 50 1000 0 1200 800 Annual 1000 600 800 400 (e) Whole region 800 600 Whole region 400 600 200 400 1750 1800 1850 1900 1950 2000 1750 1800 1850 1900 1950 2000 yr Fig.