Twentieth-century climatic warming in China in the context of the Holocene

Abstract

Development of an annual mean temperature series of China for the period of AD 1880-1998 indicated that 1998 was thie wanrest year since 1880. During 1998, temperature was 1.38C higher than the normal (1961-90). Annual mean temperatures of China were found using a weighted average of 10 regional series, whliich covei-ed the xvhole lanid ai-ea of the coutliry fromii Xinjiang and Tibet iI the west to Tailwan i the eCast. Gaps in temperatture obseivations were filled by USing ice-core i' 0 and tie iing data for thice regions in the west. and docuimenitary data for scven regions in the east. Since 1 951. only obser X ational data were usecl. Fiftyyear mean teiimperatture anomnalies were calculated trom the ninth to trwentietlh cernturies. The series do not show any conisistenit warm peiliod in west China durinig the 'Mediaeval Warmii Period (AD 900 to 1300), but temiperatures in east China in At) 850-1099 anid 1200-99 were abouit 0.2C higher than the average for recent years. Centurv-mean ternperatures combininlg west and east re0}ions fi-rom t'he niintlh to twentieth centuries slhowed thlat the twenitieth centLiry was 0.4 C wa5-5.1mid than the imieani of the wshole period. Tempeiatures of the ninith, tenith, clev entli amdI thli-tcentirh cintl aes i xx're oily Slight)y .O.05---0. 0"C) I:mchr thn tl' x avragW. The-retce. tl e twentieth century seems the wamiiest one in China for the last ilmilleniiitiniu or miiore. The last imiillenniumi xvas not the wannest one in comparing with others for the last 10 miilleiinia. Ten regional temperatuLre series from 1O ka BP to the p-esent xweccanalysed wcith the same time r-esolutioni (205ra) awld identical normiial (I 880 1 9791. Gaps in a few ser-ies were filled by the data fromii preViois woirk. Average temperatures were also founid on the hasis of area xveiehting of regional series, showing that the Megatlhemmial was maniifested xwell in China, witli teriiperatures for thie period of 8.0 to 3.0 ka BP fromi 1 5 to 2.)0C liglher tlhani the presenit. Studies of the relationship between temperature and precipitatioti indicated no consistenit correlation. I-loxever, warmdiy dominated oxer wanrm-wet climiiate in niorth Chilna. but the opposite is the case in the very south anid in the west. In east Chinla, the twenitietlh cenltury was probably tIre driest one dur-ing the last millenlnium. Severe droughts occurred itn 20 of the 100 scimmiiiiers of 1900-1999, hut the miieani frequiecy xwas only 10.6 per ceinttiry.