Observed coherent changes in climatic extremes during the second half of the twentieth century

Climate Research

A. M. G. Klein Tank¹  , P. Della-Marta¹  M. Haylock¹  P. Frich¹  T. Peterson¹  L. V. Alexander¹  B. Gleason¹ 

关键词: Observed climatic extremes;    Derived indicators;    Temperature;    Precipitation;    Climate monitoring;    Global change;   

DOI  :  10.3354/cr019193

来源: Inter-Research Science Publishing

【 摘 要 】

ABSTRACT: A new global dataset of derived indicators has been compiled to clarify whether frequency and/or severity of climatic extremes changed during the second half of the 20th century. This period provides the best spatial coverage of homogenous dailyseries, which can be used for calculating the proportion of global land area exhibiting a significant change in extreme or severe weather. The authors chose 10 indicators of extreme climatic events, defined from a larger selection, that could be appliedto a large variety of climates. It was assumed that data producers were more inclined to release derived data in the form of annual indicator time series than releasing their original daily observations. The indicators are based on daily maximum andminimum temperature series, as well as daily totals of precipitation, and represent changes in all seasons of the year. Only time series which had 40 yr or more of almost complete records were used. A total of about 3000 indicator time series wereextracted from national climate archives and collated into the unique dataset described here. Global maps showing significant changes from one multi-decadal period to another during the interval from 1946 to 1999 were produced. Coherent spatial patternsof statistically significant changes emerge, particularly an increase in warm summer nights, a decrease in the number of frost days and a decrease in intra-annual extreme temperature range. All but one of the temperature-based indicators show asignificant change. Indicators based on daily precipitation data show more mixed patterns of change but significant increases have been seen in the extreme amount derived from wet spells and number of heavy rainfall events. We can conclude that asignificant proportion of the global land area was increasingly affected by a significant change in climatic extremes during the second half of the 20th century. These clear signs of change are very robust; however, large areas are still not represented,especially Africa and South America.

【 授权许可】

Unknown