Global Temperature Indices at at LDEO/IRI Climate Data Library

This data set consists of average gloabl temperature from an analysis
by Hansen and Lebedeff at NASA/GISS.

These data are an update of the analyses described by Hansen and
Lebedeff (1987). Discussions of the data are given in the
references. The input data for these analyses are principally the
Monthly Climatic Data of the World (MCDW) from about 2000
meteorological stations around the world, supplemented for the most
recent several months by NOAA near real time data for most of these
stations.

This analysis is updated each month. The data for earlier months and
years changes slightly as additional stations are added and as the
near real time NOAA data is replaced by MCDW data.

Nonclimatic influences, e.g. urban warming, have not been expunged
from the meteorological station data. Hansen and Lebedeff (1987)
estimate that urban effects cause a warming of about 0.1C/century on
global average, but the effects can be larger and smaller in different
regions. The annual-mean global-mean temperature anomaly in recent
decades is estimated to have a two-sigma uncertainty of about 0.07C
due to incomplete spatial coverage of stations. Thus the relative rank
of different years is uncertain for years whose temperatures differ by
less than that amount.