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HadCRUT3 is a globally gridded product of near-surface temperatures, consisting of annual differences from 1961-90 normals. It covers the period 1850 to present and is updated monthly.
The data set is based on regular measurements of air temperature at a global network of long-term land stations and on sea-surface temperatures measured from ships and buoys. Global near-surface temperatures may also be reported as the differences from the average values at the beginning of the 20th century. The global and hemispheric plots, in a different form to that given here (which may be more suitable for certain applications), are also available.
The annual timeseries illustrates the increase since the 1850s in global mean temperatures. This increase is much larger than the known sources of error. The warming has occurred in two main phases: 1920-40 and particularly since the mid-1970s. Research at the Met Office Hadley Centre using state-of-the-art climate models has shown that this behaviour can only adequately be accounted for by a combination of natural and human factors: the latter dominate.
The annual data used to make this diagram are available in this format.
Month-to-month changes in global temperature are often larger than interannual changes, but estimates are also more affected by data coverage limitations.
The monthly data used to make this diagram are available in this format.
In any typical month there will be areas of both warm and cold anomalies. Anomalies tend to be largest over land and in the winter hemisphere.
We also produce HadCRUH, a monthly global humidity product (both absolute and relative humidity) on the same grid from the surface data. The data are available from 1973 to 2004.