Global temperature 1998
The 1998 global surface air temperature value was the highest since at least 1856. Analysis of longer-term climate records suggests this year may have been the warmest of the millennium.
Data compiled by scientists at the University of East Anglia and the UK Met. Office show that the global temperature during 1998 was a striking 0.57 degrees C above the 1961-90 mean.
The record-breaking temperature was partially the result of the marked El Niño of that year but also reflects the overall warmth of the decade. The record for the warmest year has now been broken four times during the 1990s.
Writing in Geophysical Research Letters, researchers from the University of Massachusetts and the University of Arizona report on the use of tree-ring and other indirect indicators to construct a climate record for the past 1000 years.
The new record shows slow cooling over the first 900 years then rapid warming over the most recent century. According to author Michael Mann, the abruptness of the recent warming is key, and it is a potential cause for concern.
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Global Temperatures by Phil Jones