 |  The last 100 years is more striking than either the Medieval Warm Period or Little Ice Age  Timothy Osborn, UEA |
The findings support evidence pointing to unprecedented recent warming of the climate linked to greenhouse emissions.
University of East Anglia researchers measured changes in fossil shells, tree rings, ice cores and other past temperature records or "proxies".
They also looked at people's diaries from the last 750 years.
Timothy Osborn and Keith Briffa of UEA analysed instrument measurements of temperature from 1856 onwards to establish the geographic extent of recent warming.
Then they compared this data with evidence dating back as far as AD 800.
The analysis confirmed periods of significant warmth in the Northern Hemisphere from AD 890 - 1170 (the so-called "Medieval Warm Period") and for much colder periods from 1580 - 1850 (the "Little Ice Age").
Natural records
The UEA team showed that the present warm period is the most widespread temperature anomaly of any kind since the ninth century.
"The last 100 years is more striking than either [the Medieval Warm Period or Little Ice Age]. It is a period of widespread warmth affecting nearly all the records that we analysed from the same time," co-author Timothy Osborn told the BBC.
Osborn and Briffa used 14 sets of temperature records from different locations across the Northern Hemisphere.
The records included long life evergreen trees growing in Scandinavia, Siberia and the Rockies which had been cored to reveal the patterns of wide and narrow tree rings over time. Wider rings related to warmer temperatures.
The chemical composition of ice from cores drilled in the Greenland ice sheets revealed which years were warmer than others.
Dear diary........
Click here to see the full report by Paul Rincon, BBC News science reporter
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