Earth may be even closer to 1.5°C of global warming than we thought | New Scientist
https://www.newscientist.com/...-earth-may-be-even-closer-to-1-5c-of-global-warming-than-we-thought/
The global average temperature is thought to have climbed about 1.07°C since the industrial revolution, up from a previous estimate of 0.91°C. This update brings all three of the world’s key temperature data sets in line, suggesting the true temperature rise is at the upper end of previous ranges.
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Climate change hasn’t suddenly got worse. It’s just our estimate of how much warming has taken place has improved,” says Tim Osborn at the University of East Anglia, UK, who today published a paper with Met Office colleagues on the fifth update to the data, known as the Hadley Centre Climatic Research Unit Temperature (HadCRUT5).
The 18 per cent increase is the biggest in years of HadCRUT revisions, but brings it roughly in line with the two other main data sets used to track global temperatures, run by US agencies NASA and the National Oceanic and Atmospheric Administration.
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Honestly, many of us have long recognised that the HadCRUT data set underestimated the warming,” says Michael Mann at Pennsylvania State University.
There are two main reasons for the 0.16°C upwards revision in past warming. The biggest was changes to how the HadCRUT team looked at sea surface temperatures, specifically how it was measured by ships taking the temperature of sea water in their engine rooms.
The other is that gaps in the data set’s coverage of the Arctic, which has been warming two to three times as fast as the global average, have been filled in. Previously, grid squares for the region were left empty if there was no observational data – now they are estimated with data from nearby squares.