Updates to one of the world’s major temperature datasets reveals the planet has warmed more since the 19th century than the record previously indicated.
The HadCRUT temperature dataset stretching back to 1850 is managed by the Met Office and University of East Anglia, and is one of a handful used to calculate global temperature rises due to climate change.
A new version of the record shows the world was 1.07C warmer on average for 2010-18 than in the second half of the 19th century, 0.16C more than in the previous set of measurements.
The change comes after improvements to the dataset, not because climate change has suddenly got worse, scientists said.
The main contributor to warming over the past 170 years is humans putting more greenhouse gases into the atmosphere, they added.
Improvements in the new dataset include a significant increase in weather stations used over land and adjustments to the measurements taken at sea.
The new version takes account of the different ways sea surface temperatures have been taken over the years, such as buckets and buoys, reducing the effect each method has on the records.
It also uses statistical methods to extend the dataset’s coverage in the early part of the record and in areas such as the Arctic today, where data is scarce but temperatures are rising rapidly, to make it more accurate.
The previous version showed less warming than other global temperature analyses, such as those by US scientists at Nasa and the National Oceanic and Atmospheric Administration (Noaa).
The new version is more consistent with the other datasets over recent decades and shows slightly more warming than most of them do over the full period since 1850, the experts said.
The dataset brings together measurements of near-surface air temperature made at weather stations around the world with sea surface temperatures at the top layer of the ocean.
Dr Colin Morice of the Met Office said: “Each of the main global temperature datasets, including those by Noaa and Nasa, are compiled separately using different methods, but each is based on a finite amount of global temperature observations.
“The range of approaches results in very similar estimates of overall warming and provides scientific confidence in the changes seen and also reinforces the fact that the world has warmed considerably since the mid-19th century.”
Professor Tim Osborn, director of research at the University of East Anglia’s Climatic Research Unit (CRU), said: “We made our first estimate of global warming in 1986 and since then we have regularly improved our data and refined our analysis.
“This new major update to our global temperature record sees the estimate of global warming from 1850 to 2018 revised upwards, from 0.91 to 1.07 °C.
“Climate change has not suddenly got worse: instead, we have an improved estimate of how much warming has taken place.”
A paper setting out the update is published in the Journal of Geophysical Research: Atmospheres