This January, we saw the usual flurry of announcements
by the world's major meteorological agencies as they raced to
release their official figures for global surface temperature in
No sooner had the dust settled on the news that 2014
warmest year on record than climate skeptic columnist
Christopher Booker had a
series of articles in The Sunday Telegraph claiming
scientists were "fiddling" the data.
Suggesting this tampering reveals "the biggest science
scandal ever", Booker's
records … were systematically "adjusted" to show the Earth as
having warmed much more than the actual data justified".
This isn't a new claim. It's
not uncommon in some parts of the media to see
popping up questioning the reliability of the global
temperature data record. Booker himself wrote a very similar
last summer. But scientists have shown many times that
this argument holds no water.
Taking Earth's temperature
Global temperature may be a simple enough concept, but
it's not as easy as you might think. You can read more about what
goes into taking Earth's temperature in our Carbon Brief
Scientists piecing together global temperature have to
deal with a number of issues. One of the main ones is a lack
of data in remote parts of the world, such as the
But checks are made on a more basic level, too. There are
millions of instruments across the world measuring temperature and
scientists have to check they're doing it reliably.
Prof Tim Osborn from the Climatic Research Unit at the
University of East Anglia, the group that co-produces the HadCRUT4 surface
temperature record with the UK Met Office, tells Carbon Brief:
"Temperature records from
weather stations suffer from all sorts of artificial artefacts,
whether from moving a city centre weather station to more rural
site, from the encroachment of urban sprawl around a weather
station, or from changing the time of day when readings are
It's also important if a station is moved,
explains Steven Mosher on the
And Then there's Physics blog.
"A measurement is taken at a
time and place. If you change the place or location, then basic
principles suggest that you need to examine or control for changes
in the location."
Mosher is part of the Berkeley Earth
(BEST) team, a project established in 2010 to address
concerns about potential biases from issues such as data
selection, data adjustment and station quality. The BEST scientists
reanalysed the global temperature record, finding that these issues
"did not unduly bias the record".
It's clear when a change of instrument or location has caused an
error because a station will show very different temperature
from its surroundings, explains Dr
Kevin Cowtan from the University of York in the video
below. Cowtan co-wrote a
paper last year which attempted to
reconstruct missing Arctic data in the HadCRUT4 dataset
using satellite data.