How the BBC's More or Less confused the realities of climate change
- 18 Jan 2012, 16:31
- Christian Hunt
A segment on last week's More or Less
programme on BBC Radio 4 revisited a bet between climate
scientist Dr James Annan and Dr David Whitehouse, science editor
for the climate skeptic think tank the Global Warming Policy
Foundation (GWPF).
On a previous edition of More or Less in early 2008, Whitehouse
had bet Annan £100 that no new global temperature record would be
set within 4 years, as determined by the HadCRUT3
temperature dataset. Now that it's 2012, and with HadCRUT3 still
showing 1998 to be the hottest year on record, it's seems that
Annan has lost his money.
The bet was pretty pointless, given that it tells us little or
nothing about global warming trends or their relation to man-made
greenhouse gas emissions. And instead of taking a closer look at
why yearly temperature trends have little to do with the overall
global warming curve, it allowed Whitehouse to wave the short-term
temperature red herring around unchallenged. It's no surprise,
then, that
Whitehouse, the
GWPF and various
skeptic bloggers have been all over it.
It's a shame because More or Less reaches a broad audience and
is usually very intelligent at unpacking the reality behind
different groups' claims. Instead, the More or Less segment only
served to vindicate misgivings voiced in the BBC
Trust report of 'false balance' in the corporation's climate
science coverage.
False balance
Tim Harford, the programme's presenter and the Financial Times's
undercover
economist, set the tone for the More or Less segment,
saying:
"The debate still rages about whether
global warming is continuing or whether the last ten years show
that the temperature rises since in the 1980s and the 1990s have
stopped."
This is only true if it is taken to mean that climate skeptic
bloggers and lobbyists are still arguing whether global warming is
continuing. There certainly isn't a debate raging in the scientific
community and the peer-reviewed literature. So right from the
start, the way the programme presents the debate does not
accurately reflect scientific understanding of man-made climate
change.
Harford goes on:
"At the time we spoke to David
Whitehouse, an astrophysicist and former BBC science editor, and
James Annan, a climate scientist"
It is worth noting here that Harford neglects to mention David
Whitehouse's current role as the GWPF's science editor.
This isn't the first time media outlets have glossed over his
current affiliation when quoting him.
We might allow that when the bet was first made, the GWPF was
only a twinkle in Nigel Lawson's eye. However, given that the
BBC Trust's own review of the corporation's coverage of science
described the GWPF as "active in casting doubt on the truth of
man‐made climate change", it seems reasonable to argue that More or
Less should have noted this affiliation - for the purposes of
transparency.
James Annan, meanwhile, is a member of the Global
Change Projection Research Programme at the Research Institute for
Global Change. He has something of a penchant for making wagers
with climate skeptics over temperature records.
According to the Guardian, in August 2005 Annan agreed on a bet
of $10,000 with Russian solar physicists Galina Mashnich and
Vladimir Bashkirtsev that the earth will be warmer between 2012 and
2017 than it was between 1998 and 2003.
A pointless bet
Frankly it is hard to see what the point of the bet was. Betting
on four years being hot or cold doesn't tell us anything about
long-term man-made climate change. Natural variation in the climate
means that temperatures do all sorts of things over short time
periods - up to and including decades.
For example, natural climate cycles El Niño and La Niña cause
decadal fluctuations in temperatures, atmospheric cooling from
aerosols and volcanoes has an effect, and the waxing and waning of
solar energy also a difference. This is all background noise to the
long-term upward trend in temperatures due to man-made global
warming, and any long-term temperature trend stands a good chance
of being masked by natural variation over a four-year period, a
point illustrated nicely by this video.
From Climate
Denial Crock of the Week
How the bet obscured the realities of climate
change
Take a longer-term look, and natural variability becomes less
significant. Taking the average for ten year chunks, even though
temperature rise has slowed (presumably due to natural variability
- it certainly
isn't because greenhouse gas emissions have fallen), the
noughties are still the
warmest decade on record.
So it seems strange that during the programme Whitehouse
says:
"I would like to see evidence of
sustained warming, which means more than one year"
The warm noughties provide exactly that evidence.
And, as scientists Grant Forster and Stefan Rahmstorf (of
realclimate) showed in a peer-reviewed
paper published towards the end of last year, when they removed
the effect of natural variations from temperature records, they can
extract a remarkably clear warming trend caused by man-made
greenhouse gas emissions over the last thirty years.
Source:
Skeptical Science
Whitehouse himself concedes that the last few years have been
dominated by natural variation and not man-made warming, saying in
his
blog post:
"My view was that the information in the
[temperature] dataset was important, especially if projecting it
forward just a few years when natural variations were clearly
dominant."
Over a long time period the long-term effect of global warming
would appear, and it is statistically likely that a new
record year might appear at some point in the future, but betting
on a hot year appearing in a period as short as four years is
essentially pretty meaningless.
The outcome
Fair play to Dr Whitehouse, he's a plucky gambler, and he won
the bet on the terms agreed. Unfortunately his blog and his
comments on the programme imply that this represents a victory for
the pet theory of his GWPF buddies - that global warming has
stopped. For more on why this isn't the case see our blog post on the
topic.
Not only does this theory rely on cherrypicking short-term
fluctuations over long term trends, it also relies on focusing on
the findings of just one of the three datasets used to measure
global surface temperature trends. HadCRUT3, the dataset chosen for
this bet, is known to have a
bias towards cooler temperatures, due the way it accounts for
lack of data over the polar regions compared to the other datasets.
(We have more on global temperature datasets and how they are
produced here.)
Imagine the gamblers had chosen a different dataset. Unlike
HadCRUT3, the other two principal datasets - NASA's
GISS and the NOAA's NCDC
say that 2010 was the joint warmest year on record. It's fortunate
for Dr Whitehouse that the only one of the three principal datasets
not putting 2010 as a record-breaking year was the one on which he
was wagering!
However, Dr Whitehouse seemed unwilling to cede this point when
Annan pointed it out in the show. He wrote on his
blog:
"This is a moot point that also strongly
reaffirms my stance."
Um.
Whitehouse did respond in a way, though, to the charge that only
one of the datasets supported his win. He argues that 2010 was
hotter due to a strong El Niño.
El Niño is a natural climate cycle which warms the planet
slightly while it's happening. But although 2010 started off in a
warming El Niño phase, by July it had shifted to its
cooling La Niñacounterpart. So 2010's warmth can't be explained
simply by reference to El Niño.
As it transpires, a
preview of the new Hadley Centre temperature dataset HadCRUT4,
which rectifies some of the cooling bias of HadCRUT3, also looks
like it will put 2010 as joint warmest year with 2005. So
Whitehouse's victory may well have been largely down to the cooling
bias of HadCRUT3.
Quit when you're winning
Whitehouse isn't just lucky - he's also a canny gambler who
knows better than to push his luck much further. When asked if he
would be tempted to continue with a 'double or quits' bet, he
replies that he would agree to it only if there are new temperature
records over:
"more than one year,more than one
standard deviation above the straight line of the past ten
years."
...A sensible bit of moving the goalposts. But if he thinks
temperatures are really at a standstill, why not take the same bet
again?