The Mail on Sunday gives David Rose space to repeat old (and wrong) claims that “global warming has stopped”.
- 15 Oct 2012, 16:00
- Roz Pidcock
Skeptic journalist David Rose published a two-page spread in the
Mail on Sunday yesterday entitled "Global warming stopped 16
years ago, reveals Met Office report quietly released… and here is
the chart to prove it." This is the latest in a series of articles
on the same theme. We take a look at why Rose's claims are wrong
this time.
The Mail on Sunday seems to print articles by Rose arguing that
warming
has stopped about once every six
months - so maybe we were about due for one. The Met office has
already responded to misleading information in an article in
January by David Rose on the same topic, but he seems determined to
peddle the same myths.
This time, the Mail on Sunday also gives Rose space for a
half-page comment piece in which he argues that the slow-down in
warming over the last decade "poses a fundamental challenge to the
assumptions underlying every aspect of energy and climate change
policy."
Arguing that "global warming has stopped"
In his article, Rose presents the graph below, which shows
global atmospheric temperature data for 1997 to 2012 compared to
the average for this century, and uses it to claim that it is proof
that global warming has stopped.
The data Rose cites is part of a long term data series - called
Hadcrut4
- that the Met Office is collecting with the Climatic Research Unit (CRU)
at the University of East Anglia.
Rose claims:
"The new data, compiled from more
than 3,000 measuring points on land and sea, was issued
quietly on the internet, without any media fanfare, and,
until today, it has not been reported. This stands in sharp
contrast to the release of the previous figures six months
ago, which went only to the end of 2010 - a very warm
year."
But in a rebuttal
blog, the Met Office says it has not released a new report this
week - "quietly on the internet" or otherwise. It has simply
updated the dataset to include data for 2011 and the first eight
months of 2012. So in effect, Rose is trying to use a bit of new
data to make an already widely discredited argument.
Data from Hadcrut4 shows that during the period that Rose uses
in his argument, 1997 to 2012, atmospheric warming was about 0.03
degrees Celsius per decade, which is considerably slower than in
previous decades. We'll come on to the possible reasons for this
haitus later, but the important point is that
scientists don't draw general conclusions about global
temperature trends based on such small amounts of data.
Rose knows this - he admits that Professor Phil Jones, leading
climate scientist at the CRU, that 15 or 16 years is too short a
period from which to draw conclusions. Similarly, the Met office
was careful to point this out in its interview with Rose - which
you can read on its
blog. It says:
"[C]hoosing a starting or end point
on short-term scales can be very misleading...If you use a longer
period from HadCRUT4 the trend looks very different".
The bigger picture
The graph that Rose should have shown is this one, which shows
roughly 0.8 degrees Celcius of warming since the beginning of the
20th Century.
This reveals Rose's statements that "[b]efore [1980], temperatures
had been stable or declining for about 40 years" and that "global
industrialisation over the past 130 years has made relatively
little difference" are extremely short-sighted.
As the Met Office
explained to Rose:
"Looking at successive decades over
this period, each decade was warmer than the previous - so the
1990s were warmer than the 1980s, and the 2000s were warmer than
both. Eight of the top ten warmest years have occurred in the last
decade".
A prominent role for natural variability
The bottom line is that short-term excursions from the long term
temperature trend do
not mean that the warming trend apparent over the last century
has stopped for good. We have written a previous post
discussing this is more detail.
Alongside human impacts, the world's temperature varies in
response to natural cycles, in particular the
El Nino/La Nina cycle and the 11-year solar
cycle, as well as occasional one-off events like volcanic
eruptions. As the Met Office
explained to Rose, the most likely reason that we haven't seen
an upward trend over the last decade is that such natural
variability has played a more prominent role in the climate,
masking the impact of greenhouse gases on global temperature.
"Combined, several of these factors
could account for some or all of the reduced warming trend seen
over the last decade - but this is an area of ongoing
research."
Misquoting on climate models
Rose also quotes Professor Judith Curry, head of the climate
research centre at Georgia Institute of Technology in the United
States. Curry wrote about the article in her blog yesterday and
echoed the same sentiments when Carbon Brief contacted her. She
told us that at no point in her interview with Rose did she
describe climate models as 'deeply flawed' or say that she
disagreed with Jones that 16 years is not long enough to draw any
conclusions.
What she actually said repeated Jones's concerns that the
climate is far more complex than the models can grasp at the
moment, but that research continues to develop. She says:
"Climate models are very complex,
but they are imperfect and incomplete...It is becoming increasingly
apparent that our attribution of warming since 1980 and future
projections of climate change needs to consider natural internal
variability as a factor of fundamental importance".
Ignoring other signs
Another problem with Rose's analysis is that looking solely at
atmospheric temperatures ignores a number of other indicators that
global warming is happening. Most of the heat in the earth's
atmosphere actually enters the ocean, as this
fantastically simple infographic from Skeptical science
shows:
As the graph below shows, the global ocean has been warming
considerably during the time that atmospheric temperatures appear
to have stalled, which is causing sea
level to rise substantially. The fact that ice sheets
are melting in both the Arctic and the Antarctic is another
stark indicator of global warming that Rose chooses to ignore.
Source: NOAA/NESDIS/NODC
All of this makes us wonder how many bits of established
scientific data can Rose ignore or misrepresent in one article?
However, he appears unlikely to stop producing his twice-yearly
articles despite a wealth of evidence to the contrary. So for the
next time a similar article comes up it's worth remembering
something that scientists said in a
previous rebuttal of the 'global warming has stopped' claim:
that considering only 10-15 years of atmospheric temperature data
is like
"analysing the temperature
observations from 10-17 April to check whether it really gets
warmer during spring."