Lawson’s ‘sensationalism’ claim on thin ice
- 29 Nov 2011, 17:00
- Verity Payne
"Lord Lawson accuses Sir David Attenborough of 'sensationalism'"
announces a headline on the Daily Telegraph website. The story
is based on a piece in this week's Radio Times which delves into
the science behind David Attenborough's Frozen Planet series.
In the Radio Times article Attenborough gives a quick run-through
of how the Arctic climate and cryosphere (ice) is being affected by
climate change. Given that the piece is mainly about the science of
climate, it's disappointing that the BBC felt the need to give a
sort of 'right of reply' space to two campaigners below the piece -
Lord Nigel Lawson, founder of
the skeptic lobby group the Global Warming Policy Foundation (GWPF), and
Jonathan Porritt, ex-Director of Friends of the Earth and founder
of Forum for the Future.
The Radio Times present these pieces alongside the question "Is
global warming real or myth?" With even climate skeptics now
falling over themselves to
claim they never doubted the planet was warming, the Daily
Mail's readership
apparently convinced, and with somewhere around 91%
of the UK public agreeing climate change is 'real' in 2010, this
seems an odd approach for Britain's favourite TV guide (circulation
900,000).
The scientific method uses disagreement to advance - witness last
week's paper which suggested new insights on climate
sensitivity, which are now being enthusiastically debated by the
scientific community. But the fact of global warming is not
a 'myth', it's
robust science supported by strong evidence, and framing a question
in this way is misleading and somewhat lazy.
Attenborough's article makes five main scientific points, which
are fairly easy to substantiate by looking at the scientific
literature:
Arctic sea ice is retreating
Attenborough writes
"Data from satellites collected over the
last 40 years show a drop of 30 per cent in the area of the Arctic
sea ice at the end of each summer... The ice is almost half as
thick as it was in the 1980s... The way things are going, there
will be open water at the North Pole in summer within the next few
decades."
Studies show that since the 1970s summer Arctic sea ice extent
has
decreased by nearly a third, the average Arctic sea ice
thickness at the end of the melt season has roughly halved since
the 1980s, and that the Arctic Ocean could be
ice-free in the summer months within 30 years.
'Arctic amplification'
He writes:
"The frozen Arctic Ocean acts as a huge
reflector, bouncing 85 per cent of the sun's heat back into space.
this keeps the polar regions cool and moderates the whole of the
earth's climate. But when the ice vanishes, the dark sea water that
replaces it absorbs the sun's energy, so its temperature rises.
This is why the Arctic - a region twice the size of North America -
is warming twice as fast as the rest of the planet."
The so-called 'Arctic amplification' - enhanced warming in the
Arctic - was projected by computer models, and has been confirmed
by observations, and
linked to the loss of sea ice.
Polar animals are affected by climate change at both
poles
"Polar animals are already reacting to
the changes... The [polar] bears' condition had been steadily
deteriorating as the ice, which they need when hunting seals,
diminishes. And cubs born to underweight mothers are much less
likely to survive their first year."
Polar bear survival has been
linked to sea ice breaking up early, and polar bear cub
survival linked
to a lack of available food.
"In 2010 it was announced that every
single ice front here [the Antarctic Peninsula] is in retreat. So
the Adélies [Adélie penguins], which rely on ice-loving krill for
food, find it hard to survive and colonies that I visited in 1992
have now disappeared altogether."
Ice
fronts on the Antarctic Peninsula (the leading edge of
glaciers) are all in retreat. And scientists have linked trends
in Adélie penguin abundance with the amount of krill available,
explaining the Antarctic Peninsula Adélie penguin population is
decreasing in response to climate change.
Melting polar ice will cause sea level rise
"The meltwater from Greenland's glaciers
alone could cause a rise in global sea levels of up to half a metre
by the end of this century... If any of these [Antarctic ice
shelves] collapse, vast quantities of land ice and melt-water will
slide into the sea and cause a major rise in sea-levels around the
globe."
This could be an overestimate - a recent
paper suggested that both Antarctic and Greenland ice sheets
continuing to melt at their current melt rate could cause the
average global sea level to rise by around half a metre.
Arctic melting could eventually affect ocean
currents
"...Increasing amounts of meltwater are
now flowing back into the polar sea. This could eventually disrupt
the flow of ocean currents around the Earth and are critical in
maintaining the climates we've known for centuries. The
implications of that are hard to overstate."
Research is ongoing into the effects of meltwater flowing into
the Arctic Ocean ('freshening') on ocean circulation, but climate
modelling indicates that ocean circulation is likely to be
affected, potentially altering climate patterns.
The 'right of reply'
Comparing Attenborough's article against the scientific
literature shows that for the most part he gives a fair and
accurate representation of the science.
Nevertheless, Nigel Lawson accuses Attenborough of "[seeming] to
prefer sensation to objectivity", and describes his description of
the impacts of polar warming as "sheer speculation".
In order to substantiate this criticism, Lawson makes a number of
points:
"...Whilst satellite observations
confirm that the extent of Arctic sea ice has been declining over
the past 30 years, those satellite observations show that, overall,
Antarctic sea ice has been expanding over the same period."
Antarctic sea ice is indeed increasing at around
1 per cent every decade as result of a loss
of ozone over the Antarctic. Scientists believe however that as
the
stratospheric ozone recovers from the impact of CFCs, the
Antarctic sea ice is likely to begin retreating. And the land-based
Antarctic ice sheet - where most of the ice is - has been decreasing
over the last couple of decades, with the largest ice loss
occurring in West
Antarctica.
So while Antarctic sea ice has been increasing, this isn't
particularly relevant to a discussion of climate change. Suggesting
it as a reason to not worry about Arctic sea ice - if this is what
Lawson is doing - is really just cherrypicking a phenomena that has
little or nothing to do with climate change.
"...The polar bear population has not
been falling, but rising."
Where does this claim come from? It doesn't agree with the
International Union for Conservation of Nature (IUCN)'s Red
List of Threatened Species, which states that polar bear
populations are decreasing and classifies them as 'vulnerable'
- indicating a high risk of endangerment in the wild. Examining the
status
of polar bear populations in 2010 showed that only one of
nineteen polar bear population groups was increasing, eight were in
decline, three were stable and seven did not have enough data to
determine how the population was changing. The US geological Survey
(USGS)
made a 'conservative' estimate that the projected loss of
Arctic sea ice is likely to lead to around two-thirds of the
world's polar bears disappearing by the middle of the 21st
century.
"...Recent research findings show that
the increased evaporation from the Arctic ocean, as a result of
warming, will cause there to be more cloud cover, this
counteracting the adverse effect he is so concerned about.
Cloud dynamics are an area of significant uncertainty in climate
science. It has been assumed that clouds high in the atmosphere
reflect heat energy back to Earth, exacerbating warming, and the
low-lying clouds reflect heat energy out to space, reducing
warming. However, recent studies indicate that low-lying clouds are
actually more
likely to cause warming, and any cooling effect from clouds is
unlikely
to offset other warming feedbacks in the climate system.
Claiming that 'more clouds' will counteract an 'adverse effect' is
naive at best, and underlines the GWPF's somewhat conflicted
approach to scientific uncertainty - emphasising uncertainty when
it suits them, ignoring it when it doesn't.
"...So far this century both the Met
Office and the World Meteorological Office confirm that there has
been no further global warming at all."
As we have previously pointed
out - as have the
Met Office - the fact that over the last ten to fifteen years
global temperatures have warmed more slowly does not mean that
global warming has stopped. Over such short timescales natural
variation can dominate temperature behaviour, masking the
longer-term trend in rising temperatures. We have to look at longer
periods to gain a real idea of what is happening. Temperatures have
been rising since the 1880s, there has been
roughly 0.75°C warming since the beginning of the 20th century,
and the period 2000 - 2010 was the
hottest decade on record.
Jonathan Porritt, on the other hand, focuses less on the science.
He does, however, say:
"We roughly know how much CO2 and other
gases we can put into the atmosphere and still avoid runaway
climate change."
The phrase 'runaway climate change' is not at all useful. To the
extent that it means anything to anyone it implies that
temperatures can and will rise without any possibility of restraint
- a phenomena that most famously is
thought to have occurred on Venus.
The Intergovernmental Panel on Climate Change (IPCC)'s 2009 Expert
Meeting on Key Vulnerabilities report says "a
'runaway greenhouse effect' - analogous to Venus - appears to have
virtually no chance of being induced by anthropogenic activities."
However, researchers are
still investigating how to predict 'climate tipping points',
which describe a small change in some part of the climate system
can cause abrupt environmental change.
Scientists suggest that the climate can recover from such
abrupt changes, but on timescales varying from years to hundreds of
thousands of years.
So which of these men would you trust to tell you about climate
science? Attenborough (or his team) has clearly done his research
and knows his subject. Lawson just gets the science wrong, as far
as we can tell. And Porritt prefers to avoid it altogether. You
decide.
UPDATE 10:04 30/11/11: The Daily Mail have now
published
their take on this, quoting Lawson without questioning his
'facts'. And the Telegraph piece is in today's paper.