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.

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