Cardinal Pell lecture peddles misrepresentations of climate science

  • 02 Nov 2011, 12:00
  • Tim Holmes & Robin Webster

In the UK, the government and opposition both accept the weight of evidence which shows that climate change is happening and is caused by humans. This is not the case, however, in other English-speaking countries - notably North America and Australia, which both have opposition parties which routinely reject the science behind climate changee.

That's why it's interesting that Lord Lawson's climate skeptic think-tank the Global Warming Policy Foundation chose to have its annual lecture at Westminster Hall delivered by Cardinal George Pell, Catholic Archbishop of Sydney last week, a story which was reported in The Australian.

When the GWPF was launched in late 2009 it presented itself as an organization that is "open-minded on the contested science of global warming" but "is deeply concerned about the costs and other implications of many of the policies currently being advocated." This was recently reiterated when Lord Lawson wrote in the Sunday Times that the concern of the GWPF is

"primarily in the area of policy: in the light of the facts [about climate change], to the extent that we know them and understand them, what policy is it rational and proportionate to pursue?"

 As with so much else of the GWPF's output however, Cardinal Bell does not appear to have taken this on board. As already noted by the Canadian site desmogblog, his lecture, available on the GWPF site, is remarkable for the number of misrepresentations of climate science which it contains.

It would be difficult to thoroughly assess all of the scientific errors in the lecture, but below we have picked out a few examples.

After describing carbon dioxide as "not a pollutant, but part of the stuff of life", the Cardinal went on to say that

"Animals  would  not  notice  a  doubling  of  CO2  and  obviously plants would love it. In the other direction, humans would feel no adverse effects unless  CO2  concentration  rose  to  at  least  5000  ppmv,  or  almost  13  times  today's   concentration,  far  beyond  any  likely  future  atmospheric  levels."

Increasing the proportion of carbon dioxide in the atmosphere might not have a direct effect on animals and humans. But an increase in carbon dioxide in the atmosphere of this level could have unimaginable consequences. The IPCC concluded that the health impacts of climate change will be " overwhelmingly negative" and that " the resilience of many ecosystems is likely to be exceeded".

Their 'worst case scenario', Scenario A1F1, projects that carbon dioxide will reach a concentration of approximately 1000ppmv by the end of this century, leading to a global temperature rise of more than four degrees. The Met Office has outlined some of the impacts of a four degrees temperature rise here.  

He goes on to say that

"The conclusions of the 2007 Fourth Assessment Report of the UN's Intergovernmental Panel on Climate Change (IPCC) … are "essentially reliant on computer modelling and lack empirical support"

The First Working Group of the IPCC's Fourth Assessment report include three entire chapters specifically devoted to empirical observations of the impacts of climate change.

Models are continually tested against historical observations, through a process known as " hindcasting". We have looked at this question in more detail here.

"[The IPCC's] speculations on "the baleful influence of atmospheric carbon dioxide rest almost exclusively on unvalidated computer modelling that rests on unsubstantiated assumptions about the amplification effects of water vapour, clouds and other unverifiable factors."

The warming effect of carbon dioxide can be demonstrated in the laboratory - as shown in this BBC video. We have known that carbon dioxide is a warming agent for many years - Svante Arrhenius first calculated the impact of changing levels of carbon dioxide on the climate in 1896. That was followed by over a century of discussion, testing, and refinement of the theory, a process which provided a wealth of supporting evidence.

The amplification effects of water vapour are not unsubstantiated; while on clouds, the IPCC both acknowledges existing uncertainties and includes the writing of skeptical authors.

"The predictions based on these models "have been wrong for the last 23 years".

Models generally provide a good approximation, as comparisons of model output to data demonstrate. It is also worth noting that some - including sea-ice and sea-level rise - have been conservative.

"The influence of various solar mechanisms (such as sunspot activity) and changing ocean circulation, which are poorly understood, are "omitted from the climate models", as is the influence of major volcanoes …"

In the real world, climate scientists have not simply forgotten about solar activity - or about ocean circulation, or about volcanoes - and the impacts of all of these have been included in climate models.

"Global temperature reached a twentieth century high in 1998, corresponding to the strong El Nino episode of that year. Subsequently, the continued warming anticipated by the IPCC did not eventuate, and, after first reaching a plateau, by 2010 temperature had cooled slightly."

This is the argument that keeps coming back and back. As we have detailed recently, and here in more detail, a single decade is too restricted a period to use in testing whether climate change is occurring, or a model's predictions - because too much short-term "noise" clouds the long-term "signal". As one scientist put it, considering only 10-15 years of temperature is like

"analysing the temperature observations from 10-17 April to check whether it really gets warmer during spring."

Although the rate of warming has slowed over the last decade, it has not stopped. The Royal Society recently concluded that:

"each decade since the 1970s has been clearly warmer (given known uncertainties) than the one immediately preceding it. The decade 2000-2009 was, globally, around 0.15°C warmer than the decade 1990-1999."

The observed warming has fallen well within the predicted uncertainty bounds of the IPCC, as discussed by the science blog Real Climate.

"The "medieval warm period" was real, global, and saw temperatures exceeding today's"

It is possible that temperatures in the medieval warm period (MWP) may have been comparable with today's - uncertainties remain on this question, and coverage is somewhat patchy. But the weight of evidence suggests that the recent temperature extreme is unprecedented in the last 1,300 years. Moreover, temperatures during the MWP actually varied quite widely across different regions.

But mainly - the fact that climate has varied in the past is simply irrelevant to the observed, human-caused warming that has taken place since the mid-20th century.

"The ice-core records of the cycles of glacial and interglacial periods of the last one million years or so show a correlation between CO2 levels and temperature, but the changes in temperature preceded the changes in CO2 and cannot, therefore, have been caused by them."

The sequence Pell describes is correct; but this argument is little more than a red herring. Climate change during ice ages was triggered by other factors, such as changes in the Earth's orbital cycle. Carbon dioxide then acted as a feedback, amplifying the warming already occurring. This does not undermine the evidence that current warming is caused by manmade greenhouse gas emissions.

"I have discovered that very few people know how small the percentage of carbon dioxide is in the atmosphere. … today's total CO2 concentration represents less than one-twenty-fifth of one per cent."

As former Director of the UK's Tyndall Centre on Climate Change Research Kevin Anderson pointed out in a recent debate with Nigel Lawson:

"This idea that they're only a small part of the total gases in the atmosphere - of course that's true, but it's a really silly thing to say. I mean … if you put a small amount of arsenic into a human being, they don't respond particularly well. So changing something that is really important in the balance of the climate, even if it's a small part of that, is actually hugely significant."

Such figures, then, are little more than a meaningless distraction from the real issues.

Rather confusingly, Pell also states that the "case for the sceptics…has "so far has been completely ignored by the Australian media and political class". This statement would be somewhat surprising to anyone who has been observing the torrent of Australian media articles rejecting the science of climate change; or the vitriolic debate which has led to Australian climate scientists receiving death threats. Like so much else of the rest of the lecture, it is, simply, an inaccurate and misleading statement.

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