David Rose's climate science - half truths and bias

  • 24 May 2011, 14:00
  • Verity

David Rose, writing in the Mail on Sunday over the weekend, criticised the science behind the government's decision on carbon budgets, which committed the UK to halving emissions of carbon dioxide by 2025.

This isn't the first time that Rose has written about climate science.  A piece he wrote for the Mail in December 2010, entitled "What happened to the 'warmest year on record': The truth is global warming has halted" was eviscerated by the Guardian columnist George Monbiot, using scientific references provided by the Climate Science Rapid Response Team.

With that in mind, we took a look at his claims in last Sunday's article….

Rose starts by taking issue with both the 2008 Climate Act and Chris Huhne's statement that cutting emissions of greenhouse gases would protect the climate, saying:

 "Underlying them both is an assumption that remains widespread - at least in the Westminster policy-making bubble - that the science of man-made global warming is 'settled'….Good scientists detest that phrase, pointing out that science is never 'settled' but rather an ongoing process of testing, refinement and rethinking."

It is true that the scientific process relies on testing, refinement and rethinking - this  is the process by which climate science has progressed. Since Arrhenius first calculated the potential effect of changing CO2 on climate in 1896, the theory has been rigorously tested. A century of subsequent research has not disproved the theory, and no plausible hypotheses have been proposed which can account for the overall warming trend over the past 50 years. There is a mass of evidence indicating that the globe is warming, with significant impacts on physical and biological systems around the world. This is why 97 out of 100 of climate researchers are convinced by anthropogenic climate change.

Rose goes on to discuss a statement made by Dr Phil Jones of the University of East Anglia:

"Dr Jones has previously admitted that, in surprising contrast to what computer models were predicting 20 years ago, there has been 'no statistically significant warming' since 1995."

Dr Jones agreed in a BBC interview last year that the warming trend between 1995 and 2009 was "only just" statistically insignificant - a statement which has was seized upon by climate skeptics (see for example here, here and here). 

The headlines neglected to mention that in reality, climate scientists avoid drawing general conclusions about global temperature trends based on such small amounts of data. As one scientist has 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."

There has been roughly 0.75°C warming since the beginning of the 20th Century. Short-term variations in temperature 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.

Rose moves on to an exchange with Professor John Mitchell, principal research fellow at the Met Office:

"I raised this with Mr Mitchell, asking how long this would have to continue, despite uninterrupted increases in the level of CO2, before he would start to question the validity of the models and the theory of man-made warming that they underpin.

His answer sounded peculiarly unscientific, implying it would take a lot more than the absence of actual warming to shake his faith. 'People underestimate the power of models. Observational evidence is not very useful,' he said. 'Our approach is not entirely empirical.'"

The question that Rose put to Professor Mitchell implies that scientists do not question the validity of the models that they use and their underpinning theories. In reality, climate scientists are constantly questioning, refining and improving models. The IPCC AR4 report devotes an entire section to that very topic.

It is obvious that models that are attempting to construct what may happen tomorrow cannot rely solely on observations of what is happening today. Scientists instead rely on sensitivity studies or comparing outcomes from many different models.

Rose moves on to the skeptics:

"Others at the conference presented powerful opposing arguments. Ian Plimer, professor of geology at Adelaide University in Australia, showed how the world was often much warmer before industrialisation. He added that only three per cent of the CO2 in the atmosphere comes from human activity, the rest originating from sources such as volcanos."

The argument that "the climate has warmed in the past, therefore the current warming cannot be man-made" has been described in a recent book as "….akin to saying 'forest fires have occurred naturally in the past so any current forest fires must be natural'."

The natural processes controlling climate in the past are insufficient to explain the warming trend over the 20th century. Similarly, the argument that only 3% of the C02 in the atmosphere comes from human activity ignores the fact that man-made emissions of C02 are additional to the natural carbon cycle. As a result of man's activities atmospheric CO2 is now at the highest level for 15 to 20 million years.

Plimer's claim (also made elsewhere) that most of the carbon dioxide in the air is a result of volcanos is totally unfounded. The US Geological Survey (USGS) has assessed the scientific literature regarding CO2 emissions and finds that CO2 emissions resulting from human activity are around 100 times higher than CO2 emissions resulting from volcanos.

Rose continues by citing work from Professor Henrik Svensmark, who argues that

"…one of the key determinants of climate is the level of cosmic rays from outer space that hit the Earth: these high-energy particles 'seed' the clouds by forming what he termed 'ultra-fine condensation nucleii'. More rays mean more clouds, and in turn, a cooler climate.

"According to Prof Svensmark, quite small variations in the amount of cloud cover have a big effect on temperature, leaving man-made CO2 emissions with a small 'residual' role."

The theory that cosmic rays influence cloud cover has been under discussion since Svensmark first suggested it in 1996. A review of the evidence published in March concluded that:

"No correlation is found between cosmic ray changes and the whole cloud cover…Cosmic rays have negligible effect on the global temperature and on climate."

Rose goes on to discuss a report recently written for the GWPF by Lord Turnbull:

"Lord Turnbull…warned that the 'real inconvenient truth' of UK climate policy is not that described by Al Gore's alarmist film, but the fact that the 'whole structure is built on shaky foundations'…

We have addressed the five key scientific errors in Lord Turnbull's report in a previous blog.

Rose continues:

"He identifies some of the warmists' bigger difficulties, such as having to explain why there have been several periods since the Industrial Revolution started when temperatures have declined."

As outlined above, the fact that temperature has gone up and down over the last 150 years does not disprove the overall warming trend.

"Another is that even if CO2 were to double, even the most gloomy warmists agree that this alone would cause a temperature rise of just one degree - a far cry from the three to six degrees posited by their models.

"To justify this, they claim small increases in CO2 will trigger amplifying 'positive feedback' - a rise in atmospheric water vapour and a more effective 'greenhouse gas' than carbon dioxide. But is this true? Citing unimpeachable scientific sources, Lord Turnbull says it is 'assumed, but unproven'."

In response to the last point, climate scientists assess a measure known as 'climate sensitivity' - how much the world would warm if the amount of carbon dioxide in the atmosphere doubled. The IPCC estimates that climate sensitivity is between 2 and 4.5 ˚C.

The amplifying effect of water vapour was predicted by climate models and has been experimentally confirmed. There have been suggestions that warming will increase low-level cloud cover, and that this will provide a cooling feedback, regulating climate change. However, a number of recent studies indicate that even low-lying clouds are more likely to cause warming, and any cooling effect from clouds is unlikely to offset the water vapour amplification and other warming feedbacks.

The "unimpeachable scientific sources" referred to appears to be a sentence in the GWPF report:

"Some scientists such as Professor Lindzen of MIT argue that the net [feedback] effect [of water vapour] could go either way."

However this statement is not referenced, so it is not clear to what research he is referring.

Overall, Rose's article is a collection of biased half-truths and unreferenced statements. Many of these have been repeated elsewhere many times by climate skeptics - and the overall effect is to give an entirely misleading picture about the current state of climate science.

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