Ray Bates replies to criticisms of climate modellers and "doomsday" politicians, stating that we should continue to take climate change seriously.
At a time when the public is being alerted constantly to the dangers posed by climate change, and governments are facing difficult and costly decisions as to what actions to take on greenhouse gas emissions, it is healthy that not only the consensus view of the climate research community but also the views of reputable dissenting scientists be heard.
The consensus view is well represented by the recent Summary for Policymakers issued by the Intergovernmental Panel on Climate Change (IPCC) in advance of its Fourth Assessment Report (www.ipcc.ch).
Briefly summarised, this states that global warming is unequivocal, that it is with more than a 90 per cent probability caused by human activities, and that it will become much more serious with time, due mainly to CO2 emissions.
A dissenting view has been taken by Dr Henk Tennekes, an expert in the field of atmospheric turbulence, in his provocative Irish Times article "Happy to rain on parade of arrogance".
Dr Tennekes angrily criticises the general community of climate modellers and all politicians who take global warming seriously, reserving his particular ire for the IPCC.
His assertions may be summarised as follows:
• The IPCC is preoccupied with CO2 emissions and the climate models used to predict their consequences. These models are unreliable and the modellers themselves are arrogant and lacking in integrity, using alarmism to get increased funding.
• Climate predictions should be regarded as of secondary importance and a policy of permanent adaptation to whatever changes may occur in the planetary ecosystem should be adopted.
As a climate researcher who has no present connection with the IPCC I will here contest the above assertions of Dr Tennekes insofar as they lie within the scientific arena.
Anybody who reads the IPCC's Summary for Policymakers will find that it gives at least as much emphasis to observed data as it does to model predictions. There is ample evidence from the recent data to justify serious concern about the changes occurring in the global climate.
To name a few, the global average temperature is increasing, mountain glaciers are retreating, the Arctic permafrost is melting, Arctic sea ice is decreasing and the global sea level is rising.
The extent of the changes to date is not disastrous, but the trends are accelerating. It is true that the IPCC takes the increase in CO2 and other greenhouse gases seriously, and there is good reason to do so, even in the absence of model predictions.
If present trends continue, the atmospheric concentration of CO2 will reach twice its pre-industrial level within this century.
The paleoclimate record for the past 400,000 years from ice cores and other sources shows a very strong correlation between CO2 concentration, global temperature and sea level, with all three quantities rising and falling together between interglacial and glacial periods.
Changes in CO2 concentration of the order of those already caused by human activities were associated in the paleo-record with changes in temperature of 5 degrees and changes in sea level of 100 metres. Never within the 400,000 years of this record did the CO2 concentration approach its present level.
In pushing up the CO2 concentration, mankind is performing a global experiment whose long-term consequences are impossible to predict with certainty, but which are potentially catastrophic.
Coming to the large computer models, they undoubtedly have their limitations, but they are successful in simulating the gross features of the present climate and have recently been shown to simulate successfully the climate changes that have occurred over the past century when the changes in greenhouse gases and other perturbing influences are included.
They are the best prediction tools we have and their predictions of an approximate rise of 3 degrees in global temperature in response to a CO2 doubling cannot be dismissed as lightly as in Dr Tennekes's article.
As to Dr Tennekes's charges against the modellers themselves, they are over the top.
Many of the modellers involved in compiling the IPCC Report are known to me personally. Collectively, I would characterise them as sober and responsible people. I doubt if any of them would write anything as lacking in humility as Dr Tennekes's article (where the phrase "I am angry" occurs six times and the pronoun "I" 20 times in all).
Dr Tennekes suggests that he was forced into early retirement because of his contrary views on global warming. If this is the case, it is, of course, unfortunate, but it does not justify him in making outrageous accusations against his peers.
Nor can his experience be generalised to say that only nay-sayers on global warming suffer negative consequences: many US climate scientists have complained of attempts by the current administration to silence them because they are concerned about global warming.
In conclusion, the article tells us that Dr Tennekes is angry, but it provides no convincing reason to doubt the findings of the IPCC. The politicians who have been taking global warming seriously should continue to do so.
Ray Bates is Adjunct Professor of Meteorology in the School of Mathematical Sciences at UCD. He was previously Professor of Meteorology at the University of Copenhagen and a senior scientist at NASA's Goddard Space Flight Centre.