The end of scientific consensus
The Royal Society, which is Britain’s top dog in science (indeed many scientists would say the world), has just published a report signalling the end of claims of a consensus by some climate scientists and some governments that the world faces dangerous warming unless governments act quickly to reduce emissions of greenhouse gases.
The report, Climate Change: a summary of the science, points out that climate change “continues to be the subject of intensive scientific research and public debate” and divides the existing state of knowledge into three categories – science that is well established, where there is wide consensus but continuing debate, and where there remains substantial uncertainty.
In the latter category, for example, the acknowledgment that the uptake of CO2 by the land and oceans is “very poorly understood” is tantamount to saying that it is not possible to predict with any confidence the future concentration levels of CO2 in the atmosphere. It certainly leaves open the possibility that the uptake of CO2 by land and oceans will be considerably higher than the extreme 25% rate projected by the Intergovernmental Panel on Climate Change (it is currently 50%). If that happened it would mean that concentrations of CO2 (and other greenhouse gases) would reach supposedly dangerous levels at a significantly later date than the alarmists are predicting – and temperatures would rise less.
Further, while claiming “strong evidence” exists that warming has been caused “largely by human activity”, it acknowledges that the size of future temperature increases and other aspects of climate change are “still subject to uncertainty” and that the attribution of forced climate change to particular causes is “not straight forward”. Remarkably, the report also accepts that since 1910 increases in temperature have occurred in only two periods – from 1910 to 1940 and from 1975 to around 2000 – that is, for only about half of the last century. Although the usual scientific explanation of the warming thesis is that temperature increases are caused by increased concentrations of CO2 in the atmosphere, the Royal Society report provides no explanation of why the increase in CO2 concentrations during most of the century did not result in continuing temperature increases.
However, perhaps the most devastating statement for alarmists is that “It is not possible to determine exactly how much the Earth will warm or exactly how the climate will change in the future”. This leaves in doubt what policy should be adopted, and when, to reduce emissions. The report’s acceptance that uncertainty exists about the effect clouds have on temperatures is one important reason for delaying action. Another is the acknowledgement of poor scientific understanding in various other areas, such as the likely extent of reductions in ice sheets in Greenland and West Antarctica from any further temperature increases. Yet another is the admission that “there is little confidence” in projections by models of climate change in regions, including Western Europe. This also suggests that predictions of worsening drought conditions in the Murray Darling Basin have no scientific basis.
The report’s conclusion on possible increases in sea levels also implies only scanty science supports what may happen there. The main statement is that “it is very likely that for many centuries the rate of global sea level rise will be at least as large as the rate of 20 centimetres per century that has been observed over the past century”. Such an increase would constitute little or no threat by comparison with many of the scares promulgated in various quarters in recent years, including by our CSIRO. It effectively lowers the Intergovernmental Panel on Climate Change upper estimate of a 59 cms rise by 2100 and certainly challenges the need for the restrictions on property development which government authorities have started to impose around Australia’s coast lines.
The contrast with the conclusions drawn from the 2007 report of the IPCC is marked. The IPCC not only claimed that warming is “very likely” due to human activity (which suggests a 90 per cent certainty) but its temperature projections have been widely interpreted as requiring policy action to counter likely increases of 2.4-4.5C degrees by 2100, with a so-called tipping point of 2 degrees by 2050 beyond which further temperatures increases would not be reversible. The Royal Society report, however, offers no temperature ranges, no tipping point, is (as noted) uncertain about the possible extent of increases in temperatures and, beyond saying that climate change has “significant implications”, it offers no assessment of its possible impacts. While it does claim that temperatures in the decade 2000-2009 were globally around 0.15C higher than in the decade 1990-1999, analysis of the changes since 2000 shows no statistically significant increase.
Where to now? At Copenhagen it will be recalled that some world leaders attempted to secure an agreement for early action to start reducing emissions on a global basis. Media reports are now suggesting any agreement will not occur at the next meeting, scheduled for Cancun in Mexico next month, and is being set for South Africa next year.
As for Australia, the statement by new Climate Change Minister, Greg Combet, that the government accepts “mainstream economic thinking” now raises the question – well, given the Society’s report what is the mainstream? The terms of reference of the committee established to examine how to introduce a carbon price must surely be changed to examine whether and when any price might be implemented.
The report by the Royal Society, members of which are highly qualified scientists, is a response to complaints by a small group that the Society’s claim of a consensus was untenable and contrary to science itself. The report suggests a review in Australia that included the sceptical scientists here would produce a similar outcome.
Des Moore, Director, Institute for Private Enterprise, has a BSc degree from London University