Challenging the climate sceptics

A rebuffal to the latest media scepticism about climate change has been made by Sir John Houghton, formerly Oxford Professor of Atmospheric Physics, chief executive of the Meteorological Office and Co-Chairman of the IPCC Scientific Assessment. He is currently President of The John Ray Initiative.

In the latest paper produced by the John Ray Initiative, 'Copenhagen and the Climate Change Crisis' JRI Briefing paper 19, Sir John Houghton argues that Christians and other faith communities must keep up the pressure for more action on climate change at the next UN climate meeting in Mexico in December 2010. He suggests that many of the voices of scepticism have been orchestrated by vested interests, especially in the United States, with the intent of discrediting and silencing the Intergovernmental Panel on Climate Change (IPCC).

He expresses concern about public acceptability in developed nations like our own of the science of human induced climate change. In the autumn of last year, polls reported that in the UK only about 60% of the general population (less than half in the USA) believe that human induced climate change is the serious problem that scientists make it out to be. Now, at the beginning of 2010, those numbers appear to have been substantially reduced, largely it seems because of recent media attention on doubts that have been raised about the underlying science and its credibility. As a result some feel they might have been steamrollered into believing something that may not be true and that may seriously impact their lifestyle. He says:

'If governments are going to be comfortable about taking the necessary action, therefore, an urgent need is for better information and education about the evidence for climate change and its likely impacts to be presented to a confused public in a completely honest and open way. In addressing this need, let me first address the reliability of the science.

The most reliable source of scientific information about likely climate change is the Inter-governmental Panel on Climate Change (IPCC) that was founded in 1988 to produce accurate, balanced and honest assessments about human induced climate change. It has involved many hundreds of scientists from many different countries, cultures and disciplines in producing major reports in 1990, 1995, 2001 and 2007. I was the chair or co-chair of the first three of the basic science reports and can vouch for the diligence, integrity and openness of our work. We had lively, heated debates in which non-scientific influences from political or personal agendas were not allowed. If in doubt we steered away from anything that might seem alarmist. These reports were subject to a very thorough review process and their Policymakers. Because of this careful scrutiny process, the
conclusions of the IPCC reports are accepted by nearly all governments and have also been endorsed by the world's major scientific academies. With the vast increase of climate data and of scientific effort that has taken place over the 20 years since the IPCC was formed, its conclusions in the later reports have become stronger. Let me summarise the most important ones.

Most people accept the fact of global warming. But is it due to human emissions of green-house gases such as carbon dioxide, they ask? The IPCC cites two pieces of strong evidence. First, there is no doubt that carbon dioxide has increased in the atmosphere over the last 200 years by about 40%, largely due to the burning of coal, oil and gas. That carbon dioxide absorbs infra red radiation, acting like a blanket over the earth's surface and increasing its average temperature, is a piece of science called the greenhouse effect that has been known for over 200 years. Secondly, computer models of the climate that take into account all known natural forcings of climate (due to volcanoes, changes in sun etc) and anthropogenic forcings (due to increase of greenhouse gases, carbon dioxide and methane, and atmospheric particles from various sources) give good agreement between observed and simulated global average temperatures. Agreement cannot be achieved with either natural or anthropogenic forcings on their own. Model simulations of recent and past climates having been tested against observations provides confidence in future projections with different emissions scenarios.

The IPCC's main conclusions about future impacts on human populations relate to the effects of sea level rise on coastal communities, to changes in the frequency and intensity of climate extremes such as heat waves, droughts and floods, and to changes in available water resources. Because the Earth takes time to warm, with the climate change to which we are already committed, these impacts are likely to be substantial and will become increasingly apparent over the next decades. Further, if mitigation action is delayed or if little or no action taken, before the end of the century average sea level rise is likely to be up to about 1 m, the risk of droughts and floods in many places is likely to have increased by a factor of 5 or more from its value in the 1970s or 80s and acute shortages of water will occur in many places especially in Asia and South America. Since floods and droughts are the most damaging on average of all natural disasters, more of them and increasing severity is very bad news particularly for those living in the most vulnerable areas. These likely impacts have been folded into estimates of the cost of global warming in economic terms in the Stern Report by the distinguished economist, Lord Stern from the UK. He concludes, as does the IPCC, that the cost of likely damage much exceeds the cost of mitigating action. That is the case even when the damage is ignored that cannot be expressed in money terms, such as that of displacement, insecurity and misery suffered by hundreds of millions of refugees forced to move from disaster areas - and where would they go in our increasingly crowded world?

Throughout IPCC Reports, statements of levels of uncertainty aremfrequently made; in the latest report many of these are quantified. For instance, the increased risk of extremes may be described as likely (67% likelihood) or very likely (90% likelihood). Some who look at IPCC reports interpret these references to uncertainty as an indication that the science of climate change is as a whole very uncertain. Such a superficial interpretation is quite false; the IPCC has always sought to distinguish clearly those conclusions that are relatively certain from those where there is large uncertainty. Few if any scientific conclusions concerning the climate can be completely certain but to ignore those that appear likely or very likely would be highly irresponsible.'

The full document is available at: www.jri.org.uk/wordpress/wp-content/uploads/JRI_19_Copenhagen.pdf