Challenging Climate Science

In recent weeks as the IPCC has revealed a number of misquotes in their 4th Assessment Report and with the UEA e-mail issue rumbling on, climate science has come under intense scrutiny. A couple of weeks back I commented on the way in which we all seem to love technology, but at the same time society is becoming increasingly uneasy with science.

As has been the case over the many years of this issue, the media is also playing a role. In the past we have often seen reports of apocalypse and whilst many of these reports had a basis in science, they sometimes reported one extreme end of the spectrum of potential outcomes. Today, it is climate science that is undergoing a similar treatment. Late last year the Daily Express compiled its “100 Reasons Why Global Warming Is Natural” (, first published during Copenhagen but now rolled out again in the context of the start of the government enquiry into the University of East Anglia e-mail break-in. Like the stories of apocalypse, it could make the reader think that the scientific basis for anthropogenic warming had utterly collapsed. But on closer scrutiny the 100 reasons don’t present a reasoned arguement to believe that everything has suddenly changed.

Let me illustrate: In the region of half of the statements, whether true or not, have no bearing on the relationship between increasing greenhouse gas levels in the atmosphere and recorded warming over the last 100 years (e.g. India plans to reduce the ratio of emissions to production by 20-25% compared to 2005, but all government officials insist that since India has to grow for its development and poverty alleviation, it has to emit, because the economy is driven by carbon). Then there are numerous statements which are just that, statements, with apparently no quoted evidence or substantiation. For example;

Statement 2 argues that man-made carbon dioxide emissions throughout human history constitute less than 0.00022 percent of the total naturally emitted from the mantle of the earth during geological history. This may well be the case, but has no bearing on the fact that we have added nearly 2 trillion tonnes of CO2 and other greenhouse gases to the atmosphere in just 200 years and that this has been sufficient to see a marked shift in the CO2 levels in the atmosphere today.

Statement 7 argues that the 0.7C increase in the average global temperature over the last hundred years is entirely consistent with well-established, long-term, natural climate trends. The problem here is that this has been shown not to be the case. Page 11 of the Summary for Policymakers (Fourth Assessment Report) of the report of Working Group 1 of the IPCC shows that both natural and anthropogenic forcings need to be applied to explain the changes in temperature over the 20th century. No other approach consistently matches the observed data.

Statement 15 argues that it is absurd to accuse a single trace gas of radically changing the climate. But the IPCC makes it abundantly clear that climate change is the result of many anthropogenic forcings, including CO2, other trace gases, aerosols and changes in cloud cover (e.g. contrails from aircraft). However, there is also clear evidence that CO2 is a very important forcing component in the atmosphere.

Whilst every media outlet and every person is more than entitled to express an opinion, and I welcome the debate, we urgently need to raise the level of the debate and understanding of climate science. There is little doubt that much is still to be learned about this great physics experiment we are undertaking in our atmosphere by changing its composition. Perhaps warming will proceed dramatically over the next few decades, but there is a chance other factors might just supress everything for a while and leave us in a state of complacency. Either way, we can’t actually be certain today, but we can go some way to quantify the risks that we are running. This is where much of today’s scientific study is focussed. Shell sponsors MIT’s Joint Program on the Science and Policy of Global Change which undertakes such risk analysis.

More to the point, the complication with this issue is that we have to act before we can be absolutely sure of the outcome. If we don’t act and it transpires that the outcome is not something the world likes, there is then no going back. This means that society needs to both understand the science and come to terms with the risks that it shows we are collectively running.