The environment comes first, so we must drive down transport CO2 Local Transport Today, March 18th  2016

The interview with Benny Peiser of the Global Warming Policy Forum in LTT 691 raises some interesting points which merit a response.  Peiser, it seems, is not a ‘climate change denier’; he accepts the underlying science – that greenhouse gases trap heat and that human activities are generating those gases.  The graph that accompanied his article shows average global temperatures continuing to rise, though not as quickly as some climate models had predicted.  The crux of his argument is that the rate of change may be slower and the consequences more benign than the scientific consensus projects.  To make costly changes in response to projected climate change would therefore waste money and cause unnecessary economic disruption.

The Stern report offers one possible response to that argument; Stern calculated that action would be much cheaper than inaction in the long-term.  Both of these lines of argument rely on uncertain predictions about the future, so the debate is really about how we respond to uncertainty.  This is where transport professionals may legitimately get involved.

There are broadly three types of evidence on climate change: the basic science, the measurements and the projections of climate models.  The level of certainty is highest for the basic science and lowest for the projections of the future.  Between those two, the data on greenhouse gases are as accurate as the measuring equipment.  Likewise with temperatures, although the averaging process introduces further uncertainties, which explains some of the variation in global temperature series.

Graph: Atmospheric CO₂ (left scale, ppm), Annual global temperature anomalies (right scale ^oC).  Source: IPCC (CO₂ to 2010) NAOO (CO₂ 2010 – 2015 and temperatures)

The graph above shows the concentration of CO₂ and changes in average global temperature, taken from the websites of the IPCC and the US National Oceanic and Atmospheric Administration.  If anyone believes there has been a global conspiracy to misrepresent the data, I would recommend they read the Final Report of the Independent Climate Change E-mails Review, which followed the ‘Climategate’ hacking incident.  Look at the methodology they used.  Instead of trying to unpick the original analysis the panel ran their own analysis using publically-available temperature records, created by different organisations in different parts of the world.  The graph on page 47 shows that even if Prof. Phil Jones had been part of a conspiracy with the IPCC, Al Gore and Al Qaeda to bring down Western civilisation anyone with the software skills, using different data sources, would have come to broadly similar results, differing slightly depending on which data source is used.  If you don’t believe that, you can do it yourself.

More fundamentally, would a conspiracy change the basic science? Would it change the concentration of greenhouse gases in the atmosphere? The modelling projections are subject to uncertainty; would a conspiracy change that fact?

The twin elephants in this room are political values and ‘the evidence we want to believe syndrome’.  We all prefer to believe evidence that supports our world view or contradicts people we dislike but that does not change the evidence itself.  The Global Warming Policy Forum clearly places a higher weight on economic growth than they do on environmental sustainability.  They prefer to believe that global warming will be slow and benign.  I believe that protecting the planet is more important than economic growth; I don’t believe humans should be changing the composition of the atmosphere, even without climate change.  I might be tempted therefore to believe more catastrophic projections but I am not a climate scientist and neither is Benny Peiser or Lord Lawson.  None of us knows how quickly and in what way the Earth will warm in response to what level of carbon emissions.  The science is evolving all the time but certainty only comes in retrospect.  So when deciding what to do about it we have to invoke the precautionary principle. 

Although Peiser doesn’t actually use that term, he applies that principle to the economy, which he places above environmental concerns.  I would reverse those priorities and attach a particularly high weight to avoiding catastrophic change, even if the likelihood is small and even if (as seems likely) the worst consequences occur in the distant future.  The predictions of the climate models vary (which is difficult to reconcile with the idea of a conspiracy) and some or all of them may prove to be quite misleading but for predicting future consequences, they are all we have to go on.  If the Global Warming Policy Forum can provide a better method of doing that, they should publish it for scientific scrutiny.

When considering the implications of all this for transport, there are many reasons for moving away from fossil fuels and towards more active travel, such as local air pollution, energy security and public health.  If you believe those reasons are valid then climate change simply adds urgency to them. 

“Every scientist is a layman in another’s field” a physicist friend once explained to me and that is a useful maxim for this debate.  Transport professionals would be well advised to leave climate science to the scientists.  We may refer to it but if we try to second-guess projections or causal explanations then we are deluding ourselves and others.  On this and on many other issues (speed cameras, for example) where we differ on policy prescriptions because of our values or political beliefs then let’s openly acknowledge that, instead of trying to hide behind different and sometimes dubious interpretations of factual evidence.

Dr Steve Melia is Senior Lecturer in Transport and Planning at the University of the West of England and author of Urban Transport Without the Hot Air.