IPCC report and climate change

Tue, Apr 8, 2014, 02:00

Sir, – Frank McDonald’s article (Opinion & Analysis, April 4th) and your editorial of April 1st are welcome responses to the urgency of the latest report from the IPCC. But the fact remains that the issue of climate change has failed to engage public discourse in the way that it surely ought to have by now.

Arguably the factor that more than any other contributes to this failure is a general misunderstanding of how risk is assessed. For example, the persistent misuse of the term “sceptic” in this context only serves to obscure the reality of the risk inherent in climate change.

Two components come into play with risk assessment: a) the probability of an event occurring and b) the consequences of such an event occurring. An event with a 98 per cent chance of occurring but with minimal consequences would not generally warrant much in the way of preventive measures being adopted. On the other hand a potentially catastrophic outcome with a 2 per cent probability of realisation would warrant more diligent attention. To be clear, risk assessment cannot predict the future: what it does well is identify and model probable outcomes, derived from currently identified trends.

The overwhelming, peer-reviewed, scientific consensus about climate change is a) that it is happening and its temperature-raising component is currently largely driven by human activity and b) that left unchecked, the consequences of this will be catastrophic. “Overwhelming” here is conservatively estimated at 98 per cent on both counts – ie the aggregate level of risk is huge.

So-called sceptics are entitled to disagree with this consensus, but if they are to be true to the sceptical tradition they must surely acknowledge the reality of the identified risk. By flatly denying the validity of current models of future climate – saying, in effect, that the probability of catastrophic outcomes has a 0 per cent chance of occurring – without offering any credible alternative models of future climate, they are in denial and not in any way engaging with the evidence in a way that the term “sceptic” would imply.

A straw increasingly clutched at by denialists as weather events become more unpredictable – as current climate models predict they will – is to seize on cold weather events as evidence against climate change predictions. This would equate to attempting to construct tide tables based on a one-minute study of wave motion: another example of a complex, chaotic phenomenon masking a far simpler underlying trend.

Also the apparent pause in atmospheric heating observed in recent years as the oceans absorb for the time being unexpectedly high levels of energy – incidentally accompanied by growing acidification as more carbon dioxide is absorbed with devastating impacts on marine ecology – has “sceptics” champing at the bit to shout down the overwhelming scientific consensus of the urgent reality of human-driven (aka anthropogenic) climate change. In truth, the risk to the planet is both real and unaffordable, this being the only home we have.

PETER WALSH

Heathervue,

Greystones,

Co Wicklow