Donate

Climate change: a model cock-up

A climate model program downloaded by thousands of PC users had an internal error that meant it overstated how hot the world might get. Oops.

Rob Lyons
Columnist

Topics Science & Tech

Researchers behind a much-hyped climate model downloaded by hundreds of thousands of home PC users have had to admit that many of their results are wrong because of errors in the program. And it’s not just their software that’s flawed.

The software, produced by Oxford University in conjunction with a consortium of research institutions, was launched with great fanfare in February by the BBC. Around 200,000 people downloaded the programme, which runs in the background on PCs, each one working on one of thousands of very slightly different scenarios about how the world’s climate might change in the future.

However, after two months it’s been discovered that there were errors in a data file which was supposed to take account of particles in the atmosphere that suppress rising temperatures. Consequently, the world was – virtually, at least – getting too hot, too quickly.

The project’s principal investigator, Dr Myles Allen, found a silver lining to this climate-modelling cloud. ‘What we’ve seen in the runs is the unadulterated impact of global warming which means that all of the models have warmed up too fast’, he told BBC News. ‘At some point in the future, we may have done an experiment like this anyway.’

The real problem is not an individual cock-up in one computer program, but the excessive reliance on models in the broader debate about global warming.

That is not to say models are completely without value. It is reasonable to put together our best guesses as regards future trends like gas emissions, population change, solar outputs and so on with what we know about climate physics to produce some broad estimates about what might happen next. But these are sophisticated guesstimates, no more. They allow us to think through what are the parameters of the discussion; they do not represent viable predictions of the future.

There are many good reasons why the models will be inadequate, not the least being the possibility of bias, conscious or unconscious, in the initial setup. For one thing, the data we have will always be incomplete. Satellite measurements are better than they were in the past, but they only go back to the late Seventies. Before that, weather records are based on stations that were unevenly spread, with relative high concentrations in developed countries and relatively few over the 70 per cent of the Earth covered by water.

The physics of individual climate elements is not fully understood, particularly in relation to clouds; we don’t know how much cloud will be produced in a warming world and what the net effect of that cloud will be. In addition, new announcements from research teams are made regularly about factors that hadn’t been fully appreciated before.

Also, models are, by their very nature, simplifications of the real world. Consider a non-climate example: the Millennium Bridge in London. This was a relatively simple system to model. But when the bridge opened in June 2000 it had to be quickly closed again because the effect of people actually walking on it caused the whole thing to ‘wobble’. So even engineers with far less complex problems than world climate to solve can get things badly wrong.

Which brings us to the bottom line in climate modelling. How can we test that the models actually work? Attempts to see how the models replicate the known temperature from the past are problematic because we know, given the inadequate coverage and mixed standard of ground-based weather stations in previous decades, that this temperature record is incomplete and almost certainly inaccurate. We could wait a few decades to see how real temperatures pan out, but that rather defeats the object of the exercise, especially if you believe we’ll all be parched or drowned in a century’s time.

So, we should accept the conclusions of climate models critically, and look into how other sources of experience agree or disagree with them. But unfortunately, this is not what happens. Instead, for reasons quite unrelated to climate science, each new set of results and each new report is leapt upon by one side or the other as confirmation of their own position.

Take the recent comments by Britain’s chief scientific adviser to the government, Sir David King. On BBC Radio 4’s Today programme he said, ‘If you ask me where do we feel the temperature is likely to end up if we move to a level of carbon dioxide roughly twice the pre-industrial level – and the level at which we would be optimistically hoping we could settle – the temperature rise could well be in excess of three degrees celsius.’

This immediately sparked fevered discussion about how many millions – or billions – of people would be effected. In fact, the effect of that rise in carbon dioxide in isolation from other factors would be about one degree celsius. Whether the temperature would rise more than this depends on feedback effects that are still not properly understood. Plucking one figure out from a report as if there were any certainty about it is unhelpful.

The discussion, driven by excessive enthusiasm for one particular form of research, is one-sided and perverse. It is one-sided because it very often ignores the fact that societies adapt to changing circumstances. If the world did see a significant rise in temperature overnight, it is quite likely that there would be dramatic and negative consequences for many people – although equally, warmer weather would benefit other areas, too. However, over the course of the next century it is perfectly possible to change how land is used, to build flood defences and create proper water supply infrastructure, especially if societies become wealthier in the meantime. So anything that holds back development would cause far more problems than it would solve.

And the discussion is perverse because it ignores very major problems in the here and now in favour of flagging up some potential medium-term apocalypse. These are not just technical or scientific problems, either. Why is it, in the twenty-first century, that so much of the world lives such a marginal existence that changing weather patterns could prove disastrous for them? That is a political problem that has slipped a long way down the agenda in popular debate.

Most perversely of all, the discussion of climate science has become a political clash between, in the main, environmentalists on one side and free marketeers on the other – while political debate about the best future direction of society is left in the hands of climate modellers.

Read on:

spiked-issue: Global warming

To enquire about republishing spiked’s content, a right to reply or to request a correction, please contact the managing editor, Viv Regan.

Topics Science & Tech

Comments

Want to join the conversation?

Only spiked supporters and patrons, who donate regularly to us, can comment on our articles.

Join today