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Can we trust climate models?

Posted by on June 10, 2013

Climate change. Photo by Nick Russill, Flickr Creative Commons.By Rebecca Nesbit, Society of Biology

On Friday I attended an extremely interesting discussion at the Cheltenham Science Festival on ‘can we trust climate models?’.

Our climate is influenced by a vast number of inputs and feedback loops, from ocean currents to changes in albedo. Based on these complex factors, climate models have to make predictions about air temperature, sea levels, ice cover and more. That’s before we even introduce the uncertainty of how humans will change greenhouse gas concentrations.

Tamsin Edwards (climate scientist and blogger at All Models are Wrong) and Jonathan Jones (physicist at the University of Oxford) debated whether, even as climate models improve, we should trust them to predict the future. Tamsin remained confident, while Jonathan was sceptical.

Unsurprisingly, some kind of stale mate was soon reached, with the answer of “we’ll have to wait and see”. It’s true, we don’t know whether our predictions will play out. However, “I’ll tell you in 10-20 years’ time” isn’t of much use to policy makers.

Claire Craig from Government Office for Science explained that she can’t discuss the graph of changing global temperature every time a policy decision is needed, and she can’t wait for models to be perfect.

We started with the question of how well models and reality align, and were left with the question of how well reality, models and policy align.

The discussion with the audience was fascinating, and I would be very interested to hear your views.

Based on the level of uncertainty within our models, do you think our level of response to climate change is appropriate? Many of the vocal members in the audience felt that as we can’t be sure how climate change will affect us, we shouldn’t do anything which will, as they put it, harm us now.

If we act now based on our current predictions, we need to constantly review the evidence as new data comes available and models improve. Scientists and policy makers have to be ready to change their views.

Do you think scientists are too reluctant to change their minds? And does that go for everyone? Politicians included?

13 Responses to Can we trust climate models?

  1. Rebecca Nesbit

    Here’s an interesting piece about a complaint to the press complaints commission about reporting of predictions in the Daily Mail

  2. Dr Aaron Thierry

    “Many of the vocal members in the audience felt that as we can’t be sure how climate change will affect us, we shouldn’t do anything which will, as they put it, harm us now.”

    This view unfortunately shows that many people in your audience seem unaware of how we should make decisions under uncertainty.

    The risk associated with an event is determined by the product of the probability of it occurring (it’s uncertainty) and the impact of it occurring i.e. it’s cost (also known as the hazard).

    So it is worth mitigating against the risk of an event if it’s probability of occurrence is high (even if the hazard is low) and likewise it would be sensible to take action even if the probability was low if the impact was very large.

    An example here would be the risk of your home catching fire. We buy home insurance (even though it has a cost) to hedge against this occurrence, because even though a house fire is fairly unlikely the impact of one were it to occur would be huge.

    The consequences of our emitting a given amount of Carbon dioxide are still somewhat uncertain, but there remains a large possibility that the impacts could be catastrophic. This means that it would be very rational to take action now to avoid the possibility of triggering the worst-case scenarios which would be beyond our capacity to adapt.

    For further discussion on the points I’ve raised above I recommend this talk by Prof. Timothy Palmer of the Met Office:

  3. Jenni

    I think most people struggle with change: politicians, scientists and people all over the world, especially when there is the feeling of blame associated with the debate- “Your actions have caused this”. I echo the sentiments posted here already that we should focus on the solution and benefits of taking certain action. By considering our consumption of food, fuel and materials we are helping to minimise our lifestyle’s impact on future generations.
    Climate models may not be able to offer perfect predictions for future climate but they can certainly guide our approach and strategy for change.

  4. Jamie

    The climate is always changing, that is the issue, if we weren’t on this planet there would still be climate change! The fact that people are being more careful and starting to protect the planet can only be a good thing. The earth is becoming dirty and polluted and it is being utterly totally destroyed by us, but the last 10 years or so the climate hasn’t warmed at all, if anything it is cooling slightly, so to me it seems very unlikely that we are the cuse of ‘climate change’
    In fact climate records (ice cores etc) show that in the past co2 levels rise AFTER global warming, so surely that must mean something?

  5. Daniela Peukert

    It will be always difficult to predict the precise consequences of climate change, simply because it is such a complex issue involving so many factors. I think it should be our general responsibility to reduce the human impact on nature, as best as possible (e.g. with recycling, reducing food waste, alternative energy…). My biology teacher said once “nature can live without humans but humans can’t live without nature”.
    So I agree with JC that our response to climate change can be only a good thing. However, better models will help us to set priorities in this complex discussion.

  6. Rebecca Nesbit

    That’s certainly another example of an action which, rather than ‘causing harm’ as some of the men in the audience were keen on stressing, brings multiple benefits. Do you have any links about it?

    On my stand at the festival I was showing the two forms of the peppered moth…

  7. Barry Woods

    One of Jonathan’s points is to first choose no regrets options for policy (ie the low hanging fruit, tackling black carbon might be one (which is my opinion) ie soot.

  8. Jonathan Jones

    An excellent summary; I’m glad you enjoyed the event. Do you happen to know who the biologist was who made the comment about models in his own field?

    • Rebecca Nesbit

      Sadly not – his seemed one of the most interesting/ intelligent questions. Thanks for an interesting event.

  9. JC

    I think our legislative responses to climate change – switching to renewables, recycling, re-use, carbon capture, etc etc can only be a good thing whatever the models say, and however climate change will impact our lives (or not).

    For me it’s not about predicting the future, it’s about being responsible citizens for future generations – if we know fossil fuels will run out, and we know carbon emissions are harmful pollutants, then there’s no question – we have to find and fund alternatives. The rhetoric needs to be changed on the climate change debate, because it’s too easy to blame a supposed ‘lack of evidence’ to justify our lifestyles and policies.

    On being too reluctant to change our minds, this is a great podcasts on Republicans and climate change in the US:

    • Rebecca Nesbit

      I agree that we are in the (arguably) fortunate situation that so many of the ways we need to tackle climate change have other benefits too – eg renewable energy is needed to deal with the finite nature of fossil fuels, protecting forests has benefit for biodiversity etc.

      At the talk Claire was keen to emphasise that we should look for solutions which have duel benefits.