AR5s coming get busy: why scientists must get better at communicating uncertainty
A senior climate scientist has warned colleagues must get better at conveying the nature of scientific uncertainty in preparation for a greater range of future climate projections in the Intergovernmental Panel on Climate Change (IPCC)’s next report.
Quoted in the Times, Mark Maslin, a former director of University College London’s Environment Institute, was speaking at the Cheltenham Science Festival. He’s just published a commentary in the journal Nature on why it’s important to explain that the range of projections climate scientists make using models will increase as they improve the modelling process, while preserving the central message that greenhouse gases warm the climate.
Writing the article was a tough decision, Maslin said, as “sceptics will jump on this and say, ‘Actually climate change modellers know nothing'”. But he said a “warning shot” is necessary to prepare the IPCC authors – who so far have been slow to engage with the public – to say, “You need to deal with this, and with the media”.
One example in the IPCC’s AR5 report – due out in 2014 – is how climate change will affect major waterways:
“[U]ncertainty means that forecasts of the future flow of the Mekong river as a consequence of climate change range from a fall of 16 per cent to a rise of 55 per cent.”
But greater uncertainty about particular effects shouldn’t obscure the “broader outcome” of climate models. He said:
“Increasing our knowledge doesn’t change our story. If you put more greenhouse gases in the model, it gets warmer.”
Scientists are able now to create a greater range of projected climate outcomes because they’re now able to introduce “known unknowns”, Maslin said. According to the Times these include:
“[C]hanges in vegetation growth and reflection from clouds, whose feedback mechanisms were previously too complicated to include.”
We’ve looked at this process in a blog yesterday – which shows that because it’s very difficult to predict how human-caused factors such as economic activity will affect the climate. Said Maslin:
“Considering we are not even sure what the economy will do in the next six months, there are unrealistic expectations that scientists can model the future to any accuracy.”
But , he said, this is not an excuse for inaction – instead it’s a clear reason why we should reduce the amount of greenhouse gases we emit.
“The introduction of new physics into the model makes some difference to our uncertainty. The biggest uncertainty, though, is what we ourselves do. If we go down a green path, we know our effect on the environment will be reduced. If we go down the business-as-usual route we are looking at extreme consequences. But people seem to like to forget that.”
Read the full article here. The Nature comment piece is available here.