We can spend a lot of time worrying about unlikely probabilities. (Image news.com.au)
Fear of flying- it’s something that many of us have, and even those who don’t can at least understand what there is to be afraid of. Planes crash, there’s no two ways about it. Yet to have a fear of climate change? That seems a lot less logical. Why is it we focus on the remote probability but often don’t spare a thought for something that is a lot more likely to have an impact on us?
Maybe for the case of climate change it’s due to not knowing the numbers involved- is this “dangerous” level of climate change politicians like to focus on something that will actually happen? If we somehow manage to keep carbon dioxide concentrations at the current level of about 400 parts per million, (bearing in mind that this level was exceeded in May 2013 at Mauna Loa in Hawaii for the first time since 1958 and in April 2014 became a monthly average) then the chances of 2 degrees warming in relation to pre-industrial levels is 30%. 2 degrees is a figure that should be prevented according to the UN and the EU and is often quoted as being a dangerous level, bringing with it global consequences including significant increase in wildfire, sea level rise and decreasing crop yields. But 30% likelihood doesn’t sound so bad, or does it?
Put this into a context we might better understand and this figure doesn’t look so good. There are currently an average of 30 fatal flying accidents per year. If the probability of fatal flying accidents was the same as the chance of 2 degrees warming this figure would rise to over 9 million. That’s over one thousand fatal flying accidents per hour. Increase carbon dioxide concentration to 450 parts per million and this figure nearly doubles.
But then again even if we knew the statistics, would that matter? Maybe it’s an inherent fear of numbers that GCSE or O level maths leaves countless people with but in the UK we as a nation tend not to be comfortable with probabilities. European weather forecasts frequently give a percentage likelihood of rain but here the closest we really get is being told there is a slight chance of showers.
This does lead to another problem though, what does “slight chance” actually mean? Do I pack my umbrella? In the case of climate change it may well be the wording that is the problem not the numbers. The Intergovernmental Panel on Climate Change (the ‘IPCC’) use a scale of phrases to describe the probabilities of events ranging from ‘virtually certain ‘ to ‘considerably unlikely’.
A study by the University College London, Cardiff University and Shandong Normal University in China showed just how big the problem with these terms is. Only 20% of UK participants could correctly put the IPCC’s terms into the order of increasing likelihood that they were intended to represent, let alone determine what ranges of probabilities that they are trying to demonstrate. Chinese participants scored even lower than this with only 9% completing a correct order. The understanding of the terms used for the Chinese version of the IPCC report for most native Chinese speakers did not agree with the IPCC’s definition, especially for the higher probability terms such as ‘very likely’ which the IPCC believe should represent over 90% probability but was being interpreted by Chinese participants as only 70% likely. So we have an intergovernmental report, designed to give a clear guide to the world on the best that science has to tell us about the state of the climate but a wide range of ways people interpret the terms they’re using.
Maybe using numbers is the way forward, or maybe scientists are just not using the right words. Many of those with a science background have constantly been told throughout school, undergraduate degrees and beyond that climate change is happening. Perhaps for scientists the language is less important and we just don’t think how a choice of words can affect those who are less convinced.
There is much debate around whether or not scientists should get involved in policy or try to get certain messages out to the public. Some feel that science should be done just for science’s sake whether or not everyone else can understand it. But with funding bodies demanding outreach work and big publications, coupled with a great deal of taxpayers’ money funding research, the science has to be shared, regardless of how people choose to interpret it. For this to happen it needs to be clear what scientists are actually trying to show when they use probabilities and it seems that in the case of climate change this is still not happening. Will this change in the future? I’d say it’s very slightly somewhat considerably likely.
- Statistics created using http://global-risk-indicator.net/index.html It’s a really cool tool, go and play with it.
- Study mentioned: Lost in translation? Interpretations of the probability phrases used by the Intergovernmental Panel on Climate Change in China and the UK- Harris et al, Climatic Change (2013), 121:415–425, DOI 10.1007/s10584-013-0975-1