As with other br¬anches of science and mathematics, climate science involves considerable scientific uncertainty. Beyond that, however, uncertainty in climate science comes from the many complex forces that govern the earth’s climate, from the axis of the planet’s rotation to the changing composition of the atmosphere. Although, scientists have gained significant insight into how the climate system works, they do not have 100 per cent confidence in their climate change projections and, perhaps, they never will. What they can do, however, is make predictions based on the best available data and assumptions, quantifying the uncertainties associated with those predictions.
Several areas of uncertainty exist in climate change predictions. A main source of uncertainty is due to the lack of complete knowledge of how climate works. The other uncertainty is due to natural variability in the climate system, which will not go away with time. In addition, an ex¬tra element of uncertainty is due to the inability to predict human behaviour and its cumulative impact on the ea¬rth’s climate.
Future climate predictions depend on a number of changing variables in much the same way as future traffic predictions. Both systems operate under a certain level of volatility and uncertainty, but, that does not prevent either climate scientists or traffic analysts from making forecasts with the present information on hand. Although, traffic for¬ecasts days into the future may seem hard to trust, as is the case with future climate projections for some people, both are determined by algorithms based on mass data from varying sources. A un¬ique, location-specific mo¬del can provide greater accuracy for both traffic and climate scenarios. But, with both systems, full certainty comes wh¬en it is already too late and we start facing problems.
Because human beings ha¬ve a great need for predictability, uncertainty can be inherently uncomfortable to us. Predictability helps people fe¬el safe and secure, whereas, uncertainty can lead to anxiety. Predictability offers survival value. However, the hu¬man capability to prepare for the worst can be impaired by uncertainty.
Particularly, when talking about complex topics like gl¬obal climate change, it is important to find effective ways to communicate uncertain information. Too often, discussions of climate science uncertainty convey the mistaken impression that scientists are hopelessly confused about this complicated subject, wh¬en in fact, the uncertainties about exactly how much wa¬rmer the planet will be in 100 years do not change the very high confidence scientists ha¬ve that human-made emissions of greenhouse gases are warming the planet and are likely to continue doing so in the future.
To address this problem, Intergovernmental Panel on Climate Change (IPCC) scientists developed a “confidence terminology” to communicate estimates of uncertainty through everyday language. For example, “very hi¬gh confidence” was used to refer to a prediction that has at least a nine out of 10 ch¬ance of being correct.
Although, such terms have greatly permeated public discourse on climate change, there is evidence that suggests people interpret such probability descriptors more subjectively than scientists intend. For example, in a recent report, Summary for Policymakers, IPCC stated, “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG (gr¬eenhouse gas) concentrati-ons.” From the use of the term “very likely” in this sentence, IPCC meant that there is a 90 per cent or greater likelihood that emissions of greenhouse gases from human activities have caused most of the global average temperature increase si¬nce the mid-20th century. But, in a study by researchers at the University of Illinois at Urbana-Champaign, people assigned lower likelihood values to IPCC’s descriptors compared with what IPCC actually meant. Among other recommendations, the researchers suggested that IPCC consider including the associated range of probabilities whenever a probability descriptor is used, rather than only publishing a key to the terminology.
The precautionary principle has been considered internationally, including the 1992 United Nations Framework Convention on Climate Ch¬ange, which states that countries should “take precautionary measures to anticipate, prevent or minimise the causes of climate change and mitigate its adverse effects. Where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures….”
California governor Arnold Schwarzenegger referred to the principle with a metaphor when he said: “If 98 doctors say my son is ill and needs medication and two say, ‘No, he doesn’t, he is fine’, I will go with the 98. It’s common se¬nse and applies to climate ch¬ange as well. We go with the majority, the large majority....The key thing now is that since we know this industrial age has created it, let’s get our act together and do everything we can to roll it back.” In this example, Schwarzenegger ne¬atly conveyed information ab¬out climate change risk and uncertainty in terms his audience could relate to. The precautionary principle is a key consideration for making decisions under uncertainty, and it is useful to address potential harms that are true for the environmental area.
