How likely is it to rain tomorrow? How likely is it to find a table at your favorite restaurant without making a reservation in advance?

We are often faced in our daily life with uncertainty quantification, even though we might not be aware that we are actually quantifying uncertainty. Uncertainty is usually expressed verbally in these settings. But is that mostly appropriate? What about more rigorous settings?

Below you can find 2 scenarios:

According to a article in Nature Climate Change (2017), it is quite unlikely to have less than 2°C warming by 2100.

“Climate Changed” by Eiko Ojala is licensed under CC BY-NC-ND 4.0

Citation: Raftery, A. E., Zimmer, A., Frierson, D. M., Startz, R., and Liu, P. (2017). Less than 2 C warming by 2100 unlikely. Nature Climate Change, 7(9), 637.

 

According to the head of NASA, “The first person on Mars is likely to be a woman”.

Citation: Vagianos, A. (2019). “The first person on Mars is likely to be a woman”, head of NASA says.
https://futurism.com/the-byte/nasa-first-human-mars-woman

In case you have not noticed, Scenario 2 includes a Hint. In that hint you can find out how verbal uncertainty is related to numerical assessments, with the help of a so-called “calibrated language scale”. We use here the calibrated language provided by the Intergovernmental Panel on Climate Change (IPCC) to communicate assessed probabilities.