From: Health risks of climate change: An assessment of uncertainties and its implications for adaptation policies
Knowledge of the factors that govern this effect is so weak that we are effectively ignorant.
Ambiguous sign or trend
Some effect is expected, but its sign or trend is not clear. There are plausible arguments either direction (effect could be positive, could be negative; could increase or decrease).
Expected sign or trend
It is clear what the sign and trend of the effect will be. However, there is no plausible or reliable information on how strong it will be.
Order of magnitude
It is possible to give a rough indication of the magnitude of the effect, a qualitative scoring (e.g. 1–10 scale), or a rough comparison with other effects.
It is possible to estimate the bounds for the distribution of the effect, e.g. its 5/95 percentiles (effect is only 5 % likely to be more than … and only 5 % likely to be less than …). However, the shape of the distribution, or best-guess estimates, cannot be provided.
Full probability density function
It is possible to provide a full probability density function; the bounds as well as the shape of the distribution.
Don't know / no answer