The concept of Post-Normal Science (PNS) applies well to climate science and epidemiology. Science becomes post-normal when society urges clear and speedy answers in a politically and culturally charged social environment. The political utility of scientific assertions becomes more important than scientific methodology.

Post-normal conditions make communication between science and society different from that of "normal” sciences. A tendency emerges that it is no longer the scientific rigor and methodology (as covered by e.g., Merton's CUDOS norms) which makes scientific results “good”, but its consistency with a-priori cultural constructions and political preferences.

According to Silvio Funtowicz: "What matters in PNS conditions is not truth or rigour but fitness for function or purpose socially determined."

The social process of doing science also changes. Some scientific actors become social actors. Media presence and political influence become assets for scientific recognition, careers and relevance. Also, the definition of research programs and the competition of ideas is affected.

The "post-normal science" concept ws introduced by Jerry Ravetz and Silvio Funtowicz in the 1980s, and was found to fit well to the state of climate science by Brav and von Storch in 1999.

Funtowicz, S.O. and J.R. Ravetz, 1985: Three types of risk assessment: a methodological analysis. In C. Whipple and V.T. Covello (eds): Risk Analysis in the Private Sector, New York, Plenum, 217-231

Bray, D. and H. von Storch, 1999: Climate Science. An empirical example of postnormal science. Bull. Amer. Met. Soc. 80: 439-456

The purpose of science is to allow individuals and society to make sense of a complex natural and social world. Science is improving "quality of life", because it enables a promising confrontation of challenges. "Good" science repells also  knowlegde claims made by interested parties for lending support to certain political or economic goals and strategies.

In environmenal sciences, in particular, some scientists act as stealth advocates for such positions of social interests, exploiting their purported objectivity as scientists. Merton's CUDOS norms are a measure to limit such false labelling - it requests natural fundamental scientists to accept that scientific knowledge is nobody's property; that properties such as race, gender, age, nationality and language of the creator of such knowledge are irrelevant; that such science is not done for furthering a hidden political agenda, and that all knowledge is permanently subject to open and critical review by the scientific community.

CUDOS norms are certainly not strictly followed by scientists, but their general validity is recognized among cimate scientists.

Given this framework of "good science", science cannot detemine optimal policies. Indeed, "good scientists" know their usually very limited field very deeply - are, as a German word summarizes well: "Fachidioten". If some claim having deep knowledge covering a very broad politically relevant field, they are likely not scientists.

Merton, R. K., 1973: The Normative Structure of Science, in N.W. Storer (ed.), The Sociology of Science (Chicago, IL: University of Chicago Press): 267-273
Pielke, Jr., R.A., 2007: The Honest Broker: Making Sense of Science in Policy and Politics. Cambridge University Press.
Bray, D., and H. von Storch, 2017: The Normative Orientations of Climate Scientists. Science and Engineering Ethics 23:1351–1367 DOI 10.1007/s11948-014-9605-1

Postnormality, even though named and postulated only in the 1980s, is not a new phenomenon. Also in the past sciences found themselves in such conditions. Genetics seems to have repeatedly been a prime example, with the phases of eugenics, of Lysenkoism in the Soviet Union and of GMO food today,. Other examples refer to nuclear power generation, the fight over smoking, but also various virus diseases in the late 20th century (mad cow disease, for instance)

An open question concerns the circumstances, which favour a field to become post-normal, and how it may find its way back to "normal conditions". A suggestion is that the presence of "folk science " may be favourable.

Conditional upon national conditions, the intensity of postnormailty may vary in different countries.

Ravetz, J., 1994: Economics as an Elite Folk Science: The Suppression of Uncertainty. Journal of Post Keynesian Economics 17, 165-184 http://www.jstor.org/stable/4538434

Lindzen, R.S., 1996: Science and politics. Global Warming and eugenics. In R.W. Hahn (Ed.): Risks, costs and lives saved. Oxford University Press, 85-103

To maintain the main societal service of science, namely to allow understanding of complex phenomena, scientists should provide possibilities to society, how to respond to challenging situations (such as anthropogenic climate change). Scientific arguments may disqualify some options as impossible, but cannot select a "best", simply because science canot oversee the full social and natural complex implications. Thus, policymaking, involving a variety of stakeholders ("extended peer-review"), is the final decider to chose from  possible options. When science and policymaking respect their own limitations and dynamics, the process will be constructive.

When finding oneself and one's field in  post-.normal conditions, scientists should invest in accepting that they are social actors, and not “providers of truth”, abstain from concepts as “knowledge speaks to power” or “empty vessel”. They should understand how they themselves are conditioned by cultural constructions, and that communication with the public and policy makers takes place in a societal arena of conflicting knowledge claims and interests.

von Storch, H. und W. Krauss, 2013: Die Klimafalle. Die gefährliche Nähe von Politik und Klimaforschung, Hanser Verlag, ca. 250 pp