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Time to ask the public: Why 2 degrees?

Mar 22, 2013 by | 2 Comments

This guest post is from Dr Chris Shaw, a vis­iting Research Fellow at Sussex University. Chris asks why, given the import­ance of the issue, has there never really been a public debate about the ‘two degrees’ limit, so fun­da­mental to the polit­ical con­struc­tion of cli­mate change?

Uncertainty has played a central role in public debate about cli­mate change – and how to com­mu­nicate it – from the beginning.

However, the types of uncer­tainty open to public inter­rog­a­tion are tightly policed. For example, pro­jec­tions of future cli­mate impacts are con­structed under con­di­tions of pro­found sci­entific uncer­tainty, meaning the pro­cess of defining a ‘dan­gerous’ limit is more of a social than a sci­entific judg­ment. Despite this, there has never been any attempt to involve the public in dis­cus­sions about per­haps the most fun­da­mental ques­tion of all: how much warming con­sti­tutes an accept­able risk.

Instead, the idea of a two degree dan­gerous limit has emerged as the end point target which defines the cli­mate policy debate (Anderson and Bows, 2008). My research has shown that dis­cus­sion of the two degree dan­gerous limit idea is largely ignored in the news media and where it is men­tioned, it is con­structed as sci­entific fact (Shaw, 2013), thereby denying the ostens­ibly free cit­izens of demo­cratic soci­eties the oppor­tunity to engage in the most important and basic ques­tion about cli­mate change.

I sug­gest that, in light of the fail­ings of cur­rent policy frame­works to even slow the rate at which CO2 levels are rising, the cli­mate problem should be ‘unstructured’.

A struc­tured problem is one in which the dimen­sions have been pre­defined by a priori assump­tions. Climate change has been struc­tured as a phe­nomenon with a two degree dan­gerous limit. Removing the idea of a sci­en­tific­ally defined two degree dan­gerous limit would allow for a fuller social­iz­a­tion of the cli­mate debate by legit­im­ising the risk atti­tudes of the public, rather than framing the problem as one to be delib­er­ated only by those in pos­ses­sion of com­plex cli­mate sci­ence knowledge.

Including sub­jective atti­tudes to risk in the decision-making pro­cess has been iden­ti­fied as essen­tial to the building of ‘mean­ingful envir­on­mental cit­izen­ship and par­ti­cip­atory policy’ (Ockwell et al., 2009, p. 321). If claims of a two degree dan­gerous limit prove incor­rect then public trust in cli­mate sci­ence may be under­mined, with neg­ative con­sequences for public engage­ment (Boykoff et al., 2010). Conversely, by allowing cit­izens to become ‘both critics and cre­ators in the know­ledge pro­duc­tion pro­cess’ (Rayner, 1987, p. 8), not only are the chances of finding a solu­tion improved (Cash et al., 2003) but addi­tion­ally, explicit public recog­ni­tion of the social limits to cli­mate sci­ence will ensure ‘con­tinued sci­entific authority in the inter­na­tional cli­mate regime’ (Lovbrand, 2004, p. 449).

What might such a prop­erly delib­er­ative pro­cess look like? It would begin by asking people what they would choose as a dan­gerous limit. Respondents would not need to be cli­mate sci­ent­ists in order to answer this ques­tion because the limit has not been defined through the inter­pret­a­tion of com­plex met­eor­o­lo­gical data. It is drawn from some broad brush stroke assump­tions about what might happen at dif­ferent levels of warming, as shown in repro­duc­tions such as the IPCC Burning Embers dia­gram. (Also, see here for more inform­a­tion on why two degrees has been chosen as a dan­gerous limit).

The most important determ­in­ants of the two degree limit are the social set­tings in which the delib­er­a­tions are con­ducted. Under con­di­tions of empir­ical uncer­tainty, such as those char­ac­ter­ising cli­mate change pro­jec­tions, insti­tu­tional set­ting along­side social and polit­ical values come to play a determ­ining role in defining what is con­sidered ‘true’ (Johnson and Covello, 1987: 357).

Achieving group uni­formity becomes an increas­ingly important determ­inant of decision making the greater the level of uncer­tainty. The groups that have defined the two degree dan­gerous limit are powerful polit­ical and tech­nical actors. The idea of a limit has been defined according to the interests of those groups making the decisions.

What does cli­mate change look like if the avail­able inform­a­tion is inter­preted by the values of cit­izens? The pur­pose of such an exer­cise would not be to agree a new ‘dan­gerous’ limit. Rather, it would be to allow pub­lics to better under­stand the decision making pro­cess and see how uncer­tainty – rather than offering a reason for doing nothing – actu­ally shows that there is not a single dan­gerous limit, the avoid­ance of which means safety from harmful cli­mate impacts.

There are risks and uncer­tainty at any level of warming, but being honest about these will allow more mean­ingful public engage­ment, and ulti­mately, a more sub­stantive and legit­imate soci­etal response.


Anderson, K., Bows, A., (2008). Reframing the cli­mate change chal­lenge in light of post-2000 emis­sion trends. Philosophical Transactions of the Royal Society 366 (1882), 3863–3882.

Boykoff, M.T., Frame, D., Randalls, S., 2010. Discursive sta­bility meets cli­mate instability: a crit­ical explor­a­tion of the concept of ‘cli­mate sta­bil­iz­a­tion’ in con­tem­porary cli­mate policy. Global Environmental Change 20, 53–64.

Cash, D.W., Clark, W.C., Alcock, F., Dickson, N.M., Eckley, N., Guston, D.H., Jaeger, J., Mitchell, R.B., (2003). Knowledge sys­tems for sus­tain­able devel­op­ment. Proceedings of the National Academy of Sciences of the United States of America 100 (14), 8086–8091.

Johnson, B. and Covello, V. (Eds). (1987). The social and cul­tural con­struc­tion of risk. Dordrecht: Kluwer Academic Publishing.

Ockwell, D., Whitmarsh, L., O’Neill, S., (2009). Reorienting cli­mate change com­mu­nic­a­tion for effective mit­ig­a­tion – for­cing people to be green or fos­tering grass­roots engage­ment? Science Communication 30, 305–327.

Rayner, S., (1987). Risk and relativism in sci­ence for policy. In: Johnson, B.B.,

Covello, V.T. (Eds.), The Social and Cultural Construction of Risk. Kluwer Academic Publishers, Dordrecht, pp. 5–23.

Shaw, C (2013). Choosing a dan­gerous limit for cli­mate change. Public rep­res­ent­a­tions of the decision making pro­cess. Global Environmental Change. (In press). DOI 10.1016/j.gloenvcha.2012.12.01

Turner, J. (1991). Social influ­ence. Buckingham: Open University Press

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