"The health chapter of the recent IPCC report concluded with a three tier classification of the possible health effects (see box). Though no source is quoted it may have been influenced by the “primary, secondary and tertiary” structure used in my edited book, Climate Change and Global Health, which in turn is derived from two earlier papers (Butler, Corvalán et al. 2005, Butler and Harley 2010) (see box).
No classification is perfect, none should be considered inviolable .. but the main idea of the third category is to try to convey that climate change related health risks are lot more significant (and terrifying) than (say) heatstress or a heightened chance of malaria.
To me, most conceptualisations are a bit like impressionist paintings. The other element involved with tertiary is causal distance .. there are still a lot of people denying climate change can influence conflict or migration, for example. (Which leads into the x access label in Fig 26.2) ..
Oreskes and Conway (2013), writing from the future, reflect on the collapse of civilisation, reflect on the bias most scientists have towards "type II" errors (ie waiting too long to make a conclusion). If, by say 2150 Miami etc has disappeared and WWIII has passed then we might agree climate change contributed to the devastation that had transpired .. by which time it’s too late.
The late Tony McMichael has called the tendency to not think hard enough about cause as "epidemiologising", or looking under the lamp post, because that's where the light is, even if the keys aren't likely to be.
When I give lectures on this (eg see slides given to the ANU medical students last month), I spend a lot of time on Fig 26.2. I tell people it’s the most important slide in the whole lecture, the whole book.. (No one so far has either challenged or explicitly agreed with me on that, so I’m not sure if people understand..)
Butler, C. D., C. F. Corvalán and H. S. Koren (2005). "Human health, well-being and global ecological scenarios." Ecosystems 8(2): 153-162.
Butler, C. D. and D. Harley (2010). "Primary, secondary and tertiary effects of the eco-climate crisis: the medical response." Postgraduate Medical Journal 86: 230-234.
Butler, C. D. and A. Woodward (2015). From Silent Spring to the threat of a four degree world. The context of Tony McMichael’s career. Health of People, Places and Planet: Reflections Based on Tony McMichael’s Four Decades of Contribution to Epidemiological Understanding. C. D. Butler, Dixon, J., Capon A.G. Canberra ACT Australia, ANU Press: 11-30.
Oreskes, N. and E. M. Conway (2013). "The collapse of Western civilization: a view from the future." Daedalus 142(1): 40-58.
Smith, K., A. Woodward, D. Campbell-Lendrum, D. Chadee, Y. Honda, Q. Liu, J. Olwoch, B. Revich, R. Sauerborn, C. Aranda, H. Berry, C. Butler, Z. Chafe, L. Cushing, K. Ebi, T. Kjellstrom, S. Kovats, G. Lindsay, E. Lipp, T. McMichael, V. Murray, O. Sankoh, M. O’Neill, S. B. Shonkoff, J. Sutherland, S. Yamamoto, U. Confalonieri, A. Haines and J. Rocklov (2014). Human health: impacts, adaptation, and co-benefits. Climate Change 2014: Impacts, Adaptation and Vulnerability, Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. C. B. Field, V. Barros and D. J. Dokken. Cambridge and New York Cambridge University Press.