Sunday, October 14, 2018

Climate change, health and existential risks to civilization: a comprehensive review (1989-2013)

International Journal of Environmental Research and Public Health (published October 16, 2018)

See here for full text (open access)


Background: Anthropogenic global warming, interacting with social and other environmental determinants, constitutes a profound health risk. This paper reports a comprehensive literature review for 1989-2013 (inclusive), the first 25 years in which this topic appeared in scientific journals. It explores the extent to which articles have identified potentially catastrophic, civilization
endangering health risks associated with climate change.  

Methods: PubMed and Google Scholar were primarily used to identify articles which were then ranked on a three point scale. Each score reflected the extent to which papers discussed global systemic risk. Citations were also analyzed.

Results: Of 2143 analyzed papers 1546 (72%) were scored as one. Their citations (165,133) were 82% of the total. The proportion of annual papers scored as three was initially high, as were their citations but decline to almost zero by 1996, before rising slightly from 2006.

Conclusion: The enormous expansion of the literature appropriately reflects increased understanding of the importance of climate change to global health. However, recognition of the most severe, existential, health risks from climate change was generally low. Most papers instead focused on infectious diseases, direct heat effects and other disciplinary-bounded phenomena and consequences, even though scientific advances have long called for more inter-disciplinary collaboration.

Keywords: citation analysis; civilization collapse; climate change; comprehensive review; conflict; existential risk; famine; global warming; global health; migration

Sunday, October 7, 2018

Climate change, health and categories of effects

I wrote this for another paper, currently under review. However, it was cut, due to lack of space. Eventually, I hope to weave this material into another article, and also into the forthcoming second edition of my edited book “Climate Change and Global Health”. This also builds on a blog I posted in 2015 called “Climate change and heath: primary, secondary and tertiary effects.

1. Primary and secondary effects

The first categorizations of the health effects of climate change and health appeared in the early 1990s. Principally these identified two broad kinds of effect, most often called “direct” (such as from heatwaves, reduced cold or physical trauma from a more powerful storm) and “indirect”, such as from ecological shifts leading to an altered distribution of vectors (such as mosquitoes) or of food sources (see tables 1,2).

Table 1. There are many classifications of the health effects of climate change. This is one suggestion for the most obvious, least contentious effects. All of these effects interact with other factors, such as governance, infrastructure, technology and economic and other capabilities.

Heat stress, heat stroke (including occupational); heat stress resulting in impairment of chronic diseases (e.g. multiple sclerosis, cardiac or renal failure) or death, possible fetal abnormalities; in some cases improved health from reduced cold
Physical and or psychological harm and trauma from an intensified storm, flood, fire or other extreme event, such as drought or a storm surge
Long-lasting psychosocial effects from exposure to a climate change aggravated extreme event including post traumatic stress disorder, depression, loss of place and “solastalgia
The burden of disease of “direct” (“primary”) effects can be severe, as with the tens of thousands of excess deaths attributed to heatwaves in France in 2003 [1] and Russia in 2010 [2]. The burden from excessive heat is likely to substantially increase, especially if the Paris commitments are not met. Regions in which hundreds of millions now live are forecast as at risk of large-scale human abandonment late this century, including the North China plain and parts of the Middle East [3,4]. Looking further ahead, if urgent action to slow climate change by accelerating the energy transition is further delayed, substantial regions of the globe could experience wet bulb temperatures of 35 degrees or more, calling into question the habitability of even more some regions [5].
The burden of disease of the secondary effects (see table 2) of climate change, particularly of infectious diseases such as malaria, has long been forecast as significant [6]. However, although it is likely that climate change has increased cases of malaria in some settings, especially in highlands [7] the overall global burden of malaria has declined substantially in recent decades, mostly because of the increased use of insecticide impregnated bednets and more funding [8]. Note however, that such progress has recently stalled, especially in parts of sub-Saharan Africa [9]. I am unaware of any recent attempts to estimate the global burden of disease of malaria or other infectious diseases attributable in part to climate change, although a recent editorial in Geospatial Health provides an excellent summary of the key issues [10].

Table 2. Climate change has many less direct effects, which can be called “secondary”. Few if any of these are controversial. These effects also interact with other factors, such as ecological change, governance, trade, infrastructure, technology and economic and other capabilities.

Vector borne diseases (eg malaria, dengue fever, yellow fever, chikungunya, Zika), non-vector born zoonotic disease (e.g. schistosomiasis, Ebola, HIV/AIDS); other infectious diseases (e.g. gastro-enteritis, soil transmitted helminthiases)

Impaired food or water safety (microbial or toxic), reduced food diversity; reduced micronutrient concentrations in crops (due to higher CO2 levels)

Allergies, including thunderstorm asthma; asthma
Cardio-respiratory-neurological effects, such as from worsened tropospheric air pollution, or from climate change aggravated fires

Reduced food sovereignty, reduced micronutrient intake, but without the threat of starvation
Impact on other chronic diseases, such as cardiac failure, diabetes

2. Tertiary effects

Two papers, each published in December 1993, identified a third category of health effects, which the authors called “tertiary” [11,12] (see table 3). One paper stated “indirect effects are secondary, such as changes in vector-borne diseases or crop production, and tertiary, such as the social and economic impacts of environmental refugees and conflict over fresh water supplies”. The other paper additionally noted that: “There is a considerable literature on the effects of climate on disease which focuses principally on the primary effects of temperature on health. In relation to global climate change, however, it is likely that the secondary and tertiary impacts will outweigh the importance of the primary effects” [12].

This idea of a third major category of health effect has not yet been widely accepted. A 1996 book on climate change and health mentioned “more diffuse” effects including conflict and population displacement, but grouped these with indirect effects, rather than as a separate category [13]. An assessment for the U.S. National Assessment on climate change and health, published in 2000, identified five categories of health outcomes [14]. These were related to temperature, to extreme weather events (storms, tornadoes, hurricanes, and precipitation extremes); to air-pollution, and to two categories of infectious diseases. In turn these were each divided into two kinds; related to water and food, and vectors and rodents. This report did not discuss migration, social disruption, or conflict, perhaps because its scope was restricted to that of the U.S.

As mentioned above, it has long been understood that climate change can influence important social consequences (with health effects) such as population displacement, conflict and malnutrition. Malnutrition refers both to undernutrition (e.g. stunting, wasting and at its most extreme, death) and, also, to obesity and other problems associated with excessive calorie intake, sometimes (also) associated with micronutrient deficiency. Two of these effects (malnutrition – albeit probably meaning undernutrition – and conflict) were mentioned in the the first article I know of about climate change and health, published in the peer reviewed literature, a 1989 editorial in the Lancet [15], while Alexander Leaf, also in 1989, discussed both population displacement and the possibility of increased hunger [16].

These effects may also be considered tertiary not only because they are the least direct, but also because of their capacity to harm health is at such a large scale. For example, the conflict in Syria, which several experts think was contributed to by the most severe drought in its instrumental record [17] has displaced millions, had profound geopolitical effects in Europe, and killed hundreds of thousands of people, including children. The health effects upon survivors, both physical and mental, both in Syria and for those displaced, are undoubtedly immense [18]. Of course, climate change is not solely responsible for this catastrophe, and its exact contribution is disputed [19,20]. The total health impact of the Syrian conflict is likely to far exceed that of the 2003 European heatwave, particularly as much of the health harm to Syrians is to infants, children and young adults, whereas deaths from heatwaves typically result in a comparatively low per person loss of disability adjusted life years, as it is primarily the already frail and elderly who die [21]. The morbidity and mortality from the Syrian conflict due to anthropogenic climate change is likely to already be very significant, even using a highly conservative causal attribution.

It has also been suggested that the 2018 crisis of refugees seeking entry to the U.S. from Central America has been exacerbated by drought (interacting with social and other environmental factors including inequality and high population growth rates), which in turn probably has a climate change contribution [22]. There are many other examples, already, in which climate change has been argued to contribute to conflict, undernutrition, migration and other forms of population displacement [23]. For example, Hurricane Maria, which directly killed 64 people in Puerto Rico, contributed to at least 4,000 additional deaths in the following four months, due in part to the interaction of the storm with an already vulnerable social and physical system, with large-scale and long-lasting damage to electricity infrastructure [24]. It also led to migration to the U.S., particularly by younger people and those more economically able. 

Table 3. This lists the most obvious “tertiary” consequences of climate change that will have significant health effects. As with the primary and secondary effects, these interact with governance, infrastructure, technology and economic and other determinants.
Increased hunger, starvation or famine (exceeding a reduction in nutrient variety)
Mass migration or population displacement, including from climate change aggravated events such as famine, drought, sea level rise, violence and intolerable heat
Large scale conflict (leading to physical and mental trauma, death and morbidity, including from damaged health systems)
Significant social and economic disruption, impairing health and/or health systems

In 2005 a paper written by health workers, published outside the health literature, argued that the global health effects of eco-climatic change could be classed into four categories; three equivalent to primary, secondary and tertiary (though the paper did not use these terms), and a fourth, which it called “systems failure”, a euphemism for global civilization collapse [25]. This paper also predicted that the loss in disability adjusted years for the third and fourth categories would exceed the first two.

A figure in a chapter on climate change and health published in 2007 in the third report of the Intergovernmental Panel on Climate Change (IPCC) also recognized three broad categories of health effects. It called these “direct”, “indirect” and via “social and economic disruption” [26]. However, the text did not discuss the third category.

In 2010 the terms (and closely corresponding concepts) of primary, secondary and tertiary were revived, in a paper, and later, an edited book that failed to identify the earlier use of these terms [27,28]. Also in 2010, a report for several U.S. government agencies [29] classified the human health consequences of climate change into eleven kinds. These were listed alphabetically as asthma, allergies and airway diseases; cancer; cardiovascular disease and stroke; alterations in normal development; heat-related morbidity and mortality; mental health and stress disorders; neurological diseases and disorders; nutrition and food-borne illness; vector-borne and zoonotic disease; waterborne disease and weather-related morbidity and mortality. The report discussed displaced people (such as due to Hurricane Katrina) as a cross-cutting issue. It also recognized the possibility of conflict, war (outside the U.S.) and extensive undernutrition, both domestically and globally.

The health chapter in the most recent IPCC report [30] also referred to three kinds of health effects of global warming. It called these “direct” (mainly from “heat, drought, and heavy rain”), “mediated through natural systems” (e.g. “disease vectors, water-borne diseases, and air pollution”) and “heavily mediated by human systems” (e.g. “occupational impacts, undernutrition, and mental stress”). The first two categories in this classification correspond with primary and secondary, but in the third category only large-scale undernutrition would be classed as a tertiary effect, as defined above.

In 2015 another major Lancet report was released [31]. It proposed that impacts can be “direct” (e.g. “heatwaves and extreme weather events such as a storm, forest fire, flood, or drought”) or “indirectly mediated through the effects of climate change on ecosystems economies, and social structure” (e.g. “agricultural losses and changing patterns of disease” and “migration and conflict”). It thus grouped “tertiary” effects with “secondary”, though it used neither term. A figure in that paper which outlined the main direct and indirect effects focused solely on what this essay suggests are more parsimoniously termed as primary and secondary effects.


Apprehension of what I prefer to call the "tertiary" health effects of climate change has always been the primary motivator for my writing and researching on climate change (since my first letter, published in the Medical Journal of Australia, in 1991) [32]. I have argued above that these potential aspects were apparent in 1989, when articles first appeared mentioning all major "tertiary" components. I have also shown that the term "tertiary" was introduced in two papers published in 1993, already a quarter of a century ago. 

Although there is increased recognition of these risks, the vast majority of the climate change and health literature continues to focus on issues such as heat, infectious diseases and allergies. Important as these issues are - and they are certainly are valid - I believe that their future burden of disease is likely to be dwarfed by that of the tertiary issues; conflict, population displacement and famine. 

In 2014, in a chapter in my edited book called "Mental health, cognition and the challenge of climate change [33] I published a version of the following figure. In the next issue of the book the figure may be adapted, so that the label for the x axis (the horizontal axis) reads 2030. In 2014 I suggested that it might take until 2050 for the high burden of disease of the tertiary effects to be accepted, but that book was drafted before as much was reported about climate change and conflict in Syria, although an early paper was published in 2014 [34}.

I fear, given the events of 2018 - the fires, the floods, the hurricanes and typhoons, and the ongoing population displacement, as well as a gradually increasing acceptance of the role climate change plays in conflict - that the time in which the overwhelming risk of the tertiary health effects of climate will be widely understood may well be before 2050.  On the other hand, the vast majority of articles in the climate and health field continue to completely ignore its existential risk [35].

The proportional burden of disease of primary, secondary and tertiary effects (averaged over the 21st century) and the approximate time when these concepts and their relative burdens are accepted.

A powerful opposing force, however, is not just denial, nor just the political factors that seek to repress any whiff of legal liability, and hence minimize the risk of future reparations. One way to suppress such exploration is to refuse to fund research into the possible links. I think another reason has evolutionary roots. People like to portray themselves as “good", even moral. Even the Nazis probably did .. so while on one hand populations fully support policies that contribute to unspeakable misery, on the other hand they deny the reality of the links between their behaviour and the more displaced effects, especially if they are harmful. If the causes can be ascribed elsewhere ("local politics in Syria, not environment") then we can feel better about ourselves. A good example is that most Australians support offshore camps for asylum seekers, claiming this is “humane” because “it saves lives at sea”.  However, my view is that the causation of this and other tertiary effects is multi-factorial. Developed countries have largely contributed to climate change, but there are also many local factors that have contributed to the war, famine, displacement, and the risks people take which see some drown at sea.  
However, the  pendulum on the causes of the tertiary effects of climate change is currently too remote from recognition of the role that high-income countries have played in these catastrophes [36}, already and in future. And some people increasingly understand that climate change and other forms of planetary overload [37] pose profound risks to human well-being in high-income settings, such as 15 year old Swedish climate activist Greta Thunberg, who also keenly appreciates the equity dimension (see figure).

A tweet from 15 year old Greta Thurnberg, posted October 7, 2018


1.         Robine, J.-M.; Cheung, S.; S, L.R.; Van Oyen H; Griffiths, C.; Michel, J.-P.; Herrmann, F. Death toll exceeded 70,000 in Europe during the summer of 2003. Comptes Rendus Biologies 331, 171-178 (2008).

2.         Shaposhnikov, D.; Revich, B.; Bellander,T.; Bedada, G.B.; Bottai, M.; Kharkova, T.; et al. Mortality related to air pollution with the Moscow heatwave and wildfire of 2010. Epidemiology 25, 359-364 (2014).

3.         Kang, S.; Eltahir, E.A.B. North China plain threatened by deadly heatwaves due to climate change and irrigation. Nature Communications (2018).

4.         Pal, J.S.; Eltahir, E.A.B. Future temperature in southwest asia projected to exceed a threshold for human adaptability. Nature Climate Change 6, 197–200 (2016).

5.         Sherwood, S.C.; Huber, M. An adaptability limit to climate change due to heat stress. Proceedings of the National Academy of Science (USA) 107, 9552-9555 (2010).

6.         Martens, W.J.; Niessen, L.W.; Rotmans, J.; Jetten, T.H.; McMichael, A.J. Potential impact of global climate change on malaria risk. Environmental Health Perspectives 103, 458-464 (1995).

7.         Siraj, A.S.; Santos-Vega, M.; Bouma, M.J.; Yadeta, D.; Carrascal, D.R.; Pascual, M. Altitudinal changes in malaria incidence in highlands of ethiopia and colombia. Science  343, 1154-1158 (2014).

8.         Bhatt, S.; Weiss, D.J.; Cameron, E.; Bisanzio, D.; Mappin, B.; Dalrymple, U.; Battle, K.E.; Moyes, C.L.; Henry, A.; Eckhoff, P.A., et al. The effect of malaria control on pPasmodium falciparum in Africa between 2000 and 2015. Nature 526, 207-211 (2015).

9. Alonso, P., and A.M. Noor. The global fight against malaria is at crossroads. The Lancet 390:10112 (2017).

10. Bergquist, Robert, Anna-Sofie Stensgaard, and Laura Rinaldi. Vector-borne diseases in a warmer world: Will they stay or will they go? Geospatial Health 13 (1): 699 (2018).

11. Haines, A.; Epstein, P.R.; McMichael, A.J. Global health watch: Monitoring impacts of environmental change. Lancet 342, 1464-1469 (1993).

12. Haines, A.; Parry, M.L. Climate change and human health. Journal of the Royal Society of Medicine 86, 707-711 (1993).

13. McMichael, A.J.; Haines, A.; Slooff, R.; Kovats, S. Climate change and human health. World Health Organization: Geneva (1996).

14.       Patz, J.A.; McGeehin, M.A.; Bernard, S.M.; Ebi, K.L.; Epstein, P.R.; Grambsch, A.; Gubler, D.J.; Reiter, P.; Romieu, I.; Rose, J.B., et al. The potential health impacts of climate variability and change for the United States: Executive summary of the report of the health sector of the U.S. National Assessment. Environmental Health Perspectives 108, 367-376 (2000).

15. Anonymous. Health in the greenhouse. Lancet 333:819-820 (1989).

16. Leaf, A. Potential health effects of global climatic and environmental changes.  The New England Journal of Medicine 321 (23):1577-1583 (1989).

17. Kelley, C. P., Mohtadi, S., Cane, M.A., Seager, R. and Kushnir, Y. Climate change in the Fertile Crescent and implications of the recent Syrian drought. Proceedings of the National Academy of Sciences (USA) 112 (11):3241-3246. doi: 10.1073/pnas.1421533112 (2015).

18. Anonymous. Syria: A health crisis too great to ignore. The Lancet 388, 2 (2016).

19.       Selby, J.; Dahi, O.S.; Fröhlich, C.; Hulme, M. Climate change and the Syrian civil war revisited. Political Geography (2017).

20. Ide, T. Climate war in the Middle East? Drought, the Syrian Civil War and the state of climate-conflict research. Current Climate Change Reports:1-8; doi: 10.1007/s40641-018-0115-0. doi: 10.1007/s40641-018-0115-0 (2018).

21. Kovats, R.S.; Hajat, S. Heat stress and public health: A critical review. Annual Review of Public Health 29, 41-55 (2008).

22.       United Nations World Food Programme. Food security and emigration. (2017).

23.       Schleussner, C.-F.; Donges, J.F.; Donner, R.V.; Schellnhuber, H.J. Armed-conflict risks enhanced by climate-related disasters in ethnically fractionalized countries. Proceedings of the National Academy of Sciences, 113, 9216-9221 (2016).

24.       Kishore, N.; Marqués, D.; Mahmud, A.; Kiang, M.V.; Rodriguez, I.; Fuller, A.; Ebner, P.; Sorensen, C.; Racy, F.; Lemery, J., et al. Mortality in Puerto Rico after hurricane Maria. New England Journal of Medicine, doi: 10.1056/NEJMsa1803972 (2018).

25.       Butler, C.D.; Corvalan, C.F.; Koren, H.S. Human health, well-being and global ecological scenarios. Ecosystems, 8, 153-162 (2005).

26.       Confalonieri, U.; Menne, B.; Akhtar, R.; Ebi, K.L.; Hauengue, M.; Kovats, R.S.; Revich, B.; Woodward, A.; Abeku, T.; Alam, M., et al. Human health. In Climate change 2007: Impacts, adaptation and vulnerability. Contribution of working group II to the fourth assessment report of the intergovernmental panel on climate change, Parry, M.L.; Canziani, O.F.; Palutikof, J.P.; Linden, P.J.v.d.; Hanson, C.E., Eds. Cambridge University Press: Cambridge, UK,, 2007; pp 391-431 (2007).

27.       Butler, C.D.; Harley, D. The climate crisis, global health, and the medical response Postgraduate Medical Journal 86, 230-234 (2010).

28.       Butler, C.D. Climate change and global health. CABI: Wallingford UK, Boston, US; p xxiv + 303 (2014); paperback issue published 2016.

29.       Portier, C.J.; Thigpen Tart, K.; Carter, S.R.; Dilworth, C.H.; Grambsch, A.E.; Gohlke, J.; Hess, J.; Howard, S.N.; Luber, G.; Lutz, J.T., et al. A human health perspective on climate change: A report outlining the research needs on the human health effects of climate change. Research triangle park, NC: Environmental Health Perspectives / National Institute of Environmental Health Sciences. doi:10.1289/ehp.1002272 available: (2010).

30.       Smith, K.; Woodward, A.; Campbell-Lendrum, D.; Chadee, D.; Honda, Y.; Liu, Q.; Olwoch, J.; Revich, B.; Sauerborn, R.; Aranda, C., et al. Human health: Impacts, adaptation, and co-benefits. In Climate change 2014: Impacts, adaptation and vulnerability, contribution of working group ii to the fifth assessment report of the intergovernmental panel on climate change, Field, C.B.; Barros, V.; Dokken, D.J., Eds. Cambridge University Press: Cambridge and New York; pp 709-754 (2014).

31.       Watts, N.; Adger, W.N.; Agnolucci, P.; Blackstock, J.; Byass, P.; Cai, W.; Chaytor, S.; Colbourn, T.; Collins, M.; Cooper, A., et al. Health and climate change: Policy responses to protect public health. The Lancet 386, 1861–1914 (2015).

32.      Butler, C.D. Global warming, ecological destruction and human health. Medical Journal of Australia 155:351 (1991)

32.      Butler, C.D., Bowles, D.C; McIver, L., and Page, L. Mental health, cognition and the challenge of climate change. In Climate Change and Global Health, edited by C.D. Butler, 251-259. Wallingford, UK: CABI. (2014).

34.       Gleick, P.H. Water, drought, climate change, and conflict in Syria. Weather, Climate, and Society 6 (3):331-340. doi: 10.1175/wcas-d-13-00059.1 (2014).

35.      Butler, C. D. Climate change, health and existential risks to civilization: a comprehensive review (1989-2013).  International Journal of Environmental Research and Public Health (under review). 

36.      Butler, C.D. "Regional overload” as an indicator of profound risk: a plea for the public health community to awaken. In Medicines for the Anthropocene: Health on a Finite Planet, edited by S. Quilley and K. Zywert. Toronto, Canada, University of Toronto Press, 2019 (in press).  

37.     Butler, C.D. Planetary overload, limits to growth and health.  Current Environmental Health Reports 3 (4):360-369 (2016)

Friday, October 5, 2018

Planetary epidemiology: towards first principles

Published in Springer Environmental Reports, topical collection on Global Environmental Health and Sustainability (W. Al-Delaimy, Section Editor) (December 2018)

doi: 10.1007/s40572-018-0220-1 See (sorry, behind a paywall) (An earlier version is available on my website)


Purpose of review: To combine evolutionary principles of competition and cooperation with Limits to Growth models, generating six principles and one proposition for a new sub-discipline, called “planetary epidemiology”. Suggestions are made for how to quantify four principles.

Recent findings:
Climate change is one of a suite of threats increasingly being rediscovered by health workers as a major threat to civilization. Although “planetary health” is now in vogue, neither it, nor its allied sub-disciplines have, as yet, had significant impact on epidemiology. Few if any theorists have sought to develop principles for Earth system human epidemiology, in its ecological, social and technological milieu.

Summary: The principles of planetary epidemiology described here can be used to stimulate applied, quantitative work to explore past, contemporary and future population health, at scales from local to planetary, in order to promote enduring health. It is also proposed that global well-being will decline this century, without radical reform.

Earth system, climate change, environmental epidemiology, global health, limits to growth, planetary boundaries, planetary health.

The recent release of the Intergovernmental Panel on Climate Change (IPCC) report on the difference between a 1.5 and a 2 degree C world (i.e. above the pre-industrial level, although note that the 2015 Paris climate agreement is vague about the baseline and hence the target) should be drawing the attention of policy makers, as well as all who care about public health. 
But global warming is only one of many threats faced by civilization. Another milestone is nearing. In 2022 it will be half a century since publication of the book Limits to Growth. The exercise it describes is a still poorly understood simulation of our future, warning (like the IPCC) that “business as usual” will meet a wall, perhaps within a generation. When that happens, human well-being will decline, and perhaps, even population size, contrary to all sanctioned forecasts.
As appreciation of existential risk grows, health movements trying to avert catastrophe proliferate, although most (including forms of Planetary Health) avoid close encounter with the most frightening possibilities, perhaps worried that too much bad news will be disempowering.
Numbers that warn policy makers of growing peril may help them to change course. A new paper (sorry it’s not open access) attempts, for the first time, to identify quantifiable principles which can complement those already used in epidemiology to consider public health and human well-being at the truly global scale. The paper argues that, like 17th century London haberdasher John Graunt, existing data (collected for another purpose) can be used to uncover epidemiological insights, hidden in datasets, together with human characteristics as diverse as satellite measures of ground water, the tenets of evolution, ingenuity and norms (“institutions”) such as co-operation, conservation and prudence (or its lack). The paper proposes that these principles may even be used to establish a new sub-discipline, tentatively called “planetary epidemiology”.
But such a discipline may not have any significant impact. Many forces, including corruption, self-censorship, misinformation, and denial collectively inhibit the many actions needed. A policy shift also needs pressure, from the media, from the middle class, from the young, and from professionals.  
Neither the Limits to Growth nor this paper on planetary epidemiology predict the inevitable demise of civilization this century, but this possibility cannot be excluded. These arguments are unlikely to alter the view of optimists. However, irrespective of ideology, it is clear that the health implications makes this topic relevant to epidemiology.

Six Principles:

Principle 1: Malthus, Evolution, and the Most Fundamental Biological Principle 
Principle 2: Ingenuity and Natural Resources
Principle 3: Ingenuity, Institutions, and Human Well-being
Principle 4: Pollution and Resources
Principle 5: Resource Scarcity, Overshoot, Trade, and War 
Principle 6: Disease, Undernutrition, and Planetary Epidemiology 
Proposition 1: Scarcity, Well-being, and Health at the Planetary Scale


Wednesday, October 3, 2018

Climate change and health: Tony McMichael and an "index of existential risk"

It's another average day for me, except that that, were Tony McMichael still alive, it would be his 76th birthday. Tony was one of the the first leading figures in public health to recognize the risk to human health from climate change.

The trough in the annual cycle of carbon dioxide levels is now over 405 ppm (parts per million). The Federal President of the Young Liberals has just pronounced that Australia should not take any leadership role in tackling climate change. Even more worryingly, he has suggested that the billion or so people without electricity should be illuminated by coal burning. (But Indian President Modi does not agree (see endnote - PPS)). The lead author of a new article on ancient climate (about 50 million years ago) has just been quoted as saying that “Some climate models suggest that the tropics just became a dead zone with temperatures over 50 degrees Celsius (122 degrees Fahrenheit) like in Africa and South America.. but we have no data so we don’t know.” At the time he was discussing (called the early Paleogene), carbon dioxide levels may have been 1000 ppm.

I have an article under review which reports an "index of existential risk" for climate change and health, identified in the climate and health literature. I looked at 2,146 articles, editorials and news items, published in the first 25 years of this literature (1989-2013 inclusive). Each paper was given a score between 1 and 3, depending on the degree to which they recognized that climate change may pose an "existential risk" to civilization, and thus health. The average score of these papers was 1.37. 

The average score of Tony's 74 papers was 1.99 (see figure). I mentioned this last week, when I had the chance to talk at the Public Health Association of Australia's 2018 conference, after I received the 2018 award for public health, ecology and environment, named after Tony McMichael. The slides for my talk ("From life support to regional overload") are here

The press release for this award stated that I see civilization at risk, not life, if we continue the current trajectory of fossil fuel burning (and other approaches to planetary boundaries). This is not because it may become so warm that there may again be crocodiles and palm trees in the Arctic Circle, but because the chaos that will be inflicted upon human society through many processes associated with "regional overload" (of which unfavourable climate  change is but one) are likely to outweigh human coping capacity. Here are three candidate contributors, in no order: (1) drought, heat and rising food prices triggering more political instability; (2) sea level rise on the US East Coast leading to a massive loss in property values and thus worsening a financial crisis; (3) a mass human flight from north east China later this century, due to intolerable heat and humidity. 

Even now, solutions might be found. The technology for electricity and elective transport is rapidly advancing. California seeks to be 100% carbon free by 2045. Education reduces fertility (reduced fertility in many settings is important, not to slow climate change, but to reduce climate change related catastrophes in the global South). But these solutions need high level recognition by our political leaders, and that needs the global middle class to understand that rapid transition, towards sustainability, is both urgent and attainable.   

PS Later this month I am teaching, in Finland, in a short course on climate change and health, based on my edited book. (I have just agreed to edit a second edition but it will take some time.)

PPS Prime Minister Modi is reported as saying that:
1. He saw the 121 country International Solar Alliance as the future OPEC for meeting energy needs of the world
2. India would add as much as 50 GW (gigawatts) of non-hydro renewable energy to its existing 72 GW and is on track to reach its target of 75 GW of clean energy by 2022
3. That India’s solar energy increased by nine times in the last four years
4. That in the next four years as many as 28 lakh (2.8 million) solar pumps would be installed which would help avoid 10 GW generation capacity. 
5. 31 crore (310 million) LED bulbs were distributed

50GW is a lot - according to the 2018 Clean Energy Report less than 6 GW of large scale renewable energy projects were under construction or expected to start in 2018, in Australia.

Tony McMichael's 74 papers (1989-2013 inclusive) on climate change and health, scored by their recognition of existential risk.