Climate Change: Preparing for the Health Impacts

Canada's Evidence Base: Where Are We Now, Where Are We Going?

Jacinthe Séguin, Climate Change and Health Office, Safe Environments Programme, Healthy Environments and Consumer Safety Branch, Health Canada

In Canada, as elsewhere in the world, research on the impacts of climate change is a relatively new field. However, a patchwork of evidence is emerging, both here and internationally, on how climate change can affect human health, and it is providing the basis for initiatives designed to protect vulnerable populations. This article provides an overview of Canadian research, including current evidence and future directions, and identifies some of the major gaps. It also explores the challenges for policy makers as they move from research to action in this area.

Health and Climate Change: An Emerging Domain

 

Since many factors interact to determine health, one of the challenges for health researchers is to consider all of these factors and evaluate the relative importance of environmental risks in influencing disease or causing death. In the case of complex environmental issues like climate change, no one discipline can find all the answers. In Canada, climate change has traditionally been the domain of the physical sciences. But the policy momentum of the 1990s, combined with targeted funding, has drawn researchers from many disciplines including geography, economics, health sciences and, more recently, the social sciences and humanities.

Limitations in data, methods and funding have not permitted a full analysis of how climate interacts with the physical and social environment, or what health risks are associated with different climate scenarios. Instead, studies have focused on establishing regional or local evidence of the relationship among one or several aspects of climate (e.g., precipitation, temperature), a particular pathway (e.g., water, air, insects), and one or more health outcomes (e.g., enteric diseases, respiratory illnesses). As these relationships become better understood, researchers are beginning to explore how risks and exposures are likely to change under future climatic scenarios.

What is the Evidence Telling Us?

Canadian and international research shows that climate change will increase the incidence of some diseases, affect the well-being and security of individuals, and influence the type and delivery of health services.^{1, 2, 3}

There is undeniable evidence that environmental changes in the Arctic have already caused - and will continue to cause - significant disruptions in the northern way of life, particularly among Canada's indigenous groups.⁴ Nowhere in Canada is the evidence of climate change and the immediate biophysical impacts, including health, more compelling for action. Scientific evidence, corroborated by traditional (indigenous) knowledge and local observations, suggests a wide range of health impacts as a result of exposure to increased levels of ultraviolet radiation, loss of traditional foods, unsafe ice and winter road conditions, contamination of drinking water and culture changes (see also article on page 22).

The effect of heat and cold stress on morbidity and mortality is one of the better understood environment-health interactions (see article on page 16). A solid body of international work documents the physiological responses to temperature. As well, there are some epidemiological studies of heat episodes, and work has progressed on the development and application of methods for calculating heat stress indicators and heat health warning systems.⁵ In Canada, recent work on developing baseline data from hospital administrative records⁶ has been instrumental in identifying and quantifying the health effects of temperature-related stress - including who may be vulnerable and under what conditions. The strength of the international evidence, coupled with recent incidences of heat waves in some cities, has convinced public health officials in Toronto and Montréal to implement measures for populations at risk.^7,8 Ongoing Canadian studies and future work - in particular, on the combined effects of heat and air pollution - will help public health officials refine these approaches, identify thresholds, better understand adaptive behaviours and determine long-term adaptation strategies.

As the article on page 27 illustrates, researchers in Canada are also breaking ground on Canadian concerns, such as the relationship between climatic conditions (e.g., temperature, moisture conditions) and the incidence of gastrointestinal illnesses,⁹ as well as the distribution and ecology of vectors such as those carrying Lyme disease.¹⁰ The long-term effects of natural disasters have received less attention as the ability to gather data is limited by their infrequent occurrence. The fact that they often occur in very different social settings further limits the comparability of results. However, some interesting studies have been conducted, such as one of the 1998 ice storm in Québec and Eastern Ontario that explored the effect of women's exposure to stress during pregnancy on the general intellectual development of children born shortly after the storm.¹¹

While Canadian research is largely focused on defining climate-related hazards based on the climatic status quo,² some studies incorporate future climate modelling and scenario-based hypotheses in their research methodologies (e.g., the work by Garneau on trends in airborne allergens, Waltner-Toews on the relationship between the incidence of gastrointestinal illnesses and precipitation, and Charron on modelling the relationship of foodborne illnesses and temperature).^9,12,13

Research Gaps and Future Directions

Gaps in knowledge about the potential health impacts of climate change are almost as well defined as the evidence. Over the past five years, researchers have identified knowledge needs that cut across key health issues.¹⁴ Several of these gaps are worth highlighting:

Participatory Research

Climate change will affect all of Canada, but its impact will vary across regions and populations (see article on page 5). This presents a tremendous challenge in determining what areas will require attention at a national or even a provincial level, and calls for locally-based and participatory research that can mobilize interest, raise awareness and, ultimately, bring about change. Methods are needed to systematize and incorporate local and traditional knowledge into research approaches. Because change often comes about only when people are faced with the inevitable or after an event has occurred, participatory research can act as an early warning system and trigger change in policies and practices at all levels.

Short- and Long-Term Impacts

Just as responses to climate change must account for varying impacts at different geopolitical levels, they must also recognize short- and long-term impacts. Factors producing the most noticeable changes in near-term disease rates may not be the same as those causing long-term changes. Long-term impacts are more difficult to discern, measure and attribute to a particular cause. In particular, long-term psychosocial effects from natural disasters^11,15,16 can have a pervasive impact on communities or specific population groups. For this reason, there is a need to broaden the base of disciplines studying the long-term social impacts of climate change.

Methods, Modelling and Integrated Assessments

Assessments of climate change impacts are based on assumptions about the state of a future world. This type of research involves a certain level of uncertainty, whether about the status quo or predictions based on trends or scenario analyses.¹ Because different studies pose different questions about the same potential risk, it can be hard to compare studies. This presents particular problems for decision makers, who want to base their choices on a clear picture. At the same time, studies with varying perspectives are often necessary to support decision making in different sectors. The World Health Organization recognizes two valuable approaches to climate change research that can lead to different conclusions based on the same evidence: one involves traditional hypothesis testing; the other is a "what if" analysis that can be useful for risk management decisions and contributes to the "weight-of-evidence" argument.¹ To further develop the Canadian evidence base, there is a need to build experience on both these fronts, as well as to adapt existing methods.

Coping Ability and Adaptive Capacity

Variation in adaptive capacity needs to be better understood as it has a considerable effect on health outcomes, even when exposure to risk is the same. As discussed in the article on page 22, adaptive capacity is influenced by a range of other determinants of health (e.g., income and social status, education, gender, biology, genetics and culture). To be effective, adaptations need to take into account behavioural responses to stress, social context and economic factors.¹⁷ Increased understanding about the behavioural aspects of adaptation, such as the influence of risk perception, is needed to develop better measures for reducing and mitigating risks.

Social Impacts and Transdisciplinary Approaches

Climate change can place additional strain on other key determinants of health, such as employment rates, the provision of social and health care services, and support networks. Current research on these determinants of health may need to consider the predicted impacts of climate change. One way to stimulate a more comprehensive assessment of climate change risks is to encourage transdisciplinary approaches that incorporate a range of disciplinary strengths and methods into formulating and testing hypotheses. This type of research usually consists of multidisciplinary teams developing and applying best methods and approaches to answer complex research questions.

Technologies and Climate Change Mitigation Measures

Little work has been done in Canada on the possible health costs and benefits of technologies and measures to reduce Canada's greenhouse gas emissions (e.g., new fuels, engine technologies, energy efficient building technologies, carbon sequestration techniques). However, research in the United States^1,18 indicates that some technologies may pose risks to human health. More work is needed to determine if these risks outweigh the benefits of reducing greenhouse gases, and whether they can be reduced to an acceptable level. Although this field of research is very uncertain, predictive modelling of potential future exposures and risks is needed to guide current investments and strategies designed to stem the rate of global climatic change.

From Impacts to Adaptation: Designing Effective Policies

Policy makers are poised to consider evidence that will support action to reduce the risks of climate change (see also article on page 35). Yet we are only beginning to understand how the relationship between climate change and our uniquely Canadian natural and social environments can affect health outcomes. Many unresolved questions remain about how particular health outcomes are affected by weather, climate variability and climate-induced environmental conditions. When and how individuals, communities and governments need to change current practices or put new measures in place depends, in large part, on the perceived vulnerability of populations, including their adaptive capacity. If systems are currently in place to mitigate these risks, the perception may be that further action is not required. However, it is only once they are put to the test that we can truly know whether particular populations have an acceptable degree of resiliency and if adjustments are necessary.

That being said, enough information is currently available for researchers to begin examining the vulnerability of key populations and developing suitable adaptation options. Early efforts can focus on developing policies and other measures that address vulnerabilities to current climate conditions, and offer flexibility for future scenarios. The challenge for public health decision makers will be to balance efforts to alleviate today's stresses with the need to prepare for the unexpected.

Myths appearing throughout this issue contributed by Marcia Armstrong, Climate Change and Health Office, Health Canada

Myth?

The warming trend experienced in Canada's Arctic would have only positive impacts for northern residents. The impacts of climate change can be seen as negative or positive, depending on one's interests. Reduced sea ice in the Arctic as a result of climate change will likely be devastating for polar bears and ice-dependent seals, with repercussions on local people who depend upon these animals as a food source. At the same time, reduced sea ice provides expanded opportunities for shipping, and offshore oil exploration and extraction. But environmental damages from these activities could harm the marine habitat and negatively affect the health and traditional lifestyles of northern people.¹ Some of the positive health impacts of climate change may include a reduction in cold-induced injuries and cold stress. Among the direct negative impacts on health are increased heat stress and accidents associated with unusual ice and weather conditions. Indirect negative impacts include changes in the availability of traditional foods, increased stress related to changes in environment and lifestyle, outbreaks of mosquito-borne disease, decreased access to good quality drinking water and illnesses resulting from poor sanitation systems.

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Issue 11 References

Some of the following hyperlinks are to sites of organizations or other entities that are not subject to the Official Languages Act. The material found there is therefore in the language(s) used by the sites in question.

References for Canada's Evidence Base: Where Are We Now, Where Are We Going?

1. McMichael, A.J., Campbell-Lendrum, D.H., Corvalan, C.F., Ebi, K.L., Githeko, A., Scheraga, J.D., et al. (Eds.). (2003). Climate Change and Human Health: Risks and Responses (pp. 1-17). Geneva, Switzerland: World Health Organization.

2. Riedel, D. (2004). Human Health. In D.S. Lemmen & F.J. Warren (Eds.), Climate Change Impacts and Adaptation: A Canadian Perspective (pp. 151-170). Ottawa, ON: Natural Resources Canada.

3. Lemmen, D.S., & Warren, F.J. (Eds.). (2004). Climate Change Impacts and Adaptation: A Canadian Perspective. Ottawa, ON: Natural Resources Canada.

4. Hassol, S.J. (2004). Impacts of a Warming Arctic: Arctic Climate Impact Assessment. Cambridge, UK: Cambridge University Press.

5. Koppe, C., Kovats, S., Jendritzki, G., & Menne, B. (Eds.). (2004). Heat-waves: risks and responses. Geneva, Switzerland: World Health Organization.

6. Mao, Y., et al. (2005). A Multi-centre Approach to Investigate the Health Impacts of Extreme Heat and Cold Events due to Climate Change and Climate Variation. Research in progress. Public Health Agency of Canada.

7. Campbell, M., & Cheng, C.S. (2005). Differential and combined impacts of winter and summer weather and air pollution due to global warming on human mortality in south-central Canada. HPRP File No. 6795-15-2001/4400011. Ottawa, ON: Health Canada.

8. Drouin, L., King, N., Jacques, L., Fortier, I., Roy, L-A., Litvak, E., et al. (2005, May 4-7). The Response of the Montréal Public Health Board to Climate Change: Preventing Excess Morbidity and Mortality due to Extreme Summer Temperatures in Vulnerable Human Populations. Paper presented at the Adapting to Climate Change in Canada 2005 Conference, Montréal, QC.

9. Charron, D.F., & Waltner-Toews, D. (2005). Links between climate, water and waterborne illness, and projected impacts of climate change. HPRP File No. 6798-15-2001-4400016c. Ottawa, ON: Health Canada.

10. Ogden, N.H., Bigras-Poulin, M., Barker, I.K., Lindsay, L.R., Maarouf, A., O'Callaghan, C.J., et al. (2005). A dynamic population model to investigate effects of climate on geographic range and seasonality of the tick Ixodes scapularis. International Journal of Parasitology, 35, 375-389.

11. Laplante, D.P., Barr, R.G., Brunet, A., Galbaud du Fort, G., Meaney, M.J., Saucier, J-F., et al. (2004). Stress During Pregnancy Affects General Intellectual and Language Functioning in Human Toddlers. Pediatric Research, 56, 400-410.

12. Garneau, M., Guay, F., & Breton, M-C. (2005). Modélisation des concentrations polliniques à partir de scénarios climatiques (Partie I). Montréal, QC: Consortium Ouranos, Université du Québec à Montréal, département de géographie et Centre de Modélisation Régionale du Climat.

13. Fleury, M., Charron, D., Holt, J., & Maarouf, A. (2005, May 4-7). Modeling the Relationship Between Temperature and Foodborne Disease. Poster session presented at the Adapting to Climate Change in Canada 2005 Conference, Montréal, QC.

14. Health Canada. (2004). Climate Change and Health: Research Report. Ottawa, ON: Author.

15. Maltais, D., Lachance, L., Fortin, M., Robichaud, S., Fortin, C., & Simard, A. (2000). L'état de santé psychologique et physique des sinistrés des inondations de juillet 1996: étude comparative entre sinistrés et non-sinistrés. Santé mentale au Québec, XXV(1), 116-138.

16. Hutton, D. (2004). Psychosocial Effects of a Natural Disaster: A Post-Flood Assessment in the Red River Valley. Environments Journal, 3(2), 27-43.

17. Gosselin, P. & Grondin, J. (2002, August 27-28). Changing behaviours in a time of climate change: Social science perspectives on the health impact assessment of climate change and adaptive behaviours. Report on a workshop held in Québec City, QC. Office of Climate Change and Health, Health Canada, and Institut national de santé publique du Québec (INSPQ), Québec.

18. The Heinz Center and the Health Effects Institute. (2000, November 29-30). Health Implications of Technological Responses to Climate Change. Report of a workshop held in Washington, DC.

References for Did you know? Myths

1. Arctic Council and International Arctic Science Committee. (2004). Impacts of a Warming Arctic: Arctic Climate Impact Assessment. Retrieved July 10, 2005, from http://amap.no/acia/.