Health Impacts of Climate Change
Against this background, in 2008 the World Health Organization (WHO) chose the theme 'protecting health from climate change' for World Health Day.11 This involved public talks, media releases and national policy reports launched around the world by a variety of organisations. Dr Margaret Chan, Director of the WHO, stated that
Climate change is one of the greatest challenges of our time. Climate change will affect, in profoundly adverse ways, some of the most fundamental determinants of health: food, air, water. In the face of this challenge, we need champions throughout the world who will work to put protecting human health at the centre of the climate change agenda.12
Key messages for the 2008 World Health Day included that the health sector is one of the most affected by climate change, that climate change already accounts for more than 60 000 deaths from climate-related natural disasters every year and that many of the important global killers, such as malaria, diarrhoea and malnutrition, which cause more than three million deaths each year, are expected to be exacerbated by changing weather patterns and water availability.13 It is clear that the health impacts of climate change are already distributed inequitably around the world with the burden falling most heavily on those who are least responsible for the greenhouse gas emissions that have caused the problem.14 So whilst developed countries such as the US are responsible for the vast majority of the cumulative greenhouse gases since the industrial revolution, it is the poor countries in Africa and parts of Asia that are predicted to bear most of the increased health risks of climate change.15 Some of the health risks of climate change are summarised in table 1.
Table 1: Summary of Health Risks of Climate Change
Increased risk of malnutrition from impaired/failed agriculture
Increased risk of gastroenteritis (for example, from salmonella, campylobacter and other temperature sensitive vibrios)
Increased risk of injury or death from extreme weather events such as floods, fires or storms
Increased morbidity and mortality associated with more frequent and intense heat waves
Change in the range and seasonality of outbreaks of mosquito borne infections such as malaria, dengue fever or Ross River virus
Increased risk of respiratory illnesses from higher ground level ozone and air pollution
Exacerbation of asthma and allergic conditions from regional increases in pollens and spores
Health risks for environmental refugees and the host populations
Increased mental health risks such as post-traumatic stress disorder associated with extreme weather events or depression/ suicide risk associated with loss of livelihood/displacement
Risks associate with more frequent droughts and long term drying such as exposure to heat, dust smoke
Source: Adapted from Blashki, McMichael and Karoly, 'Climate Change and Primary Health Care'.
The increased health risks associated with climate change have been quantified by the WHO using a technique called comparative risk assessment.16 This approach attributes the global health burden to a wide range of health risk factors. In the case of climate change, researchers have focused on five of the pathways by which climate change can impact on health whilst acknowledging that these represent a subset of numerous other mechanisms. These are: thermal stress, weather disasters (such as flooding), malaria, diarrhoea and malnutrition (related to reduced agricultural yields).17 Using a range of modelling approaches, the effects of climate change are predicted to be concentrated in poorer populations where important climate sensitive diseases are common, and in particular in vulnerable populations such as children under the age of five.18
Global climate change is not spatially uniform and consequently the potential health impacts vary according to location. Not all effects are predicted to be negative; for example, in some high latitude countries warmer winters are predicted to reduce cold related deaths, and increasing precipitation in some sub-tropical areas is predicted to increase agricultural yields.19 However, the overwhelming impact of climate change is predicted to be negative.20 Key health risks around the globe are described by location in the IPCC report, and some examples of the risks are described below for Africa, Asia, Australia and the Pacific Islands.21
People living in African countries are especially vulnerable to climate change because of large populations, underlying existing public health problems and poor capacity to adapt. For example, water stress is expected to be worsened by climate change affecting between 75 and 250 million people by 2020.22 Food security is also at risk for many populations due to impaired agriculture affecting those relying on subsistence farming or depending on farming for their livelihoods.23 Communities that are heavily reliant on fishing are at risk of deteriorating fisheries due to a combination of over fishing and warmer water temperatures.24 The transmission zones of malaria are predicted to alter due to climate change, with models suggesting increasing malaria in the eastern and southern African highlands as these areas become warmer and wetter, whilst some parts of Western Africa may become drier and less favourable to malaria.25 In the long term, populations on low lying coastal regions are also at risk of sea level rise.
For countries in Asia, many of the risks of climate change lie in alterations to the normal water cycle—too much water, too little water or the risk of water borne infectious diseases. For example, by 2050, freshwater availability in Central, South, East and South- East Asia, particularly in the large river basins, is predicted to decrease.26 In the Himalayas, glacial melt and retreat is likely to cause an initial increased risk of flooding, however, in the longer term there will be reduced flows of fresh water in the large river systems that course through the Asian continent.27 Large populations living in coastal regions or near the mega-deltas (for example, Bangladesh) are also at increased risk of flooding. The combination of droughts and floods are predicted to increase the risk of water borne diseases with an increase in morbidity and mortality associated with diarrheal diseases.28
Small islands are another example of high vulnerability to climate change. Sea level rise and storm surges can result in inundation of fresh water supplies, disruption of infrastructure, destruction of settlements and loss of livelihoods.29 For example, Pacific islands such as Tokelau, the Marshall Islands and Tuvalu are extremely vulnerable to increases in sea levels, and, in the case of the latter, plans for some of the population to migrate to New Zealand are being explored.30
Although Australia is wealthy developed nation, it is also vulnerable to climate change. In particular, more frequent droughts and long term drying are a major challenge. Average temperatures in Australia have increased 0.9 degrees C since 1950, with significant variations across the country.31 Overall, the frequency of hot days and nights has increased and rainfall has decreased, especially in southern Australia.32 There are numerous flow-on impacts of drought, including impacts on livelihoods (mainly the viability of farms), on local economies and on the physical and mental health of, especially, rural and remote communities.33 Individuals and, especially, communities experiencing underlying disadvantage will be the hardest hit.34 For example in Australia, there are grave concerns for Aboriginal communities.
Fire risk is also expected to increase in Australia with warmer and drier conditions. According to the Commonwealth Scientific and Industrial Research Organisation (CSIRO) the number of days with very high and extreme fire danger ratings is likely to increase between 4 and 25 per cent by 2020 and between 15 and 70 per cent by 2050.35 Risks include injuries and deaths associated with the fires, respiratory problems from dust and smoke and a range of health risks to the fire fighting workforces.36
Heatwaves are predicted to be more frequent in Australia, leading to higher morbidity and mortality. A report conducted by the Australian Conservation Foundation and the Australian Medical Association outlines the risks of heatwaves in Australia. It estimates that without substantial reductions in greenhouse gas emissions, by 2100 the number of annual heat-related deaths is projected to be 8000-15 000 compared with 1100 deaths per year in 2005 .37
Australia is also at risk of changes in the distribution and intensity of infectious disease which are spread by mosquitoes. For example, dengue fever, which has generally been restricted to areas north of Broome, Katherine and Cairns has the potential to extend much further south, even into New South Wales.38 Other infectious diseases such as Ross River fever and Barmah Forest virus also are predicted to extend their transmission zones with rising temperatures.39
Continue reading here: Role of Primary Health Care
Was this article helpful?