Imagine you take your 3-week old baby to the doctor with a suspected infection and fever of more than 38°C. Would you want the doctor to take specimens for bacterial culture and then wait several days for absolute certainty that there is a bacterial infection before treating your child or would you want treatment immediately? Most doctors would treat immediately because they know that the risk of calamity is real and if they wait it may be too late. This type of decision making, familiar to all health professionals, is what is required of us if we are to avert a human and planetary crisis in the coming decades.

The United Nation’s Intergovernmental Panel on Climate Change (IPCC) report on impacts, adaptation and vulnerability of communities represents a consensus on the latest evidence from hundreds of scientists who have themselves appraised the work of thousands of their colleagues from around the world. The report spells out the expected impacts of climate change on human health and social wellbeing.

Underlying the anticipated effects on human health and social wellbeing are the measured changes in the climate system itself and a variety of possible future scenarios. These scenarios have different magnitudes of impact, depending on whether we continue with business as usual in terms of greenhouse emissions and on the complexity of the interaction between the climate, natural and social systems.

Broadly speaking the relationship between climate change and health has three pathways:

Access to safe freshwater, for both urban and rural communities, is predicted to become more difficult, particularly in areas such as Southern Africa that are already water scarce. This will impact on both the quantity and quality of water available for drinking and irrigation.

Crop yields in Africa are predicted to be more variable with a decrease in coarse grains (e.g. maize, barley, sorghum) of 17-22% in the near-term future. The yields of other major crops such as wheat and rice are also predicted to decrease. Changes in crop yield and food prices due to extreme weather events have already been seen in Russia and the USA. Without adequate adaptation the number of malnourished children globally under the age of 5-years may increase by 20-25 million by 2050.

Rapid urbanisation in African cities with large informal settlements that are already at risk of flooding or fire will put large numbers of vulnerable people at increased risk from climate change. Pregnant women, people with chronic diseases, small children and the elderly will be the most vulnerable.  The number of unsafe working days due to extreme heat will increase, for example in Australia the number of such days per year is expected to rise from 4-6 days to 33-45 days by 2070.

The effect of climate altering pollutants, other than CO2, is uncertain, but 7% of the global burden of disease in 2010 is already estimated to be due to respiratory and cardio-vascular illness resulting from such air pollution.

Diseases such as malaria, dengue fever, tick-borne encephalitis, hemorrhagic fever with renal syndrome, Lyme disease and Japanese encephalitis are seen as climate sensitive infections. Changing climate can lead to a change in the habitat that supports their insect vectors and without other interventions could lead to new communities being exposed.

Climate change is just one of many human related impacts on planetary ecosystems – others include deforestation, agriculture, road building, fishing, mining and damming of rivers. Natural ecosystems provide many essential services for human health and social wellbeing. Such services include raw materials, soil formation, nutrient cycling, food production, fisheries, water regulation and supply, flood and storm protection, waste treatment, as well as cultural and recreational benefits. Many of our medicines and pharmaceutical discoveries are also dependent on chemicals derived from the natural world. Climate change, which itself represents a change in the climate regulatory ecosystem, is expected to impact on many species and to disrupt their services. For example the combination of acidification of oceans and warming of sea water will have negative effects on coastal ecosystems with loss of fish, coral reefs and associated biodiversity.

From the above description of risks from climate change one can see how these effects could lead to displacement of populations, conflict over scarce resources and a breakdown in social solidarity.

Adaptation refers to the resilience of communities and their ability to adapt to the consequences of climate change. The ability to adapt will be related to the magnitude of climate change and its consequences, and therefore also to our ability to mitigate or reduce greenhouse gas emissions. Poor, informal and vulnerable communities will be the least able to adapt to the effects of climate change – making this a major challenge in South Africa. In terms of the contribution of the health sector the resilience of communities can be increased by strong primary health care and public health expertise with warning systems that alert us to impending risks. Well-functioning disaster management and emergency medical services will also be important. The IPCC says that “climate change is a severe threat to future sustainable development” in addition to other challenges such as poverty, inequality, population growth and food insecurity.

Mitigation refers to the need to reduce greenhouse gas emissions, primarily though reducing our dependence on fossil fuels. Delays in mitigation now may mean that it is too late to avert the worst case scenarios later on. Unsustainable development is, therefore, a threat in terms of increased climate change and reduced resilience. Decision makers have a complex task in shaping policies that integrate sustainability and development. In terms of energy policy, for example, government must balance three things: the need for energy security (keeping the lights on), energy access (increasing access to affordable electricity) and environmental impact (avoiding the destruction of ecosystem services and climate change).

One way of looking at this is the concept of “unburnable carbon” – it has been estimated that we can only burn 20% of the currently known fossil fuel reserves if we want to avoid global warming above 2°C during this century.  This means that we should not support companies to explore and identify new reserves (such as Karoo shale gas), but should rather support companies that can provide alternative energy sources. Prominent South Africans, such as Archbishop Tutu, have called for disinvestment in such fossil fuel companies. The British Medical Association has also just announced that it is disinvesting from fossil fuels.

It appears that, after 20 years of global dialogue through the annual Conference Of the Parties to the 1994 United Nations Framework Convention on Climate Change, governments are unlikely to provide the leadership required to solve this problem. Increasingly civil society is realising that it must take up the challenge. The Department of Health in the Western Cape and the Faculty of Medicine and Health Sciences at Stellenbosch University are two of only a handful of health organisations to join the Global Green and Healthy Hospitals initiative. The Lancet Commission has called climate change “the biggest global threat of the 21st century.” A global movement of health professionals concerned for planetary as well as population health is urgently needed.

Professor Mash is head of Family Medicine and Primary Care at Stellenbosch University’s Faculty of Medicine and Health Sciences, and chairs the Green Committee.
This article was first published in The Cape Times on 26 February 2015.