An Integrated Assessment of Air Pollution and Climate Change for Sustainable Development in Africa has been recently published, completed by scientists from across that continent alongside international collaborators. Co-sponsored by the United Nations Environment Programme, African Union Commission, and Climate and Clean Air Coalition-sponsored Integrated Assessment, and coordinated by the Stockholm Environment Institute, it represents a needed exploration and evaluation of sustainable development pathways and their potential benefits for climate change and air quality. Here Dr Paul Young, JBA climate scientist and a lead author of the assessment, explains why the assessment is necessary, how climate change and air quality are linked, and what it tells us about the challenges and opportunities for Africa this century.
Africa this century is a continent of superlatives. More than half of the global population growth by 2050 will occur there, urbanisation continues apace and its cities are the fastest growing and youngest in the world, and it is home to the world’s largest free trade area. Within this backdrop, there is great potential for positive change across the continent, which is the central goal of Agenda 2063, the African Union’s strategic plan to transform the continent into “the global powerhouse of the future” to be delivered through “inclusive and sustainable development.”
As well as socioeconomic changes and development, including reaching zero hunger, achieving the Agenda 2063 goal also means that the continent needs to confront environmental challenges, including air pollution and climate change. Air pollution is the second largest cause of death across Africa, responsible for over 1 million premature deaths and with 63% of those due to exposure to household air pollution. Air pollution also leads to disease, meaning lost days and shorter lives overall. Climate change is already evident across Africa and its impacts are projected to cost African nations 50 billion US dollars annually by 2050. At the same time, Africa’s contribution to global greenhouse gas emissions has been 2–4% over the last 50 years.
When we consider air pollution in the context of human health, the pollutants we are referring to are reactive gases (e.g., ozone, nitrogen oxides, sulphur dioxide, methane) and small particles, especially those less than 2.5 micrometres in diameter called PM2.5 (which can be made from various compounds). The main reason to consider these together with greenhouse gases is that they share many of the same sources, particularly the emissions from burning fossil fuels to power our vehicles and generate power for industry and homes. Some air pollutants are not emitted directly but are formed from the chemical reactions of other pollutants in the atmosphere – ozone is an important example.
Many air pollutants can also impact climate. However, this is complex, not least as many pollutants have multiple roles in this regard! Some, like ozone and methane, are greenhouse gases themselves. Some, like ozone and nitrogen oxides, can affect the lifetimes – and therefore concentrations – of greenhouse gases by changing the atmosphere’s chemical conditions. Some, like sulphur dioxide and nitrogen oxides, contribute to the formation of particulate matter, which may directly warm or cool the planet through interaction with sunlight or infrared energy from the earth (depending on what the particles are made from), or indirectly warm or cool the planet through changing the properties of clouds.
Finally, the climate impacts the physical, chemical, and biological conditions important for pollutants. These impacts include through changes in temperature, precipitation, and clouds, which affects reaction rates, how quickly some pollutants are removed, and how much sunlight is available to kickstart the chemistry. And all these things affect the behaviour of the natural sources of reactive gases, such as trees, soil microbes, and even lightning.
The Assessment, coordinated by the Stockholm Environment Institute, was instigated to investigate questions related to development trajectories and environmental change. Concentrating on the five key sectors of transport, residential, energy, agriculture, and waste, the report team developed three key future scenarios: a scenario consistent with the Agenda 2063 vision, where future greenhouse gas and pollutant emissions are reduced and there are large structural changes in areas like public transport and food waste; a pollutant targeting scenario, which is slightly less ambitious and targets the most polluting sources, such as cars and indoor cookstoves; and a “baseline” scenario, where current policies continue into the future and which is the yardstick against which the other two scenarios are measured.
The headline messages from the Assessment are that the indoor and outdoor pollution reductions in the Agenda 2063 scenario will prevent 200,000 premature deaths per year by 2030 and 880,000 premature deaths per year by 2063 compared to the baseline scenario. Emissions of greenhouse gases are also reduced – by 55% for CO2, by 74% for methane, and by 40% for nitrous oxide – and the avoided climate change, air pollutant reductions, and changes in agricultural practices mean that rice, maize, wheat, and soy yields increase.
One of the real strengths of the Assessment it is Africa-led, with less than 1/3 of the authors based in institutions outside of the continent (many of whom with current or past links to Africa).
This point may seem obvious, but voices from the Global South – and Africa in particular – have been hugely underrepresented in climate science. There are several reasons for this, not least as institutional support, capacity, and research funding may be lacking. Indeed, a recent study calculated that tropical Africa climate change research receives less than 4% of the global climate change research funding. However, the same study reported that 78% of the total funding spent on climate change research in Africa was received by European and North American institutions, while African institutions received only 14.5%. It is statistics like this that remind us in the Global North (including this blog’s author!) to be mindful of “helicopter science” while also encouraging us to engage with the movements to decolonise science.
Nevertheless, with its authentic voice, the Assessment sets out, and makes a compelling case for, a detailed roadmap for positive change in Africa. The Integrated Assessment of Air Pollution and Climate Change for Sustainable Development in Africa report is freely available here and the Summary for Decision Makers (in English and French) is available here.
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