Will acting on climate help us breathe cleaner air?

Bringing about the transition to a zero-carbon world implies a massive transformation of our global society: in the ways we produce our energy, in the ways we use this energy to obtain services for decent living, in the way we treat our waste, or how we manage our forests, amongst many other aspects. Besides stabilizing global temperature rise, the societal changes required for limiting climate change can also influence other aspects of our daily lives, for better or worse. Because these impacts affect, for example, energy security, public health, or food production, it is quintessential to understand how they interact.

In a recent study we have now looked at how limiting climate change can influence air pollution. Air pollution is connected to climate change mitigation in that many air pollutants are emitted together with CO2. Policies that target an elimination of CO2 emissions will therefore also reduce sources which are emitting air pollutants. Our study shows that the possible co-benefits are huge. In an ambitious world that stabilizes temperature increase during this century to below the often discussed 2°C threshold, emissions of soot and sulphates, for example, would also decrease dramatically.

Soot and sulphate

The influence on different air pollutants varies, however. Sulphate emissions, responsible for acid rain and adverse local health effects, are almost entirely eliminated by CO2 mitigation because they are mainly emitted during the burning of fossil fuel. This is not the case for soot. A large share of soot emissions (about one third of current emissions) are resulting from the burning of biomass for cooking or heating in developing countries.

Narrow-sighted climate mitigation policy typically does not explicitly attempt to reduce traditional biomass burning activities in developing countries, as they are considered carbon neutral: the biomass used in these occasions comes from plants which during their growth have captured CO2 from the atmosphere by photosynthesis. When this biomass is then subsequently combusted, the CO2 is released again. This thus roughly results in a net zero CO2 effect. However, whether firewood in developing countries is harvested in a sustainable way is debatable. Policies fostering sustainable development should therefore also focus on sustainable biomass production.

In conclusion, climate mitigation will already remove a large share of the pollution from the air we breathe. However, to eliminate the indoor air pollution burden in developing countries, more integrated policy approaches are necessary[3]. Such approaches would include policies that foster universal access to clean forms of energy, like electricity or liquefied petroleum gas. In the end, any global problem will only be solved if we make the effort to take into account the entirety of the world that is surrounding us with all its complexity.

Dr. Joeri Rogelj (Quelle: ETH-Zukunftsblog)

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