EGU2020-3750
https://doi.org/10.5194/egusphere-egu2020-3750
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Biomass burning decline causes large reductions in NO2 burden over north equatorial Africa in spite of growing fossil fuel use

Jonathan Hickman1, Niels Andela2, Money Ossohou3, Corinne Galy-Lacaux4, Kostas Tsigaridis5, and Susanne Bauer1
Jonathan Hickman et al.
  • 1NASA, Goddard Institute for Space Studies, United States of America (jonathan.e.hickman@nasa.gov)
  • 2NASA, Goddard Space Flight Center, United States of America
  • 3Laboratoire de Physique de l’Atmosphère et de Mécanique des Fluides, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
  • 4Laboratoire d’Aérologie, Université Toulouse III Paul Sabatier / CNRS, Tolouse, France
  • 5Center for Climate Systems Research, Columbia University, New York, United States of America

Socio-economic development in low and middle-income countries has been accompanied by increased emissions of air pollutants such as nitrogen oxides (NOx: nitrogen dioxide (NO2) + nitric oxide (NO)), which affect human health.  In sub-Saharan Africa, fossil fuel combustion has nearly doubled since 2000.  At the same time, biomass burning—another important NOx source—has declined in Africa’s northern biomass burning region, attributed to changes in climate and anthropogenic fire management associated with agricultural development. Here we use satellite observations of tropospheric NO2 vertical column densities (VCDs) and burned area to identify NO2 trends and drivers over Africa. Across the northern ecosystems where biomass burning occurs—home to over 350 million people—mean annual tropospheric NO2 VCDs decreased by 4.5% from 2005 through 2017 during the biomass burning season of November through February. Reductions in burned area explained the majority of these change in NO2 VCDs, but there were also weaker relationships between changes in NO2 VCDs and fossil fuel emissions over parts of West Africa, which were stronger during rainy season. Over Africa’s biomass burning regions, NO2 VCDs tended to decrease with increasing population density up to a threshold of approximately 180 people per km2, suggesting that anthropogenic activity causes a net reduction in NO2 emissions across roughly 90% of the continent’s biomass burning regions. In contrast to the widely-held perception that socio-economic development worsens air quality in low and middle-income nations, our results suggest that countries in Africa’s northern biomass burning region are following a different pathway, resulting in regional air quality benefits. However, these benefits may be lost with increasing fossil fuel use.

How to cite: Hickman, J., Andela, N., Ossohou, M., Galy-Lacaux, C., Tsigaridis, K., and Bauer, S.: Biomass burning decline causes large reductions in NO2 burden over north equatorial Africa in spite of growing fossil fuel use, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3750, https://doi.org/10.5194/egusphere-egu2020-3750, 2020

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