Fig. 3: Shifts of Volume and Focus in Subject Literature.

a The stacked bar chart displays the proportion of literature focusing on each of ten air pollutants (PM, O₃, NO₂, SO₂, CO, Dust, BC, Sulfate, Nitrate, Pb) during four consecutive periods (1990–1997, 1998–2005, 2006–2013, and 2014–2021) from 1990 to 2010, illustrating shifts in research attention over time. The accompanying line graph shows the total volume of related publications, marking a notable rise after 2010. b Pie charts detail the composition of research types for each of the four specified periods, with segments representing “Evidence” studies that directly report the impacts of climate change on air pollution, “Mechanism” studies including real-world experiments and model optimizations, and “Discussion” articles providing analyses or comments of existing literature. c The bar and corresponding pie chart visualize the categorization of literature by climate impact-drivers mentioned, emphasizing dominant themes such as heat and cold, wind, and wet and dry conditions.