A recent review of available literature on the combined effects of climate change and air pollution, shows that closer integration, both in terms of impact assessment for human health and agricultural productivity, is needed.
According to the review, hotter temperatures due to climate change, in addition to being a risk in itself, also amplifies the negative health effects of air pollution.
Air pollution and temperature interaction
“This review shows that global warming comes with a double ‘climate penalty’: Not only can global warming lead to a deterioration of air quality in itself, for instance via impacts on emission rates and the fate of the emissions in the atmosphere, but hotter temperatures can also amplify the health effects of air pollution”, says research director Kristin Aunan at CICERO Center for international climate research.
““This review shows that global warming comes with a double ‘climate penalty’””
“The latter can happen, for instance, if people spend more time outdoors or keep windows more open in hot weather, thus increasing their exposure to ambient air pollution. Perhaps more important, hot temperatures and air pollution may multiply their health effect by acting on the same pathophysiological pathways in our bodies”, says Aunan.
Aunan explains: “The studies we reviewed indicate that air pollution can make people more sensitive to the effects of non-optimal temperatures and, vice versa, being exposed to either very hot or very cold temperatures can make people more sensitive to air pollution.”
The reviewed studies are quite diverse when it comes to which populations are included, what meteorological factors and air pollutants are looked at, and what health outcomes are focused.
Nevertheless, the studies point to substantial interactions between air pollution and temperatures when it comes to both death and disease rates, with most studies reporting joint effects for the variables particulate air pollution, ozone (O3) and daily mean temperatures.
Air pollution and crop production:
The review highlights that air pollution has also become a key concern for global crop production. The effects of air pollutants on agriculture are less well known, but global scale assessments suggest yield losses could amount to between 3 per cent and 16 per cent for staple crops due to ozone (O3) pollution, with losses set to worsen by 2030 primarily due to O3 increases in Asia (Emberson 2020).
“Climate change and air pollution can interact to amplify risks to human health and crop production” says Jana Sillmann, senior researcher at CICERO.
“Studies estimating the impacts of climate and air pollutants on human health and crops mostly treat these stressors separately, and the use of methods differs between the communities. Better insights into the methods are needed to improve our knowledge on the combined effects” says Sillmann.
Photo: Lars Sandved Dalen, NIBIO
“In the review we discuss different interacting effects of climate and air pollution on crops considering impacts on photosynthesis, growing seasons, biomass, stomatal conductance, and subsequently crop yield, which are strongly influenced by the interaction between stressors” says Sillmann.
The different interacting effects of climate and air pollution on crops. Key climate variables and air pollutants primarily impact stomatal conductance, photosynthesis, growing seasons, biomass and subsequently crop yields. The effect of these stressors is variable and strongly influenced by the interaction between stressors (Figure 6 in the article).
Policy implications
“Our study implies that heat stress and air pollution should be considered jointly in policy development. For instance, heat-health action plans should include the enhanced risk related to air pollution exposure during heat waves. Air pollution abatement policies, on the other hand, need to take into account that global warming will make it more difficult to reach air quality targets” says Aunan.
Greenhouse gases and air pollutants are to a large extent emitted from the same sources, linked to the burning of fossil fuels. Mitigation of greenhouse gases to limit global warming in line with the Paris-agreement is demanding but will have large co-benefits for human health and crop production.
“Mitigation of greenhouse gases to limit global warming in line with the Paris-agreement is demanding but will have large co-benefits for human health and crop production. ”
The review also highlights the following:
Currently, climate-related hazards, such as heat, drought, and floods, are responsible for 90% of all disasters worldwide.
There are important interactions between climate variables, particularly temperature, and air pollution in terms of impacts on human health and crop productivity. In most cases this leads to enhanced damage to health and crops.
The paper compares the methodologies applied in the two field, and discusses how methods could be further developed to enable projection of health effects and crop productivity in a rapidly changing and warming world.
More large-scale and long-term studies for human health and agricultural crops, respectively, should be carried out in climatologically hot regions (Africa, India, South-Asia), where heat extremes are becoming a serious threat.
The full text article can be read here:
References:
Emberson L 2020 Effects of ozone on agriculture, forests and grasslands Phil. Trans. R. Soc. A 378 20190327
