The increase in heat waves, and the greater number of forest fires they cause, will increasingly worsen air quality, damaging human health and ecosystems, the World Meteorological Organization (WMO) warned on Wednesday 7.
Air we breathe is polluted
For Petteri Taalas, Secretary General of the WMO, “this is a preview of the future, since a greater increase in the frequency, intensity and duration of heat waves is expected, which could further worsen air quality, a phenomenon called ´climate sanction´”.
The WMO bulletin on air quality was issued on this International Day of Clean Air for a Blue Sky, which has been commemorated since 2019 by resolution of the United Nations General Assembly.
For several years now, the World Health Organization (WHO) has warned that virtually all the air we breathe is polluted, killing some seven million people each year, and about 90% of those deaths occur in low-income countries.
“As the planet warms, wildfires and related air pollution are projected to increase, even under a low emissions scenario” of greenhouse gases, Taalas said.
In addition to the consequences for human health, “this situation will also affect ecosystems, since air pollutants are deposited from the atmosphere on the Earth’s surface,” he added.
The bulletin highlighted the impact of smoke from wildfires in 2021, when hot, dry conditions exacerbated the spread of wildfires in western North America and Siberia, leading to widespread rises in levels of small harmful particles.
“This is a preview of the future, since a further increase in the frequency, intensity and duration of heat waves is expected, which could further worsen air quality”: Petteri Taalas.
It also defines the climate penalty as the amplifying effect of climate change on tropospheric ozone production, which negatively impacts the air people breathe.
Air quality and climate interconnected
The regions where the greatest climate penalty is projected, mainly in Asia, are home to about a quarter of the world’s population.
Climate change would exacerbate episodes of surface ozone pollution, with detrimental effects on the health of hundreds of millions of people.
The study explained that air quality and climate are interconnected, because chemical species that lead to air quality degradation are emitted together with greenhouse gases, and changes in one inevitably lead to changes in the other.
The use of fossil fuels, a major source of carbon dioxide (CO2), also emits nitrogen oxide, which can react with sunlight to form ozone and nitrate aerosols.
Air quality, in turn, affects ecosystem health as air pollutants fall from the atmosphere to the Earth’s surface.
Nitrogen, sulfur, and ozone deposition can negatively affect services provided by natural ecosystems, such as clean water, biodiversity, and carbon storage, and can affect crop yields in agricultural systems.
Increase in heat waves
The sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) also includes scenarios on the evolution of air quality as temperatures increase in the 21st century.
The Group estimates that if greenhouse gas emissions remain high, such that global temperatures rise three degrees Celsius from pre-industrial levels, by the second half of the 21st century, surface ozone levels would increase in very large areas polluted, particularly in Asia.
This includes a 20% increase in Pakistan, northern India and Bangladesh, and a 10% increase in eastern China.
Most of the increase in ozone will be due to an increase in emissions from the burning of fossil fuels, but a fifth will be due to climate change, probably due to the increase in heat waves, which amplify episodes of air pollution.
A carbon-neutral global emissions scenario would limit the future occurrence of extreme ozone air pollution episodes.
Efforts to mitigate climate change by eliminating the burning of fossil fuels would also eliminate most human-caused emissions of ozone precursor gases.
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