Climate change continues to increase heatwaves’ intensity; extreme heat ‘compounded’ measurably impacts air quality, it adds

People cool off at the Brockhaus fountain in Frankfurt, Germany during a heatwave in July 2022. Photo: iStock

Climate change is increasing the frequency and intensity of heatwaves, which, in turn, increase the risk and severity of wildfires. This, along with dust, is causing a spike in air pollutants including ozone, a report by the World Meteorological Organization (WMO) has stated.

Heatwaves in both, the United States and Europe triggered wildfires, which along with desert dust, led to dangerous air quality in 2022, the report, released on September 6, 2023, noted.

“Heatwaves and wildfires are closely linked. Smoke from wildfires contains a witch’s brew of chemicals that affects not only air quality and health, but also damages plants, ecosystems and crops — and leads to more carbon emissions and so more greenhouse gases in the atmosphere,” Lorenzo Labrador, a WMO scientific officer in the Global Atmosphere Watch network which compiled the report, was quoted as saying in a statement by WMO.

Short-lived reactive gases such as nitrogen oxides and biogenic volatile organic compounds lead to the production of ozone and particulate matter (PM).

The report gave the example of the European summer of 2022, which it said was the hottest on record for the continent. The long-running heatwave led to increased concentrations of both PM and ground-level ozone. The report said:

Hundreds of air quality monitoring sites exceeded the World Health Organization’s ozone air quality guideline level of 100 μg m–3 for an 8-hour exposure. This first occurred in the south-west of Europe, later moving to central Europe and finally reaching the north-east, following the spread of the heatwave across the continent.

During the second half of August 2022, there was an unusually high intrusion of desert dust over the Mediterranean and Europe. “The coincidence of high temperature and high aerosol amounts, and therefore PM content, affected human health and well-being,” the document added.

The increase in ozone levels impacted agriculture globally, with ozone-induced crop losses averaging 4.4 per cent–12.4 per cent for staples. Losses for wheat and soybean were as high as 15 per cent-30 per cent in key agricultural areas of India and China.

“Heatwaves worsen air quality, with knock-on effects on human health, ecosystems, agriculture and indeed our daily lives,” WMO Secretary-General Petteri Taalas was quoted as saying.

“Climate change and air quality cannot be treated separately. They go hand-in-hand and must be tackled together to break this vicious cycle,” he added.

The report titled 2023 WMO Air Quality and Climate Bulletin is the third in an annual series. It was released to coincide with the International Day of Clean Air for blue skies on September 7.

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