The UN's weather agency has warned that the hazards of air pollution arising from climate change are being overlooked in the battle against global warming.
The World Meteorological Organisation, an intergovernmental group promoting international co-operation on atmospheric science, climatology, hydrology and geophysics, said air quality goes “hand-in-hand” with higher temperatures.
On Wednesday, it published its third annual Air Quality and Climate Bulletin, highlighting the danger of heatwaves and how climate change and air quality must be tackled together.
The report details how heatwaves triggered wildfires in the north-west US, while high temperatures accompanied by desert dust carried across Europe led to dangerous air quality in 2022.
“Heatwaves worsen air quality, with knock-on effects on human health, ecosystems, agriculture and indeed our daily lives,” said WMO secretary general Prof Petteri Taalas.
“Climate change and air quality cannot be treated separately. They go hand-in-hand and must be tackled together to break this vicious cycle.
“This Air Quality and Climate Bulletin relates to 2022. What we are witnessing in 2023 is even more extreme. July was the hottest ever month on record, with intense heat in many parts of the northern hemisphere and this continued through August.
“Wildfires have roared through huge swathes of Canada, caused tragic devastation and death in Hawaii, and also inflicted major damage and casualties in the Mediterranean region.
“This has caused dangerous air quality levels for many millions of people, and sent plumes of smoke across the Atlantic and into the Arctic,” said Prof Taalas.
Dr Lorenzo Labrador, a WMO scientific officer in the Global Atmosphere Watch network, said smoke from wildfires creates a “witch's brew”.
“Heatwaves and wildfires are closely linked,” he said.
“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.”
Air quality and climate are interconnected because substances responsible for climate change and the degradation of air quality are often emitted by the same sources, and because changes in one inevitably cause changes in the other, the report said.
It said last year's summer led to hundreds of air quality monitoring sites exceeding the World Health Organisation’s ozone air quality guideline level.
In Europe, this followed the heatwave from the south-west, moving to Central Europe and finally reaching the north-east, it said.
This brought an unusually high amount of desert dust over the Mediterranean and Europe during the second half of August 2022.
“The coincidence of high temperature and high aerosol amounts, and therefore particulate matter content, affected human health and well-being,” the report said.
“While high-altitude (stratospheric) ozone protects us from the harmful ultra-violet rays of the sun, ozone close to the Earth’s surface is harmful to human health. It also can reduce both the quantity and quality of yield of staple food crops.”
The WMO report said that globally, ozone-induced crop losses average 4.4 per cent to 12.4 per cent for staple food crops.
It said wheat and soybean losses were as high as 15 per cent to 30 per cent in key agricultural areas of India and China.
“Heatwaves and dry conditions are conducive to wildfires which, once started, grow rapidly as they encounter dry, easily combustible vegetation. Such situations can lead to an increase in aerosol emissions,” said the report.
However, it also emphasised how parks and tree-covered areas within cities can improve air quality, absorb carbon dioxide and lower temperatures.
On Wednesday, the Copernicus Climate Change Service (C3S), the EU's climate monitoring service, said June to August 2023 has been the warmest on record globally “by a large margin”, with an average temperature of 16.77°C – which is 0.66°C above average.
It said the European-average temperature for summer was 19.63°C, which was 0.83°C above average.
Summer 2023 saw marine heatwaves in several areas around Europe, including around Ireland and the UK in June, and across the Mediterranean in July and August, it said.
“The dog days of summer are not just barking, they are biting,” UN Secretary-General Antonio Guterres said in a statement.
“Climate breakdown has begun,” he warned. "Our climate is imploding faster than we can cope.”
C3S deputy director Samantha Burgess said August was the warmest on record.
“Global temperature records continue to tumble in 2023, with the warmest August following on from the warmest July and June leading to the warmest boreal summer in our data record going back to 1940,” she said.
Ms Burgess added that “2023 is currently ranked as the second warmest, at only 0.01ºC behind 2016 with four months of the year remaining”.
“Meanwhile, the global ocean saw in August both the warmest daily surface temperature on record, and it’s the warmest month on record,” she said.
“The scientific evidence is overwhelming – we will continue to see more climate records and more intense and frequent extreme weather events impacting society and ecosystems, until we stop emitting greenhouse gases.”
C3S said every day from July 31 to August 31 saw global average sea surface temperatures exceeding the previous record from March 2016.