Climate change: Proof in numbers.
Last month, as wildfires continued to rage across the American West, Pascal Peduzzi, a climate scientist with the United Nations Environment Programme (UNEP) in Geneva, followed the situation with air quality in Mammoth Lakes, a town high in California’s Sierra Nevada mountains.
On Wednesday 23 September on the town’s Ranch Road the PM2.5 measurement – the tally of airborne particulate matter with a diameter less than 2.5 micrometres – reached 501mg per cubic metre (µg/m3) of air. That is over 50 times the threshold that the World Health Organisation (WHO) considers safe for the average PM2.5 reading over one year. It is more than 20 times the level considered safe for a 24-hour period.
“I’ve never seen it that high,” Peduzzi stated.
The scientist was not in California, nor in the US. He was in Switzerland, over 9,000km away. Nonetheless, he, and anyone with an internet connection, can now follow in detail PM2.5 levels in the West Coast fire zone, and across the planet, via UNEP’s World Environment Situation Room (WESR). This online portal offers a near-real-time monitor of global air quality.
The intention of this platform was to connect to people,” said Sean Khan, an expert on air pollution with UNEP in Nairobi. “It was designed to inspire and stimulate action, whether that’s communities trying to convince policymakers to do things or vice versa.”
In August, following record-breaking high temperatures, lightning strikes from severe thunderstorms ignited fires in California, Oregon and Washington. By the end of September, these blazes had consumed over 2 million hectares of land across the three states. They had destroyed over 7,000 structures and left at least 40 people dead.
We now currently have five active fires that are five of the most destructive fires in the history of the state,” Gavin Newsom, the governor of California, said on 11 September, standing in smoky air among scorched trees.
The fires threw fine particulate matter into the atmosphere. Alongside producing the extraordinary orange skies seen in television reports, studies have linked elevated PM2.5 levels with a range of health problems. These include asthma, respiratory inflammation, jeopardised lung function and even cancer.
One study conducted for seven years (from 2000 to 2007) in the US indicated that average life span extends by 0.35 years for every 10 µg/m3 decrease in PM2.5. Another, which tracked 1.2 million American adults for 26 years from 1982 to 2008, found that the mortality of lung cancer increased by 15–27% when PM2.5 air concentrations increased by 10 µg/m3.
“If you are someone with pulmonary complications, then you are vulnerable, you’ll be at risk,” Khan said. The WESR Air Portal includes a mobile app which offers weekly and daily hyperlocal forecasts in addition to user customised alerts for PM2.5.
This year’s US wildfires are not an isolated meteorological phenomenon but reflect a changing climate.
In the last 20 years, California experienced more years of drought – as classified on the US Drought Monitor’s (USDM) five-point scale – than it did without drought. The USDM gradings range from D0 – an area experiencing short-term dryness – up to D4, an area experiencing “exceptional and widespread crop and pasture losses, fire risk, and water shortages that result in water emergencies.”
There were droughts between 2001 and 2005, 2007 and 2010, and from 2012 to 2017. These became more intense over time. The most severe period, between January 2014 and January 2017, led to a severe water deficit in both the soil and underground aquifers.
“It’s definitely a shift in climate, it’s no longer a 10%, extreme event,” Pascal Peduzzi said. The changing climate also creates loop effects; warmer temperatures generate more evaporation, drying out soils and vegetation, in turn leaving them more susceptible to fire. The fires themselves, meanwhile, add carbon dioxide to the atmosphere, alongside particulates, further contributing to climate change.
“If you have dry soils, and basically no precipitation, put a bit more wind on that and someone lighting a barbecue, and that’s it,” Peduzzi added. “It’s a recipe for disaster.”
The WESR platform is a collaboration between the UN and Swiss firm IQAir, which operates its own air quality monitoring platform.
At maximum zoom-out, it shows a map of the planet, with arrows depicting wind patterns and air quality in particular areas represented by a shading system; green is good, yellow moderate, orange is unhealthy for sensitive groups.
Red represents unhealthy conditions, while two shades of purple show very unhealthy and hazardous levels. Last Friday, 5,185,211,024 people, or 66.4% of the world’s population, were exposed to polluted air worse than WHO recommended limits. That figure updates every four hours.
Zoom in and you come to circles containing numbers, at first average PM2.5 readings across a region and then down to individual sensors like that on Ranch Road in Mammoth Lakes. Flame icons show burning fires. By Friday the PM2.5 tally on Ranch Road had fallen to 32.8 µg/m3
However, a mobile monitoring station in Pollock Pines, further north in the Sierra Nevada, was registering 706.4 µg/m3. The US wildfire season is not over yet.
UNEP’s novel ‘World Environment Situation Room’ provides real-time data on PM2.5 levels across the planet, informing scientists, policy-makers and citizens alike.
Story taken from UNEP’s webpage.
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