The world is in a dark place, gripped by a pandemic that could rage for months and take countless lives. But it has led to an astonishing fall in air pollution in the most heavily populated parts of the planet.
European Space Agency (ESA) satellites offer remarkable, colour-coded animations to illustrate the change: carbon emissions have declined sharply as lives are put on hold, industry is scaled down, streets quieten, aircraft grounded.
Over the past six weeks, readings from the agency’s Sentinel-5P satellite show nitrogen dioxide (NO2) levels over cities and industrial clusters in Asia and Europe were markedly lower compared to 2019, resulting in less air pollution.
The Copernicus Atmosphere Monitoring Service has found a significant drop in nitrous oxides and fine particulate matter (PM), the air pollutant produced by traffic (especially diesel vehicles) and the burning of wood, peat and coal.
With satellite observations and computer models of the atmosphere, researchers have found a 20 to 30 per cent reduction in surface PM over huge swathes of China.
“Satellites offer a unique vantage point to monitor the health of our planet. Sentinel-5P is one of seven Copernicus satellites in orbit today. It currently provides the most accurate measurements of NO2 and other trace gases from space,” explains Josef Aschbacher, ESA’s director of Earth observation.
“As NO2 is primarily produced by traffic and factories, it is a first-level indicator of industrial activity worldwide. What is clearly visible is a significant reduction of NO2 levels over China, caused by reduced activity due to Covid-19 restrictions.”
Slowdown took out the equivalent of almost 1.5 billion tonnes of CO2 in China and could curb global emissions from air travel by 11 to 19 per cent, according to Bloomberg Intelligence. As Ireland is not heavily industrialised, effects here are less pronounced but discernible with restrictions ratcheted up in the past fortnight.