It’s not often that climate data shows a significant fall in emissions, but the dramatic decline mapped by satellite images of Italy and China during their respective coronavirus lockdowns proves it is possible to change the upward trend, if only briefly.
Scientists and climate experts have said the drop alone is not enough to mitigate the effects of climate change, but the change in behavioural patterns as governments try to stall the spread of coronavirus shows what can be achieved.
Where people have been slow to swap convenience for climate conscientiousness, the coronavirus has caused a sudden shutdown in some of the world’s most polluting activities, closing factories and suspending air travel.
The impact is clearly visible in before-and-after satellite pictures of northern Italy released by the European Space Agency last week. In mid-January, prior to the coronavirus lockdown, a concentrated red splodge shows high levels of nitrogen dioxide emissions hovering over the country's industrial powerhouse.
Similar images taken when the lockdown was imposed at the beginning of March reveal a stark shift on the colour chart from dark red – indicating high levels of the pollutant – to yellow at the lower end of the scale.
"Compared to the normal situation the NO2 [nitrogen dioxide] values are about 30 per cent lower," Dr Claus Zehner, mission manager at the European Space Agency told The National.
The photos resemble similar sets shared by US space agency Nasa last month. Those pictures show emissions of the toxic gas plunging in China – the world's largest carbon emitter - from mid-February. The contrast is particularly noticeable over Wuhan, the Chinese city at the heart of the outbreak, where strict quarantine measures were imposed.
At least a quarter of China’s emissions were wiped out in just two weeks as activity from vehicles, power plants and factories died down. "This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event," Fei Liu, an air quality researcher at Nasa's Goddard Space Flight Centre, said in a statement.
NO2 is easier to capture with satellite imagery than other pollutant gases. "NO2 emissions, unlike many other types of emissions, including carbon dioxide, stand out clearly in satellite observations because NO2 is very short lived in the atmosphere. As a result, there is very little background concentration, making current emissions stand out clearly," the space agency told The National.
“It would take scientists many months of data analysis to attempt to tease out a clear CO2 signal over a specific region of the Earth.”
China appears to have passed the peak with new infections falling as numbers start to stabilise at around 80,800 while Italy, which has been the hardest hit country in Europe, faces a mounting number of infections, with numbers nearing 28,000 on Tuesday.
Elsewhere, governments are responding to rising caseloads by closing national borders and advising residents to stay at home to slow the pandemic, which has spread to more than 140 countries and killed almost 7,500 people worldwide.
At present the ESA has no plans to share similar data for other countries, but that could change, Dr Zehner said. “People are interested in this as air pollution has a known impact on health.
“If people are asking about [it] we could have a dedicated project on this,” he added.
The images are “a good lesson” on the impact of reduced road and air travel as well as the reduction in industrial activity. They “show the impact on air pollution if we behave in different way,” such as driving cars that don’t omit noxious NO2, Dr Zehner continued.
But a brief lull in the level of emissions being released into the atmosphere isn’t enough to change the trajectory of climate change.
"The Covid-19 crisis is likely to lead to a temporary decrease in global emissions, but this effect could be short in duration depending on how the economic stimulus to restart the economy is invested," Corinne Le Quere, professor of climate change Science at the University of East Anglia, told The National.
During the 2008-2009 global financial crisis, emissions decreased by 1.5 per cent in 2009 but were back up by five per cent the following year. “Experience shows that crisis only rarely leads to true structural changes in emissions. For that, the efforts need to be taken in the long term,” she said.
Where it could have a lasting impact is in setting a precedent for changing behavioural patterns on a larger scale and at a faster rate than awareness campaigns or climate action plans have typically persuaded populations to do.
“The coronavirus outbreak has seen widespread changes in human behaviour, encouraging companies to alter everyday operations by suggesting employees work from home, which is reducing congestion and enhancing air quality,” John Bryson, professor of enterprise and economic geography at the University of Birmingham wrote in a post about coronavirus and climate change on the university’s website.
The results are arguably “more important, immediate and effective” than other factors currently impacting climate change such as the “Thunberg effect”, he said, referring to the growth in carbon offsetting that has accompanied the work of climate activist Greta Thunberg.
Public holidays, such as the Chinese New Year and major events, including the 2008 Beijing Olympics, have also prompted reductions in NO2 emissions, but this is the first year that a drop of this magnitude has been seen in countries beyond China, according to Nasa.
After these events, routines – and emissions – return to normal as economic activity resumes. Now, health experts are warning that coronavirus could continue into the summer or beyond, and containment measures could last longer than anticipated.
Over time, companies may adapt to more staff working from home, reducing rush-hour traffic and easing off air travel as employees swap overseas business trips for conference calls and skip the daily commute. But as Bryson writes, “it remains to be seen whether these behaviours will trigger a longer term change”.