封锁措施导致全球每日二氧化碳排放量下降17%
By Alfredo Carpineti
The Covid-19 pandemic has so far infected over 4.8 million people and killed over 319,000 globally. To reduce the spread of the disease, many countries placed lockdown and social distancing measures on their citizens, which has changed the habits of billions of people dramatically. Given the impact of the pandemic on the United States, Europe, China, and Russia, some of the highest emitters of the greenhouse gas carbon dioxide, the level of CO2 fell dramatically over the last few months.
In a study published in Nature Climate Change, an international team of researchers looked at how government policies during the Covid-19 pandemic have altered the use and demand of energy around the world, using the effect on economic sectors and a combination of energy, activity, and policy data available up to April to establish the change in emissions for the last four months.
"Emissions reached their peak decline on 7 April, with a 17 percent decline compared to the same time last year," CSIRO researcher and Global Carbon Project Director Dr Pep Canadell said in a statement. "To put that figure in context, daily emissions declined on average between January to April by 8.6 percent again compared to the same period last year."
Of the total emission change, the largest contribution came from a reduction in surface transport, at 43 percent. Countries have needed less power, so that sector makes up 19 percent of the global emissions change; industry covers one-quarter, and aviation (which has been significantly hit) makes up 10 percent of the emissions difference. Despite everybody being confined to their homes, the increase of energy use from households has been modest and easily off-set by the gains from the other sectors.
The data covered 69 countries, 50 US states, and 30 Chinese provinces, representing 85 percent of the global population and 97 percent of the world’s CO2 emissions. They found a global 17 percent decrease in emissions in April compared to last year, most likely due to the US, India, and China all being under lockdown at the same time. On average, daily emissions decreased by 26 percent per country.
The findings highlight tackling climate change cannot be achieved by personal responsibility alone, and that the focus needs to be on governments partaking in meaningful change to their very infostructures, as has been demonstrated, for the required changes to happen.
“The extent to which world leaders consider climate change when planning their economic responses post COVID-19 will influence the global CO2 emissions paths for decades to come,” lead author Prof Corinne Le Quéré of the University of East Anglia, said in a statement. “Opportunities exist to make real, durable, changes and be more resilient to future crises, by implementing economic stimulus packages that also help meet climate targets, especially for mobility, which accounts for half the decrease in emissions during confinement.”
Investment in greener transport methods and energy production is needed to make reductions to global emissions permanent. Even with the unforeseen crisis of this year, the researchers believe that it is unlikely we will meet the goals of the Paris Agreement to keep the global temperature increase below 1.5°C (2.7°F).
To match that, the UN says we need to decrease emissions by 7.6 percent annually over the next decade. The team estimated that if all lockdown restrictions are lifted by mid-June, the annual emissions decrease will probably be around 4 percent, but with some restrictions in place until the end of the year, we could be looking at 7 percent.