As COVID-19 restrictions end, carbon dioxide emissions spike back up after a brief drop

Weather Blog

(Climate Central) — The coronavirus pandemic created an initial drop in greenhouse gas emissions as millions of people worldwide stayed home to prevent the spread of the virus. Air quality improved, and wildlife flourished. But as soon as the lockdowns slowly ended, emissions quickly rose back to pre-pandemic lengths. That short period of time with lower emissions had minimal impacts on helping against climate change.

KEY CONCEPTS

  • Global carbon dioxide emissions dropped about 7% in 2020, according to the Global Carbon Project—the biggest annual decrease since the end of World War II. In the U.S., annual CO2 emissions dropped by nearly 13%.  
  • But as COVID-19 restrictions and lockdowns ended, emissions returned to their normal climb and the brief drop in CO2 emissions had a negligible impact on rising global temperatures. 
  • The results for other air pollutants—nitrogen dioxide (NO2) and particulate matter (PM2.5)—were mixed. When everyone’s mobility was severely restricted, NO2 concentrations dropped in cities around the world. But pandemic lockdowns did not lower PM2.5 levels beyond their normal range and 2020’s record-breaking wildfire season wiped out air quality gains made during that time.
Global CO2 Emissions

Global CO2 Emissions

Emissions Lifecycles

Emissions Lifecycles

Last year, when the COVID-19 pandemic put the brakes on global economic activity, greenhouse gas emissions and some air pollutants saw a sharp but temporary reduction. Global carbon dioxide emissions dropped by about 7% in 2020, according to the Global Carbon Project—the biggest annual decrease since the end of World War II. In the U.S., annual CO2 emissions dropped by nearly 13%.  But researchers found most of the decreases occurred early in the year, with the biggest drop in April. As restrictions and lockdowns ended, emissions returned to their normal climb. 

Even with the declines in emissions, humans still added a huge amount of new CO2 to the atmosphere, and concentrations of this heat-trapping gas continued to rise. (Emissions are the amount of pollutant matter released from a specific source and in a specific time interval; concentrations are the amount of pollutant matter in the atmosphere per volume unit.) Earlier this month, the Mauna Loa Observatory measured the concentration of atmospheric CO2 at more than 420 parts per million—setting a new record.

That brief drop in CO2 emissions had a negligible impact on rising global temperatures, as CO2 remains in the atmosphere long after it is emitted. To keep the planet from warming more than 1.5°C above pre-industrial levels, a goal of the Paris Agreement, CO2 emissions would need to decrease roughly the same amount every year (7.6%) for the next decade.

Results were mixed for decreases of the air pollutants nitrogen dioxide (NO2) and particulate matter (PM2.5).

  • NO2 is primarily emitted by vehicles and airplanes during fuel combustion and is one of the chemicals that contributes to the creation of unhealthy surface ozone. Unlike CO2, it has a relatively short lifetime in the atmosphere, lasting only a few hours before it disappears. When everyone’s mobility was severely restricted, NO2 concentrations dropped in cities around the world. This was partially due to shutdowns; weather and long-term improvements in air quality were also at play. 
  • PM2.5 comes from a number of sources, including transportation (especially diesel vehicles), industry, wood-burning stoves, and wildfires. In the U.S., research found mixed results for PM2.5 concentrations, but essentially the pandemic lockdowns did not lower PM2.5 levels beyond their normal range. Another report found that pollutants from 2020’s record-breaking wildfire season wiped out any air quality improvements made during the pandemic. 

So what did we learn from the Covid-19 experience that we can apply to solving climate change? 

We need to transform our energy systems.

  • When individuals cut back on flying and driving due to the pandemic, the impact was really small compared to the baseline carbon emissions required to power homes, run factories, and move goods across the planet. In order to get to net-zero emissions, we need to switch to renewable energy and electrify our transportation systems. The shift to renewables can be a huge economic driver, unlike COVID-19. A Princeton University study found taking actions to achieve net-zero emissions could create 500,000 to 1 million new energy jobs in the U.S. during this decade alone.

SOURCE: CLIMATE CENTRAL

Climate Central is an independent organization of leading scientists and journalists researching and reporting the facts about our changing climate and its impact on the public.

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