Global carbon dioxide emissionsdropped 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%.
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.
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 emissionsdropped 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 Covid.
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.
Covid and climate change affect populations disproportionately.
In the U.S., Covid infections and death rates are highest among Black, Latino and indigenous communities. These same populations are also bearing the brunt of climate impacts, after years of exposure to environmental stressors through the redlining of neighborhoods and systemic racism. Going forward, Covid recovery policies and climate mitigation and adaptation approaches should be designed to be inclusive, equitable and accessible.
The pandemic put scientists and health experts front and center. Broad investment in basic science led to the technology that produced novel vaccines and diagnostic tests. Similarly, investment in research decades ago helped to create improved batteries that power electric vehicles and to advance climate projections. Governments, scientists, and the business community worked together to fast track the development of vaccines and deliver them to the public safely. If any progress is going to be made on climate change, it must lean heavily on science and scientists in policy and decision making.
RESOURCES FOR LOCAL REPORTING
Looking to report on local carbon emissions and air quality?
Check your state’s Carbon Dioxide Emissions Data from the U.S. Energy Information Administration. You can find local air quality data at AirNow.gov and NASA’s Global Nitrogen Dioxide Monitoring Page. Currently, 24 states and the District of Columbia have established greenhouse gas emissions targets—tracked here by C2ES.
More resources on Covid-19 and emissions:
NASA’s COVID-19 Dashboard: Air Quality and COVID-19
NASA powerpoint -- “NASA Satellite Data Enable Research on the Impact of COVID-19 on World Air Quality”
NASA & ESA Earth Observing Dashboard: The Impact of COVID-19 Pandemic on Atmospheric Greenhouse Gases
Articles on Covid-19 and climate change
Lessons from COVID-19 for the climate crisis (American Psychological Association)
5 things COVID-19 can teach us about fighting climate change (World Economic Forum)
The SciLine service, 500 Women Scientists or the press offices of local universities may be able to connect you with local scientists who have expertise on climate change in your area. The American Association of State Climatologists is a professional scientific organization composed of all 50 state climatologists. Find and contact your state climatologist.