With fewer cars on the road, emissions are down. But will any of these gains last? (Craig Miller/KQED)
When shelter-in-place orders went into effect in California, human activity changed significantly.
That got listener Anne-Marie Roschè in Berkeley thinking: "What impact does this change in human behavior have on the rest of the ecosystem?"
It's early yet, but scientists are starting to see some effects.
Bay Curious caught up with Kevin Stark, from KQED’s science team, who has been following this story.
Emissions and Air Pollution
Car traffic is the Bay Area's main source of air pollution. One estimate found traffic over the Bay Area's bridges during rush hour is down by 70%. Local air regulators say that decrease in traffic would result in a potential 20% reduction in fine particulates and a 38% drop in nitrogen oxides. Carbon dioxide emissions, the leading driver of climate change, would be down 26%.
According to Meg Thurlow, vice president of sensing systems and applied science at Aclima, a San Francisco-based air quality mapping startup, Bay Area pollution levels have continuously declined since March 17, when many counties initiated stay-at-home orders.
Shipping accounts for air quality problems in some parts of the Bay Area — specifically in West Oakland, where diesel smoke from semi-trucks picking up goods settles into the neighborhood. But with shipping traffic down by 11%, the air quality in that neighborhood has improved. Aclima has found West Oakland's carbon dioxide levels have dipped under the Bay Area's regional average.
We’re seeing an impact on carbon emissions on a global level, too. By one estimate, the pandemic could result in a 5.5% drop in worldwide carbon emissions this year. And the U.S. Energy Information Administration projects the country's emissions from gas and energy could decrease by 7%.
But even with the pause in traffic and industry, scientists say it's not enough to prevent the worst impacts of climate change. The United Nations has said emissions must be reduced by about 7.6% each year to pause the effects of climate change.
Animals also seem to be reaping some rewards during this time, pushing into areas they typically avoid because of human activity or noise. There has been an uptick of coyote sightings in San Francisco on social media. Yosemite National Park rangers say bears are coming out more frequently. In Australia, kangaroos have been caught on camera hopping about on city streets.
While it's promising to read about these environmental benefits, it's important to recognize that these gains are likely temporary unless action is taken to either move toward cleaner energy or reduce our need for energy. Still, this period of time may provide insights that will help leaders at all levels map out a cleaner future.