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Reports from Italy detail the grim reality of a nation on lockdown. All businesses but pharmacies and food stores have shut their doors. Airlines are canceling flights, and roadblocks prevent people from leaving or entering some towns.

It presents a glimpse of how dramatically American life could change if COVID-19 spreads rapidly in the United States.

Many U.S. cities are already encouraging “social distancing” practices. Schools and universities are temporarily closing or switching to remote learning platforms. Conferences, music festivals and other public events are being canceled or going virtual.

These kinds of disruptions stand to get more severe in the coming weeks. They could also come with an unexpected side effect: an impact on carbon emissions.

The spreading virus has caused a dip in global greenhouse gas emissions. Reasons include a temporary blow to industrial activities in China, falling demand for oil and a decline in air travel.

In China, the world’s largest carbon emitter, experts estimate that emissions over the past month have been about 25% lower than normal.

These effects aren’t wholly unexpected. History suggests that global disasters, particularly those with major effects on the economy, tend to drive a temporary decline in carbon emissions. The 2008 recession, for instance, was accompanied by a temporary dip in global carbon emissions.

On a local scale, the climate impact of an epidemic is more complex—it’s likely to hinge on a wide variety of changes in the way people carry out their daily lives, from how often they leave their homes to how they travel around their cities to how they do their shopping.

Scientists are still working to understand how fast the new coronavirus will spread, how it might respond to the changing weather and why it affects some demographics more severely than others.

As it turns out, the virus may also teach scientists something about the complex relationships among everyday human behaviors, their response to large-scale disasters, and their carbon footprints.

“Pull one string here, and it affects everything else,” said Christopher Jones, a climate policy expert at the University of California, Berkeley, and lead developer at the CoolClimate Network, a research consortium focused on tools to reduce carbon emissions.

“With the economy and carbon footprints, they’re so interrelated that you really quickly start to have all these complex interactions.”

The stay-at-home effect

Transportation is already taking a hit in parts of the United States.

Schools and universities are closing campuses across the country, and many companies are encouraging their employees to work from home. In places like New York City, officials are warning residents to exercise caution on public transit, where it’s often impossible to avoid close contact with large crowds of people.

Some data indicates school closures and work-from-home mandates have already reduced traffic flow around Seattle. Reports from data analytics company Inrix point to significant increases in the speed of traffic in the Seattle area as highways empty out.

Similar statistics have suggested that rush-hour traffic is down in New York City, as well, according to Crain’s New York Business.

And reports from Bay Area Rapid Transit, which serves San Francisco, said ridership on public transit has fallen precipitously in recent weeks. BART ridership dropped by 8% between the end of February and the first week of March. And it was a whopping 25% lower in the second week of March than it was the last week of February.

Under some circumstances, a decline in ridership on public transit could suggest that people are driving more. But in this case, “I would say that if transit ridership is down, all vehicle travel is down, as well,” Jones said. “I think that it’s just an indicator that people are staying home more.”

The transportation sector is the biggest contributor to greenhouse gas emissions in the United States. As schools and businesses close their doors, reduced travel could temporarily drive down carbon emissions in communities where people are spending more time at home.

More complications

Less vehicle traffic, on its own, seems good for the climate. But there’s a potential catch.

“There’s been a lot of studies on the benefits of telecommuting, and the conclusion usually is ’it depends,’” Jones said.

If people are spending more time in their homes, they could be using more energy. It depends largely on weather conditions, geography and different family lifestyles.

“If you come home to a cold house and you have to heat it, that’s going to more than offset the savings from not driving your vehicle to work, on average,” Jones said. “If you come home to a beautiful day like we have in California, and there was somebody home anyway, really we’re not using much more energy than if I were at work.”

There’s also the possibility that people may spend more time watching television or using appliances if they’re cooped up in their houses, noted Jacqueline Klopp, co-director of the Center for Sustainable Urban Development at Columbia University.

“That could end up having a higher energy use,” she said.

Pandemics like COVID-19 could also spur less obvious behavior changes, which may nonetheless affect a household’s carbon footprint.

For instance, reports have suggested a recent spike in online shopping and home deliveries, especially for groceries. This is likely another byproduct of the virus as people increasingly avoid public spaces.

The carbon footprint of online shopping, compared with making purchases in a store, is often tricky to parse out. According to at least one recent study, it may largely depend on whether the deliveries come from a store in the community or are shipped in from somewhere else, and what means of transport the shopper would ordinarily use to pick up the goods in person.

That adds one more level of complexity to the impact of COVID-19 on household carbon footprints.

To top it off, there’s a great deal of uncertainty about how much worse the virus will become in the United States and how deeply it might affect the national economy.

In China, domestic carbon emissions plummeted as industrial activities faltered. In the United States, a major economic downturn would likely drive a further decrease in greenhouse gas emissions, as people simply consume less resources.

“The biggest potential impact of this virus is the effect on the economy,” Jones said. “So if it affects the entire economy, then that’s going to affect economic output, consumption and emissions.”

Lessons to be learned

There’s nothing to celebrate about the spread of the coronavirus, even if it does contribute to a temporary decline in greenhouse gas emissions. Global carbon emissions tend to bounce back fairly shortly after a global disturbance ends, history suggests—and meanwhile, COVID-19 has already killed thousands of people around the world, including several dozen in the United States.

But the pandemic may hold some insight into the ways that cascading changes in human behavior can affect carbon emissions.

Disturbances such as hurricanes and other natural disasters have provided these kinds of lessons, as well. But one key difference with the new coronavirus—at least for now—is that a lot of the behavioral changes it’s driving are voluntary.

“I think this is somewhat novel in the way that we’re trying to do social distancing and really slowing down our economies in really significant ways,” Klopp said. “And that does sort of happen with a natural disaster, but also you have a lot of your infrastructure disrupted. We have our infrastructure in place, but we’re just slowing down our economy.”

She pointed to recent data from the New York State Department of Transportation that indicates an increase in cyclists over New York City bridges this month. The increase would seem to suggest that people who have the ability to commute by bicycle versus other forms of transit are increasingly choosing to do so as the outbreak spreads.

It’s a lesson in human behavior and motivations. It’s also a warning about disaster preparedness at the city level—and the ways that resilience in both the public health sphere and the climate sphere can often overlap.

“For resiliency in crises, public health and greenhouse gas reductions, it is critical to build cities that cater for zero emissions, healthy modes of transport,” Klopp said in a follow-up email to E&E News. “They can do that by investing in safe, segregated bike lanes and excellent sidewalks, as well as amenities not too far away from where people live, so they have the option of using these modes.

“These are all key aspects of resilient, healthy cities that sadly, are often neglected,” she added. “COVID-19 is reminding us that we badly need this kind of shift in investment and visioning.”

Whether people may continue to apply the more carbon-friendly changes in their behavior after the pandemic is another question.

“Certainly in the short term you’ll see big changes in behavior, and that is going to have an impact on emissions—either positively or negatively,” Jones said. “I think the important question is: Are there going to be long-term changes? Will any of these behaviors stick? Will people learn to telecommute; will they learn that they like online shopping; will they learn to stay at home more, or be less willing to travel?”

The present situation could offer an unusual opportunity to broach the subject, Klopp said.

“I hope that these kinds of events—where people are actually pausing and they’re in their homes and they have a chance to think—we use those moments to communicate some of these bigger issues that are facing us,” Klopp said.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.

Read more about the coronavirus outbreak here.