NEWS Faster traffic, more clicks. How COVID-​​19 affects emissionsMarch 12, 2020

For the orig­i­nal arti­cle, click here.

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.”

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,” said Jacque­line Klopp, co-​​director of the Cen­ter for Sus­tain­able Urban Devel­op­ment at Colum­bia Uni­ver­sity. “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.