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Pandemic positives: 7% less CO2 emissions in 2020

Cyril Crevoisier
Cyril Crevoisier
CNRS Research Director at the Dynamic Meteorology Laboratory (LMD*) at the École Polytechnique (IP Paris)

NB: Ini­tial­ly, the title of this col­umn stat­ed the fig­ure 8%. Since this arti­cle was writ­ten, the 8% glob­al CO2 emis­sions in 2020 has been re-eval­u­at­ed at 7%.

Before the pan­dem­ic we were on a worst-case sce­nario tra­jec­to­ry in terms of green­house gas emis­sions. Accord­ing to the Inter­gov­ern­men­tal Pan­el on Cli­mate Change (IPCC) 1, we need to pre­vent a glob­al tem­per­a­ture rise of 2°C if we are to avert irre­versible envi­ron­men­tal changes. We are cur­rent­ly set to face an increase of twice that: 4°C. The pan­dem­ic and lock­down restric­tions around the world rep­re­sent­ed a sig­nif­i­cant change in the inter­ac­tions between humans and the envi­ron­ment. My team stud­ies atmos­pher­ic com­po­si­tion and cli­mate using obser­va­tions from both ground sta­tions and satel­lites, which explains why we were rapid­ly called upon when pan­dem­ic became global.

Depend­ing on the type of gas or par­ti­cle we are refer­ring to, the observed effect of the pan­dem­ic is dif­fer­ent. Anthro­pogenic green­house gas­es like car­bon diox­ide (CO2) and methane (CH4) stay in the atmos­phere for around 100 and 10 years, respec­tive­ly. So it is dif­fi­cult to reli­ably mea­sure changes over a rel­a­tive­ly short time span. How­ev­er, high­ly reac­tive species and pol­lu­tant par­ti­cles found in the air have much short­er lifes­pans, and we did see big changes there. For exam­ple, we observed a 30% reduc­tion in ultra­fine par­ti­cles around Paris in com­par­i­son to the same peri­od over the last 10 years. More­over, obser­va­tions from the Euro­pean satel­lite, Sen­tinel-5P, revealed a decrease of over 50% NO2 – an indi­ca­tor of fos­sil fuel emis­sions – in Euro­pean megac­i­ties dur­ing Spring.

How­ev­er, to speak of a pos­i­tive impact of the lock­down on cli­mate is actu­al­ly more com­pli­cat­ed to answer than it would seem. If we look at the green­house gas­es present in the atmos­phere, we actu­al­ly don’t see much change. But this is not the best way to mea­sure effects of human activ­i­ty over short time­frames; atmos­pher­ic con­cen­tra­tions of CO2 can be masked by plant activ­i­ty across the world. Instead, we mea­sured emis­sions based on ener­gy demand and in doing so we saw a sig­nif­i­cant decrease in CO2 released into the atmos­phere. In April 2020, glob­al CO2 emis­sions were 17% low­er than last year – equiv­a­lent to 17 mega­tons of CO2 per day. And esti­ma­tions for 2020 over­all say that CO2 emis­sions were 8% less than in 2019. 

How­ev­er, when you look at the green­house gas­es in the atmos­phere, you don’t real­ly see a change.

This 8% reduc­tion in CO2 emis­sions dur­ing the pan­dem­ic is great news for the plan­et. But it is worth not­ing that this only real­ly takes us back to 2016 lev­els – car­bon emis­sions dras­ti­cal­ly increased between 2016–2019. To respect the 2015 Paris Agree­ment, we need to reduce green­house gas emis­sions by 8% per year 2. The effect of the glob­al pan­dem­ic and large-scale lock­down peri­ods is proof that the cli­mate goal is, in the­o­ry, achievable. 

Nev­er­the­less, the mea­sures have been dras­tic. The eco­nom­ic and social con­straints result­ing from the pan­dem­ic are unsus­tain­able over the long-term. ‚These results do, how­ev­er, pro­vide use with an indi­ca­tion of where we should focus our efforts. That is to say by point­ing out the glob­al sec­tors where the biggest changes can be made if we are to effec­tive­ly reduce green­house gas emis­sions. We saw, for exam­ple, a 75% reduc­tion in the avi­a­tion indus­try. But avi­a­tion is only respon­si­ble for 2–3% of glob­al green­house gas emis­sions so it is not nec­es­sar­i­ly the indus­try that is like­ly to have the biggest over­all impact. 

If we turn our atten­tion to the ener­gy sec­tor, we see that it is respon­si­ble for 44% of glob­al green­house gas emis­sions. And dur­ing the first lock­down in 2020 we saw a 6% reduc­tion in emis­sions due to low­er ener­gy demand. Anoth­er impor­tant sec­tor is ground trans­port. Almost 50% of the reduc­tion in emis­sions dur­ing the lock­down can be attrib­uted to reduced sur­face traf­fic. So, the ener­gy and road trans­port sec­tors are areas we should be pay­ing atten­tion to. 

Nev­er­the­less, there is a risk that polit­i­cal deci­sions involv­ing envi­ron­men­tal issues, or “green deals”, shift out of view whilst the world focus­es on restart­ing the econ­o­my. But the cli­mate cri­sis is not going away just because there is a health cri­sis. We should do every­thing to avoid turn­ing our back on cli­mate-relat­ed polit­i­cal decisions. 

If we look at the evo­lu­tion of CO2 emis­sions in rela­tion to pre­vi­ous eco­nom­ic crises such as the ‘Cred­it Crunch’ in 2008 the pat­tern is unset­tling. In every case we see that once the econ­o­my recov­ers, CO2 emis­sions return to their orig­i­nal tra­jec­to­ry – or more. This means that by 2021 or 2022, we are like­ly to have erased the envi­ron­men­tal ben­e­fit of the pan­dem­ic. We must stay vig­i­lant by focus­ing on new solu­tions glob­al­ly and there are many options. We should be focus­ing on spe­cif­ic sec­tors such as ener­gy and trans­port, but also invest in bio­mass ener­gy, and car­bon cap­ture and stor­age by plant­i­ng trees and devel­op­ing more advance tech­no­log­i­cal solu­tions. The next ten years real­ly count. 



Cyril Crevoisier

Cyril Crevoisier

CNRS Research Director at the Dynamic Meteorology Laboratory (LMD*) at the École Polytechnique (IP Paris)

Cyril Crevoisier and his team study atmospheric climate variables, and greenhouse gases in particular, using spatial and airborne observations. He is a Research director at the CNRS, and head of the "Atmosphere, biosphere and climate by remote sensing" team at the Dynamic Meteorology Laboratory (*LMD: a joint research unit of CNRS, École Polytechnique - Institut Polytechnique de Paris, ENS, Sorbonne University). He also chairs the Scientific Committee for Earth Sciences at the National Center for Space Studies (CNES).