Written by Josh Jackman Updated on 1 March 2022 ✔ The UK’s CO2e emissions have plummeted by 111.85 million tonnes✔That’s more than Denmark, Chile, or Bahrain have emitted in two years✔ Air travel has dropped by 66%, saving 61.1 million tonnesCoronavirus has infected 389 million people and killed more than 5.7 million.Since the article we wrote in July 2020 explaining the effects of the first lockdown on the UK’s pollution levels, COVID-19 has claimed more than five million lives.The global pandemic has changed our world beyond recognition – but one effect is that pollution levels have dropped massively.In two years, the UK has saved 111.85 million tonnes of CO2e.*That’s more emissions than Denmark, Chile, or Bahrain released in that time.It’s the equivalent of you taking 120.9 million flights from London to New York City, or 30.2 million cars disappearing off the road for a year.Let’s explore how history’s most dramatic drop in greenhouse gas emissions happened. *carbon dioxide equivalent, calculated by comparing the effect of all other gases to CO2, to find one simple measure. What’s on this page? 01 Public transport 02 Road vehicles 03 Air travel 04 Energy usage 05 The effect on London 06 Summary Public transport4.55 million fewer tonnes During the past two years, trips on public transport declined by 58% from 2019’s level, producing an overall saving of 4.55 million tonnes of CO2e.This drop was nearly four times more dramatic than the fall in road journeys, as people understandably shied away from travelling with strangers.However, because public transport is so much better for the climate than cars, the 4.55 million tonnes of CO2e saved from fewer trips on buses and trains is just one-sixth of the amount we’ve cut by driving less (more on that below).4.55 million tonnes is still a massive saving. It’s equal to the annual emissions of 758,000 Brits.But this saving required a seismic shift in people’s behaviour. From March 2020 to March 2021, the number of bus journeys fell by 2.5 billion, according to government statistics – a 61% reduction.Over the whole pandemic so far, National Rail journeys have fallen by 62%, and London Underground trips have dropped by 64%.Behind the numbersIn 2019, buses and trains emitted five million tonnes of CO2e, according to government data.The trend since 2014 has been for buses and trains to reduce their carbon emissions by 0.2 million tonnes per year, so we assumed this would have happened in 2020 if not for the pandemic, leading to a hypothetical emissions total of 4.8 million tonnes.But instead of this 4% drop, bus and train journeys fell by 55% across the year – with a 67% decline after the pandemic hit these shores in March, according to Department for Transport data.The total public transport emissions for 2020 came to 2.25 million tonnes – a reduction of 2.55 million tonnes from our projected total.In 2021, the government imposed fewer restrictions on public life, leading to a significant increase in people returning to their normal activities – a common thread throughout our investigation.This naturally led to an increase in the number of bus and train journeys, as people came back to work at various times throughout the year – but the average was still just 52% of 2019 levels.We can assume that a non-COVID world would have seen another drop of 0.2 million tonnes in 2021, to a total of 4.6 million.Instead, 2.6 million tonnes were emitted – which means an extra two million tonnes of greenhouse gases didn’t enter the atmosphere. Road vehicles27.9 million fewer tonnes People have taken 15% fewer journeys by motor vehicle over the course of the pandemic compared to 2019 levels, leading to an enormous reduction of 27.9 million tonnes of greenhouse gas emissions.That’s the biggest drop in road vehicle emissions in recorded history.This astonishing reduction, which is equal to the annual emissions of 4.7 million Brits, was largely achieved during the March 2020 national lockdown and after the sudden imposition of Tier 4 restrictions for Christmas 2020.Due to the national lockdown that followed in January 2021, road traffic didn’t go back to normal until April 2021.We returned to pre-pandemic levels from then on, until the Omicron variant scared people into staying off the roads – but within four weeks, traffic was at 2019 levels once more.Behind the numbersRoad vehicle emissions were relatively stable for the three years before COVID-19, with levels barely dropping from 112.9 million tonnes of CO2e in 2018 to 110.7 million tonnes in 2019.In 2020, this figure dropped to 89.6 million tonnes – a fall of 19.1%.This was enormous. After all, in 2018, road emissions fell by just 1.3%, and in 2019, they fell by 1.9%.This means a 1.6% drop was the average, so 2020 should have seen a reduction of about 1.8 million tonnes of CO2e.Instead, road emissions fell by a stunning 21.1 million tonnes, according to government data.In a world without COVID, 2021 would have seen a further drop of 1.6%. This would have resulted in a saving of 1.7 million tonnes, for a total of 107.2 million tonnes.In the real world, road traffic emissions fell by 11%, according to Department for Transport data, leading to an emissions total of 98.6 million tonnes – a saving of 8.6 million. Air travel61.1 million fewer tonnes For a myriad of reasons – including health fears, restrictions, and national lockdowns – air travel has been much less popular than driving or taking public transport during the pandemic.In total, there have been 2.6 million fewer flights than we’d expect in this time frame, according to UK Civil Aviation Authority data – a plunge of 67% from 2019 levels.We worked out in our first article on the effects of COVID on UK pollution that each flight emits 23.46 tonnes of CO2e, on average.That means the UK has saved 61,063,776 tonnes of greenhouse gases by flying less over the course of the pandemic – though it could have saved more without ghost flights.That’s 15% of the UK’s total annual greenhouse gas emissions. Before the pandemic, it took the country more than four years to reduce its total emissions by that much.Behind the numbersThere were 62% fewer flights in 2020 than in 2019, according to UK Civil Aviation Authority data.A little under 852,000 planes took to the skies – down from more than 2.25 million the year before. That’s more than 1.4 million flights that simply didn’t happen.In the first three quarters of 2021, the decline in flying was even more dramatic.In a normal year, we’d expect 1.7 million planes to take flight from January to September. But only 491,000 actually did, as passengers became accustomed to COVID and the idea of leaving foreign trips for another year.That’s a 71% drop in the number of flights in 2021, compared to the same period in 2019.Before 2020, UK flight numbers had been stable for a few years, with 2017, 2018, and 2019 seeing more than 2.2 million flights each.The gap between the most successful year (2018) and the least (2019) was less than 15,000 flights – a relative drop in the ocean, or breath in the atmosphere.We therefore wouldn’t have predicted any dramatic shifts in air traffic numbers without the pandemic, which is why we used 2019’s numbers as our base – and why the figures from 2020 and 2021 are so astounding. Energy usage18.3 million fewer tonnes As a country, we’ve used less energy during the pandemic, to the extent that we’ve reduced our emissions by 18.3 million tonnes.This makes sense – if people are barely travelling to public spaces, whether for work or leisure, buildings like offices, museums and cinemas need less energy.As a result of this decreased demand, energy production was considerably lower than normal, saving 19.8 million tonnes of emissions.With entire companies abandoning their offices for months at a time, business emissions fell by 4.9 million tonnes.The only increase in emissions was due to people staying at home to avoid contracting and spreading the virus.This necessity led to a 6.4 million tonne increase in residential energy usage during the pandemic, though this is relatively little compared to the reductions in other areas.And of course, the extent to which people stayed home has saved countless thousands of lives, which is all-important.Behind the numbersFor this section, we analysed government data from 2020 and 2021 to find the emissions released by businesses, residential properties, and the actual production of the UK’s energy supply.With gas price spikes, an energy crisis, and the unseasonably cold spring of 2021, it didn’t make sense for us to predict what 2020 and 2021’s energy usage would’ve been without COVID.There were just too many variables, so we used 2019’s figures as our baseline. The effect on London15.3 million fewer tonnes In the three months after the UK locked down in March 2020, London cut its greenhouse gas emissions by an astonishing 58%.For the capital, which releases 31.02 million tonnes of CO2 per year according to Greater London Authority government data, this meant a saving of 4.5 million tonnes of CO2e.Like the rest of the country, the first lockdown was London’s peak when it came to cutting emissions.Still, this gigantic city managed to reduce its emissions by 28% for the rest of 2020, saving another 4.3 million tonnes.And in 2021, emissions stayed around 21% below their pre-pandemic level, sparing Londoners from another 6.5 million tonnes of pollution.Overall, that’s an enormous saving of 15.3 million tonnes.Other London pollution sources fell tooMany other types of pollutants also declined during this period. These emissions don’t contribute to climate change in any meaningful way, but they are harmful pollutants nonetheless.One of these, nitrogen dioxide (NO2), causes reduced lung function – a consequence that’s even more important to avoid these days.NO2 was 38% less prevalent in London from March to June 2020, 30% less prevalent for the next three months, and 20% less prevalent for the year’s last quarter, according to research by Frontier Economics.Assuming this 20% drop continued throughout 2021, the capital’s residents were exposed to 18,020 fewer tonnes of NO2.The amount of particulate matter with a diameter under 2.5 micrometres (PM2.5) in the air also fell during the pandemic, which is a positive step considering that it can severely affect both the lungs and heart.PM2.5 levels dropped by 27% from 2019 to 2020, and around 20% from 2019 levels in 2021. SummaryThese emissions savings came at a price too terrible for many to bear.2020 was a disaster, a never-ending tragedy, a catastrophe that showed how shamefully unprepared the UK government was to confront a deadly pandemic.In the 10 months after COVID-19 hit the UK at the beginning of March, 76,586 people died after contracting the disease, according to government data.The pandemic caused 20% fewer deaths per day in 2021, but 73,316 of our number still passed away after testing positive.And the sad truth is that emissions have now rebounded to pre-pandemic levels, more or less.It shouldn’t take a deadly pandemic for us to fight climate change effectively.We must act now. Our national – and global – carbon footprint has to fall quickly. If it doesn’t, countless people will die, and our Earth will become uninhabitable for billions. Written by: Josh Jackman Lead Writer Josh has written about eco-friendly home improvements and climate change for the past four years. His work has been displayed on the front page of the Financial Times, he's been interviewed by BBC One's Rip-Off Britain, and he regularly features in The Telegraph and on BBC Radio.