The pandemic caused a record drop in carbon emissions. Then they bounced back.

Covid-19 caused the biggest recorded drop in carbon emissions over one year, new research from the International Energy Agency (IEA) confirms. Yet as we enter year two of the pandemic, these climate gains are fading quickly in the rearview mirror.

By December 2020, global energy-related carbon emissions were already higher than the same month in 2019. This chart from the IEA shows what’s driving that global rebound. After a rollercoaster drop in the spring, emissions in China, India, and Brazil returned to pre-pandemic emissions levels by the end of the year — and the US wasn’t far behind:

Why was the dip in emissions so fleeting? Well, let’s first look at why they fell in the first place.

We went to the gas station a whole lot less in 2020. The International Energy Agency attributes over 50 percent of the carbon emissions cuts to a decrease in oil consumption — primarily from a lack of driving, but also a decrease in flying. In 2020, emissions from international air travel fell dramatically — all the way down to levels not seen since 1999.

The decrease in international travel, as well as coal use in the electricity sector, led to an overall 7 percent decline in global emissions. The IEA researchers said the drop was equivalent to the whole European Union cutting off all its emissions for the year.

But as countries — particularly China — recovered, energy use quickly shot back up. IEA data shows that by the end of 2020, people in China reverted to flying nearly as much as they did pre-pandemic. Due to China’s swift recovery from the pandemic, it was the only major country where emissions actually increased in 2020, the researchers found.

In other emerging economies, including India and Brazil, people were also traveling more by the end of the year. By December, both had higher road traffic than the same month in 2019.

The 2020 emissions drop was largely a result of temporary behavior changes, not the long-term structural shifts in the economy and energy systems that are needed to get to net-zero emissions.

With vaccines rolling out, energy experts predict emissions will continue to rise rapidly this year — unless new policies are put in place.

Luckily, there’s some momentum from before the pandemic to continue to build off of.

A study published March 3 in Nature Climate Change shows that some 64 countries were seeing emissions drop from 2016 to 2019. These reductions were the result of climate policies and the falling cost of renewable energy. However, they were reducing emissions at one-tenth of the speed required to achieve net-zero emissions by 2050 — the target scientists have called for to mitigate the worst effects of climate change, the researchers found.

The pandemic can teach us about the scale of action needed. In 2020, the study finds, rich countries alone decreased their emissions by a whopping 1.2 gigatons — slightly more than the emissions all countries will need to be cut going forward (1 to 2 gigatons a year).

Pandemic lockdowns are clearly not a preferred route to a greener economy. But climate policy experts have proposed many ways the US can increase economic opportunity while slashing emissions, such as employing people to cap abandoned gas wells and investing in clean energy manufacturing.

So far, leading economies aren’t on track to cement their climate gains. Of the top emitters, only the EU is directing significant stimulus dollars toward green investments, according to new research from the Rhodium Group. To keep bending the emissions curve down after the pandemic, the US, as well as China, India, and other top economies, also need to redirect their spending from energy-intensive projects toward investing in a net-zero emissions future.