Renewable energy is the success story of the COVID-19 era, but the global economic recovery may see energy-related carbon dioxide emissions rise by nearly 5% this year, their second-largest annual increase ever, the International Energy Agency (IEA) warned in a report this week.

Global demand for renewable energy grew 3% last year, and it will increase again this year across all key sectors (power, heating, industry, transport). Demand for green power will expand 8%, the largest year-on-year growth on record in absolute terms, states the IEA’s Global Energy Review 2021. Renewables will provide half of the increase in global electricity this year, with solar photovoltaics and wind contributing two-thirds of the total growth in renewables.

But the IEA expects global greenhouse gas emissions to hit 33 gigatonnes (Gt, or billion tonnes) this year, nearly a 5% increase from 2020, and the largest annual increase in a decade, Reuters reports.

“This is shocking and very disturbing,” IEA Executive Director Fatih Birol told The Guardian. “On the one hand, governments today are saying climate change is their priority. But on the other hand, we are seeing the second-biggest emissions rise in history. It is really disappointing.”

Global GHG emissions fell 7% last year, “owing to the lockdowns that followed the COVID-19 outbreak. But by the end of the year, they were already rebounding, and on track to exceed 2019 levels in some areas,” The Guardian says. “The IEA’s projections for 2021 show emissions are likely to end this year still down slightly on 2019 levels, but on a rising path. Next year there could be even stronger rises as air travel returns, Birol added. Aviation would normally contribute more than 2% of global emissions, but has been almost absent this past year.”

Birol renewed his previous calls for a green recovery from the pandemic. “Last year, I expressed my hope that the economic recovery from COVID-19 should be green and sustainable,” he told The Guardian. “But these numbers indicate that this recovery is currently anything but sustainable for our climate.”

Like other recent analysis, the IEA release shows the decline in global demand for electricity in 2020 accompanied by record growth of renewables, led by wind at 12% and solar PV at 23%. Wind power will grow this year by 17% while solar PV will rise by 18%, it adds.

The share of green power will increase to 30% of world electricity this year, the highest since the start of the Industrial Revolution and up from its 27% share in 2019. Increases in output from wind and solar in China, the European Union, and the United States will, in aggregate, represent three-quarters of the global output from the two technologies.

Hydropower generation will increase in 2021, energy-from-waste power projects in Asia will drive growth of bioenergy, while the market for biofuels will recover and approach 2019 production levels, the report predicts.

Global energy demand has been dampened by the pandemic, but stimulus packages and vaccine rollouts “provide a beacon of hope” that economic output will rebound 6% this year, the IEA says. A 2% boost in global GDP over 2019 will result in significant growth in demand for all fossil fuels which, in turn, will result in a 5% rise in emissions that will reverse 80% of the 2020 decline, although the IEA predicts emissions will be 1.2% below 2019 levels.

Global CO2 emissions declined 5.8% in 2020, the largest decline ever and five times greater than the 2009 drop that followed the global financial crisis. Emissions fell farther than energy demand, as the pandemic hit the market for oil and coal harder than other energy sources.

Despite that drop, global energy-related CO2 emissions remained at 31.5 Gt, with CO2 reaching its highest-ever average annual concentration in the atmosphere of 412.5 parts per million in 2020, the IEA notes. This year, the Paris-based agency sees global energy-related CO2 emissions growing by 4.8% as demand for coal, oil, and gas rebounds with the economy, and the increase of 1,500 Mt.

Among fossil fuels this year, natural gas will mark the biggest increase relative to 2019 as demand grows 3.2%, putting global demand 1% above 2019 levels. Demand in the United States, the world’s largest natural gas market, will be squeezed by the continuing growth of renewables and rising natural gas prices, while globally, electricity generation from natural gas remains below 2019 levels.

“The pace of global vaccine rollouts, the possible emergence of new variants of the COVID-19 virus, and the size and effectiveness of economic stimulus measures all represent major uncertainties for the outlook,” cautions the IEA. “This analysis therefore not only charts a possible path for energy use and CO2 emissions in 2021 but also highlights the many factors that could lead to differing outcomes.”