LAGOS, Nigeria — Gas flaring worldwide decreased by 5% in the pandemic year, mostly because of lower demand for oil, according to a recent report from the World Bank.

While the overall drop was expected, the report offered a detailed picture of the flaring activities around the world, with steep declines in some areas, like the United States, and surprising increases in others, notably China.

Flaring occurs when the gas that emerges with crude oil is burned off rather than captured. That burning emits carbon dioxide, a gas that is the main contributor to climate change. According to World Bank officials, flaring adds roughly 400 million metric tons of CO2 equivalent emissions to the atmosphere every year.

According to the report, Russia was responsible for more flaring overall than any other country in 2020, contributing 15% of the global total. But within Russia, there were areas of progress. Burning continued to decrease in the Khanty-Mansi region of Siberia, where flaring volumes have dropped by nearly 80% over the previous 15 years.

The other top flaring countries, according to the report, were Iraq, Iran, the United States, Algeria, Venezuela and Nigeria.

China saw the biggest percentage change among the top 30 countries, with an increase of 35% despite the country’s oil production remaining flat. The report cited testing in new oil fields in the country’s remote northwest. The increase moved China up to ninth place overall in flaring volume, from 15th in 2019.

The U.S. recorded a 32% drop in 2020 from the year before, mainly because of new infrastructure to capture gas that otherwise would have been flared.

The report, published at the end of April, relied on data collected by two satellites operated by the National Oceanic and Atmospheric Administration and analyzed at the Payne Institute for Public Policy at the Colorado School of Mines.

In addition to contributing planet-warming carbon dioxide to the atmosphere, routine gas flaring can harm the health of people who live near gas sites. It also wastes a potentially useful energy source, a problem that is especially acute in poorer countries.

Analysts emphasize that there is no single solution to the global flaring problem. While the main obstacle in Russia is the remoteness of some sites, the United States faces a different challenge. For example, there are thousands of small-scale flaring sites that are difficult to connect to a single market.

Although the overall decline worldwide gave cause for optimism, Zubin Bamji, who leads the gas flaring program at the World Bank, predicted that rates could rise when the global economy fully reopens.

“In the U.S., we expect an increase in gas flaring in 2021 as operators start to increase oil production again in response to oil price increases,” Bamji said, although he also noted that improved gas infrastructure could mitigate the rebound.