Carbon dioxide emissions from the global electric power sector rebounded in the first half of 2021 to above pre-pandemic levels, according to an analysis, signaling that the world has failed to engineer a “green recovery” and shift decisively away from fossil fuels.

As electricity demand jumped from last year’s lows, the London-based think tank Ember found, it outpaced the growth of renewable energy. That pushed global electricity-related emissions 5 percent above where they stood before the coronavirus outbreak.

The new findings have major implications for the upcoming U.N. climate talks in Glasgow, Scotland, where negotiators hope to forge a pact to cut greenhouse gas emissions and keep the planet from warming more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) compared with preindustrial levels. They also suggest that a surge in electric vehicles, which President Biden and many other world leaders support, will tax the electricity grid as developers work to add wind and solar.

The report showed that places such as the United States and Europe cut emissions slightly this year. But even there, the pace of lowering greenhouse gas emissions was far too slow to keep the world on a path limiting warming to 1.5 degrees C. And rising energy use increased planet-warming pollution for the power sector in China, Bangladesh, India, Kazakhstan, Mongolia, Pakistan and Vietnam, Ember lead analyst Dave Jones said.

“Catapulting emissions in 2021 should send alarm bells across the world. We are not building back better, we are building back badly,” Jones said.

Jones said that the United States experienced a 16 percent drop in carbon emissions from electricity in the first half of 2020 compared with the first half of 2019. But the U.S. electricity sector’s emissions during the first half of 2021 were only 4 percent below those of 2019. The wind and solar sectors increased sharply, but natural gas was flat and coal use amounted to 7 percent less than 2019 levels.

Pandemic-related shutdowns curtailed transportation and energy demand more broadly in countries across the globe, helping spur a drop in greenhouse gas emissions. The Global Carbon Project estimated that daily global carbon emissions dropped by 17 percent in April 2020 compared with the average rate the year before.

But even those changes did nothing to prevent atmospheric levels of carbon dioxide from reaching a record high this May, according to the Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration, at nearly 419 parts per million.

Several energy experts said the new statistics underscored that the temporary economic downturn did not represent a fundamental change in the way in which businesses produce power across the globe.

“The only thing surprising about a rebound in emissions as economies recover from pandemic lockdowns is that anyone is surprised by it,” said Jason Bordoff, a dean of Columbia University’s climate school and founding director of its global energy center. “Emissions are the result of a complex, massive and capital-intensive energy system, and the underlying infrastructure for how we make electricity, steel and much more did not change in the last 12 months. So it is not surprising that emissions rebounded as economies opened back up and that energy infrastructure ramped back up.”

The figures were part of a midyear update to Ember’s Global Electricity Review of 63 countries, which represent 87 percent of electricity demand.

There were some bright spots. For the first time, wind and solar generated more than a tenth of global electricity and overtook nuclear generation. In addition, wind and solar power met more than half the additional electricity demand worldwide. But coal accounted for another 43 percent, while natural gas consumption remained almost unchanged.

“The goal of a ‘green recovery’ was never realistically to transform the world’s energy infrastructure overnight, but to make large government investments in economic recovery that will begin to transform the world’s energy system,” Bordoff said.

Other agencies and think tanks have been taking the temperature of the U.S. and global economies.

The Energy Information Administration, part of the Energy Department, forecast that the U.S. economic recovery and a changing fuel mix would lead to a “significant increase in energy-related carbon dioxide emissions this year.” The EIA in its August short-term energy outlook said that after tumbling 11 percent in 2020, the U.S. power sector’s carbon dioxide emissions would increase by 7 percent this year and an additional 1 percent in 2022.

EIA acting administrator Steve Nalley said then that “despite significant growth in energy-related CO2 emissions as the U.S. economy opens up, we don’t see these emissions returning to pre-pandemic levels, at least in the short term.”

China’s economy is the only major economy to experience an increase in greenhouse gas emissions last year, according to a separate report in March from the New York-based Rhodium Group. Based on preliminary data, the group estimated that China’s greenhouse gas emissions increased by 1.7 percent in 2020.

“While this is well below the 3.3 percent emissions growth that China averaged over the past decade, it is a worrying sign that the world’s largest [greenhouse gas] emitter’s focus on a fossil-fueled industrial recovery is at odds with its long-term goal of reaching net-zero emissions by 2060,” the Rhodium report said.

In China, state-owned media said the country’s power use hit a “historic high” in the summer of 2021, partly due to summer heat waves. Electricity use and coal consumption for heating in the first half of the year increased 15.6 percent and 10.6 percent respectively from the same period last year, according to the National Energy Administration.

“China is still in the stage of deepening industrialization and urbanization,” National Development and Reform Commission Vice Director Tang Dengjie wrote in a People’s Daily article published Wednesday. “With an increase in rigid demand for energy and resources, the time to achieve peak carbon emissions and carbon neutrality is tight and the workload of that is heavy.”

Alicia Chen in Taipei contributed to this report.

An earlier version of this story incorrectly attributed information about last year’s level of China’s greenhouse gas emissions to Ember instead of the New York-based Rhodium Group.