GLASGOW, Scotland — The European Union brags that its climate ambitions are more aggressive than anywhere else in the world. There’s just one problem: If the world behaved like Europe, it would be burning an awful lot of wood.

Europe gets 60 percent of its renewable energy from biomass fuels, a process that uses wood scraps, organic waste and other crops to generate heat and electricity in specially designed power plants. U.N. rules allow the European Union to write off the emissions as carbon-neutral, so long as sustainable guidelines are met, even though burning the fuel can release more warming gases into the atmosphere than coal.

The European Union’s reliance on wood-burning energy to meet its climate goals — which include cutting greenhouse gas emissions 55 percent by 2030 — is a measure of the difficulty of making the transition to clean energy even on a continent where politicians have shown political will and enjoy significant public support for their green agenda. For now, much of Europe’s emissions reductions are being achieved by burning biomass instead of coal — and then not counting the resulting greenhouse gases, which critics say they should.

That contributes to the gap detailed in a Washington Post investigation published Sunday that found that many countries are significantly underreporting their emissions to the United Nations, leading to a massive undercount of what is actually released into the atmosphere.

At the U.N. climate conference underway in Glasgow, the bloc’s top climate official, Frans Timmermans, a devoted environmentalist, doubled down on biomass this week, saying Europe needed it as a substitute for worse alternatives.

“To be perfectly blunt with you, biomass will have to be part of our energy mix if we want to remove our dependency on fossil fuels,” Timmermans told reporters. “I do admit that it’s quite complicated to get this right.”

Europe is not alone in relying on biofuels. They are also part of Biden’s climate agenda, including the Build Back Better plan being discussed in Congress.

Biofuel is also hardly the only element of Europe’s climate strategy. It has covered its landscape with solar panels and windmills. It plans to phase out new gasoline and diesel cars by 2035. It has a carbon trading market — essentially a tax on carbon emissions — that is rapidly driving coal-fired energy out of existence. Its new plan to sharply cut emissions by 2030 is a feat it says will put it on track to be carbon-neutral by 2050.

And it has pledged $25 billion a year toward helping poorer countries reduce their emissions, far more than the United States, which has offered only $11 billion — most of it still dependent on congressional approval.

“We are now entering the core of the discussion, the concrete legislation that needs to be changed,” said Pascal Canfin, chairman of the environment committee in the European Parliament and an ally of French President Emmanuel Macron. “I don’t see anywhere else in the world where you have this scope of laws being changed.”

But Europe’s dependence on biomass adds an asterisk to its green credentials, critics say. Under U.N. rules that tally emissions, when industry cuts down trees, that is counted as emissions from land use, which doesn’t factor in what actually happens to the wood in the end. It’s not counted as emissions when it’s burned — even though biomass fuel can emit a plume of greenhouse gases just as potent as coal’s.

That’s to avoid double-counting the emissions. Critics call it a loophole. The biomass industry says the current rules make sense.

“This accounting framework is based on long standing peer reviewed science,” said Taylor Fitts, a spokesman for the U.S. Industrial Pellet Association, in an email. “Counting at the smokestack would also result in an array of incentives for unsustainable harvesting and deforestation.”

Fitts said the industry followed strict rules to ensure that it was replanting trees and following established guidelines to make its products sustainable.

“Sustainability is crucial for our industry to deliver actual climate benefits, so it is rightly the most highly regulated among the entire forest products sector,” he said.

Timmermans said Europe would “try to use the biomass that is not at odds with our environmental and climate objectives.”

Excluding emissions from biomass can make a big difference. According to their official numbers, the European Union and Britain together reduced energy-related emissions by 26 percent between 1990 and 2019. Adding emissions from biomass makes the reduction 15 percent over the same period, according to an analysis last month from Chatham House, a British policy think tank. Britain — which left the European Union in 2020 — is a major consumer of biomass pellets, so the post-Brexit E.U. figures for biomass are likely to be somewhat smaller.

The dendrological sleight of hand was the subject of extensive discussion over the summer as Europeans considered a proposal to eliminate forest wood as an acceptable source of sustainable biomass. After pressure from countries that rely heavily on biomass for their energy, including Sweden and Finland, the sustainability rules were left largely unchanged.

Advocates of biomass say that the greenhouse gas accounting is sound because forests can be replanted, ultimately recapturing the carbon that is released into the atmosphere when wood and other organic materials are burned. And they say low-quality or dead wood in forests can be culled in a sustainable manner to make the fuel.

Byproducts of other industrial processes, such as sawdust, can be turned into energy without further touching forests. An E.U. study released this year found that about half of the wood-based biomass used for energy came from industry byproducts and recycled wood: About 37 percent came from treetops, branches and other tree parts, and only 14 percent probably came from whole trees.

“Biomass is an important solution in our long-term strategy,” said Slovenian Environment Minister Andrej Vizjak, who in Glasgow is charged with coordinating a common position among the 27 E.U. countries but whose own country is heavily dependent on biomass energy. “Some countries count on biomass a lot,” including Slovenia.

There was little European biomass industry before 2009, when new E.U. subsidies started to encourage the use of the fuel. Coal power plants can be converted to burn biomass pellets relatively easily, making the switch attractive.

Timmermans said he wanted to tighten the rule book to make sure the climate accounting is sound. Right now, Europe generally depends on the assurances of biomass suppliers — many of whom are in the southeastern United States — to manufacture the pellets sustainably, including by replanting trees.

“Even a little bit of mistake on the energy side has this gigantic effect on the world’s forests,” said Tim Searchinger, a senior research scholar at Princeton University’s Center for Policy Research on Energy and the Environment. He was among more than 500 scholars to sign a letter earlier this year calling for an end to biomass subsidies and a change to how the emissions are tallied.

For now, biomass appears to be firmly entrenched in Europe’s sustainable system. Climate analysts say the bottom line isn’t good for emissions.

“We need to cut emissions pretty radically now, and burning biofuels is still putting carbon into the atmosphere,” said Pieter de Pous, a senior policy adviser at E3G, a European think tank that focuses on climate policy.