Europe's power plants have slashed their use of coal by burning wood imports from the United States.

A European Union policy called the Renewable Energy Directive drove this transition by counting organic material like wood as renewable energy and subsidizing its use. A trans-Atlantic industry developed, logging American forests and processing them into pellets, which are then shipped to Europe. Critics argue that the subsidies have few climate benefits.

A committee of the European Parliament voted late Tuesday to make substantial changes to how the union subsidizes and counts emissions from burning it. It is part of a broad package of climate policies that would alter the way Europe produces electricity in the future and how the European Union meets its targets for reducing greenhouse-gas emissions.

Martin Pigeon is a forests and climate campaigner with Fern, a nonprofit group focused on European forests.

Wood is different from oil and coal because trees can be replanted to remove carbon dioxide from the air. It takes a century for the carbon dioxide emissions from burned wood to be absorbed in a growing forest, which contributes to global warming. Burning wood to generate electricity releases more carbon dioxide than burning fossil fuels. Emissions from wood were not counted toward the EU's pledges to reduce greenhouse gasses.

Direct subsidies and indirect measures like tax credits are proposed to be eliminated. The rules restrict access to certain kinds of financing and count emissions from biomass.

Bas Eickhout, a Dutch politician and member of the European Parliament who advocated for the revisions, said that they would take the important step of defining the term "primary" wood. The definition agreed to this week offers exceptions for wood from trees damaged by fires, pests, and disease.

A wood pellet plant in Garysburg, N.C.Credit...Erin Schaff/The New York Times

Some people are not happy with the proposed changes. A coalition of 10 European Union member states, led by Sweden, issued a statement this winter saying that the amendments risked Europe's ability to achieve its pledge to reduce greenhouse gas emissions by 55 percent by 2030.

The Swedish energy minister, who was one of the letter's authors, said that the changes of the legislative framework undermine the stability of the market and hamper the will to invest in renewable energy. Europe's energy transition would be more difficult, including to phase out fossil fuels from Russia, if the availability of wood is reduced.

The wood-pellet industry raised objections.

Over the past decade, the growth of bioenergy has been tremendous. Most of the European energy came from fossil fuels before the Renewable Energy Directive was passed. It has grown into a $10-billion-a-year industry and now produces around 60 percent of what the European Union considers renewable energy.

The wood-burning plants will no longer be eligible for subsidies under the revised policy. Last year was the first time in Europe that it was profitable without government support. Mary S. Booth is the director of the Partnership for Policy Integrity, a nonprofit group that promotes data-driven policy.

The effects of Tuesday's changes could stretch across the Atlantic to the southeastern United States, where much of Europe's harvest is done. More than one million acres of American forest have been cut for wood.

This week's vote is just the beginning of a long process. The proposed changes will need to be adopted by the European Parliament this summer, leaving time for further amendments. If the measure passes, national governments would have to make the changes into law.

Changes to food and feed-crop biofuel standards were also passed by the committee. Mr. Eickhout argued for changes to limit the use of biofuels in transportation because of the current food-price spikes. The committee called for a phase-out of palm and soy products by next year. These crops can lead to land use changes.