The European Union is forging ahead with a sweeping plan to become “climate neutral” by midcentury.

If implemented, the European Green Deal could mark a major advance in the effort to combat climate change, since EU members make up the third largest block of greenhouse-gas emitters behind China and the US. But it will require massive investments and rapid transformations across nearly every economic sector.

The details: A released document doesn’t provide many specifics on how nations will achieve these ambitious targets, but it lays out timetables for developing strategies to reach specific goals.

At various points next year, for instance, the European Commission plans to propose a binding European climate law; develop a plan to cut emissions 50% by 2030; create strategies for transforming the agriculture and transportation industries; and devise various funding mechanisms.

European leaders stress that the deal will strive to be “just and socially fair,” by providing support for people, businesses, and regions harmed by the rapid transition.

What’s next? The European Commission unveiled the plan on Wednesday, sending it on to additional government bodies for endorsement. The process hit a snag at the European Council, where Poland declined to commit to the 2050 goal.

But European leaders said they’ll press ahead with the plan, and the council said it will revisit Poland’s reservations in June.

Challenges: Building the amount of solar farms, wind turbines, and other sustainable infrastructure required to cut emissions in half within a decade will be extremely expensive. Meanwhile, there aren’t readily available tools to eliminate emissions from steel, cement, aviation, and agriculture at this point.