Brussels, Belgium ? Europe embarked on a bold path to fight climate change Friday, agreeing that a fifth of the energy used by the 27-nation bloc by 2020 will come from renewable sources like the sun and the wind, and challenging the rest of the world to follow.

The plan goes beyond the 35-nation Kyoto Protocol in setting targets for cutting emissions of greenhouse gases, but it still faces problems over how to share the burden among its coal- and oil-dependent countries, and what to do about nuclear power.

“We assume leadership with this unilateral reduction,” said French President Jacques Chirac, at what was likely his last summit before leaving office. “This is part of the great moments of European history.”

The European Union leaders hope their commitment to tackling climate change will encourage other leading polluters, such as the United States, Russia, China and India, to agree on deep cuts in emissions of the gases that contribute to global warming.

German Chancellor Angela Merkel, who holds both the presidency of the EU and the Group of Eight industrialized nations, will present the plans to President Bush and other G-8 leaders at a summit in June.

Merkel challenged the rest of the world to follow the EU, saying there still was time to “avoid what could well be a human calamity” caused by an overheated planet.

The leaders agreed that the EU will produce 20 percent of its power through renewable energy, an increase from the current figure of about 6 percent.