The Ukraine crisis is a wake-up call for European countries to rethink their energy policies and make the switch from Russian gas to clean, renewable sources of energy, says Connie Hedegaard, the European Union’s climate chief.

Ms. Hedegaard also said it was also a “myth” that the increased use of renewable power, such as wind and solar, was to blame for soaring energy costs in Europe.

At a meeting in Brussels on Thursday, European Union leaders are to debate further sanctions against Moscow in response to the annexation of Crimea, at which Europe’s dependency on Russian natural gas is expected to be discussed.

During the summit, leaders will also give initial consideration to proposals to reduce carbon dioxide emissions by 40% by 2030, part of a climate-change package announced by the European Commission, the EU’s executive, in January.

“What’s happening with Russia and Ukraine [should], if anything, bring the message home that Europe really needs to do something serious about its energy situation,” Ms. Hedegaard said. Europe gets about 30% of its natural gas from Russia.