* European Parliament backs accord to fight climate change

* Ratification expected to be with U.N. by Friday

* Rare political “win” amid Brexit, migration discord

STRASBOURG, Oct 4 (Reuters) - The European Parliament backed the Paris accord to fight climate change on Tuesday, the EU executive said, tipping it over the threshold needed for the global deal to enter into force.

The Paris Agreement, backed by nearly 200 nations nearly one year ago, will help guide a radical shift of the world economy away from fossil fuels in an effort to limit heat waves, floods, droughts and rising sea levels.

European Climate Commissioner Miguel Arias Canteen said the milestone heralded a harder phase of turning promises into cuts in greenhouse gas emissions.

“Our collective task is to turn our commitments into action on the ground,” he said in a statement.

European Union approval, expected to be signed off on by the bloc’s 28 nations this week, pushes the deal over the required threshold of nations representing at least 55 percent of global emissions to enter into force.

Ratification by the EU, which accounts for about 12 percent of global emissions, is expected to be deposited with the United Nations by Friday.

China and the United States, the top emitters, ratified the pact this month.

It also marked a rare show of unity by a bloc divided over Britain’s vote to leave the EU, migration and the economy. EU leaders agreed a legislative shortcut to fast-track approval of the Paris accord to avoid lagging behind other nations in backing the global pact it championed.

European Commission President Jean-Claude Juncker said: “Today we continued to show leadership and prove that together the European Union can deliver.”

The accord aims to slash greenhouse gas emissions by shifting away from fossil fuels to limit global warming to “well below” two degrees Celsius (3.6 Fahrenheit) compared to pre-industrial times.

Once ratification is deposited with the United Nations, the accord enters into force 30 days later, early enough for it to be locked into place ahead of the next round of climate talks in November in Morocco.

Cementing the accord before the U.S. presidential election on Nov. 8 would make it harder to challenge if Republican Donald Trump, who has opposed it, beats Democrat Hillary Clinton, a strong supporter.

So far, 62 nations accounting for almost 52 percent of global emissions have ratified. Within the EU, Germany, Hungary, France, Austria, Slovakia and Malta - collectively representing 4.39 percent of global emissions - have ratified individually. (Additional reporting by Alissa de Carbonnel; Editing by Janet Lawrence)