Residents of the Florida Keys ravaged by Hurricane Irma, which has left at least 12 dead statewide, discovered scenes of desolation as they returned home Tuesday amid a massive operation to restore electricity to millions of people still without power in three southern U.S. states.

As emergency workers picked through the rubble, Irma's death toll in Florida rose from an earlier figure of two. The storm has now killed at least 50 people across the Caribbean and the United States.

China said Wednesday it would extend the use of ethanol fuel nationwide as it seeks to intensify anti-pollution efforts while finding a use for its huge corn surplus.

At least eight people died in flooding after violent rains lashed the Tuscan city of Livorno over the weekend, Italian rescue services said Tuesday.

Hurricane Irma was supposed to be a monster storm, immense and record-breaking in size as it charged toward Florida packing a punch that could lay waste to a state that is home to some 20 million people.

But as the sun rose Monday, floodwaters in Florida quickly receded, and torn off roofs, tree-damaged homes and toppled boats were limited to isolated pockets of the state.

Many climate scientists are convinced that mega-storms Harvey and Irma -- which left scores dead and caused massive economic losses -- were boosted by global warming, but hesitate to say so in as many words.

Call it the hurricane paradox.

At least three people died and six were missing after a major storm caused widespread flooding in and around the Philippine capital on Tuesday, forcing schools, government offices and businesses to shut down.

Emergency crews on Tuesday scrambled to contain an oil spill near Athens after a tanker sank close to Salamis island over the weekend, the coastguard said.

Hurricane Irma weakened to a Category 1 storm early Monday as it marched up the .US. state of Florida's northwestern coast, with its eye located about 25 miles (40 kilometers) northeast of the vulnerable Tampa area.

The combined economic cost of Hurricanes Harvey and Irma could reach $290 billion, equivalent to 1.5 percent of the U.S. gross domestic product, U.S. forecaster AccuWeather said in a report Sunday.

"We believe the damage estimate from Irma to be about $100 billion, among the costliest hurricanes of all time," said the firm's CEO and founder Joel Myers. 

U.S. President Donald Trump approved Florida's request for emergency federal aid on Sunday to help with the recovery from destructive Hurricane Irma.

The federal funding includes "grants for temporary housing and home repairs, low-cost loans to cover uninsured property losses and other programs to help individuals and business owners recover from the effects of the disaster," the White House said.