The threat of the Philippines' Taal volcano unleashing a potentially catastrophic eruption remains high, authorities warned Thursday, saying it was showing dangerous signs despite a "lull" in spewing ash.

Bushfire smoke disrupted the Australian Open build-up Wednesday for a second straight day to deepen concerns about the fate of the year's first tennis Grand Slam, but a cool change late in the day raised hopes of rain soaking the blazes.

The toxic haze that descended on Melbourne, where the Australian Open is due to begin next week, drifted down from out-of-control fires that have endured for months in eastern and southern Australia.

Exhausted firefighters said they had finally brought Australia's largest "megablaze" under control Monday, as wet weather promised to deliver much-needed respite for countryside ravaged by bushfires.

Philippine authorities suspended flights from Manila's main international airport "until further notice" on Sunday after a massive ash cloud spewed from a volcano south of the capital.

2020 is the most crucial year yet for humanity's plan to dodge the bullet of catastrophic global warming, experts said Saturday, warning that the narrow path to safety was riddled with pitfalls, from the US election to Brexit. 

When nations struck the 2015 Paris agreement, which aims to limit temperature rises under 2 degrees Celsius (3.6 Fahrenheit), they agreed on five-year periods in which climate action could be implemented, assessed and boosted. 

Bushfires flared in southern Australia on Thursday as a heatwave expected to bring renewed misery set in, and officials warned some areas are "just at the beginning" of the devastating crisis.

A magnitude 4.5 earthquake on Wednesday rattled an area less than 50 kilometres (30 miles) from Iran's Bushehr nuclear power plant near the country's Gulf coast, a US monitor said.

A strong earthquake struck off the south of Puerto Rico early Tuesday, the US Geological Survey said, the latest in a series of tremors that have shaken the island since December 28.

Firefighters raced to quell massive bushfires in southeastern Australia Tuesday, taking advantage of a brief drop in temperatures and some much-needed rainfall before another heatwave strikes later this week.

Reserve troops fanned out across fire-ravaged regions in three Australian states on Monday after a horror weekend, as the government pledged $1.4 billion over two years to help recover from the devastating months-long crisis.