Japan hit by worst weather disaster in decades: Why did so many die?

Torrential rains unleashed floods and set off landslides in western Japan last week, killing at least 176 people, forcing millions to evacuate and leaving dozens missing in the country's worst weather disaster in 36 years.

Remnants of Typhoon Prapiroon fed into a seasonal rainy weather front fuelled by warm air from the Pacific Ocean - a pattern similar to one that caused flooding in southwestern Japan exactly a year ago that killed dozens on people.

The recent rainfall was unprecedented and disaster experts said torrential rains are becoming more frequent, possibly due to global warming.

"The government is just starting to realise that it needs to take steps to mitigate the impact of global warming," said Takashi Okuma, an emeritus professor at Niigata University who studies disasters.