What started the fire in Australia? Here's all you want to know

Australia is experiencing an unprecedented, drought-fuelled bushfire crisis that has burnt swathes of land across the vast continent. 

Here are some key facts that highlight the scale of the disaster:

 Size

More than six million hectares (60,000 square kilometres) -- about twice the size of Belgium -- have been burnt across the country.

In comparison, close to 2.5 million hectares of land was burnt in August in the Amazon, the world´s biggest rainforest. Almost 800,000 hectares were burnt in California in 2018 in one of the US state´s worst-ever wildfire seasons.

 Deaths 

Dozens of people have died as a result of the bushfires, 17 from the most populous state New South Wales.

The death toll for Australia´s wildlife is estimated to have hit 480 million in just New South Wales alone, according to a University of Sydney study. Experts fear the loss of animal life could be much higher than the estimates.

 Homes destroyed

More than 1,500 homes have been destroyed so far, but authorities have warned the number is expected to rise amid ongoing blazes. Entire towns in New South Wales and the neighbouring state of Victoria were destroyed New Year´s Eve.

Thousands of volunteer firefighters have been battling the fire season, which started in September. The government on Saturday also called up 3,000 military reservists -- the first in the nation´s history, according to the defence minister.

 Severe conditions 

Australia is known to be one of the most fire-prone continents and countries on Earth and bushfires are frequent summer occurrences, particularly in the southeast.

But the nation is in the midst a long-term drying and warming trend, with the continent having warmed by approximately 1.0 Celsius since 1910. January to November last year were the second-driest on record since 1902, and the hottest on record, according to the Bureau of Meteorology.

Large parts of Australia are also in a prolonged and severe drought amid a lack of rainfall. Meanwhile, strong winds during the bushfire season have helped fuelled and spread the blazes.

Scientists have warned that climate change is causing more hotter days and drier landscapes, leading to a longer fire season and more ferocious infernos.

 Previous disasters 

"Black Saturday" in Victoria state in 2009, when 173 people were killed, is Australia´s worst bushfire.

Other major fires including the "Ash Wednesday" fires of 1983 in Victoria and adjacent South Australia, where some 75 people lost their lives. Seventy-one people died in the "Black Friday" fires in Victoria.

Here is  actor and environmentalist Leonardo DiCaprio's take on the issue: