Wildfires: What causes them and why they're happening more frequently

Everything you need to know about the natural disaster taking lives in California

Firefighters battle the Woolsey Fire as it continues to burn in Malibu, California. Reuters

This week, wildfires in California have swept through communities and forests, killing at least 26.

High winds have accelerated the flames' progression - entire communities have been razed to the ground and up to 6,700 homes destroyed.

In July, 88 people were killed when a blaze tore through Greece, one of the most deadly in years.

Wildfires are becoming increasingly frequent and increasingly deadly. Here's everything you need to know about them.

What causes wildfires?

Fires start in a relatively simple manner - it only requires a spark, kindling and oxygen.

More often than not, the sparks are started by people - campfires, cigarettes and debris can all be responsible, while lightning strikes are also common.

Human-caused ignition for wildfires doesn't have to be caused by carelessness though - downed power lines and blown tyres can all start a potentially deadly blaze.

In 2016, police in Israel arrested 12 people on suspicion of arson after a massive wildfire tore through the country.

But the conditions have to be right - vegetation must be dry enough to burn in order to act as kindling.

Hot, dry climates are most at risk of wildfires, but they need to be moist enough to grow vegetation – deserts aren't flammable.

In areas where the majority of the rain, snow and fog happens during the winter and the summers are warm and dry, the climate is ripe for a wildfire.

This is most commonin climates like California and the Mediterranean, where they have wet winters and warm summers, but some areas of the Middle East are also at high risk.

How do you combat wildfires?

One of the key ways firefighters fight blazes is by establishing a control line.

This is a patch of land, natural or man-made, which cannot burn. Natural control lines could be a river or a ridge, while man-made control lines could be made from dug trenches or wet soil.

Fires can sometimes jump across the line, but when firefighters talk about fires as "percentage contained", this is what they mean.

These lines can also be burnt out, creating a line of forest with less kindling.

An aircraft drops flame retardant as firefighters battle the Woolsey Fire as it continues to burn in Malibu, California. Reuters

Using water, firefighters can start to flank out the fire - starting at the back they can try to trap the flames, making their way around the perimeter.

Wildfires are also attacked from the air air using helicopters and planes dropping water or some form of fire retardant.

This can act as an effective barrier and insulate bushes which have not yet been burnt.

US President Donald Trump has blamed the management of forest in California, saying the seriousness of the blaze is a product of poor planning.

Are wildfires happening more frequently?

Statistically, yes and they're worse than before.

In California, 10 of the largest fires since records began in 1932 have occurred since 2000.

With global warming raising temperatures by two to three degrees, the conditions for wildfires are likely to happen more often.

In Lebanon, fires are considered a greater risk due to climate change and a lack of forest management.

Oddly, human suppression of fires has made the phenomenon more commonplace.

Effective suppression of fires has meant plants in areas which would have otherwise been burnt have been allowed to grow.

This has meant when matters get out of control there is more fuel to fan the flames.

Some areas burn bush in controlled circumstances to mitigate the risk of wildfires.

What are the effects of wildfires?

Wildfires can be deadly, often taking dozens of lives within a few days. They can also destroy homes, leaving thousands of people homeless, losing their life savings if they don't have the correct insurance.

After the fire has been put out communities surrounding fires can suffer from worsening air quality, soil erosion and increased home insurance premiums.

But there are also positive effects. Wildfires are natural ways of soil replenishing its nutrients and soil can be more fertile after fires.