Almost 20 fires have ravaged California over the past two months. Some are still blazing. The region is experiencing earlier, longer and more ferocious wildfire seasons due to increasingly hot, dry temperatures.

In 2017, more than a dozen massive blazes swept through Northern California, killing 41 people, destroying 6,000 homes and devastating the area's celebrated wine country. Up until then, this had been the deadliest and most destructive series of fires in California's history.

This year, the Ferguson Fire has devastated Yosemite National Park in California, while the more northerly Carr Fire has burned more than 220,000 acres (81,000 hectares), 1,079 homes and 500 buildings.

The largest fire blanketing the region in smoke, however, is the Mendocino complex — a merger of two fires — which has burned more than 415,000 acres of northern California, 157 homes and 120 other buildings. This makes it the largest fire in the state’s history, surpassing the Thomas Fire of December 2017.

In the wake of the wildfires of 2017, this year's blazes might seem more normal — but that certainly doesn't make them any less terrifying. And as far as the future is concerned, there doesn't seem to be an end in sight to the fires sweeping the globe.

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Deadly consequences

Six firefighters have died battling Californian fires in 2018, according to state authorities. A national disaster was declared in Northern California on August 4.

Off the back of the record-breaking $2.7 billion (€2.2 billion) the state of California spent fighting fires in 2017, in 2018 the state managed to spend one-fourth of its emergency funding on firefighting by the end of July.

Across the Atlantic, an intense summer heat wave across Europe created fertile ground for fires.

More than 80 people died in Greece in July, as the country's worst wildfire in a decade razed the small resort of Mati, about 28 kilometers (17 miles) east of Athens. Thousands were evacuated and more than 1,500 homes were damaged, and many destroyed.

In Spain's Valencia region, some 2,500 people fled their homes to escape fires that swept across nearly 2,500 acres. In neighboring Portugal, a major fire broke out in Monchique, in Algarve, during early August as temperatures climbed to the mid-40s Celsius (100+ Fahrenheit).

Read more: Current heat waves are linked to climate change, scientists confirm

The Carr Fire in California has burned more than 200,000 acres

Even parts of the Arctic, where summer temperatures have been 10 degrees Celsius higher than average, have been on fire. Also typically temperate Scandivian and Baltic countries were set ablaze. Throughout July, Sweden experienced some of its worst fires in decades and the hottest July in 250 years, according to the Swedish Civil Contingencies Agency. Norway, Finland and Latvia have also been fighting flames.

Canada's province of British Columbia declared a state of emergency on August 15 as hundreds of wildfires burned across the region. Thousands have been evacuated and more than 600,000 acres have gone up in flames.

In 2017, Alberta and British Columbia endured the worse fire season since records began, with more than 3.11 million acres having burned by mid-October.

Sweden endured its hottest July in 250 years this summer

Future droughts 'locked in'

While forest fires are invariably sparked by lightning or people (either carelessly or deliberately), they are being driven by heat waves that climate scientists warn may soon be the norm, especially since climate researchers are forecasting more hot years to come.

"Wildfires are a natural feature of summers, but climate change is increasing the risk," Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment, told DW.

Read more: Great southern drought: Australian farmers crippled, climate action stalled

One major wildfire propellant is drought. The winter preceding the 2018 fire season in California in particular was "very dry," Ward said. "Droughts are a factor that mean you're more likely to generate dry wood, which is fuel for fires."

With regard to Greece, for example, "there's very clear evidence the northern Mediterranean countries are experiencing more frequent and intense droughts, and that's down to climate change."

According to Ward, we now have "no control" over the occurrence of droughts for "the next three or four decades because they are locked in by the concentration of greenhouse gases that have already built up."

So have the past two years been record wildfire years?

Land management also plays a role in the spread of fires

Tough competition

It's certainly been an intense couple of years for fires in Europe and North America. Even so, Martin Wooster, professor of earth observation science at King's College London, said other parts of the world have seen worse over the past decade.

In 2015, drought caused by the El Nino weather system created lethal conditions for Indonesian forests and peatlands already degraded by draining and logging.

The smoldering peat — ancient, decayed vegetable matter condensed into a carbon-heavy fuel — kept fires burning for months on end. "This led to huge fires, far bigger than any seen in Europe, and some of the worst air pollution ever experienced," Wooster said.

NASA satellite imagery for 2018 shows regions around the entire world on fire

Numerous factors

Despite this, there does appear to be a distinct trend, as fire seasons become longer and more intense. "In the western United States, the general perception is that there is no wildfire season any more, but that it's continuous all year round," Kevin Trenberth, a scientist at the Climate Analysis Section of the National Center for Atmospheric Research in the US, told DW.

In many parts of the world, wildfires are part of a natural cycle. Savannas, for example, are maintained by fire. Some trees not only survive fires but need them to release their seeds. Human intervention can disrupt these cycles, the scientific discipline of forest ecology has found.

Logging of old-growth forest is also a factor that has increased the risk of catastrophic wildfire. Since large, older trees are likely to have survived fires, they are more resistant than smaller, younger ones. When second-growth forests do burn, the smaller trees can carry flames to the upper canopy, making the older giants more susceptible.

A charred neighborhood destroyed by the Carr Fire

Putting out small fires can allow flammable debris to accumulate until a colossal fire starts that cannot be controlled. "One thing that can increase the risk of big fires, ironically, is the suppression of fires," Ward said.

Allowing small fires to burn, and to control them, is effective because you "get rid of the dry wood," he added. "If you don't, eventually you get a fire that is much bigger and more destructive."

Global warming is certainly resulting in hotter, drier conditions making such infernos more common, even with careful forest management. Different climatic conditions also mean forests can take far longer to recover.

Meanwhile, fire cycles are also beginning in areas like the tropics that have no natural fire ecology.

Human fingerprints

Climate change isn't the only human-induced element. Fires can also be started by careless people dropping cigarettes, letting campfires burn out of control, and are fueled by poor land management.

For this reason, Ward cautioned that in addition to reducing emissions to lessen drought, governments need to ensure the public is properly educated about wildfire risk. And people should not be building in fire-prone areas.

"Beyond that, we have the option — if we reduce our [greenhouse gas] emissions — of stopping that trend toward stronger and more frequent droughts. But that depends on us."