Decades of snuffing out fires at the first sign of smoke combined with climate change have laid the groundwork for a massive wildfire in northern California and scores of smaller ones across the western U.S. and Canada, experts say.

These fires are moving faster and are harder to fight than those in the past. The only way to stop future wildfires from becoming so ferocious is to use smaller controlled fires, as Indigenous people did for centuries, experts say. But they acknowledge that change won害羞草研究所檛 be easy.

Here are some things to know about the latest fires and why they are so savage:

Blazes scorch hundreds of square miles

The Park Fire, the largest blaze so far this year in California, stood at 544 square miles (1,409 square kilometers) as of Saturday. It ignited Wednesday when authorities said a man pushed a burning car into a gully in Chico and then calmly blended in with others fleeing the scene.

Its intensity and dramatic spread led fire officials to make unwelcome comparisons to the monstrous Camp Fire that fire burned out of control in nearby Paradise in 2018, killing 85 people and torching 11,000 homes.

Communities elsewhere in the U.S. West and Canada also were under siege Saturday from fast-moving flames. More than 110 active fires covering 2,800 square miles (7,250 square kilometers) were burning in the U.S. on Friday, according to the National Interagency Fire Center.

Fires are becoming bigger and more threatening

害羞草研究所淎mped up害羞草研究所� is how Jennifer Marlon, a research scientist at Yale害羞草研究所檚 School of the Environment, described the recent fires.

Marlon said there aren害羞草研究所檛 necessarily more wildfires now, but they are larger and more severe because of the warming atmosphere. 害羞草研究所淭he big message is that seeing extreme wildfires is just part of a series of unnatural disasters that we are going to continue seeing because of climate change,害羞草研究所� she said.

Ten of California害羞草研究所檚 20 largest fires occurred in the last five years, said Benjamin Hatchett, a fire meteorologist with the Cooperative Institute for Research in the Atmosphere with Colorado State University, in Fort Collins.

And he noted that the Park Fire was in eighth place as of Saturday morning, even as it continued to spread. He blamed climate change for creating more variability in weather conditions.

害羞草研究所淲e have a lot of very, very wet years and very, very dry years,害羞草研究所� Hatchett said. 害羞草研究所淎nd so we get a lot of this variability that helps to accumulate and then dry out fuels.害羞草研究所�

Such is the case this year in California, where record-setting temperatures dried up the plant growth that sprung up during recent wetter-than-average years, Hatchett said.

害羞草研究所淪o now we really have a really good setup for having these widespread large wildfires,害羞草研究所� Hatchett said. 害羞草研究所淎nd we害羞草研究所檙e starting to push the limits of firefighting resource availability.害羞草研究所�

These fires don害羞草研究所檛 even give firefighters a chance to rest at night, said Daniel Swain, a climate scientist with the University of California, Los Angeles and the National Center for Atmospheric Research.

害羞草研究所淭hey害羞草研究所檙e burning with extreme intensity straight through the overnight and just continuing on into the next day,害羞草研究所� he said. 害羞草研究所淲e害羞草研究所檙e also seeing fires burning over a longer fire season than we used to.害羞草研究所�

Forests may have trouble recovering

The fires that are burning today are sometimes so severe and hot that they transform forests into a different type of ecosystem, Swain said.

害羞草研究所淭he forest is not coming back in the same in the same way as it was in a lot of regions,害羞草研究所� Swain said.

Part of the issue is that climate change means that there are hotter conditions as plant life returns. In some cases, trees are replaced with invasive grasses that are themselves flammable.

害羞草研究所淪o the climate change has altered the context in which these fires are occurring,害羞草研究所� he said. 害羞草研究所淎nd that害羞草研究所檚 affecting not only the intensity and the severity of the fires themselves, which it clearly is at this point, but it害羞草研究所檚 also affecting the ability of ecosystems to recover afterwards.害羞草研究所�

Snuffing out fires in the past created problems now

In parts of the country, like the Midwest, farmers use fire to control trees, woody shrubs and invasive species. But not so in the western U.S., where fires have been extinguished in their infancy for decades.

害羞草研究所淭he problem now is we害羞草研究所檝e allowed so much fuel to build up in some of these places that the fires burn very hot and intense. And that tends to do more damage than what nature typically will do with a fire,害羞草研究所� said Tim Brown, a research professor at the Desert Research Institute and director of the Western Regional Climate Center in Reno, Nevada.

Fires were once commonplace in the West because of lightning strikes and Indigenous burning, Hatchett said. The practice stopped during colonial settlement, but it now needs to return, Hatchett said.

害羞草研究所淭hat害羞草研究所檚 the only way we害羞草研究所檙e really going to get out of this, is to really accept and embrace the use of fire on our terms,害羞草研究所� Hatchett said. 害羞草研究所淥therwise we害羞草研究所檙e going to get fire on the fire害羞草研究所檚 terms, which is like what we害羞草研究所檙e seeing right now.害羞草研究所�

Doing so isn害羞草研究所檛 easy because there are no longer big-open landscapes where millions of acres can burn unchecked, Swain acknowledged.

害羞草研究所淎nd that害羞草研究所檚 sort of the conundrum: This is something we need to be doing more of. But the practical reality of doing so is not at all simple,害羞草研究所� Swain said.

But he said there is no option to address the wildfire risk that doesn害羞草研究所檛 involve fire.

害羞草研究所淲e害羞草研究所檙e going to see more and more fire on the ground,害羞草研究所� he said. 害羞草研究所淭he question is whether we want to see it in the form of more manageable, primarily beneficial prescribed burns, or in these primarily harmful, huge, intense conflagrations that we害羞草研究所檙e increasingly seeing.害羞草研究所�

Heather Hollingsworth, The Associated Press