A S THE FLAMES moved toward Helltown, a former gold-mining settlement, the headlines wrote themselves. Part of northern California had become an inferno. A nearby town, Paradise, which a week before had 26,000 residents, was incinerated and reduced to ash. Nearly 50 people are confirmed dead and over 200 missing, making “Camp Fire” (named after the road where it began) the deadliest in the state’s history. About 130,000 acres, an area nearly the size of Chicago, has already burned.

The scent of destruction spread even further. In San Francisco, 150 miles away, the smell of smoke has been so strong that many wear masks when they step outdoors. Meanwhile, in southern California’s coastal mountains, two other fires have claimed lives and livelihoods. Six of the ten most destructive fires in California’s history have occurred in the past decade. In that time the California Department of Forestry and Fire Protection (called Cal Fire) has spent over $3.8bn fighting fires in the state, more than it spent in the previous 30 years combined. Last year was the most destructive year on record, until this year. Why is the Golden State so flammable?

President Donald Trump offered his own answer, blaming California for “gross mismanagement of the forests” and threatening to withhold federal aid (he later authorised emergency funds to help victims). Yet the majority of forests in California are under federal control, and much of the area burning in Southern California consists not of forest but of grassland and shrubs.

There are three reasons why California has been besieged by flames. First, the climate is becoming warmer. This has led to snow melting earlier, drier landscapes and a longer season when fires are likely to ignite. In western states the average fire season is 84 days longer than it was in the 1970s. “This is not the new normal. This is the new abnormal,” Jerry Brown, the state’s governor, said recently.

A second reason is that more people live in combustible places. Since 1990 60% of new homes in California, Washington and Oregon have been built in spaces abutting nature, says Ray Rasker of Headwaters Economics, a research firm. These areas, which environmentalists call the “wildland-urban interface”, are at higher risk of wildfire. Power lines can fall or make contact with trees; people can also cause the first spark. City and county governments, hungry for the tax revenue that comes from new developments, often wave through new buildings in areas that are fire-prone.

Although Californian state law requires people to manage flammable vegetation within 100 feet of their home in order to create a buffer, local officials often fail to enforce it and opt for relatively lax construction standards for new homes. “We know how to make our houses and buildings safer in an urban environment,” says Mr Rasker. “Somehow if you live in the woods, these things don’t apply.” A third reason for the more frequent and intense fires is that there is more fuel. Fires today burn twice as many acres and for twice as long as they did in the 1990s. Before western settlers arrived, fires used to happen often and naturally, which helped forests regenerate and also made less fuel available for future fires. For the past century fires have tended to be quickly suppressed. This has led to a build-up of dry brush, and makes the average wildfire much likelier to turn into a raging mega-fire. There have been efforts to make the forests safer, through thinning them and controlled burns. But they have been stymied by a lack of resources—which the forests service has tended to use up fighting wildfires—and complaints about smoke from planned burns. Despite Mr Trump’s rabble-rousing, forests are one area where the parties have come together and made progress. In March Congress passed a fix for the way the US Forest Service is funded, so that its budget is not restrained by the need to fight mega-fires, leaving more funds for prevention, maintenance and restoration. “The need is big, but the good news is that the pot is growing,” says Lynn Scarlett of the Nature Conservancy, a non-profit group. Putting out the blazes is the most immediate task for California, but not the last. Many survivors will want to rebuild their homes exactly where they were. “Politicians, in an attempt to be loving and compassionate, tend to reduce or eliminate building rules,” says Chris Dicus, a fire expert who teaches at California Polytechnic State University. In the Oakland hills, near San Francisco, which witnessed a conflagration in 1991, houses have been rebuilt; but they are larger and closer together and streets more narrow, which will restrict the ability of firefighters to tackle fires when they next break out, says Char Miller, a professor at Pomona College.

Cities and counties should question whether to allow redevelopment and how to reduce risks. San Diego, which experienced a severe wildfire in 2003, has identified over 40,000 houses that are at high risk of fire and requires property owners to maintain a “defensible space” clearance around their home. If they don’t clear flammable brush themselves, the city will do it for them and add it to their tax bill. Local governments could also consider buying out property owners in especially flammable areas, much as some have done with those who own property on flood plains, says Mr Miller.