California has a problem to the tune of 129 million dead trees, spread across 8.9 million acres. That’s 6,450 times the number of trees in Central Park, truly “astronomical,” in the words of Heather Williams, a spokesperson for the California Department of Forestry and Fire Protection.

In dry, hot times like these, the record number of decaying ponderosa pines, sugar pines, and other towering species can become kindling for errant sparks, fallen power lines, cigarette butts, and lightning strikes.

The bumper crop of kindling helps explain why this has been the worst year on record for California wildfires. Already, more than 876,000 acres have burned in California, compared to 228,000 last year at the same time. The Mendocino Complex Fire, now almost fully contained at more than 459,000 acres, is the single largest fire on record in state history. The largest fire before that, the Thomas Fire, was just put out in January this year.

These recent fires have barely made a dent in the glut of dead trees, CalFire says, and peak fire season in Southern California is still to come later this year.

The die-off, meanwhile, that’s created so much fuel is a symptom of the years-long drought that has parched the Western United States. With limited water, trees have shriveled up or succumbed to bark beetle infestations, with some of the most severe declines in central California. And as the climate warms and more people move into high-risk areas, the damages from wildfires are projected to increase.

Here is a map of how the die-off has progressed over the last four years:

State fire officials are well aware that these trees pose an immense fire hazard, but controlling them is not as simple as cutting them all down. For starters, the sheer number of these trees is poses an immense logistical challenge. Nearly 1.3 million trees have been removed so far, but many are in remote areas where it’s difficult to bring tree harvesting equipment.

It’s also expensive to try to process so many trees. Lumber companies can sell some of the wood to recoup their expenses, but many of the trees are too decayed or structurally unsound to sell. There are jurisdictional hurdles as well, since the forests span federal, state, and private land.

California put together a Tree Mortality Task Force that has awarded millions of dollars in grants to study the problem and to deploy tactics like thinning forests across public and private land. With limited personnel, equipment, and funding, the task force identified several areas as high priorities for management, including Fresno, Kern, Madera, Mariposa, and Calaveras counties. These regions face the highest risks to people and property from falling or burning trees.

But that means the vast majority of the dead trees in California will stay in place and continue to pose fire risks. “There is no way to remove 129 million trees,” Williams said.

We all share the blame for wildfires

Fires are a natural part of the ecosystem in many forests. Blazes clear out underbrush, restore nutrients to the soil, and help some plants germinate. However, the severity and the damage from recent wildfires is due in large part to human activity.

People are moving into areas prone to burning, people ignite the majority of blazes, and people are changing the climate.

How we manage forests is another key factor increasing the dangers of wildfires, from preventing natural fires from burning, to cutting down the wrong kinds of trees, to neglecting pruning in forests near population centers.

However, George Geissler, the Washington State forester, said that this situation arose from many different causes and is too complicated to blame on any individual or group.

Which means forest fires are not due to environmental terrorist groups, as Interior Secretary Ryan Zinke suggested, nor are they due to logging companies cutting down fire-resistant trees, as some activists have claimed, nor are they due to landowners opposing prescribed burns (and it’s definitely not “water foolishly being diverted into the Pacific Ocean”).

The big failure is that the US has not put in the time and money needed to be able to live next to forests, harvest the trees, and reduce wildfire risks. There is no coherent vision across all levels of government, and conflicting priorities like forest preservation and property protection have exacerbated fire risks. “The idea of caring for a forest is much like caring for a garden,” Geissler said. “You have to invest in it to keep it healthy.”

So in some areas, managing forests requires deliberately igniting fires. In others, it would require clear-cutting. Still other areas demand planting new trees to reduce fire risks.

Doing all this takes money, and bringing down fire risks will take years. Politically, it’s easier to muster the resources to put out a fire than it is to prevent one, especially when groups like the timber industry and environmental activists are diametrically opposed on certain kinds of management techniques, like forest thinning. That means states and the federal government will face a slog of litigation and red tape as they try to bring fire risks down.

“It took decades to get to this point, it will take decades to get out of it,” Geissler said. “It requires commitment and unfortunately it requires a hell of a lot of patience.”

California is taking some steps to systematically reduce fire hazards. The state legislature on Friday passed a $1 billion fire risk reduction package. It give grants over five years to communities to cut fuel breaks, thin flammable brush, and educate firefighters. The bill also relaxes rules on logging to make it easier to get to some of the most flammable trees.

However, the bill also contains a controversial provision that would allow Pacific Gas and Electric to pass off some its liabilities to customers. The utility is facing billions of dollars in damage payouts after its power lines were blamed for starting some of the fires in California last year. California Gov. Jerry Brown is expected to sign the bill.

Meanwhile, fire officials are still bracing for more blazes this year. “We’re always optimistic that things will stay quiet, but the past two years have shown that is very unlikely,” Cal Fire’s Williams said.