As vast areas of Northern California burn, we must act now to address the root cause of climate change, which is worsening these blazes. That’s why we are joining with officials across the state to call on Gov. Jerry Brown to make a plan to phase out fossil-fuel production.

Wildfires aren’t new in California, but what is new is their severity — worsened by climate change. In October, Sonoma County lost more than 91,000 acres, nearly 7,000 structures and 25 lives in the Tubbs and Nuns fires. The Tubbs fire was the most destructive wildfire in state history.

The Mendocino Complex fire is now the largest in state history. It has already damaged more than 400,000 acres and isn’t yet fully contained.

Our warming planet has created a hotter, drier California — ideal conditions for these fires. California wildfires are burning more than six times more acreage than wildfires in the 1970s, and the wildfire season is more than two months longer.

Daniel Berlant, an assistant deputy director of Cal Fire, recently told the New York Times, “It’s our changing climate that is leading to more severe and destructive fires.”

Many use the term “the new normal” to refer to our extreme fire season. But a “new normal” implies that it has plateaued. It hasn’t. Scientists tell our governments that fire seasons will continue to lengthen and intensify.

As fires become more destructive, the human cost is greater. More than 50 people have died in the past two years alone.

Brown will host the Global Climate Action Summit that begins today in San Francisco. We appreciate the governor’s leadership in advocating for climate action and his policies on energy efficiency and clean energy. Now, he must take the critical next step, while he still can.

Three-quarters of California’s oil production is as detrimental for the climate as Canada’s tar sands crude, according to study from the Center for Biological Diversity. Yet instead of phasing out fossil fuels, Brown has poured gas on the fire. Under his watch, the state has approved 20,000 new oil and gas wells.

The impacts of drilling and burning fossil fuels, including fires, pollution, droughts, storms, mudslides and sea level rise, are costing Californians more than 12,000 lives and $100 billion every year. Yet the fossil-fuel industry makes up less than 0.3 percent of the state’s GDP and a small number of jobs.

That’s why, as elected officials who swore to serve and protect our communities, we are standing with more than 200 officials from a majority of counties in California who are calling on Brown to deal with the source of the climate problem and phase out fossil-fuel production.

In his final term, the governor can act with the bold climate leadership we urgently need.

Dan Hamburg is a Mendocino County supervisor, and Julie Combs is a Santa Rosa city councilwoman.

You can send a letter to the editor at letters@pressdemocrat.com