The 'new abnormal' — California megafires explode with off-the-charts fury

Nov. 16, 2018

California is on the burning edge of climate breakdown. Record-breaking drought and heat have turned the Golden State into a tinderbox. The megafires have followed. In the last two years a string of off-the-chart wildfires have exploded with stunning speed and ferocity across forests, grasslands, rural areas and city neighborhoods. California Governor Jerry Brown has called it "the new abnormal."

To illustrate this new abnormal, I’ve charted California’s biggest and most destructive wildfires since modern records started being kept around 1930.

Top 20 largest wildfires

Let’s start by looking at the state's list of top-20 largest fires. My chart below arranges them by year. The height of each bar shows the number of acres burned. The red bars are the fires from 2017 and 2018. Two things jump out.

First, you can see that California's megafires are becoming much more frequent. These gigantic fires used to be rare events. Now Californians are struggling against them with dizzying frequency.

Second, you can see how they suddenly leap off-the-charts in scale.

Less than a year ago I wrote about 2017's freakish Thomas Fire. It not only became California's chart-topping wildfire, it did it during the month of December during California's "rainy season." It was the first “rainy season” fire to burn its way into the top-20.

Just seven months later, in July 2018, the Mendocino Complex fire exploded out of control. By the time an armada of fire fighters, bulldozers, tankers and water bombers could put it out, more than 450,000 acres had burned — sixty per cent more than the old record.

As I write this (Nov 16, 2018), the Camp Fire is still burning at 145,000 acres and is less than half contained. It joins the Thomas Fire as the second "rainy season" fire to break into the top-20 largest.

Here are the same top-20 fires arranged by the month of the year they occurred.

As you can see, California's megafire season is spilling out of its "old normal" boundaries.

Top 20 most destructive wildfires

Now let's look at the state's top-20 most-destructive fires. As before, my chart below arranges these by the year they occurred. In this case, the height of each bar shows the number of structures destroyed. The fires from 2017 and 2018 are highlighted in red.

The same two troubling patterns jump out here as well.

First, you can see that these destructive megafires are becoming much more frequent and much more extreme.

For example, seven of these top-20 destructive fires happened in the last two years (red bars).

The second similar pattern is the recent off-the-charts leap in scale.

Take a look at the red bar showing the destruction from the Tubbs Fire. This megafire ripped through Napa and Sonoma counties in October of 2017. Before thousands of firefighters working 24-hour shifts could put it out, over 5,600 homes and buildings were destroyed. That didn't just break the previous record for destruction — it nearly doubled it.

While that was literally off-the-charts, far worse was on the horizon.

In the following year, six more megafires burned their way onto California's most destructive top-20 list.

And the most recent of these is the monstrous — and still burning — Camp Fire in Butte county. It started on November 8, 2018. Within 36 hours it had exploded with such speed and fury that it had already destroyed more homes and buildings than the previous never-seen-anything-like-thisTubbs Fire did in total. At the time of writing, the Camp Fire has already burned down more than 10,000 homes and commercial buildings plus another 2,000 other structures. When it is finally put out the bar on my chart will need to be significantly higher than it already is.

The still-raging Camp Fire has also killed more people than any other American fire in the age of modern firefighting, weather forecasting and rapid communication.

Hotter and drier

The largest and most destructive wildfires in California have occurred when the conditions are both exceptionally hot and dry. Sadly, such hot & dry years have become both more common and more extreme.

To illustrate this trend, my next chart shows the average temperature and precipitation for all of California's wildfire seasons since 1895. (NOAA data with h/t to @RARohde)

Grey circles show all the years before 2000. Coloured dots show the years since. Red indicates 2017 and 2018.

The first thing to note is that every fire year in the new millennium has been hotter than average. Even more troubling, many of these were hotter than any fire season in the past century.

You can also see that most of the fire seasons since 2000 have also been drier than the "old normal."

Several years have jumped up to a whole new level of "hotter & drier" — note the red dots for 2017 and 2018. As we saw above, both years witnessed a whole new level of extreme fires as well.

There will always be both natural lightning strikes and human-caused sparks to start fires in California. But to turn a common brush fire into a city-eating megafire requires a lot of kindling-dry fuel (forests, brush, grassland) that is capable of burning explosively. Hot and dry years do just that.

The new abnormal

Now that some of the first big, unmistakable, climate impacts have started to hit home in recent years, commentators often refer to these events as a “new normal.” If only we were that lucky. The word “normal” implies a new predictable plateau that we can get used to. Something different but ultimately … “normal.”

That is not what is happening. As long as humanity continues dumping billions of tonnes of climate pollution into the air and water each year, climate breakdown will continue to accelerate into an ever more extreme and unpredictable future.

As three scientists explained earlier this year in the Guardian: “California’s governor, Jerry Brown, has characterized these devastating wildfires as California’s “new normal.” But it would be a mistake to assume that the region has reached any semblance of a stable plateau. Instead, the likelihood of large, fast-moving, and dangerous wildfires will continue to increase in the coming decades....”

That was last year. After yet another off-the-charts fire year, Governor Brown is now more clear about what’s unfolding: “This is not the new normal. This is the new abnormal … Unfortunately, the best science is telling us that dryness, warmth, drought, all those things, they’re going to intensify … We have a real challenge here threatening our whole way of life...”

How “abnormal” could it get in the Golden State?

I remember vividly a winter day, back in 2009, when U.S. Secretary of Energy Steven Chu, a Nobel Prize-winning physicist, voiced his deep concerns for what climate change could do his home state: "I don't think the American public has gripped in its gut what could happen … We're looking at a scenario where there's no more agriculture in California." And, he added, "I don't actually see how they can keep their cities going."