This story has been updated.
It’s turning into quite a summer for wildfires across the United States. And the latest conflagration worrying authorities is the Rocky Fire north of San Francisco (see map here), which has burned 69,600 acres so far and is only 30 percent contained.
The fire has consumed 43 homes and threatens thousands more — the list of areas under mandatory evacuation is quite long. Nearly 3,500 firefighters are currently on scene, fighting with 17 helicopters, 4 air tankers, and much more.
Alarmingly, fire pros have been describing this fire’s behavior as pretty un-heard of. “Over the weekend, we saw this fire burn 20,000 acres in a five hour period,” says Daniel Berlant, chief of public information at Cal Fire. “That type of speed for a wildfire, without a weather condition like Santa Anas, is really unprecedented in recent times, or in even veterans of our department’s recollection.”
The Rocky Fire has burned twice as many acres any other California fire this year, Berlant says. Fortunately, so far it is is nowhere near as large as some of the worst fires in California history — the top four of which have all occurred since 2000. All of these behemoths burned over 200,000 acres.
Still, the Rocky Fire is clearly the worst fire — so far — of a California fire year that is already ahead of pace for the number of fires and the number of acres burned — with still quite a long way to go.
Across the United States, 2015 is shaping up to be quite a fire year — and, indeed, part of a trend. To see as much, all you have to do is look at the statistics.
Before 2000, there is no year on record with more than eight million acres burned across the U.S., according to figures going back to 1983 provided by the National Interagency Fire Center. (Note that the agency provides stats back to 1960, but warns that those compiled prior to 1983 were based on different methods of gathering data and are not necessarily comparable to those after that break point in time.)
Since 2000, however, there have been six years with more than eight million acres burned, and three with over 9 million burned. And 2015, with nearly six million acres burned already — well above the ten year average for this time of the year — could potentially join this list.
Indeed, six million acres exceeds the total acreage burned in the majority of prior years on record going back to 1983. And it’s only August 5.
There’s one key caveat to this analysis, though — nearly five million of those six million acres have burned in Alaska this year, so it’s a bit of an anomaly in that respect. Other years have seen much more burning in the lower 48.
Nonetheless, the year overall is shaping up to be quite a doozy for acres burned, especially given how far there is still to go. “We’re probably going to see fire activity, at least in the western states, until November,” says Mike Ferris, a public information officer for the U.S. Forest Service who works in fire.
It is becoming almost trite to state that this has something to do with climate change. Wildfire risks are strongly influenced by local climatic factors which, in turn, are trending because of changes to the global climate. Heat and dryness favor wildfires — that’s why this year has fire-watchers so concerned, because western drought has been so widespread.
So wildfires are getting worse, and more expensive to fight. The practical consequences of course include greater risks to individuals and communities in harm’s way (which themselves are growing in number), and also to wildland firefighters. They also include downwind air quality risks from smoke to people who do not necessarily live anywhere near the raging fires.
But when you take a step back, it’s hard not to also emphasize long term changes to the country’s forests that could be brought on by an increased rate of burning — which could increase still further in coming years.
I’ve already outlined the particularly sensitive situation in Alaska, where wildfires burning atop permafrost can change entire ecosystems — bringing in different tree regimes and also potentially leading to greater carbon emissions to the atmosphere.
That’s not an issue in the lower 48 states. However, the 2014 U.S. National Climate Assessment outlined a troubling scenario in which the nation’s forests, which currently store a great deal of carbon — enough to offset 16 percent of national emissions — flip from being a carbon “sink” (storing more than they emit) to being a source (emitting more than they store). This could, potentially, happen by 2030, the report said, brought on by changing climate factors that include wildfires.
A recent study in Nature Communications similarly found that on a global scale, not only are the seasons of the year conducive to wildfires getting longer, but this change is correlated with less carbon storage in ecosystems.
So, in sum: The more you watch wildfire trends, the more you tend to worry not only about each fire year as it arrives, but also broader implications for U.S. and global forests and ecosystems — and how those, in turn, affect the planet.
Also in Energy & Environment: