Home Climate Change California's Wildfires Are About Last Year's Rain Not This Year's Heat

California’s Wildfires Are About Last Year’s Rain Not This Year’s Heat



It’s deeply depressing when even purported experts – and the newspapers that push them – get basics about the world so entirely wrong. Here it’s about those California wildfires. These are being blamed upon the current excessive heat that, of course, all being a function of climate change.

Nonsense, in fact worse than mere nonsense it’s piffle. Fires in vegetation like California’s depend upon the level of rainfall in the year before, not the heat of the summer after. This is such basic ecology that anyone not noting it should be castigated not just ignored.

Over millennia California’s landscape has adapted to burn, with some tree species requiring the heat of flames to open their seed cases, and lightning-sparked wildfires are not unusual.

That, at least, is true. It’s an environment built to burn on a regular basis.

In the last decade, amid drought and searing heat, California has entered the “era of megafires”. Our new book, Fire in Paradise, tells the story of a town that was almost entirely wiped out by a fire of unheralded speed in 2018. It killed 85 people, making it the deadliest ever fire in California. Other notable blazes include a 1,000-ft wide fire tornado that churned through the town of Redding a few months before the Paradise catastrophe, and fires in California’s Wine Country that killed 44 people.

All of this is why, as we scan the headlines for the planetary shift that will mark the true arrival of the climate crisis, we risk losing sight of the fact that places like California are already experiencing it.

It’s not about heat. The environment as a whole doesn’t get hot enough to burn, clearly, nor does it get hot enough to even ignite. It does get dry enough to ignite if the correct spark is added. But then except for the truly exceptionally wet summer it always does get dry enough to do that. You know, ecology built to burn on a regular basis?

What matters is the amount of dry brush there is to burn. The limitation here being precipitation in the previous year.

It’s necessary to understand that California (like southern Portugal as another example) has inverted growing seasons in the native flora. It’s in the winter, during the rains, that the grasses and shrubs and all that grow explosively. It’s all over by spring and by July or so they’re just dry and dead husks with the root system hiding away awaiting another winter’s rainfall. The goat herder near us is out foraging for fodder by May at the latest – exactly when in the UK you’d let animals just roam to eat their fill – because of this.

It is precipitation the year before that determines the fire season:

This was going to be a bad year for fires. Last year was not going to be a bad one. Well, at least that’s what we’d predict from the rainfall. Hmm:

Oh, right. So there we are then.

Now, if you want to predict that California will have wetter winters as a result of climate change and that this is then driving the fires then you go right ahead. With perhaps some proof maybe. But the claim that the wildfires are being driven by summer heat is wrong. So, don’t do it.



  1. Possible other factor
    Forest management.
    It was long established practise to clear brush, or at least clear paths through it, in order to prevent, or limit the spread of fires.
    Now the environmentalist have had that stopped in order to spare the critters that live in the brush from disturbance.
    Funnily enough we get more and faster spreading fires.
    Whether this is better of worse for the wildlife living in the brush, the critters the new policy was meant to save, than the alternative of regular clearance I will leave as an exercise.for the reader.

    • The postmortems on the Aussie bushfires last summer revealed that the State governments, frightened of the Green voters, didn’t burn off enough. They naturally then blamed the Commonwealth government, which doesn’t control burn-offs. This was helped of course by the fact that ScoMo was LNP and so many of the states Labor. Victoria was a notorious example.

      I’ve always felt that this vicious media criticism was the reason ScoMo over-reacted so badly to Covid. He’s trying duck in advance.

  2. It is the result of decades of wildland mismanagement. A load of Green BANANAs (Burn Absolutely Nothing Anywhere Near Anybody) has removed controlled burns as a management technique. It is a combination of overlapping bureaucratic agencies conspires to stop any controls from moving forward.

    Much of the public land in California is owned by three agencies; the National Park Service (NPS), the Forest Service, and the Bureau of Land Management (the original BLM). The NPS and the BLM belong to the Interior Department; the Forest Service belongs to the Agriculture Department. So before burning they have to make peace with the Environmental Protection Agency and the Fish and Wildlife Service. There are others involved if near a reservation or military base.

    That being done then we turn to the state agencies. The biggest one is the Air Pollution Control District where the burn will take place. They will dictate the day and time of the burn to minimize air pollution. Also involved are the various local fire and law enforcement agencies.

    Then there are the NIMBYs near where the burn will take place. They do not like the hassle of the burn, smoke, maybe traffic controls and heavy equipment and aircraft coming by. They will also object to the fact that they will be looking at a burned area for the next year until the understory starts to grow back.

    All of this means that there a handful of days that may be used for controlled burns over the course of a year. Having a successful burn is like winning the lottery.


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