Thread by @bedwardstiek

Hello to everyone suddenly paying attention to the orange skies of the west coast!
Local journalist here, fresh off weeks of interviewing weather, climate, forest, and fire experts to give you . . . a #CaliforniaFires explainer thread:

1. Our sky looks crazy because the sunlight is filtering through up to 50,000 feet of smoke and ash to reach the ground.

https://twitter.com/Weather_West/status/1303710477696946177?s=20

2. This happens when fires are so
a) big, and
b) intense
that they make their own weather: a column of super-heated air that launches smoke and ash miles up into the atmosphere.

https://twitter.com/SweetBrown_Shug/status/1302462700438433795?s=20

3. Now, California's forests are adapted to burning on the regular.
BUT: California's forests are not adapted to burning *like this.*
So, why are we getting these firestorms now?
sierraforestlegacy.org/Resources/Cons…

4. For about a century the US Forest Service (which owns ~58% of California's forests today) had a zero-tolerance approach to wildfires.
(Timber is a commodity. The government didn't want it to burn. And it got really, really good at putting fires out.)
foresthistory.org/research-explo…

5. Without regular burns , California's forests got . . . crowded. They spent decades accumulating things that would have burned off: small trees, scrub, dead branches. (What firefighters call "fuel." )
motherjones.com/environment/20…

6. Crowded forests are also thirsty forests:
the scrub that's not burning off sucks more water out of the soil. onlinelibrary.wiley.com/doi/full/10.10…

8. So California's forests get unnaturally crowded with plants that:
-are small, thus easy to ignite
-closely-spaced, thus easy for fire to spread between
-stressing the bigger trees by competing for water
Then comes this: drought.gov/drought/califo…

9. One hundred forty-seven million trees died in a decade. They dry into tinder. They fall over, into fire-log position. (The deaths were particularly concentrated in the place where the #Creekfire is launching smoke 50,000 feet into the atmosphere.) sfchronicle.com/california-wil…

10. Now when fires ignite, they burn super-hot and spread super-fast.
And we tend to get lots of fires *at the same time*--
either because of lightning storms (see: August), or seasonal bouts of hot, dry wind (September) that damage power equipment and fan sparks into infernos.

11. The final reason everyone's freaking:
Fire season is just starting in California -- our worst months are usually September and October -- but we've already burned more acres than any year since we started keeping records. cbsnews.com/news/californi…