Why the LA Wildfires Have Little to With Drought or Climate Change

Some climate activists and media outlets are claiming the drought or climate change were major contributors to the recent wildfires around Los Angeles (see sample below)

These claims can easily be shown to be false.

Drought had little impact on the LA fires.

Climate Change had little impact.  

Let me provide the facts below.

The Fuels

The vegetative fuels for the fires were predominantly light fuels such as grasses and range vegetation.  To illustrate, consider the area where the Palisades fire started (below).

Most of these fuels are 1-10 hr fuels, which means they typically dry out after 1-10 hours of drying conditions.   

So even if the previous period had been wetter than normal, then a half-day of drying conditions would make them ready to burn.  The meteorological conditions immediately preceding the fires were so drying (very strong winds with  very low humidities) that even if it had rained the week before, the fire still would have occurred.

Consider a plot of the ten-hour fuel moisture at the nearby Topanga Canyon site over the past year (below).  Keep in mind that when the moisture level gets below 15% rapid fire spread is possible.  

Interestingly, even during every wet periods (such as the first part of 2024), fuel moisture levels return to burning-level fuel moisture between showers.

But grasses and bushes were not the only thing that burned.  Once the wildfires got to the homes or burning embers reaches the homes, the homes THEMSELVES supplied the fuels.  

One house ignited the next.   

This is very similar to the situations of others major urban wildfires, such as the Camp Fire (Paradise, CA), Lahaina (Maui), and the Marshal Fire (Superior, CO).   Homes flammability has little to do with weather conditions.   But poorly constructed homes (e.g., flammable roofs, no screens to stop embers moving into home spaces) are major problems.

There is No Trend of Less Precipitation in Southern California

Several media and other outlets suggested climate change associated dry conditions was a contributor to the LA wildfires.   First,  as noted above, the light fuels that brought the fires to the homes did not need a drought period to be sufficiently dried to burn.  

But even if drought had been important, there is no evidence than climate change could have contributed.   How can I be be so sure?  Because there is no long-term trend for less precipitation over the region.

Consider the trends of October 1 to January 6 precipitation at Los Angeles from 1950 through this year (see below).  The trend line is UPWARDS (brown line).   More rain, not less.  Yes, the past autumn was dry, but that is not climate but normal weather variability.

Not convinced?    Below is the annual precipitation of the region since the late 1940s.  

No downward trend.  And the last several years have been wetter than normal, which would contribute to more bountiful vegetative growth and thus more fire potential.

The LA Fires Were Associated with Strong-Dry Santa Ana Winds.  Such winds are predicted to WEAKEN, NOT Strengthen under global warming.

The LA wildfires were associated with very strong (up to 100 mph) and dry Santa Ana winds, which were generally from the northeast.

There is an extensive peer-reviewed science literature indicating that global warming will reduce the strength, intensity, and frequency of such Santa Ana winds.

It makes complete sense that global warming would weaken the Santa Ana winds.  

Such winds are driven by difference in pressure between inland high pressure and lower pressure to the south and west.  This high pressure is associated with low-level cool air (cool air is denser and heavier than warm air), which will be warmed due to global warming, thus reducing the pressure difference that drives the Santa Ana winds.

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Very strong video and photographic evidence indicated the Los Angeles Eaton fire, which resulted in the most deaths was due to a faulty power line.  Clearly, this transmission line was not de-energized even with the forecast of severe Santa Ana winds.

Increasing Winds Threaten Southern California

 Let me say at the onset, that the threat is nothing like last week, but strong winds today and powerful winds tomorrow are a serious problem....both in dealing with current fires and for starting new ones.

The National Weather Service is again putting out a strong message (see below),

These warnings need to be taken seriously, including shutting down the power to some areas.

Winds have accelerated today, with maximum gusts reaching 60 mph in the mountains and 40-50 mph at lower elevations around Malibu (see below)

The strong wind are generally from the northeast, a classic of Santa Ana conditions.

Looking at the winds observed at Topanga Canyon near Malibu, one can see that the winds today are strong but not the equal of January 7-8.

Now lets examine the surface wind gust forecasts from the relatively high resolution HRRR model.  Keep in mind that the orange and reds indicate serious winds (50 mph and more).

Monday morning at 8 AM, shows strong winds reaching the coastal zone around Oxnard and Ventura.  Lesser but serious winds over northern Orange County.

By 10 AM Tuesday winds will be really cooking over the mountains and the lower elevation Ventura area.  The power should have been off for the previous 12 hours and for the rest of that day.

The region of strongest winds are within the responsibility of Southern CA Edison.   I hope they are more responsible than the Los Angeles folks.  That means Public Safety Power Shutoffs (PSPSs).   Their web page worries me....