October 2024 Heat Wave

 The October 2024 heat wave was the warmest early-October weather in the Bay Area since 1980. Above average temperatures began for San Geronimo Valley just before the autumnal equinox, which was the beginning of 18 days over 80 degrees F, 10 days over 90 F, and 3 days over 100 F. Two of the days in the 90s occurred in September, then there was one cool day--September 25th, where the high only reached 69 degrees. After that there were 13 days in a row exceeding 80 F and 8 days in a row exceeding 90 F. In October, it had never been over 95 F before, but 3 days over 100 F and 3 days over 95 F set new October monthly records (since I started recordkeeping in 2012). October has now become a month when it can not just get hot, but really hot.

As with many heat waves, the remarkable thing was how warm it was at night above the inversion layer. In the graph below, you can see red and blue lines for the temperature on the ridges, and a green square for the highs and lows on the valley floor (with blank spots for occasional missing data). Starting September 30th, for 9 nights in a row, valley floor temperatures were below 60 F while ridgetop temperatures were in the upper 60s or warmer. And some nights were much warmer, with the ridges staying near 80 F all night! Who would have guessed that Marin County would have low temperatures in the 80s in October, rivaling Death Valley temperatures!

Death Valley-like nighttime temperatures in the 80s in Marin County

The third remarkable thing (after the extreme October heat and the heat above the inversion layer) was the short duration of each day's heat on the valley floor. Because the October days are shorter, the 50-degree temperature uptick was packed into fewer daytime hours. On multiple days I would be cold all morning, then go outside in the afternoon to warm up, then get too hot. Inside our house, temperatures never got above the upper 70s, with some mornings starting at a cool 62 F. Another year (like 2017 or 2019, when nights were in the 30s and highs were in the 70s) we might have turned on our heat to keep our house warm, but this year the heat wave provided our house heating!

So while this October heatwave was extremely anomalous and concerning, the impacts were lessened on the valley floor due to the lateness of the season and the nighttime cooling. But the concerns are big ones--warmest October high temperatures ever, warmest October water temperatures ever, driest soils and vegetation ever, and the impacts to plants and animals on the ridges of seven days in-a-row of low temperatures in the 70s and 80s.

The California Water Cycle

 The causes of most problems are solutions. We rarely unbuild big things that we've built. Instead we layer on solutions--some of them big new things that create their own big new problems. Sometimes you gotta just take out the big thing that started the whole cycle.

Soil Science Joke

 Mono Basin Textural Triangle:

Note that in some lentic zones you might encounter loamy sand, sandy loam, sandy clay loam, or sandy clay. But there will be sand. In other areas you might encounter gravelly sand, cobbly sand, stony sand (not just near the dispensary), or bouldery sand.

Insurance

Last week, the Marin Open Space District created a "shaded" fuel break along a fire road in French Ranch. They chipped and bucked a lot of trees near the road, some of which had fallen during winter storms. They took out a good number of trees in the lower grassland, before you reach the forest. It feels a lot more open and sunny now. Forest management isn't always pretty, but in a couple of years things grow back and look a lot better. And the long-term context is that over the last 40 years (with no grazing, no fires, and warmer temperatures) the woody vegetation is spreading, slowly converting the grassland to coyotebush and Douglas-fir forest. Perhaps the management goal is to revert these transitioning slopes back to a grassland? Or more likely, with work only occurring along the road, it is to give vehicles more room and safety during a wildfire.

But now imagine someone cutting down your favorite shade tree in your local park. The loss of individual shade trees on the steep hot sunny hike up to ridgetop forest makes this hike less accessible to kids and elderly and less pleasant for everyone. On a recent hike with my daughter and her friend, they were tired and we stopped to rest at one of these missing trees before heading back down. Doing that hike today would be a hotter and sunnier and less-pleasant experience.

February (left) and July (right) photos show the loss of 25-year-old shade trees on a hot south-facing slope.

A young solitary Pacific Madrone (Arbutus menziesii) was cut down in a Marin Open Space Preserve last week.

Honorable Mention

 About thirty years ago, when I was at Cal Poly San Luis Obispo, I took an environmental law class. At the end of the class we had to write a brief and present it to a panel of volunteer judges in a real courtroom. The judges awarded students first, second, third place for the best briefs, and I had an honorable mention--for being clever.

The case we had to argue was a real one from our environmental law book--a developer had proposed a housing development in the Central Valley, and a raptor center had challenged it on various environmental and CEQA grounds. Our instructor was also clever--he assigned which side of the case we were to argue based on our opposite inclinations. Since I probably exhibited signs of populism, caring about good governance, and prioritizing environmental and people protection over developers making money at public expense, I was assigned the developer's side of the case to argue.

This put me in a difficult position. In a real job, I just would have rejected it--frankly, I felt the developer's case sucked. I saw no way to win, or even argue that side with a straight face. But as a student, I couldn't say no. I had to do it somehow.

Then I had an idea.

Storm Totals, Storm Damage, Power Outages, Falling Trees, and Moving Logs

January 2023 will go down in the record books as one of the stormiest, snowiest, and rainiest months for many parts of California. As of January 16th, San Geronimo Valley had received 19 inches of rain--making it our second-wettest January in the last decade (after 2017). In addition, the wind, landslide, and flood damage has been widespread. And the month is only half over. Much of that was packed into the first 11 days.

The story starts in December, after a dry October-November start to the 2023 water year (following 3 dry years). Here in San Geronimo Valley, I measured 16.59 inches of rain in December, at 240% of average, the wettest December in 8 years and second-wettest in the last decade.

Logs began moving in San Geronimo Creek in early December, when a series of storms brought rare lightning and thunder, and enough rain to get San Geronimo Creek up to 200 cfs. This was not a large flow, but trees fell in the creek and rafted down to an engineered logjam that was placed in the creek in 2020. An October 2021 storm that peaked at 2,500 cfs had already moved around the logs connected to boulders in this logjam--logs that were designed to stay in place. Surprisingly, a log that didn't move in 2021 was scooted several feet downstream by the 660 cfs flow on December 27th, 2022. It stopped when the boulder it was anchored to bumped up against another log embedded in the creekbed.

Note the moving log bolted to a boulder at the lower right corner of the
photos on December 10th (left) and December 28th (right).

Two storms at the end of December were impressive. The one on the 27th dropped half-an-inch of rain an hour for six hours. Once again there was rare lightning and thunder. Read about "snow level bending" as freezing levels fluctuated near Lake Tahoe. Twenty-two foot waves towered along the coast.

On December 26th, 2022, seventeen-foot waves were oversteepened
and trailing banners of spray because of the east wind. They foreshadowed
the 22-foot waves that were forecasted on the 27th.

Inhabiting a fire-adapted land

The land used to be inhabited. People lived some or all of the year in almost every place in California, with exceptions of extreme high elevations and extreme desert. This made tending the land feasible--over 4 million acres could be burned each year easily, in areas where people were intimately familiar with the vegetation and weather, around people's homes, without traveling long distances to conduct the burns. Networks of trails--dense in inhabited places--would have been natural fire breaks under these conditions.

Today, much of the land is uninhabited, except temporarily by rangers and recreationists. The inhabited landscape has shrunk to a small fraction of California, and even there, outside of Southern California chaparral ecosystems where fire frequency has increased, most burning has been suppressed. So we have a build up of fuels in forests, a takeover of grasslands by non-native invasive weeds, and general ecosystem degradation.

Simply increasing the acreage burned each year would be a feasible approach to solving this problem if the land was still inhabited. But it is not. So people unfamiliar with the land (topography, vegetation, weather) must travel long distances to conduct controlled burns. This model is expensive, inefficient, and not scalable to the acreages that need to be burned each year--estimated to be over 4 million acres that burned in pre-European times and that is a sustainable level for maintaining California's ecosystems with a natural fire regime, and lessening the likelihood of catastrophic fires.

In addition, large areas of federal public land, formerly inhabited by Indians or patrolled by rangers, have been defunded by Congress year after year to the point where it is rare to see a ranger. The uninformed and uneducated public trashes these lands without guidance or oversight. And the neglected lands have a fire recurrence and intensity that is out of whack and getting wackier.

Hiring more rangers who actually manage and live and camp on the land is one way to solve this problem. Inviting indigenous people to live on and manage land is another. Both approaches should be used to get our public--and private--lands back in balance.