17.7: Detailed Figure Descriptions

Detailed Figure Descriptions

17.1

Low water levels at Nicasio Reservoir in Marin during 2021 during severe drought conditions. Baked-dry polygonal mudcracks lie in land that should be under significant water. This period reflected part of recent drought cycles, and though such reservoirs recover, they will also inevitably drain again as California water demand, and out of control population growth, far exceeds the ability of precipitation to provide for the state in the way it has in the past.

17.1.1

Solar energy imbalance created when greenhouse gases act to trap a portion of solar radiation that would otherwise escape to space and cool Earth. Includes incoming solar radiation, some of which is deflected immediately by high clouds, some of which reaches the ground and is absorbed, and some of which is reflected by ice on land and sea. The flux of energy returns to space, and in normal conditions, the incoming and outgoing would be more or less in balance. Today, however, greenhouse gases are stimulated by the infrared radiation emitting from the warmed Earth, and these greenhouse gases therefore return some of that energy back toward Earth, leading to an imbalance.

Solar radiation inputs include absorbed radiation on continents and oceans, minus reflected radiation from clouds and sea ice. Energy absorbed on Earth is then dissipated via "infrared radiation emitted by the surface," which then may interact with anthropogenic gases and be "absorbed and reemitted by greenhouses gases: carbon dioxide, methane, water vapor, nitrous oxide, and others."

17.2.1

A stand of long-lived Bristlecone pines growing on Reed Dolomite in the White Mountains, CA. The stand of trees grows almost entirely on the white Reed Dolomite, and very sparsely on any other formations visible (probably the early Cambrian Deep Springs or Campito Mountain formations). The soil has a variety of healthy brush growing on it, most plants do not thrive on dolomitic soils; however, Bristlecones have evolved to exploit the opportunity of this less-used substrate, perhaps because of the lessened competition with other faster-growing plans. Many of these Bristlecones are over four thousand years old.

17.2.2

A Bristlecone pine (Pinus longaeva) from the White Mountains, CA, with the characteristic barren, twisting corkscrew shape of the trunk, adorned with sparse green leaves. Little of the tree has foliage; nonetheless, these trees are still alive and, in fact, provide a record of growth that proves very useful for paleoclimatology, though they will not provide the clear tree rings found in faster-growing trees at lower elevations.

There is plentiful residual snow on the ground, which is an important source of the plant's water supply, but also reinforces the high altitude, typically above 10,000 feet, at which Bristlecones thrive. Part of their ecological niche is to live on soils and in places where few other plants are able to make a living.

17.2.3

The dendrochronology principle of differential annual tree ring growth. All else being equal, wider rings indicate periods of wetter climate and greater growth, while narrower rings indicate a drier and less productive year. Note that these rings may be sampled by a hollow core that does not kill the tree; not every dendrochronologic sample involves cutting down the tree. If the tree is cut down, then the slice of the trunk used to establish dendrochronology is referred to as a "cookie." These cookies and cores allow for examination of growth differentials and extraction of material for isotopic analysis.

17.2.4

The Palmer Drought Index Scale from the year 1000 to the year 2000. Lower numbers (-8, -6, -4, etc.) indicate drier climate conditions, while higher numbers (2, 4, 6, etc.) indicate wetter years. This thousand-year record shows showing dry periods/wet periods in California from the years 1000 to 2000, as shown from a baseline of 0, with variation upwards indicating wetter periods, and variations downward drier periods.

The period of 1900-2000 show some wet spikes and dry spikes; the fear of climate change-induced drought is that future iterations of this graph will show primarily dry numbers. Of particular note at the low (dry) pulses that occur after the year 1100 and again, in several pulses, throughout the 1200s, 1300s, and 1400s.

17.3.1

Monthly precipitation profile for San Francisco using NOAA data from 1991 to 2020. The twelve steps on the bottom each correspond to a month (Jan to Dec), while the axis to the left shows precipitation in mm, from 0 to 130. January and December clock in between 110 and 120 mm, respectively, while July-August-September report zero to a few mm.

What this pattern shows is the "Mediterranean" climate noted by long, dry summers with virtually no precipitation from June-Sep, punctuated by wetter winters with rainfall concentrated Nov/Dec/Jan/Feb. Even these rainfall concentrations are something of a misnomer, because precipitation does not fall steadily, as it would in, say, Seattle, but rather comes from just 1-2 major storms that inundate and overwhelm city water systems.

17.3.2

A elevation cross-section of California from Monterey to Death Valley, with a vertical exaggeration of 30x. Starting in the west near Monterey, we move past the coastal ranges into the flatness of the Central Valley, then begin a long climb up the west face of the Sierra Nevada. At this point the diagram shows a rainclouds with drops of rain descending on the Sierran foothills, indicating the process of moisture being precipitated as it rises in elevation (orographic precipitation). The steep east side of the Sierra Nevada therefore creates a rain shadow in the Owens Valley. The White-Inyo mountains created another rain shadow for the Panamint Valley, and the Panamint Hills likewise form another one for Death Valley.

What this shows is that while precipitation flows from the west (left) to the east (right), when it encounters the Sierra Nevada, much of that moisture is removed by orographic precipitation, and indicated by the cloud and rain drops. Additional rain shadows remove even more moisture before whatever is left arrives in Death Valley, which is one of many factors why Death Valley is one of the driest spots on the planet.

The profile is exaggerated in order to display the height differences in a way greater than would actually be encountered if one were, for example, seeing this profile in a plane traversing the same course.

17.3.3

California with different regions parsed into various Köppen climate classifications. The Köppen climate classifications are a way of parsing climate zones such as "Dsc (Dry-summer subarctic)" and "BSh (hot semi-arid)."

This diagram divides California into 11 such categories (Bwh hot desert, BWk cold desert, BSh hot semi-arid, BSk cold semi-arid, Csa hot summer Mediterranean, Csb warm summer Mediterranean, Csc cold summer Mediterranean, Cfb oceanic, Dsb warm summer Mediterranean continental, Dsc dry summer subarctic, and ET tundra). Note that only 4 of the categories indicate "Mediterranean" conditions, though "Mediterranean" is the most common way to describe California's climate. Problems with this oversimplification are detailed in the chapter section.

The diagram discusses its sources as "Data sources: 1991-2020 climate normals from PRISM Climate Group, Oregon State University; outline map from US Census Bureau."

17.3.4

Extremes in maximum temperature from 1910 to 2022, with percentages above or below a baseline. Above-average temperatures begin to become much more common after 1980, and after 2010 are all classified as "much above normal." This reflects the warming trends worldwide during these time periods.

The title is "West extremes in maximum temperature (Step 1) annual (January - December)." Lines indicate "much above normal," "much below normal," and a "9-point binomial filter."

Particular note should be given to the low extremes associated with the 1982-1983 and 1997-1998 El Nino events. Also of note is the trend that after the year 2000, virtually every temperature reading is listed as "much above normal."

The trend from 1910-1980 begin swith a small range; however, this range grows greatly in the 1982-1983 period and then expands dramatically after 2010.

17.3.5

Snow Water Equivalent (SWE) at Donner Summit from the years from 1910 to 2020. SWE is in inches, ranging from 0 to 90. What there is significant variation, both high and low, across the time period, the lowest measurements occur within the last few decades, including a reading in 2015 near zero.

17.3.6

A Jan 2023 atmospheric river forming in the Pacific and heading directly toward California, with a narrow counter-clockwise rotation of moisture moving from the west to the east, hitting California and spreading out along the California coastline. This is typical of the way we receive the majority of our rainfall.

17.3.7

The Jan 2023 reference used to create Figure 17.3.6.

17.3.8

The quixotic Reber Plan, which was never enacted, but which would have catastrophically altered California water by building a dam across San Francisco Bay, capturing the largest freshwater drainage in the state. The main barrier in the Reber Plan would have been a dam from Pt. San Quentin to Richmond, west to east, roughly following the course of the Richmond-San Rafael bridge. Other inlets and bays would have been paved over. To the north, a shipping channel and lock system would have been constructed right through the current city of Richmond, allowing shipping to each the upper Sacramento river.

This plan was never fulfilled, but one can imagine the environmental devastation this would have wrought had it been constructed.

17.4.1

King Tide conditions at the San Francisco Embarcadero, where sea level is even with sidewalks and small waves splash salt water onto San Francisco streets. These King Tides give us an indication of what future seal rise will look like, when the ocean level is this high at the normal at high tide.

17.4.2

Projected sea level rises, with a range of uncertainty indicated on either side of the middle line. One axis tracks from the years 2020 to 2140, while another shows sea level change in meters from 0.2 to 1.6. The middle scenario shows over a meter of sea level rise by 2140.

17.4.3

Historical, current, and project temperature changes in California. One axis shows years from 1900 to 2100, while another shows temperature changes in ^oF from -2 to 12. Projected changes are split between "high emissions" and "low emissions" scenarios. The lower emissions track puts us somewhere between 2 to 7^oF by 2100. However, we are firmly on the higher emission pathway right now, and if we follow that to its worst conclusions, then we could be looking at increases in overall temperatures on the order of 12^oF by 2100.

17.5.1

An AI imagining of the future Los Angeles skyline under severe climate change. Note the flooded roads lined with palm trees, on which cars gingerly make their way through standing water, while the sky is reminiscent of the actual sky conditions on 9 September 2020, which involved an orange-red sky created by an inversion of particles created by out of control wildfires. It is interesting to contemplate that all of our infrastructure--skyscrapers, bridges, roads--will remain abandoned for a while, even if future climate change makes conditions on Earth unlivable for humans.