Mysteries of Time and Climate
Clues to Change
Cycles of Time and Climate
When I traveled back in time of my imagination to look at the life of California grizzlies, I realized that the period we live in is a sliver from a giant block of time in continuous flux. The landscape was always changing, animal and plant numbers and distributions fluctuating, according to the archaeological and paleontological remains and eyewitness records. And most glaringly, the climate has never been static; there have been drought years and wet years, periods of cooler, moister centuries, and times of aridity lasting for hundreds or thousands of years.
One thing that seems to remain constant is the cyclic nature of this flux. Cycles within cycles can be detected from various sources: pollen preserved in lake muds, tree ring data, glacial till patterns, alpine treeline fluctuations, ocean temperatures inferred by varying amounts of oxygen isotopes in foraminifera (microscopic planktonic organisms), fossils, historic precipitation charts, and others.
Huge planetary supercycles of 400 million years may be based on differential heat welling up from the Earth’s core into varied parts of the molten zone below the crust, shaping large landmasses and breaking them apart; ripping through sea floors at times to release CO2 to warm the planet and turning our climate into successively a “Greenhouse” phase and an “Icehouse” phase during the last billion years (White 1998). We are currently in one of the Icehouse phases, where the poles are covered with ice, and glacial and interglacial cycles dominate. The dinosaurs of the late Cretaceous period 80 to 65 million years ago and mammals of the early Cenozoic Era, peaking during the Eocene Epoch 40 million years ago, lived in a Greenhouse phase, where the poles had no ice cover, and world temperatures averaged much warmer than today -- tropical forests and crocodiles lived as far north as Alaska.
Shifting to smaller cycles, great astronomical events that we in our everyday lives are not aware of pull and shift the Earth in subtle ways that cause profound ripple effects in climate, vegetation, and faunas. Gravitational interactions with the Moon and the planets give rise to cyclic variations in the Earth’s orbital eccentricity --this causes 100,000 year cycles; variations in the Earth’s obliquity cause 41,000 year cycles; variations in the Earth’s precession cause a 23,000 to 19,000 year cycle. These cycles affect climate by slightly changing the latitudes that receive solar insolation (warmth from the sun’s rays hitting the Earth’s surface) (deMenocal and Bloemendal 1991).
These changes may seem subtle, but even slight decreases in solar warmth over the Northern Hemisphere, perhaps triggered by an increase in the 41,000-year cycle, caused major sheets of ice to grow over the northern continents at 2.37 million years ago (ibid.). Glaciers, too, capped the Sierra Nevada Range. Of perhaps nine ice ages, the latest, and apparently one of the strongest ice advances was the Wisconsin Glacial (called the Tioga in the Sierra), which peaked at about 18,000 years ago. During this time ice scoured the central and northern Sierras, glaciers coalesced into great ice fields which overtopped the canyon divides and blanketed the Sierra down to 8,000 to 6,000 feet. Valley glaciers at times flowed down their west-slope canyons to as low as 1,900 feet. In the southern Sierra the glaciers existed mostly above 13,000 feet. On the east side glaciers crept down to 7,000 to 4,200 feet, and at times during the Pleistocene calved icebergs into Mono Lake. High-velocity meltwater rivers poured into the Central Valley, and pollen of Giant Sequoias (Sequoiadendron gigantea) was found in the San Joaquin Valley and by Mono Lake -- the scene must have been quite different from that of today. The last large glacial tongues began melting off the west side of the Sierra at about 15,000 BP, and soon the great glaciers were gone, leaving scoured granite basins and carved peaks by 11,000 years ago (Woolfenden 1996, Anderson 1990).
Mean annual temperatures dropped as much as 10 to 15 degrees, central latitudes of the United States had a precipitation increase of 10 to 15 inches (however, the Pacific Northwest became a dry steppe-tundra at the time), vegetation zones dropped 1,000 to 3,000 feet, and latitudinal shifts occurred that allowed species to grow 100 to 200 miles south of their present distributional limits (Axelrod 1981).
Between these glacials were shorter interglacial phases when climate was warmer and drier, about as in our time. We live in the latest interglacial, the Holocene. The last interglacial, the Sangamon Interglacial, lasted from about 127,000 to 110,000 years ago (Broecker 2001). The period of time covered by this book includes our present interglacial, dated back to about 10,000 or 11,000 years ago.
As deglaciation occurred worldwide and glaciers melted and sea levels rose the world warmed up rapidly from Ice Age conditions.
The early Holocene phase was somewhat cooler than today as continental ice sheets were still present, although melting fast. Continental glaciers did not completely disappear from eastern Canada, for example, until 3,400 years ago. Some regions, such as the southwestern United States, may have been moister than today.
Middle Holocene Warming
From about 8,000 to 4,000 years before present, a dry hot phase clenched California and much of the northern hemisphere. Mean annual temperatures increased 1 to 3 degrees Celsius and rainfall decreased 4-5 inches (Axelrod 1981). Also called the Altithermal (meaning “high temperature”) or Xerothermic (“dry temperature”) phase, warmth-loving plants such as Basswood (Tilia) spread further north in England than it does today, Hazelnuts (Corylus) grew north of their present limit in Scandinavia, and the European land tortoise (Emys orbicularis) spread north into Denmark, then disappeared 3,000 years ago. In the central Great Plains of North America, grasslands invaded eastward into the woodland, but have since retreated. Charcoal deposits in swamps reveal that wildfires almost doubled in frequency in the spruce forests around the Great Lakes from 7,000 to 4,000 years ago (Terasmae and Weeks 1979).
In California many xeric or arid-adapted plants spread northward or coastward in California, leaving relict populations behind today: sycamore (Platanus racemosa) went westward into the Bay Area, Honey mesquite (Prosopis glandulosa) northward into the Central Valley, Blue oak (Quercus douglasii) westward into Marin County, and Black sage (Salvia mellifera) northward into the Diablo Range (Axelrod 1981). Treelines in the mountains rose.
The warmest peak passed by about 6,000 years before the present (Goudie 1977). Climate scientists suspect slight cyclic changes in the Earth’s orbit caused this phase, allowing more solar radiation to reach the northern hemisphere in summer (NOAA 2006).
After the intense warming of the Xerothermic interval, temperatures cooled in a slow, oscillatory way, with varying drier and moister phases, approaching our present condition. Short episodes of cold and renewed mountain glaciation have been recorded at about 4,500 years before present (BP), 3,000 BP, and 1,000 BP (Emiliani 1972, Broecker 2001).
The Medieval Warm Period
A warm phase called the Medieval Warm Period from about A.D. 750 to 1200 or 1300 was also recorded in history. Alpine glaciers retreated. Treeline moved upslope again. In Canada fossil forests are found 150 miles north of the present limit, radiocarbon dated at A.D. 870 to 1140 (Goudie 1977). In medieval England grapes were cultivated for fine wines -- and have not been since. Vikings colonized Greenland in wooden ships unhindered by sea ice (Broecker 2001). Maize agriculture by Native Americans spread into favorable areas of the upper Mississippi Valley and Northeast (Goudie 1977). In California and much of the West, however, “epic” droughts hit during this period, apparently harsher and drier than any in the entire Holocene: many streams and springs in southern California dried up, fire frequencies increased in the Sierras, Mono Lake’s level dropped, and people abandoned much of the dry Great Basin and Colorado Plateau (Jones et al. 2004).
Climate researchers argue whether this warm period was widespread across the globe, and some say not enough good records exist to call this a true climatic “phase” (NOAA 2006). But with the onset of the fourteenth century this all changed, and the evidence becomes clearer.
The Little Ice Age
The climate became colder and wetter, and alpine glaciers grew greatly. Sierran glaciers increased, especially during three cold peaks at about the years 1350, 1650, and 1850 (Broecker 2001). Treeline fell, the grape harvests failed in England, not to return, sea ice gripped the coasts of Greenland and the arctic growing season shortened, forcing the Vikings to abandon their colonies there. The regions of favorable corn growing shrank in the prairies as cold, moist weather began to dominate. Frosts on wildly fluctuating cold years killed the olive trees in France (Goudie 1977). This has come to be known as the “Little Ice Age,” lasting from A. D. 1300 to 1850.
In the Sierra, the Dana, Lyell, and McClure Glaciers grew and peaked in size by 1850-55 (Stine 1996). Storm tracks from the North Pacific shifted south in California, as the Polar Jet moved. This caused a high frequency of extreme annual precipitation (big storms hit), increased stream flows in southern California, renewed erosion in the deserts, and caused lake formation on many playas in the Mojave Desert. The Pacific Northwest became drier. Subtropical moisture was also apparently directed northward into the southern Great Basin (Enzel et al. 1991).
This may have played a part in bringing some strange animals into California, such as tropical birds and fish from the south -- let us take a closer look at the birds in particular for clues about how this climatic age differed from ours today.
Seeing the Cycles
John Xantus had an eye for nature. A Hungarian with heavy accent he traveled to America just as the Gold Rush was starting and used his training to describe in vivid detail parts of southern California that have since changed dramatically. The Smithsonian Institution in Washington D.C. learned of his abilities and hired him to collect specimens for the growing catalog of life in the new lands of the country. He was stationed at Fort Tejon as a medic in 1857 and from there he wrote a series of letters about an astonishing array of birds, reptiles, amphibians, and mammals that he observed or collected. Not a small lizard nor a beetle missed his attention. Despite his flowery prose his writings open a window to the past and the view is remarkably broad in scope and detail for so early a date.
I set off to visit Fort Tejon, an Army outpost from 1854 to 1864, now a state historic park along Highway 5 in the Tehachapi Mountains. My goal was to retrace some of Xantus’ explorations. The September day was hazy and clear, hot sunlight drying the grass crisp and turning the buckeyes brown on the north-facing canyonside. Only the native buckwheats flowered white on the dry brushy slopes of scrub oak and mountain mahogany. Standing next to the old barracks and looking up with binoculars into tall valley oaks draped with green grapevines I could see many of the birds that Xantus described so well 150 years ago. They were still here. “Ultramarine” jays (Scrub jays, Aphelocoma californica) and “Red-breasted Carduelis” (House finches, Carpodacus mexicanus) which he called “quite common here” and they still were; Anna’s hummingbirds (Calypte anna) feeding on pink thistle flowers, and the noisy ever-present Acorn woodpeckers (Melanerpes formicivorus) which Xantus saw “in immense numbers” and which were still flocking about the oaks hammering acorns into the trunks for storage.
Collecting through several seasons, Xantus catalogued nests and eggs and made a long birdlist for the area (see Zwinger 1986). But what struck me most were the few anomalies in his observations, that through the myriad changes in names and taxonomy still remained as mysterious -- birds no longer found in the region, or even in the U.S., birds still living but far to the south in Mexico or tropical America.
For instance, on June 5, 1857 he wrote to Professor Baird of the Smithsonian:
“Yesterday I noticed a very important thing. I climbed a three [sic] for a hawks nest and found amongst the young ones a parrots head, feet, and scattered round long blue and red feathers; this circumstance gave me a hint, to hunt for the parrott [sic] and procure him if possible, because to my knowledge there is only one parrott in the U.S. until now known, and the remains in the nest, were decidedly of an other, quite different and larger species.” (Zwinger 1986)
Natural history writer Ann Zwinger thinks it was an escaped pet, but later Xantus writes,
“I am extremely sorry now, that I did not keep the wrecks of the parrot, I find in a nest, and mentioned to you. I see it was carelessness, but to [sic] late to philosophise about now. I never have seen the bird itself, although I heard that around San Gorgonio, and San Bernardino, even on the timbered lands SE of San Diego, they are sometimes met with. I didn’t give up the hope altogether to get one, but the chances are few I see it so well!” (Zwinger 1986)
What did Xantus see? Did native parrots wander up from Mexico in the past? I searched the university libraries for illustrations and descriptions, but none exactly matched. The nearest possibility could be the Thick-billed parrot (Rhynchopsitta pachyrhyncha), which breeds in the mountains of northern and central Mexico, and which historically was noted to wander to southeastern Arizona and southwestern New Mexico in irregular, irruptive movements. Further, the Espejo expedition of 1582-83 noted parrots in northern Arizona. Thick-billed parrots live in oak-pine forests usually in rugged mountain areas, where they feed mostly on pine nuts, but also acorns, agave seeds and even nectar from the agave flowers. They need large dead trees with holes for nesting, although one population uses limestone cliffs. Flocks of 1,000 parrots were noted to wander widely in search of seed crops, which they stripped clean from the pines and then moved on. Although the body color of these birds is green, with a maroon forehead, instead of the “red and blue” feathers described by Xantus, I can only speculate that in the past perhaps large native parrots of some kind did enter the rugged pine-covered mountain ranges of southern California after nut crops, leaving only a few eye-witness accounts as to their presence.
This was not a unique record, however, as many other strange birds were reported in the West before 1900. Xantus also reports seeing Passenger pigeons (Ectopistes migratorius) at Fort Tejon, although Zwinger rightly questions this as being more probably Mourning doves (Zenaida macroura). Xantus was observing many new animals, and some new to science, so care must be taken in interpreting his letters. But these old records should not be tossed out if they disagree with our notions of how things should be or how the past looked. The possibility remains that Passenger pigeons did wander into California before their extinction in the wild in 1899.
On September 10, 1867, a skin of a Passenger pigeon was collected in the Humboldt Mountains of eastern Nevada (Howard 1937) (see map); another skin was procured at Pack River, Idaho on June 17, 1860; two were shot at Spokane Falls, Washington, and more were recorded from Coville and Puget Sound on the coast. Archaeological remains of Passenger pigeons have been retrieved from digs in San Juan County in New Mexico from A.D. 975-1030, and one bone from a Taos site from A.D. 1300-1350. Another bone was recovered from archaic deposits from Stansbury Island in the Great Salt Lake of Utah. They are noted to have been historically “casual in Oregon” (Howard 1955b). Within California, historical reports of Passenger pigeons have been traced to flocks of Band-tailed pigeons (Columba fasciata) according to ornithologist Hildegarde Howard (1937), but she did find definite remains of Passenger pigeons in three different pits of the Pleistocene Rancho La Brea tars of Los Angeles, predating our Holocene study period, but nevertheless indicating that the species did occur in the here prior to 11,000 years ago. Howard gives an interesting clue as she speculates on the western ranges of the once abundant bird: Passenger pigeons might have extended west of their normal range during mesic intervals, such as the periods at A.D. 1100 and A.D. 1335-1425 in New Mexico. California’s extensive oak woodlands with abundant acorns, which the great flocks of pigeons swallowed whole, would be an attraction causing possible flights west.
John James Audubon wrote and illustrated his massive volumes of the Birds of America over the years 1840 to 1844. He could not travel to all parts of the country, so he tried to gather all the reports he could from exploring ornithologists. More mysterious birds showed up in his accounts from California: the “Columbia magpie or jay” which Audubon illustrates from a specimen collected at the Columbia River. It was recorded as also occurring in “the woody portions of Northern California” and from Mexico (Audubon and MacGillivray 1839). This mystery bird is now the Magpie-jay (Calocitta formosa), common today in Mexico and south into the tropics. I saw these dazzling blue birds with dainty feather crests in the Pacific dry tropical forests of Costa Rica one day, a pair hopping about eating nutlets from a tree and making querulous calls in typical jay fashion. Perhaps in Old California they dined on acorns and the miniature avocado fruits of the California bay-laurel (Umbellularia californica).
Then there is the mystery of the giant woodpeckers reported by several workers. Mr. Gould reported that in a “little explored district of California which borders the territory of Mexico” specimens of a woodpecker the size of an Ivory-billed woodpecker were obtained (Nelson 1898). They had a crest of silky feathers four inches long, black in the female and scarlet in the male, and black bristles around the bill (these are white in the Ivory-billed). The back was glossy greenish-black and the wings had large white patches. Not only in California, but in the Rocky Mountains, Townsend saw several of these large black woodpeckers, “very shy,” in tall pines in August of 1834.
Xantus as well saw them in his travels through the San Gabriel Mountains above San Fernando Valley, in lush forests with abundant Nuttall’s woodpeckers (Picoides nuttallii), Acorn woodpeckers, and Red-breasted sapsuckers (Sphyrapicus ruber). He describes them as 27 inches long, iridescent blue and green mixed with black, and wings snow white, “the largest and rarest woodpecker known” (Schoenman and Schoenman 1976).
These specimens and descriptions are of the Imperial woodpecker (Campephilus imperialis), the largest woodpecker in the world and a close relative of the Ivory-billed. Today the species is restricted to remote old-growth pine forests above 7,000 feet in northwestern Mexico, where it may be recently extinct due to logging. It lived in family groups in giant old pines with grassy openings nearby, where it excavated deep pits in bark to find beetle larvae. Thick-billed parrots competed with these woodpeckers for nest holes (Short 1982).
As I reconstructed a possible scene of Imperial woodpeckers in the San Jacinto Mountains of southern California, I thought of the description of these birds by Nelson as he watched them in “one of Nature’s wildest and most secluded regions “ of Mexico:
“They fly from tree to tree with rather slow, heavy wing strokes similar to those of a Crow, and when about to alight, by an added impulse, glide upward along the trunk in a graceful curve and firmly grasp the bark or smooth wood. After a short pause and a glance around, they ascend the trunk in little runs of from one to three feet, with alternating pauses, usually keeping along the main stem of the tree, but when searching for food sometimes traveling out on the larger branches. At such times they were often seen clinging, back down, to the lower side of the branch, chiseling away with powerful blows. Now and then one ‘drums’ for amusement upon a resonant branch or trunk after the manner of many smaller Woodpeckers, but the strokes are much louder and slower than those of other species.” (Nelson 1989).
Perhaps the primeval forest haunts of this shy giant became too disturbed by settlers, miners, lumbermen, and road-builders in the late 1800s, precipitating a large range shrinkage, but I wonder if other reasons caused its disappearance from western North America.
I could list dozens of other out-of-range birds appearing in California in the past, but if this is a pattern what does it mean? Certainly many typically Sonoran birds spill over into southern California and can still be observed, even if not commonly.
Looking at deep time, large-scale climatic fluctuations during the last one million years have caused major changes in the distributions of extant plant and animal species. Full glacial conditions in California caused an overall cooling of 10 degrees Fahrenheit, moister conditions, but also apparently less extremes in temperature -- winters were warmer and summers cooler than today. This allowed a peculiar mixing of northern and southern species whose ranges do not come close during our time. During the Pleistocene, for example, Spruce voles (Phenacomys intermedius) were found well south of their modern range in Canada and the Rocky Mountains, to Arkansas and Tennessee; conversely Capybaras (Hydrochoerus) were found north into Florida during the Ice Ages, animals we normally associate with South American rivers (Kurten and Anderson 1980). These non-analog conditions make paleoenvironmental reconstructions interestingly complex.
The Little Ice Age was a period of worldwide neoglaciation, temperatures cooler by about 2 degrees Celsius, and altered storm tracks. Although little is known of the biological consequences of this climatic phase, historical accounts give evidence of strong cultural impacts. Brian Fagan in his book The Little Ice Age (2000) documents how storms increased off the Atlantic, swallowing up whole parishes in the Low Countries of Europe with sea-flooding, building huge dunes where none had been before.
In the American Southwest climate may have become rainier. At the time of the Gold Rush, California was just coming out of the Little Ice Age and I believe keen naturalists of the day picked up evidence for it. On the cusp of climate change in 1869, John Xantus told of March weather that “rained for weeks in torrents” (Zwinger 1986). Severe snows in February in the mountains had blocked the road to Los Angeles.
Xantus may have seen Mexican birds that ranged north into California with moister conditions. A drying phase followed that culminated in the Dust Bowl years of the 1930s (Millar and Woolfenden 1999). These birds may then have naturally contracted their ranges back to core areas in the tropics or to the monsoonal mountains of Mexico.
Increased Little Ice Age precipitation in the southern California mountains is also recorded in sedimentation rates at Bouton Creek near the mouth of the Los Angeles River: a rapid jump in sediments indicating increased freshwater flows mark the onset of the Little Ice Age at around A.D. 1300. A huge deluge in 1860 was recorded by flood deposits. Freshwater input slowed after this, as the Little Ice Age faded away (Boxt et al. 1999). Most likely an increase in winter storms during this period favored birds colonizing California that we in our brief time of observations would find highly “anomalous.”
The complexity of climate becomes ever more apparent, however, when simply trying to understand the summer monsson of the southwestern U.S. and Mexico: take a look at this web page from the National Weather Service, Albuqurque, New Mexico (pdf), for modeling outlooks on what the 2020 monsoon forecast might be. Cycles overlapping cycles, and teleconnections from ever further regions of the glode impacting the local weather patterns.
These more intense winter storms may be related to the El Niño cycle. During the winter of 1982-1983 storm upon storm beat rain down upon the windows of my house facing the Bay. The rain was fierce I recall -- mudslides slumped down hill slopes, and local streams flooded higher than I had ever seen. This was an El Niño event, when sea temperatures jump in the Eastern Pacific as much as 10 degrees, and equatorial waters flow west. The air pressure drops in the Eastern Pacific, while it rises in the Western Pacific; this was termed the “Southern Oscillation,” and linked with El Niño in the term used to describe the event, El Niño-Southern Oscillation (ENSO).
El Niño years are really the warm extreme of the normal oscillation of winds and sea currents. Cold extremes, or La Niñas, occur when the easterly Tradewinds become stronger across the Pacific. In warm (ENSO) phases the Pacific Northwest, often but not always including northern California, becomes warmer in winter, sometimes drier and sometimes moister. Central California often becomes much rainier in winter. The Southwest becomes cooler and wetter. The Great Basin may have increased summer rains (Ropelewski and Halpert 1990).
These ENSO events show how interconnected our world is: small instabilities in sea surface temperature and convection over the tropical Pacific will impact distant locations and ultimately alter global climate within months. This is called the “teleconnection pattern.”
ENSO events have been recurring with greater or lesser frequency for the entire Holocene. Moderate to strong ENSO events occur about every five to six years, and every 12 to 14 years very strong events happen (Ware 1991). Evidence of giant floods associated with extreme ENSO episodes cycling about every 1,000 years was found in Peru: in A.D. 1325 gigantic floods apparently caused huge trouble for the Inca Dynasty of Nyamlap -- this may have been a worldwide climatic event (Wells 1990).
Sea, Surf and Sardines
Just as changing climate affected birdlife in the mountains and valleys, the warm-cold fluctuations of seawater off California’s coast had drastic effects on fish faunas through time, causing awe-inspiring abundance for fishermen as well as catastrophic declines in commercial catches that have swung the economy of the state. In their world of blue-filtered light illuminating the water column rushing schools of fish responded not only to El Niños and La Niñas, but to even more complex cycles of tropical water phases and frigid periods that reveal how little we know about the climate and its grip on our lives.
Deep-sea fishing in the Santa Barbara Channel was practiced at least since A.D. 500 by the Chumash, who used sea-canoes made of wooden planks (tomols) to chase warm-water swordfish with spears and barbed harpoons. When Euro-Americans “discovered” California’s teeming marine life, the idea of climate change influencing the big game fish (and their small fry prey) was little considered.
In 1889 Dr. Charles Holder, zoologist and sport fisherman from Massachusetts came to Santa Catalina Island, specifically a little hotel at Avalon in a small cove. The fish impressed him. “It was a common sight to see schools of sardines and anchovies being cleverly crowded into the shallow water along the shoreline by ravenous yellowtail and white sea bass,” as fishermen caught them on bait lines to feed to the sea lions and sharks. He thought this waste was appalling and he therefore initiated a “change of consciousness” to start conserving the sea life around the island. Hating “game hogs”who piled up dead animals and fish at their feet, Holder was one of the few American hunters of his time who idealized restraint, cultivating kinship and respect for one’s prey (Starr 1973: 176). He promoted tourism and sport fishing at the “Isle of Summer” and by the 1890s Avalon was booming (Farrior 2004).
The warm waters of certain years brought the famous “leaping tuna,” the Bluefins (Thunnus thynnus), that he found arriving near Avalon in summer in great schools. They fed in breathtaking frenzies, churning the water white. At this time angler “Mexican Joe” changed the original name of the fish “tunny” to tuna. Flocks of California flying fish (Cypselurus californicus) awed the boating tourists, as the little prey leapt out of the water to escape the on-rushes of the tuna. After Holder caught a 183-pound leaping tuna on a modified rod and reel, the anglers came in droves for the excitement, and Holder helped to form the Tuna Club in 1898 in order to protect the game fishes, stopping the “unsportsmanlike conditions” he had encountered (ibid.).
Long time San Diego resident Herbert Minshall (1980) recalled with fondness in the 1920s the beginning of the deep-sea sport fishing adventures out of the south coast. The kelp forests abounded with big game fish feeding on abundant sardines after April when the waters warmed. From “Albacore City” boats took fishermen to barges parked in the kelp beds where rods and reels, or long Calcutta cane poles with piano wires and large hooks were set up. The fishing was spectacular. “Schools of game fish boiled around the barge, competing frantically for the bait,” Minshall recalled (ibid.). Yellowtail tunas (Thunnus albacares) powerfully surged after the sardine bait, and “[s]uddenly the green depths were filled with dark, hurrying shapes with bright yellow tails,” wildly threshing and jerking the rods. Eighteen-pounders were gaffed and pulled on board. The Yellowtails taken from the water were blue-purple and silver on their sides, fading as the fish died. After a lull, a California barracuda (Sphyraena argentea) might then strike at the bait.
At the same time, commercial ships trolled the kelp beds for the big fish. In 1916, 30 million pounds of tuna, mostly Albacore (Thunnus alalunga), were canned in California before the sardine industry took over. As warm-water cycles turned to cold, the sardines declined, and pollution helped to reduce the sport fishing in southern California.
Sometimes the tropical waters returned. During the 1982-83 El Nino swarms of Pacific bonito (Sarda chilensis), small near-shore tunas rarely found north of Point Conception, were seen in San Francisco Bay. In 1997 other unusual fish appeared along the southern and central California coast. Skipjack tuna (Euthynnus pelamis), Albacore, and Sheephead (Semicossyphus pulcher) headed north to Santa Catalina Island. A warm-water El Nino brought tropical exotics such as Mahi mahi (Coryphaena hippurus) as far north as the Farallones Islands, as well as Bluefin tuna and Swordfish (Xiphias gladius). Striped marlin (Tetrapturus audax), usually found in southern Baja, checked out lures by boats off Santa Cruz (Martin 1997).
But countering non-climatic trends continue to operate: a world-wide decline in big ocean fish has been noticed -- the tunas, sharks, halibut, swordfish and others have decreased 90% in numbers since the early days of fishing, and body sizes have become smaller everywhere from the Tropics to the Arctic, even in the middle of the Pacific. The U.S. has at times curtailed overharvesting, but many other countries are still “in denial” about the situation, sometimes stretching nets 60 miles long to catch as much as possible (ABC News, May 14, 2003).
Thus, when fish landings are plotted against sea surface temperatures, White sea bass (Atractoscion nobilis), Bluefin tuna, and Barracuda spike in numbers during warm-water years, but overall have declined due to commercial overfishing. The spikes may be due to increased accessibility of the fish populations, rather than to increased stocks. The exception to this pattern is shown by Swordfish, whose landings increased starting in 1976. As is usual for the natural world in which we are embedded the situation is complex: this date marked both a broad oceanic warming shift, and simultaneously a switch from traditional harpoon-fishing to gill netting for Swordfish, which greatly increased the catch of that in-demand fish (Sund and Norton 1990). Environment and exploitation are sometimes difficult to separate as causes.
The drivers of so many of the big fish populations, such as tunas, are not only ocean temperature, but smaller prey fish numbers, which also fluctuate with climate. The complex ways that species interact with the physical environment, with climate, and with each other have recently become strikingly apparent among some of the world’s most important fisheries, those of the “small pelagics” such as California sardine (Sardinops sardax) and Northern anchovy (Engraulis mordax). These small fish often dominate the open ocean in highly productive upwelling regions, specifically in the California Current. Their historic numbers are the stuff of legend.
“Sardines are reported so abundant in San Francisco Bay that they literally obstruct the passage of boats through the water,” said one observer in 1892 (Skinner 1962). The first West Coast cannery for sardines opened in San Francisco in 1890. This is a pelagic schooling fish, found in bays and open ocean waters, and by 1915 the industry for this species became the largest single fishery in California measured by poundage landed. The peak hit in 1941 -- over a billion pounds were caught off California (ibid.).
South in Monterey Bay an observer in 1891 told how sardine schools darkened the waters just off the beaches for long distances at certain seasons (Gordon 1974). In 1868, another observer described how,
“The number of fish in Monterey Bay is almost incredible.... In 1863, an immense shoal of herrings, from some unknown cause was stranded... along the beach, on the Santa Cruz side of the Bay. They extended for nearly three miles, and were spread to the depth of from six inches to nearly two feet over the entire beach” (Gordon 1974).
Commercial fishing for sardines began at Monterey in 1916, a product of the “Great War” as world sardine imports came to a halt. By 1920 a giant canning industry developed. The packers demanded large fish, so boats went out at night during the two weeks of the darker Moon phases when schools could be easily located in calm water. At night the sardines gave off a pale phosphorescent light as they swam; very dense schools at a distance could be seen as a dull “fire.” Fishermen distinguished the fish by the course they took dashing away from the boat: smelt left undulating snaky trails of light; anchovies darted in short curved dashes; sardines powerfully swam away leaving luminous paths like sky rockets. During the day the schools were located by watching for gulls, Fulmars (Fulmarus glacialis), and shearwaters flying in circles and feeding upon the splashing fish. Then the large Japanese round-haul nets were laid out. After dip-netting tons of fish into the 50-foot boats, the crews made a run back to the cannery (Thompson 1921).
“In the morning when the sardine fleet has made a catch, the purse-seiners waddle heavily into the bay blowing their whistles. The deep-laden boats pull in against the coast where the canneries dip their tails into the bay. The figure is advisedly chosen, for if the canneries dipped their mouths into the bay the canned sardines which emerge from the other end would be metaphorically, at least, even more horrifying.”
-- John Steinbeck, Cannery Row, 1945:1(Bantam Books: New York).
Abruptly in the mid 1940s the sardine population crashed, forcing the closure of these plants in the 1950s (Ware 1991).
What caused the crash? The short answer is that climate change was exacerbated by intense overfishing. But trying to determine how these factors affect economically important fish such as sardines and their waterscape for sustainable fishery management is another story. The deeper researchers go in trying to understand ecosystems and their changes, the more questions seem to come up. Cycles within cycles of climatic variation surface, each influencing the Coastal Upwelling Domain associated with the California Current Ecosystem that extends from Baja California to British Columbia and from 70 to 1600 miles out into the Pacific.
What is upwelling? In the Northern Hemisphere the rotation of the Earth causes the wind-driven surface currents to deflect in a certain direction. Deeper layers of seawater are deflected more slowly, dragging along, and then spiraling back on themselves so that at 300 feet down the currents actually flow in the opposite direction as the surface flow. The top layer of blue-green ocean is pushed away from the coast and is replaced by upwelling of deep cold water (Stowe 1979).
Yearly seasonal cycles in the California Current are dominated by the Aleutian Low Pressure system that brings winter storms, and the North Pacific High Pressure system that brings summer aridity to California. The California Current is generally strongest during the spring and summer (off southern California it is stronger in winter and early spring).
Sardines lay their eggs floating in the upper seawater layers, stirred by he winds and rich with nutrients and plankton, around the inshore areas off Mexico and southern California. But climatic cycles affect them. El Nino events favor the floating sardine eggs and larvae -- upwelling is weakened or turned off, and the pelagic small invertebrates such as tunicates that prey on the tiny new fish are reduced in number by the warmth, allowing more sardines to survive to adulthood. During cold years, when upwelling is strong, sardine eggs and hatched larvae may be “blown out to sea” by the churning currents and lost, and cold-loving planktonic predators are more numerous. Adult sardines migrate north in the summer to feed in the rich waters off the northwest coast. By migrating, the fish can partly overcome the climatic variability that affects their habitat, but the fish’s migratory lifestyle also causes great fluctuations in their distribution. One good year of warm seas is not enough to produce an increase in their population; only many warm years in a row, or an increased frequency in El Ninos will allow the sardine population to surge in numbers (Agostini 2005).
But not only do yearly fluctuations in climate affect the sardines, but interdecadal variation (multi-decade cycles) such as the Pacific Decadal Oscillation (PDO), which was discovered by science in 1996. These long-lived El Nino-like patterns, the causes of which are still unknown, produced a cold phase from 1890 to 1924, and two warm phases from 1925 to 1946 and 1977 to about 1999, when sea surface temperatures increased in the California Current, the number of El Nino events increased, and the Aleutian Low Pressure system deepened and moved eastward, changing winds and currents off California (PDO events last about 30 years). This last warm PDO allowed the sardine biomass to grow again (and did well for swordfish too). Spawning grounds increased north of Point Conception, and feeding migrations moved farther north.
These expansions had great impacts on the local ecosystem structure, for sardines are prey to Yellowtail, Bonito, Tuna, Marlin, Barracuda, Coho and Chinook salmon, sharks, pelicans, cormorants, gulls, sea lions, seals, porpoises, and whales. And Monterey again began to flourish with restaurants serving up the delicious little fish.
In addition, the California Current is variable in its habitats and climatic triggers geographically: south of San Francisco the current may be dominated by inter-annual climatic signals; north of this a seasonal signal appears to dominate. Moreover, different depths of the current are affected differently: the PDO appears to dominate upper layers, while ENSO changes dominate lower down. Some fish appear to be more influenced by interannual climate cycles, while sardines are more affected by interdecadal changes (Agostini 2005). Apparently salmon and flatfish respond more to PDO variations, while White sea bass respond more to El Nino patterns (Hollowed et al. 2001).
And these cycles go back in time. Sea-dwelling micro-algae that leave minute cells buried in the seafloor oozes, known as diatoms, occur in a variety of species that record what the temperatures were in past ages in the Pacific, and can tell a lot about the state of coastal upwelling. Banded layers of ocean sediments off California show that El Nino conditions weakened or turned off upwelling in three to seven year cycles, and that these cycles occurred in variable decadal and millenial cycles back into the Pleistocene (Anderson et al. 1990).
But the Pleistocene world must have been very different as cold dry winds blew from the east off the continent, depositing silt and loess (fine wind-carried “rock flour” produced by runoff from the great glaciers) into the oceans, and apparently no upwelling happened off central California. By 13,000 years ago atmospheric temperatures warmed and summer fogs began to bathe the California coasts with their cool mists. But in the early Holocene upwelling was irregular and often shut off, indicated by the presence of tropical diatoms that favor warmer waters with low nutrient availability (Sancetta et al 1992). By 7,000 years ago the cold upwelling currents fully developed, attracting burgeoning populations of coldwater fish such as anchovies, seabirds, and sea mammals.
The Pacific Ocean may shift in places to a “sardine regime” or an “anchovy regime” with varying sea temperatures and current patterns. Anchovies decline during warm ENSO phases. When sardines are abundant, anchovies are not, and vice versa. Archaeological remains in Peru’s coasts show anchovies were much more abundant 8,000 years ago that today, when El Nino frequencies were less (Sandweiss 2004). Strangely, the reverse pattern happens on the other side of the Pacific in rich waters off Japan, as Japanese anchovies (Engraulis japonicus) increase in warm water climate phases while eastern sardines (Sardinops melanostictus) decrease as they favor colder conditions, in an exact see-saw reflecting the western Pacific (Takasuka et al. 2005).
What happens in California is related to planet-wide climate oscillations. Fishery managers have had to incorporate a more holistic view of marine life, taking into account how species interact with each other, and knowledge of the physical environment they occupy -- this is quite a challenge. Habitat is a dynamic entity, whose boundaries change with climate, and climate is still not well understood. Simply to try to predict the levels that sardines can be fished, managers may need to start looking at multispecies communities embedded in ecosystems that are constantly changing in unpredictable ways. There may exist what ecologists call “multiple alternative steady states,” many ways an ecosystem can run smoothly and sustainably.
“The farther backward you can look, the farther forward you are likely to see.”
"We have deep traditional knowledge of the atmosphere, your position on Earth, and the fish."
--Frank Lake, Karuk Tribe craftman, scientist, Research Ecologist with the U.S. Forest Service. Klamath TREX 2019.
Anthropogenic Climate Change
Yet another long-term climate pattern has been recently recognized, one that shifts warm-water fish northwards and reduces coldwater species. Sardines have been labeled “sentinel species,” because they are so sensitive to temperature, and can help alert humans to changes sooner than other measures. They can help us to understand climate-ecosystem links, a net in which we are unavoidably enmeshed. Key to this is observation, watching the changing ocean habitats, but also other sensitive landscapes such as ice sheets.
By the 1880s the Sierran glaciers were in full retreat as the Industrial Revolution swung into high gear and greenhouse gases filled the skies. The Palisades Glacier alone during the years 1933-38 thinned 27 feet (Stine 1996), and continues to shrink today. The 20th century experienced a steep warming trend that culminated in the warmest decade since temperature measurements were begun in the mid 1800s. All ten of the warmest years in the global record occurred in the 1990s, and include the warmest six years since people started using the thermometer for weather observations (NOAA 2006).
What’s more, the consensus among climate scientists is that these unusually high temperatures have not been matched in the distant past. Temperature curves reconstructed from proxy data (such as tree rings and sediment records) show that the last 15 years have been the warmest the Earth has seen in the last 1,000 years, and possibly the last 2,000 (NOAA 2006) -- warmer than the supposed Medieval Warm Phase -- and beginning to match the heat of the mid-Holocene Xerothermic period. But our current warm epoch is not due to orbital changes as was the Xerothermic. Temperature extremes have also increased, as well as extreme weather surges such as Polar Vortex events, where intense cold dips down in winter below the Arctic Circle. So what is going on here?
Understanding climate change is very difficult, and researchers speculate through the ever-present mantra “more work is needed.” Often theories seem to boil down to a battle of computer models, which differ radically. So many complicating factors feed into the system that trying to measure them all through a long enough time to see patterns is tough. But strides are being made. In recent years longer and finer ice cores are pulled out of Greenland and Antarctica, allowing a greater understanding of paleoclimates.
“Climate Chaos” has come to be recognized as due to the artificial input of carbon dioxide into the atmosphere from fossil-fuel burning beginning in the Industrial Revolution and lately from car exhaust too. As I sat one day and watched CSPAN, a House committee argued about whether the warming was natural or human-caused, whether we are seeing natural climatic and carbon dioxide cycles, or human-generated increases. Susan Solomon, one of the panel of climate scientists, pointed out that the human signature is quite clear: the particular isotope of carbon recently building up in the atmosphere comes from the burning of fossil fuels, differing from the carbon isotope that comes from natural sources such as forest fires and volcanoes (U. S. House Science and Technology Committee 2007). Drastic graphs of atmospheric CO2 rising well beyond the normal cycle for the last 400,000 years, disobeying the predicted glacial-interglacial fluctuations found in deep ice cores, have been widely shared in the media. The anthropogenic causes of this current climate change seem clear to me, and possibly caused the end of the Little Ice Age.
Yet the climate in California has seen huge fluctuations in the past, both historic and ancient. Global extinctions currently are largely driven by habitat destruction, development, and resource extraction, on top of climate threats. Renewable energy project development and long high-voltage transmission lines on pristine natural habitats and public lands is not the answer to curtialing carbon emissions and conserving species. As I tell my audiences during my talks, we need much more information on how to adapt to an always-changing world--including looking at energy efficiency, energy conservation, and renewable energy policies and technologies that favor Distributed Energy Resources and microgrids in the built environment. Any Green New Deal should include environmental justice and equity policies, as well as maximize the conservation of our last natural lands and habitats.
Climate Clues From the Grinnell Method
Subtle changes are continuing to happen due to Climate Change. Models aside, changes are occurring that only good old-fashioned naturalists have deduced. I have been told by certain modern biologists that the study of natural history is passé, that genetic research is all the rage -- but this is mostly lab-work. Only by spending hours, days, weeks in the field can important trends in our changing landscape be seen. Lab work is also very important, but is founded on base studies in the natural world.
I continually recogize how imprtant teaching is in a long line of traditional knowledge bases founded by remarkable individuals and upheld by oral and written traditions that imprint on students. Native tribes used this method of Traditional Ecological Knowledge passed on through the oral tradition over thousands of years, with very accurate memory stores. More recent teaching institutions can similarly pass on traditions of knowledge, using oral, written , field work, and digital media.
I am only recently realizing the scientific tradition that I happened to be rasied in, and am grateful to have received the experience and knowledge from this important scientific method.
Annie Alexander (1867-1950) was way ahead of her time. She was a great natural historian, and amazing explorer of the remote and biodiverse western landscapes, and patron of science creating entire institutions before women even had the right to vote. She had the means to endow a new instiution: the Museum of Vertebrate Zoology at the University of California, Berkeley, and she chose Joseph Grinnell as its director.
Grinnell proceeded to survey species along huge transects across the Sierra Nevada, Mojave Desert, and the Great Basin from 1904 to 1940. He was seeing, already nearly a century ago, changes to the biota of the mountains, and he had the patience to begin the careful collecting and recording of data that he knew would be useful 100 years in the future. He was right. In 2003 the staff of the Museum of Vertebrate Zoology, including mammalogist Jim Patton, launched a Resurvey project of Grinnell’s localities. I was fortunate to join them.
I had taken Jim Patton’s class years ago at Cal where we tried to keep up with him on field trips as he marched up the steepest hills with great endurance, and tirelessly set traplines through forest and brush. We set hundreds of rodent live-traps consisting of small metal boxes baited with oats; as a kangaroo rat or pocket mouse entered the door that night it stepped on a hinged plate that triggered the door to snap shut behind it. The next morning we weighed each rodent and took measurements of such anatomical parts as the hindfoot and ear, which aided in identifying the often similar-appearing species. We recorded our notes in the same design of field book developed by Grinnell during his surveys.
Now Dr. Patton was trying to locate as exactly as possible Grinnell's old study sites, and then spending days camping there and resurveying the small mammal fauna just as Grinnell had done more than a century ago.
This is a beautiful example of a repeat science project to compare evidence gathered in about the same location and using the same methods, by the same institution--the Museum of Vertebrate Zoology, where I had studied. I was honored to participate in the Resurvey efforts near Death Valley National Park.
Read more on the Death Valley Resurvey Project in an article I wrote for the desert journal El Paisano, February 2018, page 4--PDF here.
Participating in this survey in the field made me realize there are more questions than answers concerning climate change impacts. We need much more research in order to see the way forward based on science, and not oversimplify models of how California wildlife and plant communities will react.
For example, the case of the Death Valley pronghorn antelope herds migrating south deserves more study.
Park staff started to observe something unusal in 2020: pronghorn antelope appearing in the park, where none had been seen. I too started observing more antelope south of core areas in west-central Nevada, seemingly migrating southward to take advantage of abundant wildflowers produced by good late winter rains at 3,000 feet elevation and above.
Instead of moving north with climate change, the situation appears to be more complex. Geographic pockets of rainy conditions and green vegetation patches may attract animals that can travel to them across long distances. The pronghorn may have ancient lineages of memory about such places, and we are only beginning to see and undertand these patterns. The Los Angeles Times sent a reporter and photographer up to look into this mystery.
See my field notes about these Death Valley pronghorn populations, and more about their behavior that is so well-adapted to arid regions, in the Antelope Chapter.
This underscores the importance of gathering data that anyone can collect with a notebook and pen for future generations. What will the natural world be like in the future? Climate change is a very complex subject, and only on-the-ground observations, notes, and scientific surveys will tease out the current fall out and lead to better-informed decisions for the future.
Into the Future
Paleoclimatic information can help us try to understand how climate change effects our world today and in the future, but we are racing far beyond the natural range of variation for CO2 levels known. Thus what is not yet known is where this trend is going. What will the climate be like in 100 years? Some climate scientists have modeled the next century for California as having a 3 degree F rise in temperature, depending on CO2 emission rates. Central California may have warmer, wetter winters, with increased ENSO activity, and slightly warmer summers (Dukes and Shaw 2007), but the rainfall trend is difficult to know. The Mojave Desert might have increased rainfall as well.
Will this wildly high carbon level lead us into a period of epic droughts in the western U.S.? Will warming sea surface temperatures intensify storms and rain events? Or will polar freshwater melting trigger the next Ice Age because of changes in ocean current circulation patterns? Those teleconnection patterns are still too complex to predict.
As we have seen, animal and plant ranges change with climate change, and this will most likely happen in the future, although with attendant difficulties because of habitat destruction, fragmentation, and loss of migration corridors that have gone hand-in-hand with global industrialization. Humans too, will undergo difficult changes, as history and prehistory have indicated. Observing and understanding the changing landscape we live on so that we may adapt with it may be our best survival behavior.
The new COVID-19 reality focuses our attention squarely on habitat destruction, species extinction, and poaching of wildlife as central forces that highlight how conserving wildlands is extremely important to human survival. Zoonotic diseases that jump from wildlife to humans have been with us for thousands of years. That bats may have harbored the virus that jumped to humans in 2019 and currently grips the planet in an anthropogenic pandemic in 2020, highlights the necessity to view habitat destruction and capturing wildlife into public meat markets, where animals such as bats are stressed and may have exfluxed the virus outwards onto humans, as serious threats we currently deal with.
Climate change and the global coronavirus pandemic look to me right now looks like symptoms of a fundamental lack of understanding of basic natural history. Observing the health of natural systems is ever more linked to human popluation health, and we ignore this at our peril.