I was looking at a posting at IceAgeNow.info that was talking about Texas:
A little overstated, but it got me wondering… What evidence is there that Texas has a change of climate / long duration weather patterns, other than some narratives of early Spanish explorers saying it was cold? Turns out, there is. But first, some bits from the two links that are in that article.
“What do floods in Texas have to do with the coming Ice Age?” asks reader Caroline Snyder.“Quite a lot actually!“Looking at the historic record, we only have to go back to the 16th Century; a time when the Little Ice Age was causing devastation across Europe, but what of the South-West US?“This article, amongst other things, looks to first hand accounts by Europeans amongst other things.
This article is about 3 pages long, so lots more than I’m going to quote.
The Little Ice Age
Sure, It’s a Little Chilly in Here, but…
by Jay Sharp
OK, so it can get pretty nippy in the desert basins of the Southwest in the wintertime. Temperatures fell to nearly 10 to 15 degrees below zero Fahrenheit in western Texas and southern New Mexico – the northern Chihuahua Desert – in 1962. Temperatures dropped to zero in southern Arizona – the northern Sonoran Desert – back in 1913. The thermometer fell into the mid-twenties in the southern tip of California, in the northwestern Sonoran Desert, in 1971 and again in 1990. The temperature even got down to eight degrees at Trona, a community near Death Valley, in the Mohave Desert, in 1990. Occasionally, a foot of snow may fall in some parts of our Southwestern deserts.
In the Southwest, suggests Steven A. LeBlanc (well-known archaeologist with the Peabody Museum of Archaeology, Harvard University), the Puebloan Indians of the Four Corners region, the northern Chihuahuan Desert and the northern Sonoran Desert had to abandon old homelands and migrate to more favorable locations, such as the better-watered upper Rio Grande drainage basins. In some areas, Pueblos fought each other over control of the substantially reduced arable land, water, game and firewood.
This statement about the Pueblo Indians looking for places with more water is a bit in opposition to the article that started this chain that asks if the added rain and floods in Texas mean anything, but we’ll press on. It is speculative just why they moved anyway.
From the time the Europeans and their descendants began arriving in the Southwest in the 16th century, they would often speak of the icy winters.
In December, 1540, Francisco Vásquez de Coronado’s conquistadors had to halt their march to wait out a winter storm near the New Mexico/Arizona border, not far from the Zuni pueblos. “…during the ten days that the army was delayed,” said chronicler Pedro de Castañeda, “it did not fail to snow during the evenings and nearly every night, so that they had to clear away a large amount of snow when they came to where they wanted to make a camp… It was a dry snow, so that although it fell on the baggage and covered it for half a man’s height it did not hurt it. It fell all night long, covering the baggage and the soldiers and their beds, piling up in the air, so that if any one had suddenly come upon the army nothing would have been seen but mountains of snow. The horses stood half buried in it…”
On December 9, 1775, Lieutenant Colonel Juan Bautista de Anza led a caravan of Spanish colonists across the desert sands of southern California into the teeth of a fierce winter storm. “…the sierras through which we had to travel were more deeply covered with snow than we had ever imagined would be the case,” said Anza in his diary. The weather “had been very hard on our people, especially the women and children… …several persons were frozen, one of them so badly that in order to save his life it was necessary to bundle him up for two hours between four fires,” he said. “…several persons were frozen to the point of being in danger of death.”
In 1841, two decades after Mexico’s successful revolt against Spain and several years before the war between the United States and Mexico, the Mexicans captured a sick and exhausted Texas expeditionary force in eastern New Mexico and, during the following winter, sent it under guard in a tortuous trip down the famed Chihuahua Trail through southern New Mexico and to imprisonment in Mexico City. At the caravan’s encampment beside the trail where it entered the Chihuahuan Desert, the winds grew “biting and chilly,” according to George W. Kendall in his Narrative of the Texan Santa Fe Expedition, “but at midnight the weather moderated, and then commenced a violent fall of snow…
“When morning light came I raised my head and surveyed the scene. Far as the eye could reach the face of nature was clothed in white, the snow having fallen to the depth of five or six inches. My companions were lying thick around me, their heads and all concealed, and more resembled logs imbedded in snow than anything else to which I can compare them…”
In 1858, a San Francisco Daily Evening Bulletin Special Correspondent, who rode John Butterfield’s stage from San Francisco to St. Louis in 1858, said that as his coach approached western Texas’ Guadalupe Mountains on a cold November day, “…we were informed by the driver that we were near a lay of sand four miles in length, and that we must walk through if we expected ever to arrive at our next station…the Pinery… Scarcely had we commenced our tramp on foot, before the young moon was veiled in a fleecy mist, which came down upon us poor devils and continued to play away upon our dusty hats and blankets until we had plodded our weary way four miles through the deep and heavy sand…”
In February of 1862, during the Confederate force’s march northward up the Rio Grande from Fort Thorne, north of Doña Ana, to the Civil War Battle of Valverde, in central New Mexico, Private William Randolph Howell noted in his journal, published by Jerry D. Thompson in Westward the Texans, “Ice floating down river. Water almost too cold to drink.” Rebel trooper Ebenezer Hanna said in his journal that a sleet and snow storm blew “so hard as to almost pelt the skin off our faces,” according to Don E. Alberts in Rebels on the Rio Grande.
OK, it can be cold in Texas and even on down into Mexico. Though ice on the Rio Grande seems a bit much.
The other link leads to a story of Cabeza de Vaca and an expedition that had his group effectively as slaves of servants to some Indians, and his complaints about being cold. Interesting, yes, but not exactly the stuff of ice ages, though.
More Academic Evidence
So I went looking for less anecdotal and more academic evidence for some connection of water / rain / precipitation levels and the Little Ice Age and / or a 1500 year periodicity.
I’ve bolded a few bits.
7000 Year Climate Record Shows Century-Long Droughts in North America and 1500 Year Solar Cycle
by Paul on August 20, 2008 in Uncategorized
A stalagmite in a West Virginia cave has yielded the most detailed geological record to date on climate cycles in eastern North America over the past 7,000 years. The new study confirms that during periods when Earth received less solar radiation, the Atlantic Ocean cooled, icebergs increased and precipitation fell, creating a series of century-long droughts.
A research team led by Ohio University geologist Gregory Springer examined the trace metal strontium and carbon and oxygen isotopes in the stalagmite, which preserved climate conditions averaged over periods as brief as a few years. The scientists found evidence of at least seven major drought periods during the Holocene era, according to an article published online in the journal Geophysical Research Letters.
“This really nails down the idea of solar influence on continental drought,” said Springer, an assistant professor of geological sciences.
Geologist Gerald Bond suggested that every 1,500 years, weak solar activity caused by fluctuations in the sun’s magnetic fields cools the North Atlantic Ocean and creates more icebergs and ice rafting, or the movement of sediment to ocean floors. Other scientists have sought more evidence of these so-called “Bond events” and have studied their possible impact on droughts and precipitation. But studies to date have been hampered by incomplete, less detailed records, Springer said.
The stalagmites from the Buckeye Creek Cave provide an excellent record of climate cycles, he said, because West Virginia is affected by the jet streams and moisture from the Gulf of Mexico and the Pacific Ocean.
So a 7000 year record ought to cover at least 4 cycles. A few years resolution is darned good. Now it says 7 drought periods, and that’s more like one every 1000 years, so I’m wondering about that 1500 year cycle. Then again, I’ve speculated that there are sub-harmonics of it with 750 or so year periods.
Strontium occurs naturally in the soil, and rain washes the element through the limestone. During dry periods, it is concentrated in stalagmites, making them good markers of drought, Rowe explained. Carbon isotopes also record drought, Springer added, because drier soils slow biological activity. This causes the soil to “breathe less, changing the mix of light and heavy carbon atoms in it,” he said.
Gee… C12 / C13 ratios can change even without humans burning oil….
The data are consistent with the Bond events, which showed the connection between weak solar activity and ice rafting, the researchers said. But the study also confirmed that this climate cycle triggers droughts, including some that were particularly pronounced during the mid-Holocene period, about 6,300 to 4,200 years ago. These droughts lasted for decades or even entire centuries.
Though modern records show that a cooling North Atlantic Ocean actually increases moisture and precipitation, the historic climate events were different, Springer said. In the past, the tropical regions of the Atlantic Ocean also grew colder, creating a drier climate and prompting the series of droughts, he explained.
And here we have a bit of a confounder on drought vs hot or cold. “Modern” records have cold / wet, while the paleo record has cold / dry. There is a pattern in the Sahara where during the mid-holocene period it became very wet too. That would be the hot / wet and cooler / dry pattern. So this might just indicate something like a shift of where the rain bands fall, or that there is a larger shift with greater cold. At any rate, it’s a loose end. But this isn’t Texas anyway… which is what I’d started wondering about.
The story has 2 links in it that specify particular articles, but on landing on the site, you just get the top page; so I can’t explore those articles at this time.
The one that looks like it is for the stalagmite paper has the abstract quoted, so I’m going to paste that all here (once things start breaking, like links, I like to preserve what I reference if possible). I’ve added some white space and bolded some bits to make it more readable.
Solar Forcing of Holocene Droughts in a Stalagmite Record from West Virginia in East- Central North America
Elevated Sr/Ca ratios and δ13C values in Holocene-age stalagmite BCC-002 from eastcentral North America record six centennial-scale droughts during the last five North Atlantic Ocean ice-rafted debris (IRD) episodes, previously ascribed to solar irradiance minima. Spectral and cross-spectral analyses of the multi-decadal resolution Sr/Ca and δ13C time series yield coherent ~200 and ~500 years periodicities. The former is consistent with the de Vries solar irradiance cycle. Cross-spectral analysis of the Sr/Ca and IRD time series yields coherent periodicities of 715- and 455-years, which are harmonics of the 1,450±500 year IRD periodicity.
These coherencies corroborate strong visual correlations and provide convincing evidence for solar forcing of east-central North American droughts and strengthen the case for solar modulation of mid-continent climates. Moisture transport across North America may have lessened during droughts because of weakened north-south temperature and pressure gradients caused by cooling of the tropical Pacific and Atlantic Oceans. across the region throughout much of the year. As such, hydroclimates of eastern NA are dually sensitive to the climate state of the North AO and mid-latitude transcontinental teleconnections linking the Pacific and North Atlantic oceans [McCabe et al., 2004; Seager, 2007]. Herein, we demonstrate that this dual dependency allowed an east-central NA paleoclimate archive (speleothem) to directly record solar-forcing of Mid- to Late Holocene droughts that were caused by weakening of moisture transport over east-central NA in response to cooling of the Pacific and Atlantic Oceans.
Seven significant Mid- to Late Holocene droughts are recorded in West Virginia stalagmite BCC-002 as elevated Sr/Ca ratios and δ13C values. Six droughts correlate with cooling of the Atlantic and Pacific Oceans as part of the North Atlantic Ocean ice-rafted debris cycle, which has been linked to the solar irradiance cycle. The Sr/Ca and δ13C time series display periodicities of ~200 and ~500 years and are coherent in those frequency bands. The ~200-year periodicity is consistent with the de Vries (Suess) solar irradiance cycle. We interpret the ~500- year periodicity to be a harmonic of the IRD oscillations. Visually, the Sr/Ca and IRD time series show strong correlations and cross-spectral analysis of the Sr/Ca and IRD time series yields statistically significant coherencies at periodicities of 455 and 715 years. These latter values are very similar to the second (725-years) and third (480-years) harmonics of the 1450±500-years IRD periodicity [Bond et al., 2001].
Collectively, these findings and a 1,200-year periodicity in the Sr/Ca time series, demonstrates solar forcing of droughts in east-central North America on multiple time scales. Droughts typically occur during solar minima when SST in the Atlantic and Pacific Oceans are comparatively cool. These SST anomalies cause migration of the jet stream away from east-central NA, yielding decreased meridional moisture transport and reduced convergence over east-central NA. Our findings appear to corroborate works indicating that millennial-scale solar-forcing is responsible for droughts and ecosystem changes in central and eastern North America [Viau et al., 2002; Willard et al., 2005; Dennison et al., 2007], but our high-resolution time series provide much stronger evidence in favor of solar-forcing of North American drought by yielding unambiguous spectral analysis results.
This looks to be the paper that talks about a 1500 year cycle in West Virginia:
Solar forcing of Holocene droughts in a stalagmite record from West Virginia in east-central North America
Gregory S. Springer,1Harold D. Rowe,2Ben Hardt,3R. Lawrence Edwards,3and Hai Cheng3
Received 9 June 2008; revised 1 August 2008; accepted 8 August 2008; published 10 September 2008.
Elevated Sr/Ca ratios and [sigma]13C values in Holocene-age stalagmite BCC-002 from east-central North America record six centennial-scale droughts during the last five North Atlantic Ocean ice-rafted debris (IRD) episodes,previously ascribed to solar irradiance minima. Spectral and cross-spectral analyses of the multi-decadal resolution Sr/Ca and [sigma]13C time series yield coherent ~200 and ~500 years periodicities. The former is consistent with the de Vries solar irradiance cycle. Cross-spectral analysis of the Sr/Ca and IRD time series yields coherent periodicities of 715-and 455-years, which are harmonics of the 1,450 ± 500 year IRD periodicity. These coherencies corroborate strong visual correlations and provide convincing evidence for solar forcing of east-central North American droughts and strengthen the case for solar modulation of mid-continent climates. Moisture transport across North America may have lessened during droughts because of weakened north-south temperature and pressure gradients caused by cooling of the tropical Pacific and Atlantic Oceans.
Citation: Springer,G. S., H. D. Rowe, B. Hardt, R. L. Edwards, and H. Cheng (2008),Solar forcing of Holocene droughts in a stalagmite record from WestVirginia in east-central North America,Geophys. Res. Lett.,35,L17703, doi:10.1029/2008GL034971.
This seems to show proof of a solar driven shift to a meridional jet stream and to modulation of water patterns with drought showing up in the East during cold periods of low solar output.
I also note that they find both cycles close to the 2nd and 3rd harmonics of the 1470/1500 year cycle. One of them being the same period I observe as Half Bond Events in historical records. (And where I think the Little Ice Age was one such, as we had a doozy of a cold period in Bond Event 1 in The Dark Ages starting in about 540 AD.)
There’s a little more cycle-mania here than I care for, what with 200 (208?), 500 (455/480), 715 (725), 1450 (1470 / 1500) but +/- 500 per Bond, so could be 950, 970, 1000, 1950, 1970, 2000 years… but in a stochastic resonance system, you can have such harmonics and “jitter” of actual trigger of events.
The “big deal” is that there is a clear solar change / climate change connection shown, and it is shown to have both full Bond Event and Half Bond Event cycles (with the potential for a 1000 year cycle of some degree). Since all of those are seen in the actual data and history, it’s nice to see them reflected in the facts in the dirt.
There’s a lot more folks finding the 1500 year cycle too. This site has a PDF listing 400 such papers:
Hundreds More Scientists Have Found the 1,500-Year Climate Cycle
Posted on March 3, 2008 by cgfi
Hudson Institute, Washington, D.C., March 3, 2008:
The following list includes more than 400 additional qualified scientists, with their home institutions, and the peer-reviewed studies they have published in professional journals, which reveal evidence of the moderate 1,500-year Dansgaard-Oeschger cycles. Together with a previous list released by Hudson on Sept. 12, 2007, this brings the total of scientific researchers who have published evidence of this natural cycle to more than 700. The lists also include dozens of authors who have published studies on the linkage of the 1,500-year cycle to variations in solar activity.
All of which makes me think we can depend on it existing.
Personally, I think it is a lunar / tidal driven event that is synchronized with solar slow periods via orbital resonance effects. So we get correlation with solar, but nobody can show the physical link. Orbital resonance is a Very Big Thing in the solar system with darned near everything in some kind of resonant relationship. So the gas giants perturbing the sun into hot / cool cycles also perturb the lunar / earth orbits in the same pattern over time.
But that still doesn’t get me back to Texas…
This link has a pop-up ad for a book, but hitting reload seems to make it go away without that dangerous ‘click’ to activate anything. Texas State Historical Association, so not a lot of risk anyway. I’m going to quote the whole top page just because I think pop-ups are evil and I want to save folks the annoyance. I’m adding some white space and bolding a few bits, as I usually do.
PALEOENVIRONMENTS. Changes in Texas vegetation during the past 30,000 years offer us clues about climatic changes, about the animals that once lived here, and about the hardships the earliest Texans, the Paleo-Indians, had to face in their daily quest for food and shelter. The remains of ancient plants yield the most reliable information about past vegetation. Unfortunately, most soils in Texas are unfavorable to plant preservation. In most of the state the less resistant plant parts decompose quickly after they are buried and leave no visible traces. Through the techniques of phytolith (plant crystal) research, through palynological investigation (see POLLEN), and through evidence from other fields, however, we can now assemble a rough conjectural view of the major vegetational changes in Texas during the past 30,000 years.
The years 30,000–22,500 B.C. were an interlude between two major glacial periods in North America. During this time conditions in Texas were stable and favorable. Pollen records from deposits in West Texas reveal that at first most of the area north and west of Austin was covered by a large prairie and few trees. Grasses dominated the land, and pine, juniper, Douglas fir, and spruce trees were restricted mostly to the higher elevations of the Guadalupe, Davis, and Chisosqv ranges. The prairie of the Edwards Plateau probably supported stands of juniper and piñon in some higher and more protected habitats.
The probable climate of West Texas in this period was cooler and wetter than today, with fewer temperature extremes. Pollen evidence suggests that minor climatic fluctuations occurred. These are reflected in the fossil record by cyclical increases and decreases in the proportion of tree pollen to pollen from other plants. Some cycles lasted several thousand years and suggest that at times large islands of pine and juniper invaded the grasslands. Prairie remained dominant in West Texas for this entire period, however, and provided grazing for many species of now-extinct animals. Knowledge about the early vegetation of the same period in Central, South, or East Texas is limited. An extensive oak-hickory-pine forest probably dominated East Texas, but its western limit is unknown. It probably extended as far west as Huntsville.
Research indicates that during this early period much of the currently forested regions in the central United States was covered by vast prairies marked with patches of shrubs. It is possible that this vegetation pattern extended through Central Texas as far south as San Antonio. Other research, however, suggests that a vast oak-hickory-pine forest extended across the southern United States and terminated somewhere in East or Central Texas. South Texas from San Antonio west to Del Rio and south to Mexico was probably covered by a mosaic of grassland and prairie interspersed with islands of shrubby oaks. But even minor changes in the amount of rainfall could have changed the vegetation quickly.
So to me it sounds like a pretty nice place even during the Ice Age Glacial. Though they are saying that this particular part was a warm spike inside the glacial. I take that as cooler than today, but not as cold as the flat out glacial. Still, it looks like Texas does well in a glacial. (All you Canadians, “Come on down!”… in a few hundred or thousand years when the ice sheet builds up…)
Between 22,500 and 8,000 B.C. changes in world climates led to a buildup of large continental ice sheets in North America that reached their maximum growth around 20,000 years ago.
Now this is just sloppy. First off, mixing BC and YA. Second, having a “things happened” ending in the START of this period and right near the end of the last period. Ice doesn’t just show up in a year, so this ought not be stated as a point effect. Oh well. So it’s 18,000 BC that the ice sheet was greatest, or about 4000 years into this period, then it shrinks… maybe…
The disruption of wind patterns and the cooling influence of such large masses of ice in North America affected the vegetation and climate of the whole continent. In Texas the average annual temperature dropped to about five degrees centigrade cooler than it is today. The difference that this made would be equivalent to the difference between the climate in Uvalde, in South Texas, where summers are hot and dry and where it rarely freezes, and that in Lubbock, in the Panhandle, where summers are cooler, winter days are freezing, and snows are frequent.
Pollen records from West Texas suggest that as this period began, the cooling reduced evaporation and led to the formation of large playas in many areas of West Texas. The resultant cooler and wetter climate encouraged existing forests and produced parklands. The spruce, juniper, Douglas fir, and pine forests of the West Texas mountains expanded downward to lower altitudes and spread out onto the mountain flanks, where they mixed with grasslands to form parklands and savannas. These changes produced a perfect habitat for vast numbers of now-extinct giant herbivores, including mastodons, mammoths, horses, Pleistocene bison, and camels.
The oak-hickory-pine forests of East Texas probably did not expand significantly during this period. However, the dominant species of trees probably changed somewhat. Pollen records show that from about 22,500 to 12,000 B.C. the cooler-weather oak, elm, spruce, maple, hazelnut, alder, and birch may have dominated the forests. Likewise, atmospheric conditions in East Texas during this period were like those in West Texas. The existing vegetation in South Texas during this period did not change significantly. Areas of oak and juniper parklands expanded in the northern portion of the region just south of San Antonio, and the drier regions near the Mexican border filled with lush grassland. Vegetational variations were caused primarily by cycles of drought and wet years.
So Texas looks like the place to be during an Ice Age Glacial. Nice to know. So folks worried about the loss of farm land in north Canada can just look to the desert areas of Texas and the scrub lands for new places to farm, then. Next, what happens as the ice melts up north?
During the last few thousand years of this period the large glaciers receded as the North American continent warmed. By 10,000 years ago the ice sheets were gone; the path of the jet stream probably moved northward to bring warmer and drier winds to much of Texas. In West Texas the large playas dried, and the forests of pine, Douglas fir, and juniper contracted until they were again confined only to the protected mountain summits. Spruce disappeared entirely. The pine and juniper trees that once formed the prairie parklands also disappeared. Once again the West returned to a giant, uninterrupted grassland. Around the lower Pecos area of Southwest Texas the canyons and protected hills lost most of their piñons and junipers, and many desert plants presently found in that region, such as cacti, agave, yucca, and sotol, were already becoming quite common.
The vegetation on the rolling hills of the Edwards Plateau in Central Texas changed during the last few thousand years of this period from a dominance of piñon and juniper to a dominance of scrub oak and juniper. East of the Balcones Escarpment the forests lost most of their cool-loving species between 14,000 and 8,000 B.C. Alder, maple, spruce, and hazelnut disappeared entirely from the East Texas forests. Most of the birch species also disappeared from these forests, leaving behind only small patches of the warm-tolerant river birch. Basswood, dogwood, chestnut, and a few other forest species that grow best in cooler, wet habitats did not disappear entirely but were reduced to minor components in the new deciduous forests. Expanding into these forests were the species that now dominate them-new species of oak, hickory, walnut, pecan, sweet gum, and elm. Loblolly pines also may have expanded their numbers around 8,000 B.C. Yet many scientists believe that the dominance of pines in East Texas is fairly recent.
By 8,000 B.C. the vegetation in South Texas probably looked much as it does today and as it had before 30,000 B.C.-a mosaic that changed in wet and dry years. Moisture controlled how much of the region became oak shrubs, grassland, or semidesert.
So when it is warm, Texas is hot, and West Texas drys out and becomes more scrub. Yet they mention changes with wet / dry years. We have some cycles and oscillations. They start off at 2500 years ago in 500 BC with a cooling turn. Then they speculate about why and how… but do recognize that several (many?) “brief climatic reversals” happen regularly.
The fossil pollen record reveals that the Texas climate has become progressively hotter and drier through the last 10,000 years. During that time a number of minor climatic oscillations have occurred. Around 500 B.C. West and Southwest Texas underwent a notable cooling that allowed the forests of West Texas to expand downslope and also encouraged the southward expansion of the lush grasslands of the Southern High Plains. This expansion reached the Rio Grande and was widespread enough to encourage large herds of bison to range freely as far south and east as Langtry and Del Rio.
Like most of the brief climatic reversals of the last 10,000 years, the one in West Texas was probably triggered by changes in the weather such as unusually strong hurricanes, which could have carried large volumes of water farther inland than usual; changes in ocean currents that could have caused phenomena like el niño off the coast of Chile; changes in the path of the continental jet stream that could have brought cooler or hotter surface temperatures; or localized weather changes that produced regional droughts.
Each climatic oscillation during the last 10,000 years was brief, and most were restricted in area. By 8,000 B.C. West and Southwest Texas vegetation probably consisted of prairies extending in an unbroken wave north of a line running from the site of San Angelo to that of El Paso. South of this line the vegetation consisted of a graded mosaic beginning with mixed scrub and grasslands then changing to scrublands, and ending with patches of semidesert south of a line from Marathon eastward to the edge of the Edwards Plateau. As today, moisture was the single most critical influence on the vegetation of West Texas.
In South Texas little changed during the last 10,000 years, though various vegetational components expanded or contracted. The scrub oak parklands that for thousands of years had been the dominant vegetation in areas south of San Antonio began to disappear, for example, and soon were restricted to their present moist areas. Scrublands of mesquite, acacia, and cactus expanded into the areas once covered by oaks, and throughout South Texas desert succulents such as agave, yucca, sotol, and cacti became common. Grasses became scarce in some South Texas areas that dried and turned into semideserts.
The forests of East and Central Texas also changed.
In Central Texas just east of Austin the oak-hickory forests became more open as fingers of grassland invaded. The fossil pollen records suggest that the forests probably persisted until between 3,000 and 1,500 years ago. After that time all that remained was pockets of oak and pecan isolated in a vast grassy savanna. This contraction of the Central and East Texas forests continued until the forests reached their present westward margin around Huntsville. Loblolly pines probably came to dominate the forests of East Texas at this time. Fossil pollen evidence suggests that even though the early forests of East Texas may have expanded as far west as Austin, they were primarily composed of deciduous trees. Records show that the large relic stands of loblolly pines in Bastrop State Park, in Central Texas, did not expand southward, northward, or westward during the past 15,000 years. They probably did not expand even during the height of the Wisconsin glacial period around 20,000 years ago.
Vaughn M. Bryant, Jr., and Richard G. Holloway, Pollen Records of Late-Quaternary North American Sediments (Dallas: American Association of Stratigraphic Palynologists Foundation, 1985). Vaughn M. Bryant, Jr., and Harry J. Shafer, “The Late Quaternary Paleoenvironment of Texas,” Bulletin of the Texas Archeological Society 48 (1977). Robert C. Romans, Geobotany II (New York: Plenum Press, 1981). Fred Wendorf, Paleoecology of the Llano Estacado (Santa Fe: Museum of New Mexico Press, 1961).
Vaughn M. Bryant, Jr.
So there has been a fair amount of “Climate Change” in Texas over the last 30,000 years, and with cycles down in the hundreds to couple of thousands range. And that is still going on. All without any human influence. Also, not too surprising, when things cool off, Texas gets cooler and wetter as it’s sort of hot desert in West Texas now and it can’t really do more of that…
Now as a first cut, it looks to me like Texas gets wetter and the East Coast gets dryer during a cold turn. This would also match the recent history where Texas had a drought through the hot cycle, and is now flooding as we’ve entered a cooling turn. Watch the East Coast for droughts next…
Corinne I. Wong has some interesting stuff, but I’ve not been able to find a full copy of the paper for free yet. I’ve added white space and some bold bits. I also note in passing that I’m an alumni of UCD where she is located. It has the mandatory genuflect to Global Warming…
http://www.corinneiwong.com/research/ has a link to:
2014 AGU Fall Meeting: http://fallmeeting.agu.org/2014/
Why were Past North Atlantic Warming Conditions Associated with Drier Climate in the Western United States?
Corinne I Wong, University of California Davis, Earth and Planetary Sciences, Davis, CA, United States, Gerald L Potter, NASA Goddard Space Flight Center, Greenbelt, MD, United States, Isabel P Montanez, Univ of California, Davis, Earth and Planetary Sciences, Davis, CA, United States, Bette L Otto-Bliesner, National Center for Atmospheric Research, Boulder, CO, United States, Pat Behling, University of Wisconsin-Madison, Center for Climate Research, Madison, WI, United States and Jessica Leigh Oster, Vanderbilt University, Earth and Environmental Sciences, Nashville, TN, United States
Investigating climate dynamics governing rainfall over the western US during past warmings and coolings of the last glacial and deglaciation is pertinent to understanding how precipitation patterns might change with future global warming, especially as the processes driving the global hydrological reorganization affecting this drought-prone region during these rapid temperature changes remain unresolved.
We present model climates of the Bølling warm event (14,500 years ago) and Younger Dryas cool event (12,200 years ago) that i) uniquely enable the assessment of dueling hypothesis about the atmospheric teleconnections responsible for abrupt temperature shifts in the North Atlantic region to variations in moisture conditions across the western US, and ii) show that existing hypotheses about these teleconnections are unsupported.
Modeling results show no evidence for a north-south shift of the Pacific winter storm track, and we argue that a tropical moisture source with evolving trajectory cannot explain alternation between wet/dry conditions, which have been reconstructed from the proxy record. Alternatively, model results support a new hypothesis that variations in the intensity of the winter storm track, corresponding to its expansion/contraction, can account for regional moisture differences between warm and cool intervals of the last deglaciation. Furthermore, we demonstrate that the mechanism forcing the teleconnection between the North Atlantic and western US is the same across different boundary conditions.
In our simulation, during the last deglaciation, and in simulations of future warming, perturbation of the Rossby wave structure reconfigures the atmospheric state. This reconfiguration affects the Aleutian Low and high-pressure ridge over and off of the northern North American coastline driving variability in the storm track. Similarity between the processes governing the climate response during these distinct time intervals illustrates the robust nature of the teleconnection, a novel result that provides context for understanding the climate processes governing the response of moisture variability to future climate change.
Again the finding is warm / dry in the west, that implies cold / wet. Then we have further down the list of research:
2014 AGU Fall Meeting: http://fallmeeting.agu.org/2014/
1,500 YEAR PERIODICITY IN CENTRAL TEXAS MOISTURE SOURCE VARIABILITY RECONSTRUCTED FROM SPELEOTHEMS
Eric W James1, Corinne I Wong2, Maxwell M Silver3, Jay L Banner1 and MaryLynn Musgrove4, (1)University of Texas at Austin, Department of Geological Sciences, Austin, TX, United States, (2)University of California Davis, Earth and Planetary Sciences, Davis, CA, United States, (3)Pacific Lutheran University, Dept. of Geosciences, Tacoma, WA, United States, (4)USGS, Austin, TX, United States
Hmmmm…. Again with the 1500 year periodicity… but this time reflected in “moisture”, that we’ve seen correlates with warm / cold cycling.
(Do I really need to say “added white space and bold are from me”?.. and that the obligatory genuflect to the Church Of Global Warming is in?…)
Delineating the climate processes governing precipitation variability in drought-prone Texas is critical for predicting and mitigating climate change effects, and requires the reconstruction of past climate beyond the instrumental record.
Presently, there are few high-resolution Holocene climate records for this region, which limits the assessment of precipitation variability during a relatively stable climatic interval that comprises the closest analogue to the modern climate state. To address this, we present speleothem growth rate and δ18O records from two central Texas caves that span the mid to late Holocene, and assess hypotheses about the climate processes that can account for similarity in the timing and periodicity of variability with other regional and global records.
A key finding is the independent variation of speleothem growth rate and δ18O values, suggesting the decoupling of moisture amount and source. This decoupling likely occurs because i) the often direct relation between speleothem growth rate and moisture availability is complicated by changes in the overlying ecosystem that affect subsurface CO2 production, and ii) speleothem δ18O variations reflect changes in moisture source (i.e., proportion of Pacific- vs. Gulf of Mexico-derived moisture) that appear not to be linked to moisture amount.
I note in passing that again we have CO2 production variations with weather / climate changes… No humans involved. It is also interesting that it looks like there’s a swap of source patterns that, IMHO, likely reflects the degree of mass flow from meridional vs zonal air flows.
Furthermore, we document a 1,500-year periodicity in δ18O values that is consistent with variability in the percent of hematite-stained grains in North Atlantic sediments, North Pacific SSTs, and El Nino events preserved in an Ecuadorian lake.
Golly, that 1500 year cycle sure shows up all over the place. The Atlantic as sediments, rocks in caves, isotope ratios, Pacific sea surface temps, and even a lake (likely sediments) recording El Nino patterns. Hard to disappear that sucker.
So tell me again why our present warming isn’t just part of the present cycle of warming out of The Little Ice Age and why it is that the same post warming cold plunge is not exactly what we ought to expect this time?
They do go on to do “modeling” again, but really ought to be looking more at lunar tidal influences as they are happening on just that length of schedule and tidal mixing is about the same magnitude as wind mixing when it comes to moving cold deeper water closer to the surface. Always they go for the thermohaline, never for the lunar metronome that varies tides dramatically over 1500 years as the moon orbit changes. Sigh.
Previous modeling experiments and analysis of observational data delineate the coupled atmospheric-ocean processes that can account for the coincidence of such variability in climate archives across the northern hemisphere. Reduction of the thermohaline circulation results in North Atlantic cooling, which translates to cooler North Pacific SSTs. The resulting reduction of the meridional SST gradient in the Pacific weakens the air-sea coupling that modulates ENSO activity, resulting in faster growth of interannual anomalies and larger mature El Niño relative to La Niña events.
Shades of Bob Tisdale and his observation that recent warming is in steps as El Ninos dominated, and I’d expect the coming cool down to be in steps with excess La Ninas too.
The asymmetrically enhanced ENSO variability can account for a greater portion of Pacific-derived moisture reflected by speleothem δ18O values.Delineating the climate processes governing precipitation variability in drought-prone Texas is critical for predicting and mitigating climate change effects, and requires the reconstruction of past climate beyond the instrumental record. Presently, there are few high-resolution Holocene climate records for this region, which limits the assessment of precipitation variability during a relatively stable climatic interval that comprises the closest analogue to the modern climate state.
To address this, we present speleothem growth rate and δ18O records from two central Texas caves that span the mid to late Holocene, and assess hypotheses about the climate processes that can account for similarity in the timing and periodicity of variability with other regional and global records. A key finding is the independent variation of speleothem growth rate and δ18O values, suggesting the decoupling of moisture amount and source. This decoupling likely occurs because i) the often direct relation between speleothem growth rate and moisture availability is complicated by changes in the overlying ecosystem that affect subsurface CO2 production, and ii) speleothem δ18O variations reflect changes in moisture source (i.e., proportion of Pacific- vs. Gulf of Mexico-derived moisture) that appear not to be linked to moisture amount.
Furthermore, we document a 1,500-year periodicity in δ18O values that is consistent with variability in the percent of hematite-stained grains in North Atlantic sediments, North Pacific SSTs, and El Nino events preserved in an Ecuadorian lake. Previous modeling experiments and analysis of observational data delineate the coupled atmospheric-ocean processes that can account for the coincidence of such variability in climate archives across the northern hemisphere. Reduction of the thermohaline circulation results North Atlantic cooling, which translates to cooler North Pacific SSTs. The resulting reduction of the meridional SST gradient in the Pacific weakens the air-sea coupling that modulates ENSO activity, resulting in faster growth of interannual anomalies and larger mature El Nino relative to La Nina events. The asymmetrically enhanced ENSO variability can account for a greater portion of Pacific-derived moisture reflected by speleothem δ18O values.
So to me this is showing a natural 1500 year cycle of warming / cooling and wet / dry cycling. With warming via excess El Nino events, and cooling with excess La Nina events. Which seems to be exactly what we’ve seen in the real world and unrelated to CO2 or fuel use at all.
It also looks like West Texas gets a lot greener and nicer during a Glacial interval. Places already very wet likely get floods, though, so I’d not look to places like Dallas or East Texas during a glacial. South Texas doesn’t seem to change much, so would also be nice.
This leaves open the question of how much a simple 20 year Solar Grand Minimum driven cool down has the same effect. It ought not be as much since we don’t have all the full on ice and glacial albedo and such; but might be worth watching if things get really lousy in New England (as they did in 1800 and froze to death; when hoards of farmers abandoned North East farms for the Oklahoma Land Rush and a more southern new start). History may not repeat, but it certainly ought to rhyme a bit. Might be interesting to watch relative farm prices in New England and Texas and see if they are moving in opposite directions about 2020 or so. ;-)