Texas, Rain, and 1500 Year Cycles

I was looking at a posting at IceAgeNow.info that was talking about Texas:

http://iceagenow.info/2015/05/do-texas-floods-portend-a-new-ice-age/

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.

http://www.desertusa.com/mag05/feb/cold.html

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.

First-hand Accounts

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.

http://jennifermarohasy.com/2008/08/7000-year-climate-record-shows-century-long-droughts-in-north-america-and-1500-year-solar-cycle/

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

Abstract:

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.

Conclusions:

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:

http://www.researchgate.net/publication/228571114_Solar_forcing_of_Holocene_droughts_in_a_stalagmite_record_from_West_Virginia_in_east-central_North_America

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.[1]

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:

http://www.cgfi.org/2008/03/hundreds-more-scientists-have-found-the-1500-year-climate-cycle/

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.

http://www.cgfi.org/wp-content/uploads/2008/03/hundreds-more-scientists-have-found-the-1500-year-climate-cycle.pdf

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.

https://tshaonline.org/handbook/online/articles/sop02

PALEOENVIRONMENTS

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.

BIBLIOGRAPHY:

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:

https://agu.confex.com/agu/fm14/webprogrampreliminary/Paper17650.html

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

Abstract:

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:

https://agu.confex.com/agu/fm14/webprogrampreliminary/Paper25887.html

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?…)

Abstract:

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. ;-)

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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14 Responses to Texas, Rain, and 1500 Year Cycles

  1. A C Osborn says:

    Re Solar/Lunar connections to Climate, you might be intersted in this web site, which has been highlighted on Tallbloke’s.
    http://astroclimateconnection.blogspot.com.au/2013/10/connecting-planetary-periodicities-to.html

    Also see this at Tallbloke’s
    https://tallbloke.wordpress.com/2015/05/31/paul-vaughan-sun-climate-101-solar-terrestrial-primer/

  2. Larry Ledwick says:

    Dec 14 1967 is a good example of what earlier snow and cold might have been like in the south west.
    My parents were traveling down to Arizona shortly after this storm and ran into deep snow drifts by the side of the road in what would normally be desert terrain. The Indian reservations got pounded.

    http://www.history.com/this-day-in-history/blizzard-ravages-navajo-reservation

    This was the beginning of the period into the early 1970’s when folks were talking about a coming ice age and the north east was ravaged by horrible blizzards and cold which had significant impact on the economy on top of the energy crisis of that period. Such as the Ohio blizzard of 26-27 Jan. 1978. and the blizzard of January 21, 1977. This period extended into the very early 1980’s (blizzard of 1982 here in Denver) then suddenly that sort of weather disappeared for about 20-30 years here in the northern plains until just recently (Dakota blizzard 2013 — http://www.cnn.com/2013/10/10/us/south-dakota-blizzard-kills-herds-cattle/ ) with outbreaks that have brought snow to Houston in the last few years.
    http://www.wxresearch.com/snowhou.htm


    When you get those cold plunging cold fronts into the plains states and Texas you also get serious weather patterns in the northeast great plains “great lakes” areas. Easy to imagine how this results in glacier development in that region after a few summers where snow never melts completely.

    https://en.wikipedia.org/wiki/Schoolhouse_Blizzard

    These Siberian express / Alberta Clipper cold outbreaks can plunge deep into the central plains and go far south of the modern extent of normal snow and cold we see in recent times.

  3. Clay Marley says:

    I think what we are seeing in Texas now is part of a shorter ~60 year cycle. The last major drought was in the 1950’s, which ended in flooding, followed by a cold spell.

    I have ancestors who were cattle ranchers in West Texas in the late 1800’s. Drought forced them to drive their herd to Winslow Arizona territory around 1890. I wonder if that drought ended with flooding rains followed by a cold spell.

  4. E.M.Smith says:

    @Clay:

    Not scientific and likely dominated by the 1900 Galveston hurricane and the tendency for news to be “fresh”, but a search here on “flood 1900” gives the following article counts:
    http://newspaperarchive.com/serp-lockldown?plan=18408&utm_expid=169807-111.6MGAuFuSRXS99cduQA7REg.0&utm_referrer=http%3A%2F%2Fnewspaperarchive.com%2Fus%2Ftexas%2F%3Fgclid%3DCNfgke2v7MUCFZSGfgodqhMAiQ

    1890’s 274
    1900’s 2268
    1910’s 794

    Probably ought to do a search one each year and compare peak counts…. but the Galveston hurricane alone argues for a wet time.

    Update:
    https://en.wikipedia.org/wiki/Floods_in_the_United_States:_1901%E2%80%932000#Texas_Flood_.E2.80.93_1913

    Texas Flood – 1913
    The Guadalupe and Trinity Rivers leave their banks, and the Brazos River and the Colorado River join to flood more than 3,000 square miles of land and cause the deaths of at least 177 people and massive property damage ($3,436,144 in the Brazos Valley alone). The flood causes the Brazos river to change course. It now enters the Gulf of Mexico at Freeport, Texas. Major flooding brings death and destruction of greater magnitude than previously experienced. The floods of 1913 and again in 1921 are the catalyst, which causes the state of Texas to attempt to tame the Brazos River.

    I’d say 3000 square miles of flood was a lot, but this is Texas, so probably just somebody left the sprinklers on in the south pasture too long ;-)

    30 x 100 miles in a place about 800 x 900 miles?

    Still, with the Gaveston Hurricane on the cost, and this in Central Texas inland, it’s looking kind of wet.

  5. E.M.Smith says:

    Some interesting further confirmation from other pages:

    http://www.esi.utexas.edu/featured-research-projects/tree-project/paleoclimate

    Semi-reverse chronological, but I can work with that. Bold and added whitespace mine.

    The Paleoclimate of Central Texas

    The climate of central Texas has undergone precipitation and temperature changes on millennial as well as annual time scales. In general, the region has undergone significant warming and drying since the last glacial maximum approximately 24,000 years before present. Mechanisms for these changes have ranged from millennial scale orbital cycles to annual sea surface temperatures. It is important to determine the magnitude of these changes and understand the underlying mechanisms for change. The extent to which scientists can identify and quantify these changes will assist in determining the usefulness of climate models.

    A remarkably even handed statement. Reality to determine if models are correct? GASP! Texans have clue! It’s hotter and dryer now than in the past. It cycles (and on a scale of years and of 1000s of years…). All natural.

    Mixture of date formats. Some current dates are in A.D., while long ago times tend to B.P. (Before Present, or 2000 years larger than B.C. numbers for the same date.)

    First up, 22,000 BC to 12,000 BC. Cool and wet in Texas. Plenty of grass and game animals.

    24,000 to 14,000 Years Before the Present Day

    During this period, the climate was the coolest and wettest of the last 24,000 years. There is a presence of low latitude ice sheets in North America. This is evidenced by:

    Fossil evidence indicates that large mammals once present in the region are now extinct (Lundelius, 1967; Graham, 1976)

    Animals once living in this region emigrated to regions that are cooler and wetter (Toomey et al, 1993)

    The remains of ground dwelling fauna suggest thicker soils and thus cooler conditions (Toomey et al, 1993)

    Pollen data from this time period suggests that trees which grown in cooler summer temperatures (~22° C) were living in the region (Potzger and Tharp, 1943, 1947, 1954; Bryant, 1969, 1977; Camper, 1991)

    Higher elevations once dominated by woodlands are now inhabited by desert vegetation (Spaulding et al, 1983).

    Alluvium deposited ca. 15,000 years before present also suggests that during the late Pleistocene conditions were cooler and wetter than the Holocene. This is inferred from a 13C value of -21‰, which indicates a large amount of trees and C3 grasses (40-50%) in the region (Nordt, 1994).
    Magnetic susceptibility (MS) analysis from Hall’s Cave, TX indicates the lowest value of the 19,000 years of analysis (Ellwood and Gose, 2006).

    87Sr/86Sr ratios of fossil Hackberry aragonite and vole/pocket gopher tooth enamel suggest that 20,000 years before present there was a peak in soil thickness and as time increased soil depth decreased (Cooke et al, 2003).

    Again we have evidence for plants influencing C isotope extraction ratios. Soils were thick and rich, not the thin dusty stuff of much of west Texas today.

    Then we enter the Younger Dryas range. 12,800 to 11,500 BP. They start 1200 years early and end 1000 years later, but bracket what is typically thought of as a cold excursion in Europe and the Middle East.

    https://en.wikipedia.org/wiki/Younger_Dryas

    “The Younger Dryas stadial, also referred to as the Big Freeze, was a 1,300 (± 70) year period of cold climatic conditions and drought which occurred between approximately 12,800 and 11,500 years BP (between 10,800 and 9500 BC).”

    Yet in Texas:

    14,000 to 10,500 Years Before the Present Day

    During this time period it is inferred that temperatures began to warm and glaciers began to recede to higher latitudes. This resulted in warmer and drier conditions in central Texas as the jet stream was positioned further north thus limiting the amount of cold air brought to the region. This is evidenced by:

    Disappearance of the masked shrew which prefers cooler temperatures and the appearance of the cotton rat which can live in temperatures of more than 24°C (Hall, 1981).

    Loss of the bog lemming (ca. 14,000 ybp) which indicates decreased effective moisture (Toomey et al, 1993)

    The appearance of a drier weather shrew and emigration of a shrew that requires wetter conditions (Toomey et al, 1993).

    There also appears to be an increase in grass pollen which suggests higher temperatures and less effective moisture versus the glacial period (Toomey et al, 1993).

    Alluvium deposited 11,000-8,000 years before present are inferred to be composed of 50-60% of C4 grasses and thus represents a shift to drier and warmer conditions (Nordt et al, 1994).
    Magnetic susceptibility data describe this as a time period of continued warming and drying (Ellwood and Gose, 2006).

    All I can figure is that the broad generalization over 3500 years was not displaced by a 1500 year cold excursion in the middle? It was still warming out of a full on glacial, and may have been more influenced by water changes than a few degrees of temperature. Perhaps “began to warm” is there way of saying “warmed some, cold spike, back to warming again”… In any case, it’s an interesting counter point.

    Next stop, the Holocene Optimum from 5000 BP to 9000 BP. We start to get the dry desert like environment. “Xeric” means extremely dry adapted in the text below. While “eolian” is wind driven dust deposited – think sand dunes…

    10,500 to 5,000 Years Before the Present Day

    The early Holocene is ushered in as the warming and drying trend of the previous 4,000 years continues as the earth begins a retreat from glacial conditions. This is evidenced by:

    Loss of vertebrate fauna with a preference for wetter conditions and the emergence of species that are adapted to drier conditions (Toomey, et al, 1993)

    Pollen records also indicate an increase in grass species beginning 10,500 years before present while 8700-6000 years before present pollen records indicate a larger abundance of taxa favoring more xeric conditions near Hinds Cave (Toomey et al, 1993; Bryant and Holloway, 1985).

    A site at Boriack Bog has a pollen record which indicates a gradual loss of trees and increase in grasses (Bryant and Holloway, 1985). Included in this is evidence of a shift of tree populations away from this region and into wetter regions (Bryant and Holloway, 1985).

    Archaeological evidence at Mustang Springs reveals that wells were dug around 6800 years before present, which are interpreted to be a response to drier conditions and a lowering of the water table (Metzler, 1991).

    Sedimentary records suggest “eolian sedimentation” between 6500-4500 years before present due to drier conditions (Holliday, 1989) and after 8000 years before present the rate of deposition of soil in Hall’s Cave doubled, clay deposition decreased and limestone clast deposition increased (Toomey et al, 1993).

    Vertebrate fossils indicate the disappearance of prairie dogs which need thicker soils in which to reside (Toomey et al, 1993).

    Sedimentary evidence from the Fort Hood alluvium deposited between 8000-5000 years before present indicates that C4 grasses comprise 65 to 70% of the fauna, which represents a warming and drying of the climate (Nordt et al, 1994).

    Magnetic susceptibility data from this time period indicate a general warming trend with a pronounced, extreme period of warming beginning around 8400 years before present and peaking at 8200 years before present (Ellwood and Gose, 2006).

    I note in passing that the “8.2 Kiloyear event” was a pronounced cold spike. Looks like we get the typical hot spike then cold slam from 8400 to 8200 BP.
    https://en.wikipedia.org/wiki/8.2_kiloyear_event

    The 8.2 kiloyear event is the term that climatologists have adopted for a sudden decrease in global temperatures that occurred approximately 8,200 years before the present, or c. 6,200 BCE, and which lasted for the next two to four centuries. Milder than the Younger Dryas cold spell that preceded it, but more severe than the Little Ice Age that would follow, the 8.2 kiloyear cooling was a significant exception to general trends of the Holocene climatic optimum.

    https://en.wikipedia.org/wiki/8.2_kiloyear_event#/media/File:Greenland_Gisp2_Temperature.svg

    Now looking at the graph in that wiki, it looks like from about 8400 BP to 8200 BP Greenland was in a deep cooling spike. Perhaps Texas and Greenland are anti-phase in Bond Events with the Gulf Stream backing up heat in the Gulf Of Mexico causing Texas a bit of warm and wet while Europe gets cold? Would be nice to get better precision on the dates and water / heat levels.

    If so, Texas is a great counterpoint to the doom and despair of a full on cold spike globally. I hope it isn’t just false precision causing an incorrect alignment / interpretation. (There is always the risk of unadjusted vs adjusted vs incorrect adjustement Carbon Dates getting things out of proper alignment). At 7900 BP Greenland has a big up spike from the 8200 kyEvent, so maybe it is just not enough precision to catch the fast “awshit” cold spike at 8.2 kya.

    Then they just skip forward 3000 years to 5000 BP… While the Greenland graph shows this as on average warm and likely the best of the Holocene Optimum, it has significant cold spikes in that range and the prior peak is around the 7000 BP point. Then again, the time had very wide high / low peaks and maybe the proxies in Texas don’t respond to that kind of fast whipsaw as much as Greenland ice does.

    5,000 to 2,500 Years Before the Present Day

    It appears that sometime around 5000 years before present there was a peak in warmness/dryness and the time period from 5000-2500 years before present represents the driest/warmest climate of the Holocene. This is evidenced by:

    Regional extinction of taxa requiring larger amounts of moisture such as the pipistrelle bat and the woodland vole (Toomey et al, 1993).

    Represented at Schulze Cave by the absence or minimum of wet weather shrew and the abundance of a dry weather shrew population ca. 3800 years before present (Dalquest et al, 1969).

    Gastropods samples from Bering Sinkhole suggest the driest conditions to occur between ca. 4000 and 2700 years before present (Toomey et al, 1993).

    13C values of snail shells reflect an abundance of C4 grasses and that around 5000 years before present was the warmest and driest of the Holocene (Goodfriend and Ellis, 2000).

    Magnetic susceptibility data from this time period point towards significant warming events ca. 4400 ybp, 3200 ybp, and 2900 ybp (Ellwood and Gose, 2006).

    The Greenland ice core graph also shows spikes / swings at about those times, but it is not high enough resolution nor precise enough to say “match” or “counter cycle” on those fast swings.

    The more interesting point is just how much and how fast normal climate DOES swing. No CO2 and no humans involved…

    Next we are into the range of recorded history. The Dark Ages cold plunge started about 540 AD or about 1500 BP. At 500 BC / 2500 BP we are just before the start of the Roman Warm Period ( 250 BC to 400 AD, or about 2250 BP to 1600 BP. Then into the Little Ice Age.

    The Iron Age Cold Period runs about 2900 BP to 2300 BP, so barely overlapping the start of the next interval and the end of the last.

    https://en.wikipedia.org/wiki/Iron_Age_Cold_Epoch

    The Iron Age Cold Epoch (also referred to as Iron Age climate pessimum or Iron Age neoglaciation) was a period of unusually cold climate in the North Atlantic region, lasting from about 900 BC to about 300 BC, with an especially cold wave in 450 BC during the expansion of ancient Greece. It was followed by the Roman Warm Period (250 BC – 400 AD).

    Back to the Texas link:

    2,500 to 1,000 Years Before the Present Day

    There was an apparent a return to cooler/wetter conditions ca. 2500 years before present which extends to ca. 1000 years before present. This is evidenced by:

    Fossil evidence indicates the return of the woodland vole and pipistrelle bat to the Hall’s cave area as well as a significant increase in the abundance of the least shrew (a wetter condition species) around 2500 years before present (Toomey et al, 1993).

    Pollen records indicate an increase in pine trees and grasses associated with cooler conditions or more moisture (Bryant and Holloway, 1985) and oak-woodland occurs in east-central Texas between 2500-1500 years before present (Holloway et al, 1987).

    Springs at Mustang Springs in the Southern High Plains began to discharge again around 2000 years before present (Meltzer, 1991).

    Increasingly negative average 13C values (-6.5‰) of snail shells, dating from 2700 to 1500 years before present, suggest that conditions were moving towards cooler/wetter (Goodfriend and Ellis, 2000).

    So in general it does look like Texas follows the larger trends, but perhaps without the big spikes seen in Greenland ice or with small counter moves then. More precision needed…

    It also is fairly clear that when the rest of the world is darned cold, West Texas is a nicer place, and when the rest of the world is hot, well, lets just say I’ve toured Fort Stinking Desert in the middle of nowhere West Texas in August and it ain’t my idea o’ fun.

    It’s also pretty clear that “now” is cooler and wetter than the peak of the Holocene Warm Period. We are in a general downtrend from there, with occasional cyclical spikes, but this up spike is smaller than prior ones and we are still net cooler than the Holocene Optimum. More cooling would be even better for Texas, so I’m not too worried about a bit of cooling. Just head to Texas.

  6. E.M.Smith says:

    Lots of interesting bits about Texas prehistory out there.

    http://www.texasbeyondhistory.net/bowie/environment.html

    The area that is now called Camp Bowie lies within the Rolling Plains physiographic region. Its gently rolling hills are cut by seasonally active steams and are dotted with stands of oak, juniper, mesquite, pecan and elm trees along with grasses and cacti. But the landscape we see today may scarcely resemble what hunters and gatherers saw in the prehistoric past, prior to the 17th century (1600s).

    Over the past 10,000 years, the vegetation of the Camp Bowie area shifted between grasslands and woodlands as the climate fluctuated between dry and moist periods. Brown County is in a transitional climatic zone between the semi-arid western half of Texas and the increasingly humid eastern Texas. […]

    From roughly 18,000 to 10,000 years ago, Central Texas began to change from generally cool, moist conditions to a warmer and drier environment. This period, termed the Late Pleistocene era, was followed by a moderately moist period from about 8,000 to 10,000 years ago (the Early Holocene period). The Middle Holocene (4,000 to 8,000 years ago) was generally warm and/or dry, with a brief moist (mesic) interlude sometime between 5,000 and 6,000 years ago. By Late Holocene times about 4,000 years ago, the climate shifted back to wetter conditions similar to the modern climate. These long-term generalizations are, of course, just that; short-term fluctuations, such as multi-year droughts, would have sometimes caused drastic changes in how people used the landscape.

    Several types of evidence hint at a dryer period between about 750 to 1,500 years ago, while a more mesic interval is suggested for the last 750 to 800 years. While all of the different data may not be in agreement, it is clear that the past environment was not static, but fluctuated between warmer, drier and cooler, moister conditions.

    For the Camp Bowie area, the full impact of long-term climatic changes on the plant and animal communities is—for the most part—unknown. More recent changes, largely due to human intervention, are more noticeable. These include an historic increase in woody species, especially juniper/cedar and mesquite, caused by the cessation of range fires and severe overgrazing by livestock in the late 19th and early 20th centuries, the subsequent clearing of wooded areas, the pumping of water for irrigation that has lowered water tables, and the impacts of military training.

    Looks like they find a climate cycle of wet and dry, and that from 1500 years ago to now it was one phase (dry / warm) for the first 750 years, then a different phase (cooler / wet) for the last 750 years. That argues a little bit for a “change now” timing. It was dry during the 500 AD to 1250 AD period that starts with the Dark Ages, but shifts to the Medieval Warm Period from 950 AD to 1250 AD, then continues into the Little Ice Age to modern transition. But doesn’t seem to line up with other regions. I suspect that there is either a threshold effect or just that the mix of weak precision with imprecise size of slices is making things a little obscure.

  7. Larry Ledwick says:

    And now at a University near you a study that claims global warming is bringing rain back to the Sahel in Africa. If you can’t beat them join them??

    http://www.dailymail.co.uk/news/article-3105940/Climate-change-bringing-rain-Africa-30-years-Live-Aid-tried-help-end-famine.html

  8. E.M.Smith says:

    @Larry Ledwick:

    And not a mention of the 60 year cycle of PDO / AMO / etc… even though they have a nice graph of rainfall showing a cycle…

  9. Lots of work there, Chiefio,

    In the end it all boils down to latitudinal jet stream and climate zone shifting though doesn’t it?

    The sun exerts a top down effect from the poles and after a time lag the oceans exert a bottom up effect from the oceans and climate changes are a consequence of that never ending interplay.

    CO2 being irrelevant.

  10. p.g.sharrow says:

    I once watch a very well done hour long documentary on the Sahara Desert. Shown on the Discovery Channel. All about it’s geography and history. At the very end was the paid political statement.
    ” All this can be Destroyed in a few decades by AGW caused increase in RAIN!”
    8-) LoL bring it on! pg

  11. E.M.Smith says:

    @Stephen Wilde:

    Thanks!

    I think you will find some of this history interesting. To me, it looks like the counter cycle drought in West Texas vs Eastern USA clearly shows a strong meridional jet stream effect. Likely you can do enough digging to demonstrate historically exactly your thesis being played out. It would be a nice bit of proof…

    @P.G.:

    Yeah, the “Doom, DOOM, DOOM I SAY!!!” folks drive me around the bend. Even having a life giving fertile green tropical paradise return to a God Forsaken Wasteland has to be painted as bad… Never mind that it would just be backing up a few thousand years to what it had been before it was devastated…

  12. p.g.sharrow says:

    One other “proof” of climate cooling change. Quite a number of years ago I had 2 visions of a future time for the places I know well.
    The climate was a bit wetter through Northern California and the Great Basin. Wet enough that the area became an important agriculture area. The land for farming was valuable enough to justify serious reclamation in irrigation and drainage.
    The wetter zonal flow is now just above the north California border. A shift 200 miles south would make most of the Great Basin farm-able. Loss of North Plains farm land might make the difference in need.
    Not very scientific. LoL pg

  13. E.M.Smith says:

    Just putting this link here as it does a great job of documenting that Texas cooled in early 2015 and that rains were in excess of recent averages during that time:
    http://realclimatescience.com/2015/06/texas-is-vulnerable-to-clueless-academics/

    Being in a Texas thread will make it easier to find again in the future.

  14. Larry Ledwick says:

    AP article on May 2015 being wettest on record
    http://hosted.ap.org/dynamic/stories/U/US_SCI_WETTEST_MAY

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