Late-Holocene Formation of Lake Michigan Beach Ridges Correlated with a 70-yr Oscillation in Global Climate

1996 ◽  
Vol 45 (3) ◽  
pp. 321-326 ◽  
Author(s):  
Paul A. Delcourt ◽  
William H. Petty ◽  
Hazel R. Delcourt
Keyword(s):  
Late Holocene ◽  
Lake Michigan ◽  
Global Climate ◽  
Temperature Oscillation ◽  
Beach Ridges ◽  
Climate Fluctuations ◽  
The Past ◽  
Fundamental Part ◽  
Atmosphere System ◽  
Centennial Time Scale

AbstractA radiocarbon-dated series of 75 beach ridges, formed at regular intervals averaging 72 yr over the past 5400 yr, provides further support for the existence of a 70-yr oscillation in Northern Hemisphere climate, postulated recently from instrument data representing less than two cycles of this climate oscillation. Results from this study lend support to the interpretation that internal variations in the ocean–atmosphere system are an important factor in climate fluctuations on a decadal–centennial time scale. A temperature oscillation with a period of about 70 yr has been a previously unrecognized but fundamental part of the global climate system since at least the middle Holocene.

scholarly journals A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

2016 ◽  
Vol 12 (2) ◽  
pp. 189-200 ◽  
Author(s):  
C. S. M. Turney ◽  
R. T. Jones ◽  
C. Fogwill ◽  
J. Hatton ◽  
A. N. Williams ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Global Climate Change ◽  
Late Holocene ◽  
Global Climate ◽  
Falkland Islands ◽  
The Core ◽  
Atmosphere System ◽  
Westerly Winds ◽  
Ocean Atmosphere ◽  
Southern Hemisphere Westerly Winds

Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high latitudes with potentially global climate implications. Unfortunately, historic observations only extend back to the late 19th century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30-year) record of past westerly wind strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated within the core latitude of Southern Hemisphere westerly airflow (the so-called furious fifties), we identify highly variable changes in exotic pollen and charcoal derived from South America which can be used to inform on past westerly air strength. We find a period of high charcoal content between 2000 and 1000 cal. years BP, associated with increased burning in Patagonia, most probably as a result of higher temperatures and stronger westerly airflow. Spectral analysis of the charcoal record identifies a pervasive ca. 250-year periodicity that is coherent with radiocarbon production rates, suggesting that solar variability has a modulating influence on Southern Hemisphere westerly airflow. Our results have important implications for understanding global climate change through the late Holocene.

AMS Radiocarbon Dating of Lake Michigan Beach-Ridge and Dune Development

1997 ◽  
Vol 48 (1) ◽  
pp. 137-140 ◽  
Author(s):  
John Lichter
Keyword(s):  
Radiocarbon Dating ◽  
Lake Level ◽  
Sand Dune ◽  
Lake Michigan ◽  
Beach Ridge ◽  
Radiocarbon Dates ◽  
Beach Ridges ◽  
Ams Radiocarbon Dating ◽  
Climate Fluctuations ◽  
Radiocarbon Chronology

Strandplains of shore-parallel beach ridges bordering the Great Lakes are valuable for reconstructing histories of climate-related lake-level fluctuations. However, imprecise radiocarbon dates of ridge formation have frustrated development of dependable chronologies from which information about variation in the frequency of ridge formation and inferred climate fluctuations can be obtained. The resolution and precision of radiocarbon chronologies can be improved with AMS 14C dates of roots and rhizomes of plant species associated with the formation and growth of the sand-dune caps of breach ridges. These dates reliably estimate the timing of shore progradation when the base of the previously established beach ridge becomes inundated by the water table. An AMS radiocarbon chronology of beach-ridge formation in northern Lake Michigan shows that information about variation in the frequency of ridge formation is important for paleoclimatic interpretation.

Origin of the Whewellite-Rich Rock Crust in the Lower Pecos Region of Southwest Texas and Its Significance to Paleoclimate Reconstructions

1996 ◽  
Vol 46 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Jon Russ ◽  
Russell L. Palma ◽  
David H. Loyd ◽  
Thomas W. Boutton ◽  
Michael A. Coy
Keyword(s):  
Calcium Oxalate ◽  
Late Holocene ◽  
Paleoclimate Reconstruction ◽  
The Holocene ◽  
Climate Fluctuations ◽  
The Past ◽  
Desert Species ◽  
Paleoclimate Reconstructions ◽  
Wet Climate ◽  
Lower Pecos

A calcium oxalate (whewellite)-rich crust occurs on exposed limestone surfaces in dry rock and open air shelters in the Lower Pecos region of southwest Texas. The crust, which also contains gypsum and clay, formed over silica-rich limestone during the Holocene. SEM and optical photomicrographs reveal similarities between whewellite microstructures and the lichen Aspicilia calcarea. This desert lichen is known to produce calcium oxalate, and has been found in several sites in the region. The ubiquity of the whewellite-rich crust in the Lower Pecos shelters suggests that the lichen flourished in the past. Since A. calcarea is a desert species, the virulence of the organism likely peaked during xeric climate episodes then waned during mesic periods. Thus, radiocarbon ages of whewellite would correspond to dry climate periods experienced in the region, while periods with few or no 14C data would indicate wet climate episodes. A preliminary paleoclimate reconstruction based on fourteen AMS14 C dates indicates the Lower Pecos experienced dry to wet climate fluctuations during the late Holocene. This reconstruction generally agrees with other models established for Texas.

Dominance of an ∼150-Year Cycle of Sand-Supply Change in Late Holocene Dune-Building along the Eastern Shore of Lake Michigan

2000 ◽  
Vol 54 (3) ◽  
pp. 414-422 ◽  
Author(s):  
Walter L. Loope ◽  
Alan F. Arbogast
Keyword(s):  
Lake Level ◽  
Late Holocene ◽  
Lake Michigan ◽  
Probability Distributions ◽  
Buried Soils ◽  
Lake Levels ◽  
Eastern Shore ◽  
Soil Burial ◽  
The Past ◽  
Sand Supply

Outcrops of buried soils on lake-plains and glacial headlands along Lake Michigan's eastern shore suggest that periodic dune-building has occurred there after relatively long (≥100 yr) periods of low sand supply. We located, described, and radiocarbon dated 75 such buried soils that crop out in 32 coastal dune fields beside the lake. We assume that peaks in probability distributions of calibrated 14C ages obtained from wood, charcoal, and other organic matter from buried A horizons approximate the time of soil burial by dunes. Plotted against a late Holocene lake-level curve for Lake Michigan, these peaks are closely associated with many ∼150-yr lake highstands previously inferred from beach ridge studies. Intervening periods of lower lake levels and relative sand starvation apparently permitted forestation and soil development at the sites we studied. While late Holocene lake-level change led to development and preservation of prominent foredunes along the southern and southwestern shores of Lake Michigan, the modern dune landscape of the eastern shore is dominated by perched dunes formed during ∼150-yr lake highstands over the past 1500 yr.

scholarly journals A 250 year periodicity in Southern Hemisphere westerly winds over the last 2600 years

2015 ◽  
Vol 11 (3) ◽  
pp. 2159-2180 ◽  
Author(s):  
C. Turney ◽  
R. Jones ◽  
C. Fogwill ◽  
J. Hatton ◽  
A. N. Williams ◽  
...  
Keyword(s):  
South America ◽  
Southern Hemisphere ◽  
Late Holocene ◽  
Global Climate ◽  
Falkland Islands ◽  
Late Nineteenth Century ◽  
The Core ◽  
Atmosphere System ◽  
Westerly Winds ◽  
Late Nineteenth

Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high-latitudes with potentially global climate implications. Unfortunately historic observations only extend back to the late nineteenth century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30 yr) record of past westerly air strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated under the core latitude of Southern Hemisphere westerly airflow, we identify highly variable changes in exotic pollen derived from South America which can be used to inform on past westerly air strength and location. The results indicate enhanced airflow over the Falklands between 2000 and 1000 cal. yr BP, and associated with increased burning, most probably as a result of higher temperatures and/or reduced precipitation, comparable to records in South America. Spectral analysis of the charcoal record identifies a 250 year periodicity within the data, suggesting solar variability has a modulating influence on Southern Hemisphere westerly airflow with potentially important implications for understanding global climate change through the late Holocene.

Late-Holocene fluctuations of monsoonal Qiangyong Glacier, southern Tibetan Plateau

The Holocene ◽  
2021 ◽  
pp. 095968362110032
Author(s):  
Xiaolong Zhang ◽  
Baiqing Xu ◽  
Jiule Li ◽  
Ying Xie ◽  
Gerd Gleixner
Keyword(s):  
Tibetan Plateau ◽  
Late Holocene ◽  
Global Climate ◽  
The Tibetan Plateau ◽  
Temperature Changes ◽  
The Past ◽  
Physiochemical Parameters ◽  
Continuous Record ◽  
Southern Tibetan Plateau

Glaciers on the Tibetan Plateau (TP) are reliable water sources for Asia. Continuously high-resolution and high-accuracy long-term glacier fluctuations have been examined to improve the reliability of predictions regarding future TP glacier behavior under global climate change. In this study, we analyzed physiochemical parameters in typical glaciolacustrine sediments to reconstruct multidecadal activities of the monsoonal Qiangyong Glacier over the past ~2500 years. The results show that the glacier advanced most strongly during 560 BC–AD 100, followed by AD 1050–1850 and AD 600–850. It retreated most severely during AD 1850–present, followed by AD 100–600 and AD 850–1050. This continuous record corresponds well with changes in the temperature and regional precipitation before the Current Warm Period, exhibiting “warm-humid-retreat” and “cold-dry-advance” patterns. This indicates that temperature changes, rather than precipitation variations, control the monsoonal glaciers at the southern TP at multidecadal to centennial scales. As global warming continues, although the precipitation on the southern TP is projected to increase, the mass loss of TP monsoonal glaciers is expected to continue.

Denouement: World Politics, Systemic Leadership, and Climate Change

2018 ◽  
Author(s):  
William R. Thompson ◽  
Leila Zakhirova
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
World Politics ◽  
First Century ◽  
Modern World ◽  
Climate Fluctuations ◽  
The Past ◽  
Agrarian Economy ◽  
Historical Processes

In this final chapter, we conclude by recapitulating our argument and evidence. One goal of this work has been to improve our understanding of the patterns underlying the evolution of world politics over the past one thousand years. How did we get to where we are now? Where and when did the “modern” world begin? How did we shift from a primarily agrarian economy to a primarily industrial one? How did these changes shape world politics? A related goal was to examine more closely the factors that led to the most serious attempts by states to break free of agrarian constraints. We developed an interactive model of the factors that we thought were most likely to be significant. Finally, a third goal was to examine the linkages between the systemic leadership that emerged from these historical processes and the global warming crisis of the twenty-first century. Climate change means that the traditional energy platforms for system leadership—coal, petroleum, and natural gas—have become counterproductive. The ultimate irony is that we thought that the harnessing of carbon fuels made us invulnerable to climate fluctuations, while the exact opposite turns out to be true. The more carbon fuels are consumed, the greater the damage done to the atmosphere. In many respects, the competition for systemic leadership generated this problem. Yet it is unclear whether systemic leadership will be up to the task of resolving it.

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

Modulation of the relationship between summer temperatures in the Qinghai–Tibetan Plateau and Arctic over the past millennium by external forcings

2021 ◽  
pp. 1-9
Author(s):  
Feng Shi ◽  
Anmin Duan ◽  
Qiuzhen Yin ◽  
John T Bruun ◽  
Cunde Xiao ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Global Climate ◽  
Volcanic Eruptions ◽  
Warm Period ◽  
Temperature Correlation ◽  
The Past ◽  
External Forcings ◽  
Centennial Variation ◽  
Summer Temperatures ◽  
Past Millennium

Abstract The Qinghai–Tibetan Plateau and Arctic both have an important influence on global climate, but the correlation between climate variations in these two regions remains unclear. Here we reconstructed and compared the summer temperature anomalies over the past 1,120 yr (900–2019 CE) in the Qinghai–Tibetan Plateau and Arctic. The temperature correlation during the past millennium in these two regions has a distinct centennial variation caused by volcanic eruptions. Furthermore, the abrupt weak-to-strong transition in the temperature correlation during the sixteenth century could be analogous to this type of transition during the Modern Warm Period. The former was forced by volcanic eruptions, while the latter was controlled by changes in greenhouse gases. This implies that anthropogenic, as opposed to natural, forcing has acted to amplify the teleconnection between the Qinghai–Tibetan Plateau and Arctic during the Modern Warm Period.

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