scholarly journals Intertropical convergence zone variability in the Neotropics during the Common Era

2020 ◽  
Vol 6 (7) ◽  
pp. eaax3644 ◽  
Author(s):  
Yemane Asmerom ◽  
James U. L. Baldini ◽  
Keith M. Prufer ◽  
Victor J. Polyak ◽  
Harriet E. Ridley ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Intertropical Convergence Zone ◽  
Cold Climate ◽  
Ice Age ◽  
Convergence Zone ◽  
Social Unrest ◽  
Current Trends ◽  
Mass Migration ◽  
The Common ◽  
Common Era

Large changes in hydroclimate in the Neotropics implied by proxy evidence, such as during the Little Ice Age, have been attributed to meridional shifts of the intertropical convergence zone (ITCZ), although alternative modes of ITCZ variability have also been suggested. Here, we use seasonally resolved stalagmite rainfall proxy data from the modern northern limit of the ITCZ in southern Belize, combined with records from across the Neotropics and subtropics, to fingerprint ITCZ variability during the Common Era. Our data are consistent with models that suggest ITCZ expansion and weakening during globally cold climate intervals and contraction and intensification during global warmth. As a result, regions currently in the margins of the ITCZ in both hemispheres are likely transitioning to more arid and highly variable conditions, aggravating current trends of increased social unrest and mass migration.

scholarly journals Climate pacing of millennial sea-level change variability in the central and western Mediterranean

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Matteo Vacchi ◽  
Kristen M. Joyse ◽  
Robert E. Kopp ◽  
Nick Marriner ◽  
David Kaniewski ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Little Ice Age ◽  
Sea Level Change ◽  
Western Mediterranean ◽  
Ice Age ◽  
Cold Event ◽  
Level Change ◽  
The Common ◽  
Common Era

AbstractFuture warming in the Mediterranean is expected to significantly exceed global values with unpredictable implications on the sea-level rise rates in the coming decades. Here, we apply an empirical-Bayesian spatio-temporal statistical model to a dataset of 401 sea-level index points from the central and western Mediterranean and reconstruct rates of sea-level change for the past 10,000 years. We demonstrate that the mean rates of Mediterranean industrial-era sea-level rise have been significantly faster than any other period since ~4000 years ago. We further highlight a previously unrecognized variability in Mediterranean sea-level change rates. In the Common Era, this variability correlates with the occurrence of major regional-scale cooling/warming episodes. Our data show a sea-level stabilization during the Late Antique Little Ice Age cold event, which interrupted a general rising trend of ~0.45 mm a−1 that characterized the warming episodes of the Common Era. By contrast, the Little Ice Age cold event had only minor regional effects on Mediterranean sea-level change rates.

Dynamics of the intertropical convergence zone over the western Pacific during the Little Ice Age

2015 ◽  
Vol 8 (4) ◽  
pp. 315-320 ◽  
Author(s):  
Hong Yan ◽  
Wei Wei ◽  
Willie Soon ◽  
Zhisheng An ◽  
Weijian Zhou ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Intertropical Convergence Zone ◽  
Western Pacific ◽  
Ice Age ◽  
Convergence Zone ◽  
The Western Pacific

scholarly journals Millennial-to-centennial patterns and trends in the hydroclimate of North America over the past 2000 years

2017 ◽  
Author(s):  
Bryan N. Shuman ◽  
Cody Routson ◽  
Nicholas McKay ◽  
Sherilyn Fritz ◽  
Darrell Kaufman ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Ice Age ◽  
The Arctic ◽  
Medieval Period ◽  
The Past ◽  
Past 2000 Years ◽  
Annual Range ◽  
The Common ◽  
Common Era ◽  
Millennial Scale

Abstract. A synthesis of 93 hydrologic records from across North and Central America, and adjacent tropical and Arctic islands, reveals centennial to millennial trends in the regional hydroclimates of the Common Era (CE; past 2000 years). The hydrological records derive from materials stored in lakes, bogs, caves, and ice from extant glaciers, which have the continuity through time to preserve low-frequency (> 100 year) climate signals that may not be well represented by other shorter-lived archives, such as tree-ring chronologies. The most common pattern, represented in 46 (49 %) of the records, indicates that the centuries before 1000 CE were drier than the centuries since that time. Principal components analysis indicates that millennial-scale trends represent the dominant pattern of variance in the southwest and northeast U.S., the mid-continent, Pacific Northwest, the Arctic, and the tropics, although not all records within a region show the same direction of change. The Pacific Northwest, Greenland, and the southernmost tier of the tropical sites tended to dry toward present, as many other areas became wetter than before. Twenty-two records (24 %) indicate that the Medieval period (800–1300 CE) was drier than the Little Ice Age (1400–1900 CE), but in many cases the difference was part of the longer millennial-scale trend, and, in 25 records (27 %), the Medieval period represented a pluvial (wet) phase. Where quantitative records permitted a comparison, we found that centennial-scale fluctuations over the Common Era represented changes of 3–7 % of the modern inter-annual range of variability in precipitation, but the accumulation of these long-term trends over the entirety of the Holocene caused recent centuries to be significantly wetter, on average, than most of the past 11 000 years.

scholarly journals From hunting-based to nomadic reindeer herding in Røros and surrounding areas (In Norwegian with Summary in English)

Rangifer ◽  
2005 ◽  
pp. 21-30
Author(s):  
Sverre Fjellheim
Keyword(s):  
Little Ice Age ◽  
Large Population ◽  
17Th Century ◽  
Cold Climate ◽  
Ice Age ◽  
Reindeer Herding ◽  
Crop Failure ◽  
Reindeer Population ◽  
Surrounding Areas ◽  
Wild Reindeer

Until today most researchers have named central Sweden and the Arjeplog area as the cradle of reindeer nomadism. However, there are reasons to believe that the practice of nomadic reindeer herding goes at least as far back in Røros and surrounding areas. The transition was probably initiated by large-scale climatic changes during the 16th and 17th century. Local historian, Anders Reitan, characterises the end of the 16th and the beginning of the 17th century as very difficult for the Røros district, with cold weather and crop failure. He refers to the year 1591 as the "black year", when "the grass didn't turn green north of Dovre", and in 1599 there was "general crop failure throughout northern Europe". 1635 was ostensibly as bad as the "black year", and it was told that in 1647 several people died right next to the trees they had stripped for bark to eat. The cold climate is confirmed by today's climate researchers. In the sources the period from 1550 to 1850 is referred to as "the little ice-age". For the Trøndelag area this meant regular north-westerly and north-easterly winds during the spring, causing later snow-melting and more frequent snowfall and periods of frost than we have today. Summers were shorter and colder, and there was less sun and more rain than in our days. Under such circum¬stances there must have been a good market for meat, which must have put considerable pressure on the wild reindeer stock. However, the cold climate with shortage of food and famine during the 16th and 17th century did not only lead to an increase in the hunting of wild reindeer, but it must also have had a direct influence on the wild reindeer population. Researchers have found that the spring in particular was getting colder during the "little ice-age". And spring weather is of crucial importance to the dynamics of population and the procreative powers of wild reindeer. According to Julie Axman the weather was bad and conditions for the reindeer very difficult in the Røros area around 1867. Reindeer calves died as a result of the long and cold springs, and her father had to borrow money in order to buy more animals. When climatic conditions during the 1860s had such a dramatic impact on the population of wild reindeer, it must have had at least as great consequences in the Røros area during the 16th and 17th century. Even though the reindeer in nomadic times were very tame and under continuous supervision, the herds were left to graze freely on open lands. With the presence of a large population of wild reindeer close to the tame herds, the risk of losing reindeer would be great, especially during winter and in the mating season. The wild reindeer population in Røros would therefore have to be reduced, either before or in parallel to an increase in the number of tame reindeer. The climate contributed to this reduction, and the Sami took care of the rest as far as it was necessary. This could take place in parallel to the building up of herds of tame reindeer. According to the sources there were at least 6 Sami villages in the 17th century, from Tydal in the north to Østerdalen in the south, which kept herds of tame reindeer, and at the same time the Sami population was accused of extinguishing the wild reindeer. A picture emerges. In sum, we can see that circumstances at the time were in favour of a change in strategy, from a hunting-based economy to nomadic reindeer herding.

scholarly journals Placing the Common Era in a Holocene context: millennial to centennial patterns and trends in the hydroclimate of North America over the past 2000 years

2018 ◽  
Vol 14 (5) ◽  
pp. 665-686 ◽  
Author(s):  
Bryan N. Shuman ◽  
Cody Routson ◽  
Nicholas McKay ◽  
Sherilyn Fritz ◽  
Darrell Kaufman ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Ice Age ◽  
Medieval Climate Anomaly ◽  
Climate Anomaly ◽  
The Holocene ◽  
The Past ◽  
Past 2000 Years ◽  
The Common ◽  
Common Era ◽  
Millennial Scale

Abstract. A synthesis of 93 hydrologic records from across North and Central America, and adjacent tropical and Arctic islands, reveals centennial to millennial trends in the regional hydroclimates of the Common Era (CE; past 2000 years). The hydrological records derive from materials stored in lakes, bogs, caves, and ice from extant glaciers, which have the continuity through time to preserve low-frequency ( > 100 year) climate signals that may extend deeper into the Holocene. The most common pattern, represented in 46 (49 %) of the records, indicates that the centuries before 1000 CE were drier than the centuries since that time. Principal component analysis indicates that millennial-scale trends represent the dominant pattern of variance in the southwestern US, northeastern US, mid-continent, Pacific Northwest, Arctic, and tropics, although not all records within a region show the same direction of change. The Pacific Northwest and the southernmost tier of the tropical sites tended to dry toward present, as many other areas became wetter than before. In 22 records (24 %), the Medieval Climate Anomaly period (800–1300 CE) was drier than the Little Ice Age (1400–1900 CE), but in many cases the difference was part of the longer millennial-scale trend, and, in 25 records (27 %), the Medieval Climate Anomaly period represented a pluvial (wet) phase. Where quantitative records permitted a comparison, we found that centennial-scale fluctuations over the Common Era represented changes of 3–7 % in the modern interannual range of variability in precipitation, but the accumulation of these long-term trends over the entirety of the Holocene caused recent centuries to be significantly wetter, on average, than most of the past 11 000 years.

scholarly journals Galápagos hydroclimate of the Common Era from paired microalgal and mangrove biomarker 2H/1H values

2016 ◽  
Vol 113 (13) ◽  
pp. 3476-3481 ◽  
Author(s):  
Daniel B. Nelson ◽  
Julian P. Sachs
Keyword(s):  
Southern Oscillation ◽  
High Sensitivity ◽  
Tropical Pacific ◽  
Ice Age ◽  
The Common ◽  
Climate Forcings ◽  
Global Atmospheric Circulation ◽  
Hydrogen Isotope Ratios ◽  
Precipitation Changes ◽  
Common Era

Tropical maritime precipitation affects global atmospheric circulation, influencing storm tracks and the size and location of subtropical deserts. Paleoclimate evidence suggests centuries-long changes in rainfall in the tropical Pacific over the past 2,000 y, but these remain poorly characterized across most of the ocean where long, continuous proxy records capable of resolving decadal-to-centennial climate changes are still virtually nonexistent despite substantial efforts to develop them. Here we apply a new climate proxy based on paired hydrogen isotope ratios from microalgal and mangrove-derived sedimentary lipids in the Galápagos to reconstruct maritime precipitation changes during the Common Era. We show that increased rainfall during the Little Ice Age (LIA) (∼1400–1850 CE) was likely caused by a southward migration of the Intertropical Convergence Zone (ITCZ), and that this shift occurred later than previously recognized, coeval with dynamically linked precipitation changes in South America and the western tropical Pacific. Before the LIA, we show that drier conditions at the onset of the Medieval Warm Period (∼800–1300 CE) and wetter conditions ca. 2 ka were caused by changes in the El Niño/Southern Oscillation (ENSO). Collectively, the large natural variations in tropical rainfall we detect, each linked to a multicentury perturbation of either ENSO-like variability or the ITCZ, imply a high sensitivity of tropical Pacific rainfall to climate forcings.

Millennial-scale increase in winter precipitation in the southern Rocky Mountains during the Common Era

2020 ◽  
Vol 94 ◽  
pp. 1-13 ◽  
Author(s):  
Meredith C. Parish ◽  
W. John Calder ◽  
Bryan N. Shuman
Keyword(s):  
Large Change ◽  
High Elevation ◽  
Winter Precipitation ◽  
Ice Age ◽  
Annual Precipitation ◽  
Fossil Pollen ◽  
The Past ◽  
Tree Ring Data ◽  
The Common ◽  
Common Era

AbstractWe employed the modern analog technique to quantitatively reconstruct temperature and precipitation over the past 2500 yr based on fossil pollen records from six high-elevation lakes in northern Colorado. Reconstructed annual temperatures for the study area did not deviate significantly from modern over the past 2500 yr despite hemispheric expressions of Medieval Climate Anomaly warmth and Little Ice Age cooling. Annual precipitation, however, shifted from lower than modern rates from 2500 to 1000 cal yr BP to higher than modern rates after 1000 cal yr BP, a greater than 100 mm increase in precipitation. Winter precipitation accounts for the majority of the change in annual precipitation, while summer precipitation rates did not change significantly over the past 2500 yr. The large change in winter precipitation rates from the first to second millennium of the Common Era is inferred from a shift in fossil pollen assemblages dominated by subalpine conifers, which have southern sites as modern analogs, to assemblages representing open subalpine vegetation with abundant Artemisia spp. (sagebrush), which have more northern modern analogs. The change helps to explain regional increases in lake levels and shifts in some isotopic and tree-ring data sets, highlighting the risk of large reductions in snowpack and water supplies in the Intermountain West.

Greenhouses, hot water bottles, cycles and the future of New Zealand climate

2009 ◽  
pp. 61-67
Author(s):  
W.P. De Lange
Keyword(s):  
New Zealand ◽  
Thermal Energy ◽  
Infrared Radiation ◽  
Little Ice Age ◽  
Hot Water ◽  
Ice Age ◽  
The Sun ◽  
Weather Patterns ◽  
Time Periods ◽  
Almost All

The Greenhouse Effect acts to slow the escape of infrared radiation to space, and hence warms the atmosphere. The oceans derive almost all of their thermal energy from the sun, and none from infrared radiation in the atmosphere. The thermal energy stored by the oceans is transported globally and released after a range of different time periods. The release of thermal energy from the oceans modifies the behaviour of atmospheric circulation, and hence varies climate. Based on ocean behaviour, New Zealand can expect weather patterns similar to those from 1890-1922 and another Little Ice Age may develop this century.

RECOVERY FROM THE LITTLE ICE AGE: GEOTHERMAL EVIDENCES

2013 ◽  
Vol 6 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Anastasia Gornostayeva ◽  
◽  
Dmitry Demezhko ◽  
◽  
Keyword(s):  
Little Ice Age ◽  
Ice Age
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