scholarly journals Climatic history of the northeastern United States during the past 3000 years

2016 ◽  
Author(s):  
Jennifer R. Marlon ◽  
Neil Pederson ◽  
Connor Nolan ◽  
Simon Goring ◽  
Bryan Shuman ◽  
...  
Keyword(s):  
Warming Trend ◽  
Ecosystem Dynamics ◽  
Ice Age ◽  
Extreme Weather Events ◽  
Past Century ◽  
Climate Conditions ◽  
Vegetation Growth ◽  
The Past ◽  
Tree Ring Data ◽  
Cooling Trend

Abstract. Many ecosystem processes that influence Earth system feedbacks, including vegetation growth, water and nutrient cycling, and disturbance regimes, are strongly influenced by multi-decadal to millennial-scale variations in climate that cannot be captured by instrumental climate observations. Paleoclimate information is therefore essential for understanding contemporary ecosystems and their potential trajectories under a variety of future climate conditions. With the exception of fossil pollen records, there are a limited number of northeastern US (NE US) paleoclimate archives that can provide constraints on its temperature and hydroclimate history. Moreover, the records that do exist have not been considered together. Tree-ring data indicate that the 20th century was one of the wettest of the past 500 years in the eastern US (Pederson et al., 2014), and lake-level records suggest it was one of the wettest in the Holocene (Newby et al., 2014); how such results compare with other available data remains unclear, however. Here we conduct a systematic review, assessment, and comparison of paleotemperature and paleohydrological proxies from the NE US for the last 3000 years. Regional temperature reconstructions are consistent with the long-term cooling trend (1000 BCE–1700 CE) evident in hemispheric-scale reconstructions, but hydroclimate reconstructions reveal new information, including an abrupt transition from wet to dry conditions around 550–750 CE. NE US paleo data suggest that conditions during the Medieval Climate Anomaly were warmer and drier than during the Little Ice Age, and drier than today. There is some evidence for an acceleration over the past century of a longer-term wetting trend in the NE US, and coupled with the abrupt shift from a cooling trend to a warming trend from increased greenhouse gases, may have wide-ranging implications for species distributions, ecosystem dynamics, and extreme weather events. More work is needed to gather paleoclimate data in the NE US, make inter-proxy comparisons, and improve estimates of uncertainty in the reconstructions.

scholarly journals Climatic history of the northeastern United States during the past 3000 years

2017 ◽  
Vol 13 (10) ◽  
pp. 1355-1379 ◽  
Author(s):  
Jennifer R. Marlon ◽  
Neil Pederson ◽  
Connor Nolan ◽  
Simon Goring ◽  
Bryan Shuman ◽  
...  
Keyword(s):  
Ecosystem Dynamics ◽  
Ice Age ◽  
Extreme Weather Events ◽  
Past Century ◽  
Vegetation Growth ◽  
The Past ◽  
Weather Events ◽  
Dry Conditions ◽  
History Of ◽  
Paleoclimate Records

Abstract. Many ecosystem processes that influence Earth system feedbacks – vegetation growth, water and nutrient cycling, disturbance regimes – are strongly influenced by multidecadal- to millennial-scale climate variations that cannot be directly observed. Paleoclimate records provide information about these variations, forming the basis of our understanding and modeling of them. Fossil pollen records are abundant in the NE US, but cannot simultaneously provide information about paleoclimate and past vegetation in a modeling context because this leads to circular logic. If pollen data are used to constrain past vegetation changes, then the remaining paleoclimate archives in the northeastern US (NE US) are quite limited. Nonetheless, a growing number of diverse reconstructions have been developed but have not yet been examined together. Here we conduct a systematic review, assessment, and comparison of paleotemperature and paleohydrological proxies from the NE US for the last 3000 years. Regional temperature reconstructions (primarily summer) show a long-term cooling trend (1000 BCE–1700 CE) consistent with hemispheric-scale reconstructions, while hydroclimate data show gradually wetter conditions through the present day. Multiple proxies suggest that a prolonged, widespread drought occurred between 550 and 750 CE. Dry conditions are also evident during the Medieval Climate Anomaly, which was warmer and drier than the Little Ice Age and drier than today. There is some evidence for an acceleration of the longer-term wetting trend in the NE US during the past century; coupled with an abrupt shift from decreasing to increasing temperatures in the past century, these changes could have wide-ranging implications for species distributions, ecosystem dynamics, and extreme weather events. More work is needed to gather paleoclimate data in the NE US to make inter-proxy comparisons and to improve estimates of uncertainty in reconstructions.

scholarly journals The Mixing Regime and Turbidity of Lake Banyoles (NE Spain): Response to Climate Change

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1621
Author(s):  
Teresa Serra ◽  
Josep Pascual ◽  
Ramon Brunet ◽  
Jordi Colomer
Keyword(s):  
Climate Change ◽  
Surface Waters ◽  
Warming Trend ◽  
Western Mediterranean ◽  
Aquifer Recharge ◽  
Temperature Changes ◽  
The Past ◽  
Deep Waters ◽  
Cooling Trend ◽  
Ne Iberian Peninsula

This study analyses the water temperature changes in Lake Banyoles over the past four decades. Lake Banyoles, Spain’s second highest lake, situated in the western Mediterranean (NE Iberian Peninsula). Over the past 44 years, the warming trend of the lake’s surface waters (0.52 °C decade−1) and the cooling trend of its deep waters (−0.66 °C decade−1) during summer (July–September) have resulted in an increased degree of stratification. Furthermore, the stratification period is currently double that of the 1970s. Meanwhile, over the past two decades, lake surface turbidity has remained constant in summer. Although turbidity did decrease during winter, it still remained higher than in the summer months. This reduction in turbidity is likely associated with the decrease in groundwater input into the lake, which has been caused by a significant decrease in rainfall in the aquifer recharge area that feeds the lake through groundwater sources. As a unique freshwater sentinel lake under the influence of the climate change, Lake Banyoles provides evidence that global warming in the western Mediterranean boosts the strength and duration of the lake’s stratification and, in response, the associated decrease in the turbidity of its epilimnion.

scholarly journals Little ice age advance and retreat of Glaciar Jorge Montt, Chilean Patagonia, recorded in maps, air photographs and dendrochronology

2011 ◽  
Vol 7 (5) ◽  
pp. 3131-3164 ◽  
Author(s):  
A. Rivera ◽  
M. Koppes ◽  
C. Bravo ◽  
J. C. Aravena
Keyword(s):  
Little Ice Age ◽  
Dynamic Responses ◽  
Ice Age ◽  
Past Century ◽  
Present Position ◽  
Tidewater Glaciers ◽  
The Past ◽  
Chilean Patagonia ◽  
Southern Patagonia ◽  
Induced Changes

Abstract. Glaciar Jorge Montt (48°20' S/73°30' W), one of the main tidewater glaciers of the Southern Patagonian Icefield (SPI), has experienced the fastest frontal retreat observed in Patagonia during the past century, with a recession of 19.5 km between 1898 and 2011. This record retreat uncovered trees overridden during the Little Ice Age (LIA) advance of the glacier. Samples of these trees were dated using radiocarbon methods, yielding burial ages between 460 and 250 cal yr BP. The dendrochronology and maps indicate that Glaciar Jorge Montt was at its present position before the beginning of the LIA, in concert with several other glaciers in Southern Patagonia, and reached its maximum advance position between 1650 and 1750 AD. The post-LIA retreat is most likely triggered by climatically induced changes during the 20th century, however, Glaciar Jorge Montt has responded more dramatically than its neighbours. The retreat of Jorge Montt opened a new fjord 19.5 km long, and up to 391 m deep, with a varied bathymetry well correlated with glacier retreat rates, suggesting that dynamic responses of the glacier are at least partially connected to near buoyancy conditions at the ice front, resulting in high calving fluxes, accelerating thinning rates and rapid ice velocities.

scholarly journals Neoglaciation in the Southern Kenai Mountains, Alaska

1990 ◽  
Vol 14 ◽  
pp. 319-322 ◽  
Author(s):  
Gregory C. Wiles ◽  
Parker E. Calkin
Keyword(s):  
Little Ice Age ◽  
Late Holocene ◽  
Ice Age ◽  
Past Century ◽  
Partial Control ◽  
The Past ◽  
Proglacial Lakes ◽  
Glacial Chronology ◽  
Historical Accounts ◽  
Ice Complex

A preliminary late-Holocene glacial chronology from the west flank of the southern Kenai Mountains, Alaska, is characterized by two major episodes of advance. Outlet glaciers of both the Harding Icefield and the Grewingk-Yalik ice complex were expanding across their present positions at 545 A.D. and again during the Little Ice Age, about 1500 A.D. The earliest of these Neoglacial advances is dated by radiocarbon ages from the outer rings of tree trunks rooted near the margins of Grewingk and Dinglestadt glaciers. Subsequently, ice margins retreated some distance behind their present positions allowing marked soil development before the last readvance through mature forest. Wood preserved in lateral moraines at Grewingk Glacier and from an uprooted stump at Tustemena Glacier date this later ice advance. Tree-ring ages, correlated with lichen diameters, suggest that this last advance was widespread and culminated in its Neoglacial maximum about 1800 A.D.. Since this time, glacier retreat has dominated in the area, punctuated by at least two pauses. Historical accounts and photographs document a mean rate of retreat of 27 m a−1 for the past century with partial control exerted by calving of ice margins into proglacial lakes.

scholarly journals Summer temperature trend over the past two millennia using air content in Himalayan ice

2005 ◽  
Vol 1 (2) ◽  
pp. 155-168 ◽  
Author(s):  
S. Hou ◽  
J. Chappellaz ◽  
J. Jouzel ◽  
P. C. Chu ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Relative Frequency ◽  
Ice Cores ◽  
Warming Trend ◽  
Summer Temperature ◽  
Temperature Trend ◽  
Ice Age ◽  
Air Content ◽  
The Past ◽  
Reconstruction Point

Abstract. Two Himalayan ice cores display a factor-two decreasing trend of air content over the past two millennia, in contrast to the relatively stable values in Greenland and Antarctica ice cores over the same period. Because the air content can be related with the relative frequency and intensity of melt phenomena, its variations along the Himalayan ice cores provide an indication of summer temperature trend. Our reconstruction point toward an unprecedented warming trend in the 20th century but does not depict the usual trends associated with "Medieval Warm Period" (MWP), or "Little Ice Age" (LIA).

Climate change and ecosystem response in the northern Columbia River basin — A paleoenvironmental perspective

2008 ◽  
Vol 16 (NA) ◽  
pp. 113-140 ◽  
Author(s):  
Ian R. Walker ◽  
Marlow G. Pellatt
Keyword(s):  
River Basin ◽  
Large Scale ◽  
Columbia River ◽  
Late Glacial ◽  
Ecosystem Dynamics ◽  
Ice Age ◽  
Columbia River Basin ◽  
Past Century ◽  
Atmospheric Circulation Patterns ◽  
Air Temperatures

A comprehensive review of Holocene paleoenvironmental data has been prepared, providing the basis for evaluating natural variability in climate and ecosystem dynamics in the northern Columbia River basin. The paleoenvironmental record reveals four major climatic shifts and a number of less well-defined climatic changes throughout the Holocene. The major climate changes are (1) a cool or cold, late-glacial climate at the end of the last glaciation (>11 500 cal. year BP), (2) an interval of drought and maximum summer warmth during the early Holocene (ca. 10500 to 8000 cal. year BP), (3) a mid-Holocene trend towards a cooler, more moist climate (ca. 8000 to ca. 4000 cal. year BP), and (4) a relatively stable climate persisting from ca. 4000 cal. year BP until the arrival of European settlers. Air temperatures have warmed by about 1 °C over the past century. Minor climate events that are emerging as global in nature include Little Ice Age (1200–150 BP) conditions, and a late Holocene cool wet period (3500–2500 BP). These are observed in some study sites examined in this paper and may be related to large-scale cycles of 2800–2000 and 1500 years. A discussion of changing atmospheric circulation patterns, and the causes of long-term climatic change are included, together with a discussion of the implications of the paleoenvironmental record for understanding future climate, and the likely response of communities and ecosystems.

The changing extent of marine-terminating glaciers and ice caps in northeastern Svalbard since the ‘Little Ice Age’ from marine-geophysical records

The Holocene ◽  
2019 ◽  
Vol 30 (3) ◽  
pp. 389-401 ◽  
Author(s):  
Julian A Dowdeswell ◽  
Dag Ottesen ◽  
Valerie K Bellec
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Aerial Photographs ◽  
Past Century ◽  
Ice Caps ◽  
The Past ◽  
Covered Area ◽  
Data Coverage ◽  
Climatic Cooling ◽  
Glacial Landforms

Climate warming in Svalbard since the end of the ‘Little Ice Age’ early in the 20th century has reduced glacier extent in the archipelago. Previous attempts to reconstruct ‘Little Ice Age’ glacier limits have encountered problems in specifying the area of tidewater glacier advances because it is difficult to estimate the past positions of their marine termini. Multibeam echo-sounding data are needed to map past glacier extent offshore, especially in open-marine settings where subaerial lateral moraines cannot be used due to the absence of fjord walls. We use the submarine glacial landform record to measure the recent limits of advance of over 30 marine-terminating northeastern Svalbard glaciers and ice caps. Our results demonstrate that previous work has underestimated the ice-covered area relative to today by about 40% for northeastern Svalbard (excluding southeast Austfonna) because marine-geophysical evidence in the form of submarine terminal moraines was not included. We show that the recent ice extent was 1753 km2 larger than today over our full area of multibeam data coverage; about 5% of the total modern ice cover of Svalbard. It has often been assumed that moraine ridges located within a few kilometres of modern ice fronts in Svalbard represent either a ‘Little Ice Age’ maximum or relate to surge activity over the past century or so. In the marine environment of northeastern Svalbard, this timing can often be confirmed by reference to early historical maps and aerial photographs. Assemblages of submarine glacial landforms inshore of recently deposited terminal moraines suggest whether a recent advance may be a result of surging or ‘Little Ice Age’ climatic cooling relative to today. However, older terminal moraines do exist in the archipelago, as shown by radiocarbon and 10Be dating of Holocene moraine ridges.

scholarly journals Radiative and dynamical contributions to past and future Arctic stratospheric temperature trends

2013 ◽  
Vol 13 (3) ◽  
pp. 6707-6728
Author(s):  
P. Bohlinger ◽  
B.-M. Sinnhuber ◽  
R. Ruhnke ◽  
O. Kirner
Keyword(s):  
Planetary Wave ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Warming Trend ◽  
Wave Activity ◽  
The Arctic ◽  
The Past ◽  
Stratospheric Temperature ◽  
The Future ◽  
Cooling Trend

Abstract. Arctic stratospheric ozone depletion is closely linked to the occurrence of low stratospheric temperatures. There are indications that cold winters in the Arctic stratosphere have been getting colder, raising the question if and to what extent a cooling of the Arctic stratosphere may continue into the future. We use meteorological re-analyses from ERA-Interim for the past 32 yr together with calculations of the chemistry-climate model EMAC and CCM models from the CCMVal project to infer radiative and dynamical contributions to long-term Arctic stratospheric temperature changes. For the past three decades ERA-Interim shows a warming trend in winter and cooling trend in spring and summer. Changes in winter and spring are caused by a corresponding change of planetary wave activity with increases in winter and decreases in spring. During winter the increase of planetary wave activity is counteracted by a radiatively induced cooling. Stratospheric radiatively induced cooling is detected throughout all seasons being highly significant in spring and summer. This means that for a given dynamical situation, in ERA-Interim the annual mean temperature of the Arctic lower stratosphere has been cooling by −0.41 ± 0.11 K decade−1 at 50 hPa over the past 32 yr. Calculations with state-of-the-art models from CCMVal and the EMAC model confirm the radiatively induced cooling for the past decades, but underestimate the amount of radiatively induced cooling deduced from ERA-Interim. EMAC predicts a continued annual radiatively induced cooling for the coming decades (2001–2049) of −0.15 ± 0.06 K decade−1 where the projected increase of CO2 accounts for about 2/3 of the cooling effect. Expected decrease of stratospheric halogen loading and resulting ozone recovery in the future counteracts the cooling tendency due to increasing greenhouse gas concentrations and leads to a reduced future cooling trend compared to the past. CCMVal multi-model mean predicts a future annual mean radiatively induced cooling of −0.10 ± 0.02 K decade−1 which is also smaller in the future than in the past.

scholarly journals Temperature changes of the past 2000 yr in China and comparison with Northern Hemisphere

2013 ◽  
Vol 9 (1) ◽  
pp. 507-523 ◽  
Author(s):  
Q. Ge ◽  
Z. Hao ◽  
J. Zheng ◽  
X. Shao
Keyword(s):  
Northern Hemisphere ◽  
Little Ice Age ◽  
Warming Trend ◽  
Warm Period ◽  
Ice Age ◽  
Global Changes ◽  
Least Squares Regression ◽  
Temperature Variations ◽  
Temperature Changes ◽  
The Past

Abstract. In this paper, we use principal components and partial least squares regression analysis to reconstruct a composite profile of temperature variations in China, and the associated uncertainties, at a decadal resolution over the past 2000 yr. Our aim is to contribute a new temperature time series to the paleoclimatic strand of the Asia2K working group, which is part of the PAGES (Past Global Changes) project. The reconstruction was developed using proxy temperature data, with relatively high confidence levels, from five locations across China, and an observed temperature dataset provided by Chinese Meteorological Administration covering the decades from the 1870s to the 1990s. Relative to the 1870s–1990s climatology, our two reconstructions both show three warm intervals during the 270s–390s, 1080s–1210s, and after the 1920s; temperatures in the 260s–400s, 560s–730s and 970s–1250s were comparable with those of the Present Warm Period. Temperature variations over China are typically in phase with those of the Northern Hemisphere (NH) after 1100, a period which covers the Medieval Climate Anomaly, Little Ice Age, and Present Warm Period. The recent rapid warming trend that developed between the 1840s and the 1930s occurred at a rate of 0.91° C/100 yr. The temperature difference between the cold spell (−0.74° C in the 1650s) during the Little Ice Age, and the warm peak of the Present Warm Period (0.08° C in the 1990s) is 0.82° C at a centennial time scale.

scholarly journals CLIMATIC, ENVIRONMENTAL AND OCEANOGRAPHIC CHANGES OVER THE PAST MILLENNIUM, RECONSTRUCTED FROM A PALYNOLOGICAL RECORD OF THE INNER URUGUAYAN CONTINENTAL SHELF / MUDANÇAS CLIMÁTICAS, AMBIENTAIS E OCEANOGRÁFICAS DO ÚLTIMO MILÉNIO, RECONSTRUÍDAS A PARTIR DE UM REGISTRO PALINÓNICO DA PLATAFORMA CONTINENTAL INTERNA URUGUAIA

2018 ◽  
Vol 3 (4) ◽  
pp. 234-252 ◽  
Author(s):  
Dominique Mourelle ◽  
Laura Perez ◽  
Till Jens Jörg Hanebuth ◽  
Hendrik Lantzsch ◽  
Felipe García-Rodríguez
Keyword(s):  
Continental Shelf ◽  
Climatic Variability ◽  
Ice Age ◽  
Past Century ◽  
Time Interval ◽  
Rio De La Plata ◽  
Long Distance ◽  
Río De La Plata ◽  
La Plata ◽  
The Past

In order to strengthen and update knowledge on climatic, environmental and oceanographic changes on the inner Uruguayan continental shelf, we studied pollen, dinocyst and other non-pollen palynomorph assemblages on the sediment core GeoB13813-4. This core was taken from the mud depocenter and its remarkable high sedimentation rate for the last ca. 1000 yr cal BP reflects the high terrigenous supply from the Rio de la Plata (RdlP). Most pollen and spores are originated from the RdlP grasslands, the vegetation that covers the lower reaches of the La Plata Drainage Basin (LPDB). They mainly represent the regionally dominant grasslands, but also the riparian forests, Butia yatay palm populations, and the herbaceous-bushy marshes around the mouth of the estuary. Pollen from salt marshes, Atlantic rainforest, and Araucaria forests located in southern Brazil reached the study site, probably transported by coastal ocean currents, whereas pollen from Andean regions would represent a long-distance transport by wind. Changes in both proportion and concentration of freshwater and marine palynomorphs indicate variability in freshwater input to the inner Uruguayan shelf. From ca. 1000 to 230 yr cal BP, significant marine influence of Subtropical Shelf Waters (STSW) was inferred, which was diluted by the freshwater supply from the Uruguayan mainland. This time interval was interrupted between ca. 690 to 575 yr cal BP by an increased freshwater contribution to the study area under the influence of Subantarctic Shelf Waters (SASW). From ca. 230 to 25 yr cal BP, a strong influence of RdlP waters was detected, only followed by another phase of dominant STSW during the past century. Such changes were related to regional climatic variability, i.e., Medieval Climate Anomaly, Little Ice Age and Current Warm Period. After ca. 1960 AD, the anthropogenic impact within the LPDB was clearly evidenced both by eutrophication and the first occurrence of Pinus pollen.ResumoA fim de melhorar e atualizar o conhecimento sobre mudanças climáticas, ambientais e oceanográficas na Plataforma Continental Uruguaia, foi estudado o pólen, os dinocistos e outras associações de palinomorfos não polínicos no testemunho de sedimentos GeoB13813-4. Este testemunho foi recolhido no depósito lodoso e a sua taxa de sedimentação durante os últimos ≈1000 anos antes do presente (BP; before present) reflete o elevado contributo terrígeno do Río de la Plata (RdlP) á área de estudo. Os resultados obtidos revelam que a maioria dos pólenes e esporos é originária das pastagens e da vegetação que cobre o curso inferior da Bacia de Drenagem do Río de la Plata (LPDB). Representam principalmente as pastagens, as quais são regionalmente dominantes, mas também matas ciliares, populações da palmeira Butia yatay e sapais herbáceos ao redor da foz do estuário. Pólen de sapais, Mata Atlântica e florestas de Araucária localizadas no sul do Brasil chegaram ao local de estudo, provavelmente transportados por correntes oceânicas costeiras. O pólen das regiões andinas poderá representar um transporte de longa distância pelo vento. Mudanças na proporção e concentração de palinomorfos de água doce e marinhos indicam variabilidade na entrada de água doce na plataforma continental interna uruguaia. Entre ≈1000-230 anos BP, os dados indicam a ocorrência de uma significativa influência marinha das Águas Subtropicais da Plataforma (STSW), misturadas com água doce do continente uruguaio. Este intervalo foi marcado, entre ≈690-575 anos BP, com uma maior contribuição de água doce para a área de estudo sob a influência de Águas Subantárticas (SASW). Entre ≈230-25 anos BP, foi detectada uma forte influência das águas do RdlP. Esta fase foi seguida, durante o século passado, por outra em que as STSW foram dominantes. Tais mudanças poderão ter sido causadas pela variabilidade climática regional, ou seja, Anomalia Climática Medieval, Pequena Idade do Gelo e Período Quente Atual. Desde ≈1960, o impacto antropogênico no LPDB está claramente evidenciado tanto pela eutrofização quanto pela primeira ocorrência de pólen de Pinus.

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