Precipitation changes in the South American Altiplano since 1300 AD reconstructed by tree-rings

Abstract. Throughout the second half of the 20th century, the Central Andes has experienced significant climatic and environmental changes characterized by a persistent warming trend, an increase in elevation of the 0 °C isotherm, and sustained glacier shrinkage. These changes have occurred in conjunction with a steadily growing demand for water resources. Given the short span of instrumental hydroclimatic records in this region, longer time span records are needed to understand the nature of climate variability and to improve the predictability of precipitation, a key factor modulating the socio-economic development in the South American Altiplano and adjacent arid lowlands. In this study we present the first quasi-millennial, tree-ring based precipitation reconstruction for the South American Altiplano. This annual (November–October) precipitation reconstruction is based on the Polylepis tarapacana tree-ring width series and represents the closest dendroclimatological record to the Equator in South America. This high-resolution reconstruction covers the past 707 yr and provides a unique record characterizing the occurrence of extreme events and consistent oscillations in precipitation. It also allows an assessment of the spatial and temporal stabilities of the teleconnections between rainfall in the Altiplano and hemispheric forcings such as El Niño-Southern Oscillation. Since the 1930s to present, a persistent negative trend in precipitation has been recorded in the reconstruction, with the three driest years since 1300 AD occurring in the last 70 yr. Throughout the 707 yr, the reconstruction contains a clear ENSO-like pattern at interannual to multidecadal time scales, which determines inter-hemispheric linkages between our reconstruction and other precipitation sensitive records modulated by ENSO in North America. Our reconstruction points out that century-scale dry periods are a recurrent feature in the Altiplano climate, and that the future potential coupling of natural and anthropogenic-induced droughts may have a severe impact on socio-economic activities in the region. Water resource managers must anticipate these changes in order to adapt to future climate change, reduce vulnerability and provide water equitably to all users.

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Precipitation changes in the South American Altiplano since 1300 AD reconstructed by tree-rings

Climate of the Past Discussions ◽

10.5194/cpd-7-4297-2011 ◽

2011 ◽

Vol 7 (6) ◽

pp. 4297-4334 ◽

Cited By ~ 1

Author(s):

M. S. Morales ◽

D. A. Christie ◽

R. Villalba ◽

J. Argollo ◽

J. Pacajes ◽

...

Keyword(s):

Tree Ring ◽

Environmental Changes ◽

Southern Oscillation ◽

Warming Trend ◽

Future Climate Change ◽

South American ◽

The South ◽

Precipitation Reconstruction ◽

Key Factor ◽

High Resolution Reconstruction

Abstract. During the second half of the 20th century, the Central Andes has experienced significant climatic and environmental changes characterized by a persistent warming trend, an increase in elevation of the 0 °C isotherm, and a sustained shrinkage of glaciers. These changes have occurred in conjunction with a steady growing demand for water resources. Given the short span of instrumental hidroclimatic records in this region, longer records are needed to understand the nature of climate variability and improve the predictability of precipitation, a key factor modulating the socio-economic development in the South American Altiplano and the adjacent arid lowlands. In this study we present the first quasi-millennial, tree-ring based precipitation reconstruction for the South American Altiplano. This annual (November–October) precipitation reconstruction is based on Polylepis tarapacana tree-ring series and represents the closest dendroclimatological record to the Equator in South America. This high-resolution reconstruction covers the past 707 yr and provides a unique record to characterize the occurrence of extreme events and consistent oscillations in precipitation, as well as to check the spatial and temporal stabilities of the teleconnections between rainfall in the Altiplano and hemispheric forcings such as El Niño-Southern Oscillation. Since the 1930s up to present a persistent negative trend in precipitation is recorded in the reconstruction, with the three driest years since 1300 AD occurring in the last 70 yr. The reconstruction contains a clear ENSO-like pattern at interannual to multicentennial time scales which determines inter-hemispheric linkages between our reconstruction and other precipitation-sensitive records modulated by ENSO in North America. Our reconstruction points out that century-scale dry periods are a recurrent feature in the Altiplano climate, and that the potential coupling of natural and anthropogenic-induced droughts in the future would have a severe impact on current socio-economical activities in the region. Water resource managers must anticipate these changes to adapt for future climate change, reduce vulnerability and provide water equitably to all users.

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Tree growth across the Nepal Himalaya during the last four centuries

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133317714247 ◽

2017 ◽

Vol 41 (4) ◽

pp. 478-495 ◽

Cited By ~ 15

Author(s):

UK Thapa ◽

S St. George ◽

DK Kharal ◽

NP Gaire

Keyword(s):

Tree Ring ◽

Tree Growth ◽

Environmental Changes ◽

Ring Width ◽

High Elevation ◽

Forest Growth ◽

Tree Ring Width ◽

Early 19Th Century ◽

Tree Ring Data ◽

Instrumental Records

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.

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A 406-year non-growing-season precipitation reconstruction in the southeastern Tibetan Plateau

Climate of the Past ◽

10.5194/cp-17-2381-2021 ◽

2021 ◽

Vol 17 (6) ◽

pp. 2381-2392

Author(s):

Maierdang Keyimu ◽

Zongshan Li ◽

Bojie Fu ◽

Guohua Liu ◽

Fanjiang Zeng ◽

...

Keyword(s):

Tibetan Plateau ◽

Tree Ring ◽

Tree Growth ◽

Ring Width ◽

Growing Season ◽

Climatic Conditions ◽

Forest Growth ◽

Drought Severity ◽

Precipitation Reconstruction ◽

Southeastern Tibetan Plateau

Abstract. Trees record climatic conditions during their growth, and tree rings serve as proxy to reveal the features of the historical climate of a region. In this study, we collected tree-ring cores of hemlock forest (Tsuga forrestii) from the northwestern Yunnan area of the southeastern Tibetan Plateau (SETP) and created a residual tree-ring width (TRW) chronology. An analysis of the relationship between tree growth and climate revealed that precipitation during the non-growing season (NGS) (from November of the previous year to February of the current year) was the most important constraining factor on the radial tree growth of hemlock forests in this region. In addition, the influence of NGS precipitation on radial tree growth was relatively uniform over time (1956–2005). Accordingly, we reconstructed the NGS precipitation over the period spanning from 1600–2005. The reconstruction accounted for 28.5 % of the actual variance during the common period of 1956–2005. Based on the reconstruction, NGS was extremely dry during the years 1656, 1694, 1703, 1736, 1897, 1907, 1943, 1982 and 1999. In contrast, the NGS was extremely wet during the years 1627, 1638, 1654, 1832, 1834–1835 and 1992. Similar variations of the NGS precipitation reconstruction series and Palmer Drought Severity Index (PDSI) reconstructions of early growing season from surrounding regions indicated the reliability of the present reconstruction. A comparison of the reconstruction with Climate Research Unit (CRU) gridded data revealed that our reconstruction was representative of the NGS precipitation variability of a large region in the SETP. Our study provides the first historical NGS precipitation reconstruction in the SETP which enriches the understanding of the long-term climate variability of this region. The NGS precipitation showed slightly increasing trend during the last decade which might accelerate regional hemlock forest growth.

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An 854-Year Tree-Ring Chronology of Scots Pine for South-West Finland

Studia Quaternaria ◽

10.2478/squa-2014-0006 ◽

2014 ◽

Vol 31 (1) ◽

pp. 61-68 ◽

Cited By ~ 4

Author(s):

Samuli Helama ◽

Jari Holopainen ◽

Mauri Timonen ◽

Kari Mielikäinen

Keyword(s):

Tree Ring ◽

Ring Width ◽

Summer Precipitation ◽

Total Sample ◽

Early Summer ◽

The South ◽

Tree Ring Chronology ◽

The North ◽

South West ◽

The North Atlantic Oscillation

Abstract A near-millennial tree-ring chronology (AD 1147-2000) is presented for south-west Finland and analyzed using dendroclimatic methods. This is a composite chronology comprising samples both from standing pine trees (Pinus sylvestris L.) and subfossil trunks as recovered from the lake sediments, with a total sample size of 189 tree-ring sample series. The series were dendrochronologically cross-dated to exact calendar years to portray variability in tree-ring widths on inter-annual and longer scales. Al though the studied chronology correlates statistically significantly with other long tree-ring width chronologies from Finland over their common period (AD 1520-1993), the south-west chronology did not exhibit similarly strong mid-summer temperature or spring/early-summer precipitation signals in comparison to published chronologies. On the other hand, the south-west chronology showed highest correlations to the North Atlantic Oscillation indices in winter/spring months, this association following a dendroclimatic feature common to pine chronologies over the region and adjacent areas. Paleoclimatic comparison showed that tree-rings had varied similarly to central European spring temperatures. It is postulated that the collected and dated tree-ring material could be studied for wood surface reflectance (blue channel light intensity) and stable isotopes, which both have recently shown to correlate notably well with summer temperatures.

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Future Environments of South America

The Physical Geography of South America ◽

10.1093/oso/9780195313413.003.0030 ◽

2007 ◽

Author(s):

Thomas T. Veblen ◽

Kenneth R. Young

Keyword(s):

South America ◽

Environmental Change ◽

Environmental Changes ◽

Human Impacts ◽

Southern Oscillation ◽

Physical Geography ◽

Tierra Del Fuego ◽

South American ◽

Policy Options ◽

Natural Processes

An important goal of this book has been to provide a comprehensive understanding of the physical geography and landscape origins of South America as important background to assessing the probabilities and consequences of future environmental changes. Such background is essential to informed discussions of environmental management and the development of policy options designed to prepare local, national, and international societies for future changes. A unifying theme of this book has been the elucidation of how natural processes and human activities have interacted in the distant and recent past to create the modern landscapes of the continent. This retrospective appreciation of how the current landscapes have been shaped by nature and humans will guide our discussion of possible future trajectories of South American environments. There is abundant evidence from all regions of South America, from Tierra del Fuego to the Isthmus of Panama, that environmental change, not stasis, has been the norm. Given that fact, the history, timing, and recurrence intervals of this dynamism are all crucial pieces of information. The antiquity and widespread distribution of changes associated with the indigenous population are now well established. Rates and intensities of changes related to indigenous activities varied widely, but even in regions formerly believed to have experienced little or no pre-European impacts we now recognize the effects of early humans on features such as soils and vegetation. Colonization by Europeans mainly during the sixteenth century modified or in some cases replaced indigenous land-use practices and initiated changes that have continued to the present. Complementing these broad historical treatments of human impacts, other chapters have examined in detail the environmental impacts of agriculture (chapter 18) and urbanism (chapter 20), and the disruptions associated with El Niño–Southern Oscillation events. The goal of this final synthesis is to identify the major drivers of change and to discuss briefly their likely impacts on South American environments and resources in the near and medium-term future. Our intent is not to make or defend predictions, but rather to identify broad causes and specific drivers of environmental change to inform discussions of policy options for mitigating undesirable changes and to facilitate potential societal adaptations to them.

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The impact of the subtropical South Atlantic SST on South American precipitation

Annales Geophysicae ◽

10.5194/angeo-26-3457-2008 ◽

2008 ◽

Vol 26 (11) ◽

pp. 3457-3476 ◽

Cited By ~ 24

Author(s):

A. S. Taschetto ◽

I. Wainer

Keyword(s):

South America ◽

Southern Oscillation ◽

South Atlantic ◽

Empirical Orthogonal Functions ◽

Convergence Zone ◽

South American ◽

The South ◽

Inter Tropical Convergence Zone ◽

The Impact ◽

Sst Anomalies

Abstract. The Community Climate Model (CCM3) from the National Center for Atmospheric Research (NCAR) is used to investigate the effect of the South Atlantic sea surface temperature (SST) anomalies on interannual to decadal variability of South American precipitation. Two ensembles composed of multidecadal simulations forced with monthly SST data from the Hadley Centre for the period 1949 to 2001 are analysed. A statistical treatment based on signal-to-noise ratio and Empirical Orthogonal Functions (EOF) is applied to the ensembles in order to reduce the internal variability among the integrations. The ensemble treatment shows a spatial and temporal dependence of reproducibility. High degree of reproducibility is found in the tropics while the extratropics is apparently less reproducible. Austral autumn (MAM) and spring (SON) precipitation appears to be more reproducible over the South America-South Atlantic region than the summer (DJF) and winter (JJA) rainfall. While the Inter-tropical Convergence Zone (ITCZ) region is dominated by external variance, the South Atlantic Convergence Zone (SACZ) over South America is predominantly determined by internal variance, which makes it a difficult phenomenon to predict. Alternatively, the SACZ over western South Atlantic appears to be more sensitive to the subtropical SST anomalies than over the continent. An attempt is made to separate the atmospheric response forced by the South Atlantic SST anomalies from that associated with the El Niño – Southern Oscillation (ENSO). Results show that both the South Atlantic and Pacific SSTs modulate the intensity and position of the SACZ during DJF. Particularly, the subtropical South Atlantic SSTs are more important than ENSO in determining the position of the SACZ over the southeast Brazilian coast during DJF. On the other hand, the ENSO signal seems to influence the intensity of the SACZ not only in DJF but especially its oceanic branch during MAM. Both local and remote influences, however, are confounded by the large internal variance in the region. During MAM and JJA, the South Atlantic SST anomalies affect the magnitude and the meridional displacement of the ITCZ. In JJA, the ENSO has relatively little influence on the interannual variability of the simulated rainfall. During SON, however, the ENSO seems to counteract the effect of the subtropical South Atlantic SST variations on convection over South America.

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Dendrochronological analysis and growth patterns of Polylepis reticulata (Rosaceae) in the Ecuadorian Andes

IAWA Journal ◽

10.1163/22941932-40190240 ◽

2019 ◽

Vol 40 (2) ◽

pp. 331-S5 ◽

Cited By ~ 3

Author(s):

C. Alvites ◽

G. Battipaglia ◽

G. Santopuoli ◽

H. Hampel ◽

R.F. Vázquez ◽

...

Keyword(s):

Tree Ring ◽

Tree Rings ◽

Stand Structure ◽

Climatic Factors ◽

Southern Oscillation ◽

Ring Width ◽

Vapour Pressure Deficit ◽

Growth Patterns ◽

Tree Ring Width ◽

Sources Of Information

ABSTRACTRelict tree species in the Andean mountains are important sources of information about climate variability and climate change. This study deals with dendroclimatology and growth patterns in Polylepis reticulata Hieron., growing at high elevation (mean of 4000 m a.s.l.) in three sites of the Ecuadorian Andes. The aims of the research were: (i) characterizing tree-ring boundaries; (ii) describing tree-ring patterns of the study sites; (iii) investigating the relationships between climate and radial tree growth; and (iv) determining the spatial correlation between seasonal climatic factors and tree-ring width of P. reticulata. Tree rings were characterized by semi-ring porosity and slight differences in fibre wall thickness between latewood and subsequent earlywood. In all sampling sites, tree rings in heartwood were more clearly visible than in sapwood. Tree-ring width was more related to temperature than to precipitation, with growth being also affected by site conditions and stand structure, as well as other local factors. No significant relationships were found between tree-ring chronologies of P. reticulata and El Niño-Southern Oscillation (ENSO) and Vapour Pressure Deficit indices. The study highlights that there is not a clear driving climate factor for radial growth of P. reticulata. Additional research is needed to study growth dynamics of this species and the impacts of local environmental variables.

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Centennial-scale precipitation anomalies in the southern Altiplano (18° S) suggest an extratropical driver for the South American summer monsoon during the late Holocene

Climate of the Past ◽

10.5194/cp-15-1845-2019 ◽

2019 ◽

Vol 15 (5) ◽

pp. 1845-1859 ◽

Cited By ~ 2

Author(s):

Ignacio A. Jara ◽

Antonio Maldonado ◽

Leticia González ◽

Armand Hernández ◽

Alberto Sáez ◽

...

Keyword(s):

Summer Monsoon ◽

Large Scale ◽

Southern Oscillation ◽

Atlantic Coast ◽

Austral Summer ◽

High Elevation ◽

South American ◽

Tropical Andes ◽

The South ◽

Precipitation Anomalies

Abstract. Modern precipitation anomalies in the Altiplano, South America, are closely linked to the strength of the South American summer monsoon (SASM), which is influenced by large-scale climate features sourced in the tropics such as the Intertropical Convergence Zone (ITCZ) and El Niño–Southern Oscillation (ENSO). However, the timing, direction, and spatial extent of precipitation changes prior to the instrumental period are still largely unknown, preventing a better understanding of the long-term drivers of the SASM and their effects over the Altiplano. Here we present a detailed pollen reconstruction from a sedimentary sequence covering the period between 4500 and 1000 cal yr BP in Lago Chungará (18∘ S; 4570 m a.s.l.), a high-elevation lake on the southwestern margin of the Altiplano where precipitation is delivered almost exclusively during the mature phase of the SASM over the austral summer. We distinguish three well-defined centennial-scale anomalies, with dry conditions between 4100–3300 and 1600–1000 cal yr BP and a conspicuous humid interval between 2400 and 1600 cal yr BP, which resulted from the weakening and strengthening of the SASM, respectively. Comparisons with other climate reconstructions from the Altiplano, the Atacama Desert, the tropical Andes, and the southwestern Atlantic coast reveal that – unlike modern climatological controls – past precipitation anomalies at Lago Chungará were largely decoupled from north–south shifts in the ITCZ and ENSO. A regionally coherent pattern of centennial-scale SASM variations and a significant latitudinal gradient in precipitation responses suggest the contribution of an extratropical moisture source for the SASM, with significant effects on precipitation variability in the southern Altiplano.

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Tree-Ring Records of Near-Younger Dryas Time in Central North America—Preliminary Results from the Lincoln Quarry Site, Central Illinois, Usa

Radiocarbon ◽

10.1017/s0033822200035980 ◽

2004 ◽

Vol 46 (2) ◽

pp. 933-941 ◽

Cited By ~ 6

Author(s):

Irina P Panyushkina ◽

Steven W Leavitt ◽

Alex Wiedenhoeft ◽

Sarah Noggle ◽

Brandon Curry ◽

...

Keyword(s):

North America ◽

Tree Ring ◽

Environmental Changes ◽

Ring Width ◽

Younger Dryas ◽

Late Glacial ◽

Radiocarbon Dates ◽

Initial Sampling ◽

Central Illinois ◽

A Site

The abrupt millennial-scale changes associated with the Younger Dryas (YD) event (“chronozone”) near the dawn of the Holocene are at least hemispheric, if not global, in extent. Evidence for the YD cold excursion is abundant in Europe but fairly meager in central North America. We are engaged in an investigation of high-resolution environmental changes in mid-North America over several millennia (about 10,000 to 14,000 BP) during the Late Glacial–Early Holocene transition, including the YD interval. Several sites containing logs or stumps have been identified and we are in the process of initial sampling or re-sampling them for this project. Here, we report on a site in central Illinois containing a deposit of logs initially thought to be of YD age preserved in alluvial sands. The assemblage of wood represents hardwood (angiosperm) trees, and the ring-width characteristics are favorable to developing formal tree-ring chronologies. However, 4 new radiocarbon dates indicate deposition of wood may have taken place over at least 8000 14C yr (6000–14,000 BP). This complicates the effort to develop a single floating chronology of several hundred years at this site, but it may provide wood from a restricted region over a long period of time from which to develop a sequence of floating chronologies, the timing of deposition and preservation of which could be related to paleoclimatic events and conditions.

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A 424-year tree-ring-based Palmer Drought Severity Index reconstruction of <i>Cedrus deodara</i> D. Don from the Hindu Kush range of Pakistan: linkages to ocean oscillations

Climate of the Past ◽

10.5194/cp-16-783-2020 ◽

2020 ◽

Vol 16 (2) ◽

pp. 783-798

Author(s):

Sarir Ahmad ◽

Liangjun Zhu ◽

Sumaira Yasmeen ◽

Yuandong Zhang ◽

Zongshan Li ◽

...

Keyword(s):

Tree Ring ◽

Palmer Drought Severity Index ◽

Southern Oscillation ◽

Ring Width ◽

Severity Index ◽

Drought Severity ◽

Mountain Range ◽

Cedrus Deodara ◽

Hindu Kush ◽

Drought Severity Index

Abstract. The rate of global warming has led to persistent drought. It is considered to be the preliminary factor affecting socioeconomic development under the background of the dynamic forecasting of the water supply and forest ecosystems in West Asia. However, long-term climate records in the semiarid Hindu Kush range are seriously lacking. Therefore, we developed a new tree-ring width chronology of Cedrus deodara spanning the period of 1537–2017. We reconstructed the March–August Palmer Drought Severity Index (PDSI) for the past 424 years, going back to 1593 CE. Our reconstruction featured nine dry periods (1593–1598, 1602–1608, 1631–1645, 1647–1660, 1756–1765, 1785–1800, 1870–1878, 1917–1923, and 1981–1995) and eight wet periods (1663–1675, 1687–1708, 1771–1773, 1806–1814, 1844–1852, 1932–1935, 1965–1969, and 1990–1999). This reconstruction is consistent with other dendroclimatic reconstructions in West Asia, thereby confirming its reliability. The multi-taper method and wavelet analysis revealed drought variability at periodicities of 2.1–2.4, 3.3, 6.0, 16.8, and 34.0–38.0 years. The drought patterns could be linked to the large-scale atmospheric–oceanic variability, such as the El Niño–Southern Oscillation, Atlantic Multidecadal Oscillation, and solar activity. In terms of current climate conditions, our findings have important implications for developing drought-resistant policies in communities on the fringes of the Hindu Kush mountain range in northern Pakistan.

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