The changing landscape of Canada's western boreal forest: the current dynamics of permafrost

2000 ◽  
Vol 30 (2) ◽  
pp. 283-287 ◽  
Author(s):  
Dale H Vitt ◽  
Linda A Halsey ◽  
Stephen C Zoltai
Keyword(s):  
Organic Matter ◽  
Little Ice Age ◽  
Water Levels ◽  
Ice Age ◽  
Ecosystem Change ◽  
Western Canada ◽  
Permafrost Degradation ◽  
Organic Matter Accumulation ◽  
The Impact

This paper examines the impact that climatic change over the last millennium has had on aggradation and degradation of permafrost peatlands and the associated change in organic matter accumulation. Permafrost reached its southernmost Holocene extent in boreal continental western Canada during the Little Ice Age with 28 800 km2 of permafrost peatland present within a sensitive zone demarcated by permafrost degradation. Subsequent degradation of permafrost has occurred in response to warming, with forested bogs changing to nonforested poor fens, associated with rising water levels. In conjunction with this ecosystem change, long-term net organic matter accumulation increases. As permafrost is in disequilibrium with climate, much of the permafrost that remains is in a relict state. Mapping of past and present permafrost distribution from peatland landforms indicates only 9% has degraded since the Little Ice Age, resulting in a 5% increase in long-term net organic matter accumulation. Of the permafrost that remains, 22% is in disequilibrium, located largely in the northern part of the sensitive zone. Additional loss of forested lands will occur in the future in boreal continental western Canada under present-day climatic conditions as permafrost approaches equilibrium, with a further 11% increase in long-term net organic matter accumulation predicted.

scholarly journals Simulated retreat of Jakobshavn Isbræ since the Little Ice Age controlled by geometry

2018 ◽  
Vol 12 (7) ◽  
pp. 2249-2266 ◽  
Author(s):  
Nadine Steiger ◽  
Kerim H. Nisancioglu ◽  
Henning Åkesson ◽  
Basile de Fleurian ◽  
Faezeh M. Nick
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Climate Forcing ◽  
Relative Role ◽  
Regional Warming ◽  
History Of ◽  
The Impact ◽  
Term Response

Abstract. Rapid retreat of Greenland's marine-terminating glaciers coincides with regional warming trends, which have broadly been used to explain these rapid changes. However, outlet glaciers within similar climate regimes experience widely contrasting retreat patterns, suggesting that the local fjord geometry could be an important additional factor. To assess the relative role of climate and fjord geometry, we use the retreat history of Jakobshavn Isbræ, West Greenland, since the Little Ice Age (LIA) maximum in 1850 as a baseline for the parameterization of a depth- and width-integrated ice flow model. The impact of fjord geometry is isolated by using a linearly increasing climate forcing since the LIA and testing a range of simplified geometries. We find that the total length of retreat is determined by external factors – such as hydrofracturing, submarine melt and buttressing by sea ice – whereas the retreat pattern is governed by the fjord geometry. Narrow and shallow areas provide pinning points and cause delayed but rapid retreat without additional climate warming, after decades of grounding line stability. We suggest that these geometric pinning points may be used to locate potential sites for moraine formation and to predict the long-term response of the glacier. As a consequence, to assess the impact of climate on the retreat history of a glacier, each system has to be analyzed with knowledge of its historic retreat and the local fjord geometry.

The impact of porosity on organic matter cycling in a two-dimensional porous medium 

2021 ◽  
Author(s):  
Hanbang Zou ◽  
Pelle Ohlsson ◽  
Edith Hammer
Keyword(s):  
Porous Medium ◽  
Organic Matter ◽  
Carbon Sequestration ◽  
Soil Carbon ◽  
Pore Network ◽  
Pore Scale ◽  
Decomposition Of Organic Matter ◽  
Organic Matter Cycling ◽  
The Impact

<p>Carbon sequestration has been a popular research topic in recent years as the rapid elevation of carbon emission has significantly impacted our climate. Apart from carbon capture and storage in e.g. oil reservoirs, soil carbon sequestration offers a long term and safe solution for the environment and human beings. The net soil carbon budget is determined by the balance between terrestrial ecosystem sink and sources of respiration to atmospheric carbon dioxide. Carbon can be long term stored as organic matters in the soil whereas it can be released from the decomposition of organic matter. The complex pore networks in the soil are believed to be able to "protect" microbial-derived organic matter from decomposition. Therefore, it is important to understand how soil structure impacts organic matter cycling at the pore scale. However, there are limited experimental studies on understanding the mechanism of physical stabilization of organic matter. Hence, my project plan is to create a heterogeneous microfluidic porous microenvironment to mimic the complex soil pore network which allows us to investigate the ability of organisms to access spaces starting from an initial ecophysiological precondition to changes of spatial accessibility mediated by interactions with the microbial community.</p><p>Microfluidics is a powerful tool that enables studies of fundamental physics, rapid measurements and real-time visualisation in a complex spatial microstructure that can be designed and controlled. Many complex processes can now be visualized enabled by the development of microfluidics and photolithography, such as microbial dynamics in pore-scale soil systems and pore network modification mimicking different soil environments – earlier considered impossible to achieve experimentally. The microfluidic channel used in this project contains a random distribution of cylindrical pillars of different sizes so as to mimic the variations found in real soil. The randomness in the design creates various spatial availability for microbes (preferential flow paths with dead-end or continuous flow) as an invasion of liquids proceeds into the pore with the lowest capillary entry pressure. In order to study the impact of different porosity in isolation of varying heterogeneity of the porous medium, different pore size chips that use the same randomly generated pore network is created. Those chips have the same location of the pillars, but the relative size of each pillar is scaled. The experiments will be carried out using sterile cultures of fluorescent bacteria, fungi and protists, synthetic communities of combinations of these, or a whole soil community inoculum. We will quantify the consumption of organic matter from the different areas via fluorescent substrates, and the bio-/necromass produced. We hypothesise that lower porosity will reduce the net decomposition of organic matter as the narrower pore throat limits the access, and that net decomposition rate at the main preferential path will be higher than inside branches</p>

scholarly journals Transformation of Lowland Rainforest into Oil-palm Plantations and use of Fire alter Topsoil and Litter Silicon Pools and Fluxes

Silicon ◽  
2020 ◽  
Author(s):  
Barbara von der Lühe ◽  
Laura Pauli ◽  
Britta Greenshields ◽  
Harold J. Hughes ◽  
Aiyen Tjoa ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Oil Palm ◽  
Fire Event ◽  
Oil Palm Frond ◽  
Lowland Rainforest ◽  
The Impact ◽  
Effects Of Land Use ◽  
Palm Frond

Abstract The effects of land use and fire on ecosystem silicon (Si) cycling has been largely disregarded so far. We investigated the impacts of land use and fire on Si release from topsoils and litter of lowland rainforest and oil-palm plantations in Jambi Province, Indonesia. Lower concentrations of Si in amorphous silica (ASi) were found in oil-palm plantation topsoils (2.8 ± 0.7 mg g− 1) compared to rainforest (3.5 ± 0.8 mg g− 1). Higher total Si concentrations were detected in litter from oil-palm frond piles (22.8 ± 4.6 mg g− 1) compared to rainforest litter (12.7 ± 2.2 mg g− 1). To test the impact of fire, materials were burned at 300 °C and 500 °C and were shaken with untreated samples in simulated rainwater for 28 h. Untreated oil-palm topsoils showed a significantly lower Si release (p≤ 0.05) compared to rainforest. The fire treatments resulted in an increased Si release into simulated rainwater. Si release from oil-palm topsoils and litter increased by a factor of 6 and 9 (500 °C), respectively, and Si release from rainforest topsoils and litter by a factor of 3 and 9 (500 °C). Differences between land use were related to initial ASi and litter Si concentrations, and to losses of soil organic matter during burning. We conclude that transformation of rainforest into oil palm plantations could be an important and immediate Si source after a fire event but may indirectly lead to a decrease in the long-term Si availability to plants.

Evaluating the impact of ballast undercutting on the roughness of track geometry over different subgrade conditions

2017 ◽  
Vol 232 (5) ◽  
pp. 1266-1276
Author(s):  
Kirk M Scanlan ◽  
Michael T Hendry ◽  
C Derek Martin
Keyword(s):  
Surface Roughness ◽  
Organic Soils ◽  
Western Canada ◽  
Railway Ballast ◽  
Track Geometry ◽  
Track Maintenance ◽  
Heavy Haul ◽  
Long Term Trends ◽  
The Impact

The progressive degradation of railway ballast is often cited as a primary factor that contributes to the development of track roughness, while ballast renewal (undercutting) attempts to manage its long-term development. Soft subgrades have been shown to strongly influence track geometry and are a contributing factor that has not been considered during conventional track maintenance. This study evaluated the impact of undercutting on long-term trends in track geometry roughness, and what impact softer subgrades had on the effectiveness of undercutting. A combined 6.90 km of Class II–IV heavy-haul track in Western Canada (undercut in 2010 and 2011) formed the basis for this analysis. Annual traffic on these sections typically totals 50 million gross tonnes. Long-term trends in the track crosslevel, alignment, and surface roughness after ballast renewal were derived from 50 track geometry surveys carried out over a five-year period (2010–2015). The results showed that undercutting significantly reduced track roughness over sand, silt, clay, or till subgrades; however, it was often ineffective when used over soft organic subgrades. Thus, while ballast degradation is the primary cause of track roughness in segments constructed on mineral subgrades, it is not a mechanism that results in track geometry roughness over soft organic soils.

Post-glacial dynamics of alpine Little Ice Age glacitectonized frozen landforms (Swiss Alps)

2020 ◽  
Author(s):  
Julie Wee ◽  
Reynald Delaloye ◽  
Chloé Barboux
Keyword(s):  
Little Ice Age ◽  
Spatial Configuration ◽  
Sar Interferometry ◽  
Swiss Alps ◽  
Ice Age ◽  
Permafrost Degradation ◽  
Mass Wasting ◽  
Ground Ice ◽  
Slope Movements ◽  
Glacier Ice

<p>Glaciers and frozen debris landforms have coexisted and episodically interacted throughout the Holocene, the former having altered the development, spatial distribution and thermal regime of the latter. In the Alps, the apogee of last interaction phase occurred during the Little Ice Age (LIA). Since then, due to glacier shrinkage, interactions between glaciers and LIA pre-existing frozen debris have gradually diminished and are leaning towards being non-existent. Post-LIA glacier forefields in permafrost environments, including associated glacitectonized frozen landforms (GFL) have shifted from a thermal and mechanical glacier dominant regime towards a periglacial or even post-periglacial regime. GFL are undergoing thermal and mechanical readjustments in response to both the longer-term glacier recession and the more recent drastic climatic warming. They can be expressed by a combination of mass-wasting processes and thaw-induced subsidence.</p><p> </p><p>In various regions of the Swiss Alps, slope movements occurring in a periglacial context have been inventoried in previous works using differential SAR interferometry (DInSAR) (Barboux et al., 2014). In the scope of this study, and focusing solely on mass-wasting GFL, the former inventory allowed the identification of the latter under various spatial configurations within LIA glacier forefields. While most observed GFL are disconnected from the associated glacier, some are still connected. Additionally, ground ice occurs as interstitial or massive (buried) glacier ice. This potentially infers the ongoing of non-uniform morphodynamical readjustments.</p><p> </p><p>To understand the site-specific behaviour of GFL, the analysis of long-term time-series of permafrost monitoring and multi-temporal high-resolution Digital Elevation Models will allow the assessment of the recent evolution of the Aget and Ritord/Challand LIA glacier forefields (46°00’32’’ N, 7°14’20’’ E and 45°57’10’’ N, 7°14’52’’ E, respectively) and their associated GFL (i.e. push-moraines). Both glacier forefields present a contrasting spatial configuration, making their morphodynamical evolution to differ partly from one another. The Aget push-moraine is a back-creeping GFL, which has been disconnected from the Aget glacier since the 1940s at latest. For the last two decades, surface displacement velocities have decelerated in comparison to the accelerating regional trend (PERMOS, 2019). Additionally, a 30% decrease of the electrical resistivity of the frozen ground, combined with locally observed thaw-induced subsidence of up to 10 cm/year suggest an advanced permafrost degradation. The Ritord/Challand system presents a push-moraine disconnected from its glacier as well as several push-moraines connected to a still existing debris-covered glacier. Between 2016 and 2019, surface lowering up to 10 m attesting massive ice melt has been locally detected in the former where buried glacier ice was visually observed. Whereas in the latter, subtle surface displacements ranging from 10 to 30 cm/year occur. This confirms the heterogeneity of the morphodynamical processes occurring in GFL, expressed as a function of both their spatial configuration and ground ice properties.</p><p> </p><p>Barboux, C., Delaloye R. and Lambiel, C. (2014). Inventorying slope movements in an Alpine environment using DInSAR. Earth Surface Processes and Landforms, 39/15, 2087-2099.</p><p>PERMOS 2019. Permafrost in Switzerland 2014/2015 to 2017/2018. Noetzli, J., Pellet, C., and Staub, B. (eds.), Glaciological Report (Permafrost) No. 16-19 of the Cryospheric Commission of the Swiss Academy of Sciences, 104.</p>

Evaluation of 2018 drought and effectiveness of adaptation measures in the Netherlands

2020 ◽  
Author(s):  
Marjolein H.J. van Huijgevoort ◽  
Janine A. de Wit ◽  
Ruud P. Bartholomeus
Keyword(s):  
Soil Moisture ◽  
The Netherlands ◽  
Capillary Rise ◽  
Hydrological Drought ◽  
Water Levels ◽  
Severe Drought ◽  
Drought Event ◽  
Groundwater Levels ◽  
The Impact

<p>Extreme dry conditions occurred over the summer of 2018 in the Netherlands. This severe drought event led to very low groundwater  and surface water levels. These impacted several sectors like navigation, agriculture, nature and drinking water supply. Especially in the Pleistocene uplands of the Netherlands, the low groundwater levels had a large impact on crop yields and biodiversity in nature areas. Projections show that droughts with this severity will occur more often in the future due to changes in climate. To mitigate the impact of these drought events, water management needs to be altered.</p><p>In this study, we evaluated the 2018 drought event in the sandy regions of the Netherlands and studied which measures could be most effective to mitigate drought impact. We have included meteorological, soil moisture and hydrological drought and the propagation of the drought through these types. Droughts were determined with standardized indices (e.g. Standardized Precipitation Index) and the variable threshold level method. Investigated measures were, for example, higher water levels in ditches, reduced irrigation from groundwater, and increased water conservation in winter. We also studied the timing of these measures to determine the potential for mitigating effects during a drought versus the effectiveness of long term adaptation. The measures were simulated with the agro-hydrological Soil–Water–Atmosphere–Plant (SWAP) model for several areas across the Netherlands for both agricultural fields and nature sites.</p><p>As expected, decreasing irrigation from groundwater reduced the severity of the hydrological drought in the region. Severity of the soil moisture drought also decreased in fields that were never irrigated due to the effects of capillary rise from the groundwater, but, as expected, increased in currently irrigated fields. Increasing the level of a weir in ditches had a relatively small effect on the hydrological drought, provided water was available to sustain higher water levels. This measure is, therefore, better suited as a long term change than as ad hoc measure during a drought. The effectiveness of the measures depended on the characteristics of the regions; for some regions small changes led to increases in groundwater levels for several months, whereas in other regions effects were lost after a few weeks. This study gives insight into the most effective measures to mitigate drought impacts in low-lying sandy regions like the Netherlands.</p>

scholarly journals Moisture Changes in the Northern Xinjiang Basin Over the Past 2400 years as Documented in Pollen Records of Jili Lake

2021 ◽  
Vol 9 ◽  
Author(s):  
Yulin Xiao ◽  
Lixiong Xiang ◽  
Xiaozhong Huang ◽  
Keely Mills ◽  
Jun Zhang ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Terrestrial Ecosystem ◽  
Warm Period ◽  
Ice Age ◽  
Pollen Record ◽  
Humid Climate ◽  
Northern Xinjiang ◽  
The Past ◽  
Climate Background

Regional humidity is important for terrestrial ecosystem development, while it differs from region to region in inland Asia, knowledge of past moisture changes in the lower basin of northern Xinjiang remainly largely unclear. Based on a pollen record from Jili Lake, the Artemisia/(Amaranthaceae + Ephedra) (Ar/(Am + E)) ratio, as an index of regional humidity, has recorded four relatively dry phases: 1) 400 BCE to 1 CE, 2) the Roman Warm Period (RWP; c. 1–400 CE), 3) the Medieval Warm Period (MWP; c. 850–1200 CE) and 4) the Current Warm Period (CWP; since 1850 CE). In contrast, the Dark Age Cold Period (DACP; c. 400–850 CE) and the Little Ice Age (LIA; c. 1200–1850 CE) were relatively wet. Lower lake levels in a relatively humid climate background indicated by higher aquatic pollen (Typha and Sparganium) after c. 1700 CE are likely the result of intensified irrigation for agriculture in the catchment as documented in historical records. The pollen Ar/(Am + E) ratio also recorded a millennial-scale wetting trend from 1 CE to 1550 CE which is concomitant with a long-term cooling recorded in the Northern Hemisphere.

scholarly journals Glacier dynamics at Helheim and Kangerdlugssuaq glaciers, southeast Greenland, since the Little Ice Age

2014 ◽  
Vol 8 (1) ◽  
pp. 1257-1278
Author(s):  
S. A. Khan ◽  
K. K. Kjeldsen ◽  
K. H. Kjær ◽  
S. Bevan ◽  
A. Luckman ◽  
...  
Keyword(s):  
Mass Balance ◽  
Little Ice Age ◽  
Initial Conditions ◽  
Ice Age ◽  
Short Term ◽  
Episodic Events ◽  
Highly Sensitive ◽  
Decadal Scale ◽  
Speed Up

Abstract. Observations over the past decade show significant ice loss associated with the speed-up of glaciers in southeast Greenland from 2003, followed by a deceleration from 2006. These short-term, episodic, dynamic perturbations have a major impact on the mass balance at the decadal scale. To improve the projection of future sea level rise, a long-term data record that reveals the mass balance beyond such episodic events is required. Here, we extend the observational record of marginal thinning of Helheim glacier (HG) and Kangerdlugssuaq glacier (KG) from 10 to more than 150 yr. We show that although the frontal portion of HG thinned by more than 100 m between 2003 and 2006, it thickened by more than 50 m during the previous two decades. In contrast, KG was stable from 1981 to 1998 and experienced major thinning only after 2003. Extending the record back to the end of the Little Ice Age (ca. 1850) shows no significant thinning of HG from 1850 to 1981, while KG underwent substantial thinning of ~265 m. Analyses of their sensitivity to sub-surface water temperature anomalies and variations in air temperature suggest that both HG and KG are highly sensitive to short-term atmospheric and ocean forcing, and respond very quickly to small fluctuations. At century time-scales, however, multiple external parameters (e.g. outlet shape) dominate the mass change. These findings undermine attempts to use measurements over the last decade as initial conditions to project future dynamic ice loss.

Soil aggregation as influenced by cultural practices in Saskatchewan: I. Black Chernozemic soils

1993 ◽  
Vol 73 (4) ◽  
pp. 579-595 ◽  
Author(s):  
C. A. Campbell ◽  
D. Curtin ◽  
A. P. Moulin ◽  
L. Townley-Smith ◽  
G. P. Lafond
Keyword(s):  
Organic Matter ◽  
Cultural Practices ◽  
Geometric Mean ◽  
Organic Matter Content ◽  
Water Stable Aggregates ◽  
Cropping Frequency ◽  
Mean Diameter ◽  
The Impact ◽  
Erodible Fraction

The impact of cultural practices on soil aggregate characteristics which determine the susceptibility of the soil to wind and water erosion was studied at two long-term (> 30-yr) crop rotation sites on Black Chernozemic soils at Indian Head and Melfort, Saskatchewan. Surface soil (top 5 cm) taken in spring and fall, 1991, was air-dried and sieved by rotary sieve to measure aggregate size distribution. The water-stability of soil aggregates (1–2 mm) was determined after: (i) slow wetting, and (ii) fast wetting. Both rotation studies employed conventional tillage management until 1990 when the Indian Head experiment was converted to zero-tillage. Summerfallowing increased the wind-erodible (< 0.84-mm) fraction of soil and decreased the geometric mean diameter (GMD) of aggregates. One year of cropping was sufficient to significantly reduce the proportion of wind-erodibile aggregates. Fertilization and legume green manure and hay crops reduced the wind-erodible fraction at Indian Head, but had no effect on the higher organic matter soil at Melfort. In monoculture wheat systems at Indian Head there was an inverse relationship between the wind-erodible fraction and cropping frequency; this was credited to the positive influence of cropping frequency on crop residue production. The wind-erodible fraction (Y) was related to GMD at Indian Head: Y = 11.8 + 117/GMD (r2 = 0.80***), and at Melfort, Y = 11.9 + 91/GMD (r2 = 0.82***). When subjected to rapid wetting, both the difference between cropped and native grassland soils, and the influence of cultural practices on water stable aggregates were pronounced. Aggregate stability was more closely related to the long-term management than to recent (< 1 yr) cultural treatments. Frequent cropping, fertilization, and use of legumes increased water stable aggregates, particularly at the Indian Head site with its lower organic matter content. Key words: Wet sieving, dry sieving, legumes, fertilization, geometric mean diameter, wind erosion

Paleoclimatic reconstruction during the Little Ice Age in the Llanganuco basin, Cordillera Blanca (Peru)

2020 ◽  
Author(s):  
Joshua Er Addi Iparraguirre Ayala ◽  
Jose Úbeda Palenque ◽  
Ronald Fernando Concha Niño de Guzmán ◽  
Ramón Pellitero Ondicol ◽  
Francisco Javier De Marcos García-Blanco ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Air Temperature ◽  
Little Ice Age ◽  
Ice Age ◽  
Lapse Rate ◽  
Ratio Method ◽  
Equilibrium Line Altitude ◽  
Paleoclimatic Reconstruction ◽  
High Resolution Satellite Images ◽  
The Impact

&lt;p&gt;The Equilibrium Line Altitude (ELA, m) is a good indicator for the impact of climate change on tropical glaciers , because it varies in time and space depending on changes in temperature and/or precipitation.The estimation of the ELA and paleoELA using the Area x Altitude Balance Ratio method (AABR; Osmaston, 2005) requires knowing the surface and hypsometry of glaciers or paleoglaciers (Benn et al. 2005) and the Balance Ratio (BR) correct (Rea, 2009).&lt;/p&gt;&lt;p&gt;In the Llanganuco basin (~ 9&amp;#176;3&amp;#180;S; 77&amp;#176;37&amp;#180;W) there are very well preserved moraines near the current glaciers front. These deposits provide information to reconstruct the extent of paleoglaciers since the Little Ice Age (LIA) and deduce some paleo-climatic variables.&lt;/p&gt;&lt;p&gt;The goal of this work has been to reconstruct the paleotemperature (&amp;#176;C) during LIA, deduced from the difference between ELA AABR&lt;sub&gt;2016&lt;/sub&gt; and paleoELA AABR&lt;sub&gt;LIA&lt;/sub&gt;.&lt;/p&gt;&lt;p&gt;The paleoclimatic reconstruction was carried out in 6 phases: Phase 1) Development of a detailed geomorphological map (scale 1/10,000), in order to&amp;#160; identify glacial landforms (advance moraines and polished rocks) which, due to their geomorphological context, can be considered of LIA, so palaeoglaciers can be delimited. Current glacial extension was done using dry season, high resolution satellite images. Phase 2) Glacial bedrock Reconstruction from glacier surface following the GLABTOP methodology (Linsbauer et al 2009). Phase 3) 3D reconstruction of paleoglacial surface using GLARE tool, based on bed topography and flow lines for each defined paleoglacial (Pellitero et al., 2016). As perfect plasticity model does not reflect the tension generated by the side walls of the valley, form factors were calculated based on the glacier thickness, lateral moraines and the geometry of the valley following the equation proposed by Nye (1952), adjusting the thicknesses generated in the paleoglacial front. Phase 4) Calculation of BR in a reference glacier (Artesonraju; 8&amp;#176; 56&amp;#8217;S; 77&amp;#186;38&amp;#8217;W), near to the study area, using the product BR = b &amp;#8226; z &amp;#8226; s, where BR= Balance Ratio; b= mass balance measured in fieldwork 2004-2014 (m); z= average altitude (meters) and s= surface (m&lt;sup&gt;2&lt;/sup&gt;) of each altitude band of the glacier (with intervals of 100 m altitude). A value BR = 2.3 was estimated. Phase 5) Automatic reconstruction of the ELA &amp;#160;AABR&lt;sub&gt;2016 &lt;/sub&gt;and paleoELA AABR&lt;sub&gt;LIA&lt;/sub&gt; using ELA Calculation tool (Pellitero et al. 2015) after 3D reconstruction of the glacial and paleoglacial surface in phases 2 and 3. Phase 6) Estimation of paleotemperature during LIA by solving the equation of Porter et al. (1995): &amp;#8710;T (&amp;#176;C)= &amp;#8710;ELA &amp;#8226; ATLR, where &amp;#8710;T= air temperature depression (&amp;#186;C); &amp;#8710;ELA = variation of ELA AABR 2016-LIA and ATLR = Air Temperature Lapse Rate, using the average global value of the Earth (0.0065 &amp;#176;C/m), considered valid for tropics.&lt;/p&gt;&lt;p&gt;The results obtained were: ELA AABR&lt;sub&gt;2016&lt;/sub&gt;= 5260m, paleoELA AABR&lt;sub&gt;LIA&lt;/sub&gt;= 5084m, and &amp;#8710;T = 1.1 &amp;#176;C. The reconstruction of air paleotemperature is consistent with different studies that have estimated values between 1&amp;#8211;2 &amp;#176;C colder than the present, with intense rainfall (Matthews &amp; Briffa, 2005; Malone et al., 2015).&lt;/p&gt;

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