This work investigates the timing, paleoclimatic framework and inter-hemispheric teleconnections inferred from the glaciers last maximum extension and the deglaciation onset in the Arid Tropical Andes. A study area was selected to the northeastward of the Nevado Coropuna, the volcano currently covered by the largest tropical glacier on Earth. The current glacier extent, the moraines deposited in the past and paleoglaciers at their maximum extension have been mapped. The present and past Equilibrium Line Altitudes (ELA and paleoELA) have been reconstructed and the chlorine-36 ages have been calculated, for preliminary absolute dating of glacial and volcanic processes. The paleoELA depression, the thermometers installed in the study area and the accumulation data previously published allowed development of paleotemperature and paleoprecipitation models. The Coropuna glaciers were in maximum extension (or glacial standstill) ~20–12 ka ago (and maybe earlier). This last maximum extension was contemporary to the Heinrich 2–1 and Younger Dryas events and the Tauca and Coipasa paleolake transgressions on Bolivian Altiplano. The maximum paleoELA depression (991 m) shows a colder (−6.4 °C) and moister climate with precipitation ×1.2–×2.8 higher than the present. The deglaciation onset in the Arid Tropical Andes was 15–11 ka ago, earlier in the most southern, arid, and low mountains and later in the northernmost, less arid, and higher mountains.

Los glaciares tropicales son indicadores sensibles del cambio climático. La pérdida del volumen de los glaciares tropicales en la cuenca Parón (Cordillera Blanca, Perú) es una muestra de esto a nivel global y se espera que tales cambios afecten a los servicios ecosistémicos que son únicos e insustituibles. Este estudio estimó el valor económico de los servicios ecosistémicos asociados con el recurso hídrico impactados por el retroceso glaciar en la cuenca de Parón-Parque Nacional Huascarán (Cordillera Blanca, Perú) entre los años 2009 y 2018. La metodología inició cartografiando los glaciares de 2009 a 2018 usando imágenes satelitales de alta resolución tomadas en temporada seca. Luego, se reconstruyeron las superficies 3D de los mismos usando la herramienta GLABTOP permitiendo calcular el volumen. Con los datos obtenidos se calculó el valor del servicio ecosistémico del turismo y recreación, y provisión de flujo hídrico. Los resultados indican que los glaciares de la cuenca Parón se han reducción de ~1.82% del área glaciar y en una tasa de deglaciación máxima de 0.08 (km2/año). Los resultados de la reconstrucción 3D muestran un 1.8% más de espesores entre los 40 y 60 m, con una pérdida de hielo de 1.02 km3, a una tasa máxima de 0.14 km3/año. Los valores monetarios presentes de los servicios de 2009 a 2018 se estimaron en $52 029.34 para el servicio de turismo y recreación y de $3 213 258.21 para el servicio de provisión de flujo hídricos, calculados a 8% de tasa de descuento. Por lo tanto, se recomienda que se debe incrementar la inversión en programas sobre la red hídrica de la cuenca de Parón, como mayores servicios, usos poblacionales o industriales.

The maintenance of the extensive parks at National Agrarian La Molina University (UNALM) generates a large amount of forest biomass, with high treatment costs. For this reason, the pyrolysis of the forest biomass is an alternative for valorization, allowing proper management producing biochar. The aim of the research was to evaluate the stability of biochar at 300°C and 500°C from forest biomass of five predominant species at UNALM, Grevillea robusta, Schinus molle, Casuarina cunninghamiana, Ficus benjamina and Eucalyptus spp. To determine the stability of biochar produced, two methodologies were used (IBI and an adaptation of the López et al.(2010) method), for which organic, labile, oxidizable, recalcitrant carbon on biochar were determined. The results showed a decrease in biochar yield of 6.50% with an increasing pyrolysis temperature. Regarding physicochemical characteristics, the biochar produced was alkaline (pH above 8); besides, the pH and electrical conductivity increased with temperature, by 0.64 and 0.38 ds/m, respectively. However, in the case of nitrogen and ashes, the opposite occurred. It was concluded that all the biochar produced complied with the stability limits according to the applied methodologies, and BSM500 had the highest value of stability considering the applied methodologies. This may indicate that it could have the greatest sequestration of C once applied to the soil and also the reduction of emissions; for that reason, it would be important to carry out future research to estimate the potential for C sequestration in the long term.

Climate patterns are natural processes that drive climate variability in the short, medium, and long term. Characterizing the patterns behind climate variability is essential to understand the functioning of the regional atmospheric system. Since investigations typically reveal only the link and extent of the influence of climate patterns in specific regions, the magnitude of that influence in meteorological records usually remains unclear. The central Peruvian Andes are affected by most of the common climate patterns of tropical areas, such as Intertropical Convergence Zone (ITCZ), Sea Surface Temperature (SST), solar irradiance, Madden Julian Oscillation (MJO), Pacific Decadal Oscillation (PDO), and El Niño Southern Oscillation (ENSO). They are also affected by regional processes that are exclusive from South America, such as the South American Low-Level Jet (SALLJ), South American Monsoon System (SAMS), Bolivian High (BH), and Humboldt Current. The aim of this research is to study the climate variability of precipitation, maximum and minimum temperature records over Cordillera Blanca (Peru), and its relationship with the intensity and periodicity of the common climate patterns that affect this region. To achieve this aim, a spectral analysis based on Lomb’s Periodogram was performed over meteorological records (1986–2019) and over different climate pattern indexes. Results show a coincidence in periodicity between MJO and SALLJ, with monthly cycles for precipitation and temperature (27-day, 56-day, and 90-day cycles). Moreover, the most intense periodicities, such as annual (365 days) and biannual (182 and 122 days) cycles in meteorological variables, possibly would be led by ITCZ and ENSO together, as well as a combination of the Humboldt Current and SALLJ. Additionally, interannual periodicities (3-year, 4.5-year, 5.6–7-year and 11-year cycles) would have coincidence with the ENSO–solar combination, while the longest cycles (16 years) could match PDO variability.

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).In the Llanganuco basin (~ 9°3´S; 77°37´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.The goal of this work has been to reconstruct the paleotemperature (°C) during LIA, deduced from the difference between ELA AABR2016 and paleoELA AABRLIA.The paleoclimatic reconstruction was carried out in 6 phases: Phase 1) Development of a detailed geomorphological map (scale 1/10,000), in order to  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° 56’S; 77º38’W), near to the study area, using the product BR = b • z • s, where BR= Balance Ratio; b= mass balance measured in fieldwork 2004-2014 (m); z= average altitude (meters) and s= surface (m2) 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  AABR2016 and paleoELA AABRLIA 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): ∆T (°C)= ∆ELA • ATLR, where ∆T= air temperature depression (ºC); ∆ELA = variation of ELA AABR 2016-LIA and ATLR = Air Temperature Lapse Rate, using the average global value of the Earth (0.0065 °C/m), considered valid for tropics.The results obtained were: ELA AABR2016= 5260m, paleoELA AABRLIA= 5084m, and ∆T = 1.1 °C. The reconstruction of air paleotemperature is consistent with different studies that have estimated values between 1–2 °C colder than the present, with intense rainfall (Matthews & Briffa, 2005; Malone et al., 2015).