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1. Evidence of a population of leaf-eared mice Phyllotis vaccarum above 6,000 m in the Andes and a survey of high-elevation mammals

   https://doi.org/10.1093/jmammal/gyac028  

   Steppan, Scott J. ; Bowen, Thomas ; Bangs, Max R. ; Farson, Matthew ; Storz, Jay F. ; Quiroga-Carmona, Marcial ; D’Elía, Guillermo ; Vimercati, Lara ; Dorador Ortiz, Cristina ; Zimmerman, Graham ; et al ( April 2022 , Journal of Mammalogy)

   Biologists have long pondered the extreme limits of life on Earth, including the maximum elevation at which species can live and reproduce. Here we review evidence of a self-sustaining population of mice at an elevation that exceeds that of all previously reported for mammals. Five expeditions over 10 years to Volcán Llullaillaco on the Argentina/Chile border observed and collected mice at elevations ranging from 5,070 m at the mountain’s base to the summit at 6,739 m (22,110 feet). Previously unreported evidence includes observations and photographs of live animals and mummified remains, environmental DNA, and a soil microbial community reflecting animal activity that are evaluated in combination with previously reported video recordings and capture of live mice. All of the evidence identifies the mouse as the leaf-eared mouse Phyllotis vaccarum, and it robustly places the population within a haplotype group containing individuals from the Chilean Atacama Desert and nearby regions of Argentina. A critical review of the literature affirms that this population is not only an elevational record for mammals but for all terrestrial vertebrates to date, and we further find that many extreme elevations previously reported for mammals are based on scant or dubious evidence.

    

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2. El Niño–Southern Oscillation signal in a new East Antarctic ice core, Mount Brown South

   https://doi.org/10.5194/cp-17-1795-2021  

   Crockart, Camilla K. ; Vance, Tessa R. ; Fraser, Alexander D. ; Abram, Nerilie J. ; Criscitiello, Alison S. ; Curran, Mark A. ; Favier, Vincent ; Gallant, Ailie J. ; Kittel, Christoph ; Kjær, Helle A. ; et al ( January 2021 , Climate of the Past)

   Abstract. Paleoclimate archives, such as high-resolution ice core records, provide ameans to investigate past climate variability. Until recently, the Law Dome(Dome Summit South site) ice core record remained one of fewmillennial-length high-resolution coastal records in East Antarctica. A newice core drilled in 2017/2018 at Mount Brown South, approximately 1000 kmwest of Law Dome, provides an additional high-resolution record that willlikely span the last millennium in the Indian Ocean sector of EastAntarctica. Here, we compare snow accumulation rates and sea saltconcentrations in the upper portion (∼ 20 m) of three MountBrown South ice cores and an updated Law Dome record over the period1975–2016. Annual sea salt concentrations from the Mount Brown South siterecord preserve a stronger signal for the El Niño–Southern Oscillation(ENSO; austral winter and spring, r = 0.533, p < 0.001, Multivariate El Niño Index) compared to a previously defined Law Dome record of summer sea salt concentrations (November–February, r = 0.398, p = 0.010, SouthernOscillation Index). The Mount Brown South site record and Law Dome recordpreserve inverse signals for the ENSO, possibly due to longitudinalvariability in meridional transport in the southern Indian Ocean, althoughfurther analysis is needed to confirm this. We suggest that ENSO-related seasurface temperature anomalies in the equatorial Pacific drive atmosphericteleconnections in the southern mid-latitudes. These anomalies areassociated with a weakening (strengthening) of regional westerly winds tothe north of Mount Brown South that correspond to years of low (high) seasalt deposition at Mount Brown South during La Niña (El Niño)events. The extended Mount Brown South annual sea salt record (whencomplete) may offer a new proxy record for reconstructions of the ENSO overthe recent millennium, along with improved understanding of regionalatmospheric variability in the southern Indian Ocean, in addition to thatderived from Law Dome. 

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3. Unusually large upward shifts in cold‐adapted, montane mammals as temperature warms

   https://doi.org/10.1002/ecy.3300  

   McCain, Christy M. ; King, Sarah R. B. ; Szewczyk, Tim M. ( March 2021 , Ecology)

   The largest and tallest mountain range in the contiguous United States, the Southern Rocky Mountains, has warmed considerably in the past several decades due to anthropogenic climate change. Herein we examine how 47 mammal elevational ranges (27 rodent and 4 shrew species) have changed from their historical distributions (1886–1979) to their contemporary distributions (post 2005) along 2,400‐m elevational gradients in the Front Range and San Juan Mountains of Colorado. Historical elevational ranges were based on more than 4,580 georeferenced museum specimen and publication records. Contemporary elevational ranges were based on 7,444 records from systematic sampling efforts and museum specimen records. We constructed Bayesian models to estimate the probability a species was present, but undetected, due to undersampling at each 50‐m elevational bin for each time period and mountain range. These models leveraged individual‐level detection probabilities, the number and patchiness of detections across 50‐m bands of elevation, and a decaying likelihood of presence from last known detections. We compared 95% likelihood elevational ranges between historical and contemporary time periods to detect directional change. Responses were variable as 26 mammal ranges changed upward, 6 did not change, 11 changed downward, and 4 were extirpated locally. The average range shift was 131 m upward, while exclusively montane species shifted upward more often (75%) and displayed larger average range shifts (346 m). The best predictors of upper limit and total directional change were species with higher maximum latitude in their geographic range, montane affiliation, and the study mountain was at the southern edge of their geographic range. Thus, mammals in the Southern Rocky Mountains serve as harbingers of more changes to come, particularly for montane, cold‐adapted species in the southern portion of their ranges.

    

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4. The impacts of warming on rapidly retreating high-altitude, low-latitude glaciers and ice core-derived climate records

   Thompson, L. G. ; Davis, M. E. ; Mosley-Thompson, E. ; Porter, S. E. ; Corrales, G. V. ; Shuman, C. A. ; Tucker, C. J. ( January 2021 , Global and planetary change)

   null (Ed.)

   Alpine glaciers in the low- and mid-latitudes respond more quickly than large polar ice sheets to changes in temperature, precipitation, cloudiness, humidity, and radiation. Many high-altitude glaciers are monitored by ground observations, aerial photography, and satellite-borne sensors. Regardless of latitude and elevation, nearly all nonpolar glaciers and ice caps are undergoing mass loss, which compromises the records of past climate preserved within them. Almost without exception, the retreat of these ice fields is persistent, and a very important driver is the recent warming of the tropical troposphere and oceans. Here we present data on the decrease in the surface area of four glaciers from low- to mid-latitude mountainous regions: the Andes of Peru and northern Bolivia, equatorial east Africa, equatorial Papua, Indonesia, and the western Tibetan Plateau. Climate records based on oxygen isotopic ratios (δ18O) measured in ice cores drilled from several glaciers in these regions reveal that the records from elevations below ~6000 m above sea level have been substantially modified by seasonal melting and the movement of meltwater through porous upper firn layers. Fortunately, δ18O records recovered from higher altitude sites still contain well-preserved seasonal variations to the surface; however, the projected increase in the rate of atmospheric warming implies that climate records from higher elevation glaciers will eventually also be degraded. A long-term ice core collection program on the Quelccaya ice cap in Peru, Earth’s largest tropical ice cap, illustrates that the deterioration of its climate record is concomitant with the increase in mid-troposphere temperatures. The melting ice and resulting growth of proglacial lakes presents an imminent hazard to nearby communities. The accelerating melting of glaciers, if sustained, ensures the eventual loss of unique and irreplaceable climate histories, as well as profound economic, agricultural, and cultural impacts on local communities. 

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5. The impacts of warming on rapidly retreating high-altitude, low-latitude glaciers and ice core-derived climate records

   https://doi.org/https://doi.org/10.1016/j.gloplacha.2021.103538  

   Thompson, L. G. ; Davis, M. E. ; Mosley-Thompson, E. ; Porter, S. E. ; Corrales, G. V. ; Shuman, C. A. ; Tucker, C. J. ( January 2021 , Global and planetary change)

   null (Ed.)

   Alpine glaciers in the low- and mid-latitudes respond more quickly than large polar ice sheets to changes in temperature, precipitation, cloudiness, humidity, and radiation. Many high-altitude glaciers are monitored by ground observations, aerial photography, and satellite-borne sensors. Regardless of latitude and elevation, nearly all nonpolar glaciers and ice caps are undergoing mass loss, which compromises the records of past climate preserved within them. Almost without exception, the retreat of these ice fields is persistent, and a very important driver is the recent warming of the tropical troposphere and oceans. Here we present data on the decrease in the surface area of four glaciers from low- to mid-latitude mountainous regions: the Andes of Peru and northern Bolivia, equatorial east Africa, equatorial Papua, Indonesia, and the western Tibetan Plateau. Climate records based on oxygen isotopic ratios (δ18O) measured in ice cores drilled from several glaciers in these regions reveal that the records from elevations below ~6000 m above sea level have been substantially modified by seasonal melting and the movement of meltwater through porous upper firn layers. Fortunately, δ18O records recovered from higher altitude sites still contain well-preserved seasonal variations to the surface; however, the projected increase in the rate of atmospheric warming implies that climate records from higher elevation glaciers will eventually also be degraded. A long-term ice core collection program on the Quelccaya ice cap in Peru, Earth’s largest tropical ice cap, illustrates that the deterioration of its climate record is concomitant with the increase in mid-troposphere temperatures. The melting ice and resulting growth of proglacial lakes presents an imminent hazard to nearby communities. The accelerating melting of glaciers, if sustained, ensures the eventual loss of unique and irreplaceable climate histories, as well as profound economic, agricultural, and cultural impacts on local communities. 

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