Glacial fluctuations since the 'Medieval Warm Period' at Rothera Point (western Antarctic Peninsula)

At a global scale, there is no evidence for synchronous multi-decadal warm (‘Medieval Warm Period’, MWP) or cold (‘Little Ice Age’, LIA) periods in the late Holocene. On the other hand, there is good correspondence globally in the timing of MWP or LIA and phases of glacier retreat and advance, respectively, with local exceptions mainly explained by the precipitation regime. Antarctica exhibits contrasting patterns, both regarding the existence of these two historical climatic periods and the glacial responses to climatic forcing. Here, we present evidence for glacial retreat corresponding to the MWP and a subsequent LIA advance at Rothera Point (67°34′S; 68°07′W) in Marguerite Bay, western Antarctic Peninsula. Deglaciation started at ca. 961–800 cal. yr BP or before, reaching a position similar to or even more withdrawn than the current state, with the subsequent period of glacial advance commencing between 671 and 558 cal. yr BP and continuing at least until 490–317 cal. yr BP. Based on new radiocarbon dates, during the MWP, the rate of glacier retreat was 1.6 m yr−1, which is comparable with recently observed rates (~0.6 m yr−1 between 1993 and 2011 and 1.4 m yr−1 between 2005 and 2011). Moreover, despite the recent air warming rate being higher, the glacial retreat rate during the MWP was similar to the present, suggesting that increased snow accumulation in recent decades may have counterbalanced the higher warming rate

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Manipulation experiments for the assessment and monitoring of climate change impacts on vegetation of alpine and polar ecosystems.

This thesis focused on the impacts of climate change on terrestrial ecosystems of alpine (Central Italian Alps) and Polar (Maritime Antarctica) tundra habitats, two of the three areas of the world where had been recorded the greatest air temperature warming since 1950. The alpine site is located at the Stelvio Pass where since the 2014 in-situ manipulation experiments started to assess the possible future responses of tundra vegetation to changes of: a) air and soil warming, b) water availability and soil moisture, c) snow-depth and snowmelt time. The PhD project confirmed and assessed the influence of these manipulation experiments, on environmental data, vegetation composition and structure and plant phenology, stressing how responses to the environmental drivers had species-specific differences, but also with influences from plant communities, species ecology and local conditions (topography). The Antarctic site is located at Signy Island (northern maritime Antarctica) where were installed manipulation experiments, comparable to those set up in the Alps, those will allow to compare in the next years the biotic and abiotic responses of different polar and alpine tundra ecosystems. The assessment of any vegetation changes was not possible, because of the logistical constrain and of the short period of manipulation (2 years); however, were presented the experiment design and the preliminary environmental data after the first year of deployment. Finally, through a paleo-climate investigation, that involved the analyses of organic sediment and moribund mosses collected at Rothera Point (southern maritime Antarctica), evidences were provided on how the climate system changed through time

Manipulation experiments for the assessment and monitoring of climate change impacts on vegetation of alpine and polar ecosystems.

This thesis focused on the impacts of climate change on terrestrial ecosystems of alpine (Central Italian Alps) and Polar (Maritime Antarctica) tundra habitats, two of the three areas of the world where had been recorded the greatest air temperature warming since 1950. The alpine site is located at the Stelvio Pass where since the 2014 in-situ manipulation experiments started to assess the possible future responses of tundra vegetation to changes of: a) air and soil warming, b) water availability and soil moisture, c) snow-depth and snowmelt time. The PhD project confirmed and assessed the influence of these manipulation experiments, on environmental data, vegetation composition and structure and plant phenology, stressing how responses to the environmental drivers had species-specific differences, but also with influences from plant communities, species ecology and local conditions (topography). The Antarctic site is located at Signy Island (northern maritime Antarctica) where were installed manipulation experiments, comparable to those set up in the Alps, those will allow to compare in the next years the biotic and abiotic responses of different polar and alpine tundra ecosystems. The assessment of any vegetation changes was not possible, because of the logistical constrain and of the short period of manipulation (2 years); however, were presented the experiment design and the preliminary environmental data after the first year of deployment. Finally, through a paleo-climate investigation, that involved the analyses of organic sediment and moribund mosses collected at Rothera Point (southern maritime Antarctica), evidences were provided on how the climate system changed through time