Potential Climatic Effects Research Articles

Organic sulfur compositions and their relationships with iron sulfides in Antarctic lake sediments

本文利用有机硫硫同位素组成（δ³⁴S_org）及活性铁的黄铁矿化度（DOP）和硫化度（DOS）研究了南极阿德雷岛受企鹅活动影响的Y2湖和未受影响的菲尔德斯半岛燕鸥湖YO沉积物中有机硫的来源组成及其与铁硫化物的联系.结果表明，Y2沉积物1~15 cm较低的δ³⁴S_org指示有机质硫化形成的贫³⁴S成岩有机硫（S_diag）占比较高，其中在8~15 cm较高的DOS指示铁硫化物形成和有机质硫化同时发生，源于该层位高含量的活性铁供给.Y2剖面48~56 cm沉积物有机硫富集³⁴S显著，对应于企鹅数量高峰期，表明大量企鹅粪的外部输入使沉积物中富³⁴S的生物有机硫（S_bio）快速增加，并超过了内部硫转化过程中成岩有机硫的增加.YO沉积物在28 cm处δ³⁴S_org显著降低，主要是由于该层位硫酸盐异化还原强，有机质硫化形成的大量S_diag成为有机硫的主要成分，同位素质量平衡计算结果显示该层位S_diag占比高达95.4%；同时，28 cm处较高的DOP指示沉积物黄铁矿的形成与有机质硫化同时发生，主要源自沉积物中高硫酸盐还原强度产生了足够多的硫化氢前体.本研究表明，有机硫组分的来源转化与有机质、活性铁紧密耦合，对区域湖泊有机质成岩埋藏及潜在的气候环境效应具有重要的指示意义.;Sulfur isotope ratios of organic sulfur (δ³⁴S_org), degrees of pyritization (DOP) and sulfurization (DOS) in sediments were analyzed to reveal the organic sulfur compositions and their relationships with iron sulfides in a penguin-affected lake Y2 and a pristine Yanou Lake (YO) at Ardley Island and Fildes Peninsula, Antarctica, respectively. The depleted δ³⁴S_org values in Y2 sediments of 1-15 cm indicated a high proportion of ³⁴S-depleted diagenetic organic sulfur (S_diag) in total sulfur. Meanwhile, the high DOS in Y2 sediments of 8-15 cm indicated a concurrent sulfurization of iron and the organic matter, likely due to the high availability of active iron in this layer. The observed much enriched δ³⁴S_org in Y2 sediments of 48-56 cm corresponding to the period of high penguin populations, which indicated that large external inputs of penguin guanos result in a rapid increase in ³⁴S-enriched biological organic sulfur (S_bio) in the sediments, and exceeds the S_diag that from the internal sulfur transformations. The depleted δ³⁴S_org in YO sediment of 28 cm indicates a high proportion (95.4%) of ³⁴S-depleted S_diag which was from strong sulfurization of organic matter, corresponding to the strongest sulfate reduction in this layer. Meanwhile, the high DOP in YO sediment of 28 cm indicated a concurrent formation of pyrite sulfur and the sulfurization of organic matter in this layer, due to the high available precursors of hydrogen sulfide and/or intermediate species of sulfur from the sulfate reduction. Our study indicates that the components of organic sulfur are coupled tightly with organic matter and reactive iron and provides a direct implication for the depositions of organic matter and thus the potential climatic and environmental effects in regional aquatic ecosystems.

Assessing Climate Suitability of Three Cities for the 2027 Women’s World Cup

Given the impacts of climate change, sport event organizations need to adapt to changes in their environment to remain feasible, safe, competitive, and profitable. Mega-events such as the Olympic Games and Fédération Internationale de Football Association (FIFA) World Cups take years to plan and, ideally, produce long-lasting legacy benefits for their host communities. In awarding these events to host cities and countries, the rightsholders must carefully consider the local climate to ensure that playing conditions will be safe and competitive. This case study examines the prospective 2027 FIFA Women’s World Cup bid in Belgium, Germany, and the Netherlands and invites students to put themselves in the position of a joint bid committee, which must assess the suitability of three cities (Brussels, Berlin, and Amsterdam) for hosting based on their climate. Furthermore, students will be asked to identify climate adaptation strategies that might be adopted by the prospective host committees to accommodate any potential climate challenges. Through this case study, students will learn to investigate the potential effects of climate, climate change, and weather issues on a mega-event; explore the relationship between sport and the natural environment; and learn to source climate data for their own communities and organizations.

Effects of climate change on river-ice processes and ice jams

ABSTRACT As the climate changes, ice characteristics and river-ice processes are altered, sometimes in unexpected ways. A warmer climate will obviously result in less ice globally, and in a general northward shift in the limits of seasonal river-ice occurrence. However, in several watersheds, the frequency of midwinter breakup events and the intensity of breakup ice jams may also change. In addition, climate change will alter other river-ice processes such as ice formation, freeze-up jams, and hanging dams. This is of concern during the design and construction of infrastructure as well as during the planning and implementation of flood-damage-reduction measures in and along rivers with seasonal ice covers. Changes in river-ice regimes will also alter the ecology of many lotic systems. The paper reviews the potential effects of a changing climate on river-ice properties and processes, and provides a discussion of future outcomes and their significance, as well as a suggested direction for future cold-regions river research.

Forest structure drives the expected growth of Pinus nigra along its latitudinal gradient under warming climate

Droughts chronically alter resource availability in forest ecosystems. The increased frequency and severity of such extreme climate events challenge the acclimation potential of tree species especially across the drought-prone Mediterranean region. Pinus nigra is a widely distributed tree species in the Mediterranean region and considered vulnerable to extreme droughts. We used a 1000 km latitudinal gradient from northern Morocco to north-eastern Spain incorporating four regions (Edge-South, Core-South, Core-North and Edge-North) and including different P. nigra provenances. We aim to identify the climate and forest structure related drivers that influence tree radial growth (BAI, basal area increment). We developed statistical models for BAI by incorporating the potential effects of climate and forest structure (diameter and age distributions). Then, we forecasted the future growth of P. nigra forests during the 21st century considering the emission scenario A2 with an expected increase of +2.7 °C at the end of this century. Our results showed large variability across P. nigra populations in terms of environmental conditions, forest structure, and growth. The northernmost P. nigra populations, subjected to wetter and cooler conditions were those presenting the lowest BAI (4.9 cm2), whereas the southernmost P. nigra populations subjected to drier and warmer conditions presented the highest BAI values (11.5 cm2). Pinus nigra growth was enhanced by high spring precipitation, but this positive effect was probably modulated by forest structure. Temperature explained a higher proportion of the BAI variance than precipitation, with warmer summer conditions decreasing growth. Growth projections forecasted a decline in BAI (from 9.6 to 7.0 cm2) across all ecological regions starting around the mid-21st century but being lower in Edge-North populations compared to the other populations. Our study provides quantitative knowledge related to how P. nigra populations have been growing across four distinctive ecological regions. We also provide a forecasting tool that incorporates both climate and stand structure related information to project dynamics in tree populations.

Iberian Protected Areas Capture Regional Functional, Phylogenetic and Taxonomic Diversity of Most Tetrapod Groups

Protected areas (PAs) have been created with the purpose of preserving biodiversity, acting as refuges from anthropogenic pressures. Traditionally, PAs have been designed and managed to represent mainly taxonomic diversity, ignoring other diversity facets such as its functional and phylogenetic components. Yet, functional and phylogenetic diversity are, respectively, connected with species’ roles on ecosystems and evolutionary history held within communities. Here, we focused on the amphibian, reptile, resident breeding bird, and non-flying mammal faunas of the national and natural parks of the Iberian Peninsula, to evaluate whether these PAs are adequately representing regional functional, phylogenetic, and taxonomic diversity of each group. Specifically, we computed functional and phylogenetic diversity within each PA, and then compared those values to the ones obtained from a random assembly of species from the regional pool, that was defined as the region encompassing the PA and a neighboring area of 50 km beyond its boundary. We also calculated the proportion of species in each regional pool that were present within the PAs. In general, the functional and phylogenetic diversity of amphibians, reptiles and non-flying mammals found within PAs did not differ significantly from random expectations generated from the species pertaining to the regional pool, although a few PAs showed a higher diversity. In contrast, resident breeding birds presented lower functional and phylogenetic diversity than expected by chance in many of the PAs, which could relate to climatic variables and the habitat specificity of some species. The proportion of species from the regional pools that are present in the PAs was high for amphibians, reptiles and mammals, and slightly lower for birds. These results suggest that the Iberian natural and national parks are effectively capturing the functional, phylogenetic and taxonomic diversity of most tetrapod assemblages present at the regional level. Future studies should identify priority areas to expand the representation of these biodiversity components, and assess potential effects of climate and land-use changes on current patterns.

Projected changes of regional lake hydrologic characteristics in response to 21st century climate change

ABSTRACT Inland lakes are socially and ecologically important components of many regional landscapes. Exploring lake responses to plausible future climate scenarios can provide important information needed to inform stakeholders of likely effects of hydrologic changes on these waterbodies in coming decades. To assess potential climate effects on lake hydrology, we combined a previously published spatially explicit, processed-based hydrologic modeling framework implemented over the lake-rich landscape of the Northern Highlands Lake District within the United States with an ensemble of climate change scenarios for the 2050s (2041–2070) and 2080s (2071–2100). Model results quantify the effects of climate change on water budgets and lake stage elevations for 3692 lakes and highlight the importance of landscape and hydrologic setting for the response of specific lake types to climate change. All future climate projections resulted in loss of ice cover and snowpack as well as increased evaporation, but variability in climate projections (warmer conditions, wet winters combined with wet or dry summers) interacted with lake characteristics and landscape position to produce variable lake hydrologic changes. Water levels for drainage lakes (lakes with substantial surface water inflows and outflows) showed nearly no change, whereas minimum water levels for seepage lakes (minimal surface water fluxes) decreased by an average of up to 2.64 m by the end of the 21st century. Our physically based modeling approach is parsimonious and computationally efficient and can be applied to other lake-rich regions to investigate interregional variability in lake hydrologic response to future climate scenarios.

Different characteristics and source contributions to aerosol aminiums over a coastal city and adjacent marginal seas

Environmental context Amines in the atmosphere play important roles in atmospheric chemistry and have potential climate effects. We characterise the concentrations, size distributions and chemical pathways of aerosol aminiums over a coastal city and marginal seas, and estimated the contribution of marine biogenic sources. This study can facilitate our understanding about the interactions between human activities, biogenic emissions and the atmospheric environment. Abstract Atmospheric amines are gaining more and more attention in the field of atmospheric chemistry owing to their important roles in new particle formation and growth. In this study, aerosol aminiums over a coastal city (Shanghai) and the Yellow and East China seas (YECS) were characterised. The concentrations of NH4+, dimethylaminium (DMAH+) and trimethylaminium + diethylaminium (TMDEAH+) over Shanghai were all found to be higher in the winter of 2018 than in the summer of 2019, suggesting their non-negligible terrestrial contributions. DMAH+ and TMDEAH+ concentrations over the YECS in summer were closely correlated and linked to surface phytoplankton biomass, implying that marine biogenic sources might be a predominant contributor to aminiums at this time. Aminiums over Shanghai generally showed a bimodal distribution with a main peak in droplet mode and a secondary peak in condensation mode, suggesting the notable contribution of aqueous-phase or heterogeneous reaction to the formation of aminiums. In contrast, aminiums over the YECS often showed a unimodal distribution, which may be caused by the competition between amines and NH3 for reaction with acidic compounds. We estimated the contributions of marine biogenic sources, ~73.6 % to DMAH+ and 80.1 % to TMDEAH+ over the YECS, using methanesulfonate/non-sea-salt SO42– as an indicator. Our results suggest that marine biogenic emission of amines from China’s marginal seas may have a potential impact on coastal cities, and this source should be considered in modelling new particle formation and air quality in coastal areas.

Climate variability and landscape dynamics in the Late Hellenistic and Roman north-eastern Peloponnese

Research on ancient Greek rural settlement and agricultural economies often emphasises political agency as a driving force behind landscape change, with comparatively less attention directed to the potential effects of climate. This study analyses climate variability and the spatial configuration of land use in the north-eastern Peloponnese during the Late Hellenistic and Roman (c. 150 BC–AD 300) periods. A synthesis of archaeological field survey data combined with new palaeoclimatological data provides novel insight into how changing climate influenced land use. The authors argue that although climatic variability alone did not drive socio-economic change, drying conditions may have influenced the relocation of agricultural production.

Potential Effects of Climate and Human Influence Changes on Range and Diversity of Nine Fabaceae Species and Implications for Nature’s Contribution to People in Kenya

Climate and land-use changes are the main drivers of species distribution. On the basis of current and future climate and socioeconomic scenarios, species range projections were made for nine species in the Fabaceae family. Modeled species have instrumental and relational values termed as nature’s contribution to people (NCP). For each species, five scenarios were analyzed resulting in 45 species range maps. Representative concentration pathway (RCP) 4.5 and three shared socioeconomic pathways (SSPs 1, 2, and 3) were used in the analysis. Species ranges under these scenarios were modeled using MaxEnt; a niche modeling software that relates species occurrence with environmental variables. Results were used to compute species richness and evenness based on Shannon’s diversity Index. Results revealed a mix of range expansion and contraction for the modeled species. The findings highlighted which species may remain competitive in an urbanized future and which ones are detrimentally affected by climate. Parts of the country where species abundances are likely to change due to climate and socioeconomic changes were identified. Management of species will be required in people-dominated landscapes to maintain interactions between nature and society, while avoiding natural resource degradation and loss of NCP.

Soil fungal community composition and functional similarity shift across distinct climatic conditions.

A large part of ecosystem function in woodland systems depends on soil fungal communities. However, global climate change has the potential to fundamentally alter these communities as fungal species are filtered with changing environmental conditions. In this study, we examined the potential effects of climate on host-associated (i.e. tree-associated) soil fungal communities at climatically distinct sites in the Tehachapi Mountains in California, where more arid conditions represent likely regional climate futures. We found that soil fungal community composition changes strongly across sites, with species richness and diversity being highest at the most arid site. However, host association may buffer the effects of climate on community composition, as host-associated fungal communities are more similar to each other across climatically distinct sites than the whole fungal community. Lastly, an examination of functional traits for ectomycorrhizal fungi, a well-studied guild of fungal mutualist species, showed that stress-tolerant traits were more abundant at arid sites than mesic sites, providing a mechanistic understanding of these community patterns. Taken together, our results indicate that fungal community composition will likely shift with future climate change but that host association may buffer these effects, with shifts in functional traits having implications for future ecosystem function.

No Cretaceous‐Paleogene Boundary in Exposed Rajahmundry Traps: A Refined Chronology of the Longest Deccan Lava Flows From 40Ar/39Ar Dates, Magnetostratigraphy, and Biostratigraphy

AbstractDeccan Traps flood basalt volcanism affected ecosystems spanning the end‐Cretaceous mass extinction, with the most significant environmental effects hypothesized to be a consequence of the largest eruptions. The Rajahmundry Traps are the farthest exposures (~1,000 km) of Deccan basalt from the putative eruptive centers in the Western Ghats and hence represent some of the largest volume Deccan eruptions. Although the three subaerial Rajahmundry lava flows have been geochemically correlated to the Wai Subgroup of the Deccan Traps, poor precision associated with previous radioisotopic age constraints has prevented detailed comparison with potential climate effects. In this study, we use new 40Ar/39Ar dates, paleomagnetic and volcanological analyses, and biostratigraphic constraints for the Rajahmundry lava flows to ascertain the timing and style of their emplacement. We find that the lower and middle flows (65.92 ± 0.25 and 65.67 ± 0.08 Ma, ±1σ systematic uncertainty) were erupted within magnetochron C29r and were a part of the Ambenali Formation of the Deccan Traps. By contrast, the uppermost flow (65.27 ± 0.08 Ma) was erupted in C29n as part of the Mahabaleshwar Formation. Given these age constraints, the Rajahmundry flows were not involved in the end‐Cretaceous extinction as previously hypothesized. To determine whether the emplacement of the Rajahmundry flows could have affected global climate, we estimated their eruptive CO2 release and corresponding climate change using scalings from the LOSCAR carbon cycle model. We find that the eruptive gas emissions of these flows were insufficient to directly cause multi‐degree warming; hence, a causal relationship with significant climate warming requires additional Earth system feedbacks.

The Real Economic Dimensions of Climate Change

The impacts of COVID-19 and efforts to stimulate recovery from the pandemic have highlighted the need for information about how disasters affect the real economy: temporal and spatial dynamics, cascading risks of disruption to employment, debt, trade, investments, bond markets, and real estate markets, among others. This commentary explores what information on the economic dimensions of climate change is needed to inform decisions about adapting to and effectively averting, minimizing, and addressing climate risks. We review the economic information presented in special reports from the IPCC AR6 cycle (SR1.5, SROCC, and SRCCL). We find that the information presented in these reports expands beyond costs of mitigation options, and potential negative GDP effects of climate impacts to include real economic dimensions in food production and land use (forestry and agriculture), coastal areas and fisheries, among others. This reflects an emerging literature which addresses a wider spectrum of economic and financial aspects relevant to climate change and national and regional priorities. Five emerging areas of work related to climate impacts on the real economy and on financial services provide essential additional information for decisions about efforts at all levels to achieve the objectives of the Paris Agreement and the overall objective of the UNFCCC Convention. Insights from economic analysis of the coronavirus pandemic—a sustained, complex disaster with global consequences across the real economy and financial services—can help highlight useful areas of research and discussion for policy makers considering climate impacts, vulnerabilities, and risks.

The domestic and international implications of future climate for U.S. agriculture in GCAM.

Agricultural crop yields are susceptible to changes in future temperature, precipitation, and other Earth system factors. Future changes to these physical Earth system attributes and their effects on agricultural crop yields are highly uncertain. United States agricultural producers will be affected by such changes whether they occur domestically or internationally through international commodity markets. Here we present a replication study of previous investigations (with different models) showing that potential direct domestic climate effects on crop yields in the U.S. have financial consequences for U.S. producers on the same order of magnitude but opposite in sign to indirect financial impacts on U.S. producers from climate effects on crop yields elsewhere in the world. We conclude that the analysis of country-specific financial climate impacts cannot ignore indirect effects arising through international markets. We find our results to be robust across a wide range of potential future crop yield impacts analyzed in the multi-sector dynamic global model GCAM.

Photochemical transformation of residential wood combustion emissions: dependence of organic aerosol composition on OH exposure

Abstract. Residential wood combustion (RWC) emits large amounts of gaseous and particulate organic aerosol (OA). In the atmosphere, the emission is transformed via oxidative reactions, which are under daylight conditions driven mainly by hydroxyl radicals (OH). This continuing oxidative ageing produces secondary OA and may change the health- and climate-related properties of the emission. However, it is not well known how the composition of RWC-originated OA changes as the function of OH exposure. In this work, emissions from two modern residential logwood combustion appliances were photochemically aged in an oxidation flow reactor (OFR) with various OH exposure levels, reaching up to 6×1011 s cm−3 (equivalent to 1 week in the atmosphere). Gaseous organic compounds were analysed by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS), while particulate OA was analysed online by a high-resolution soot particle aerosol mass spectrometer (SP-HR-ToF-AMS) and offline by in situ derivatization thermal desorption–gas chromatography–time-of-flight mass spectrometry (IDTD-GC-ToF-MS). Photochemical reactions increased the mass of particulate organic carbon by a factor of 1.3–3.9. The increase in mass took place during the first atmospheric equivalent day of ageing, after which the enhancement was independent of the extent of photochemical exposure. However, ageing increased the oxidation state of the particulate OA linearly throughout the assessed range, with ΔH:C/ΔO:C slopes between −0.17 and −0.49 in van Krevelen space. Ageing led to an increase in acidic fragmentation products in both phases, as measured by the IDTD-GC-ToF-MS for the particulate and PTR-ToF-MS for the gaseous phase. For the gaseous organic compounds, the formation of small carbonylic compounds combined with the rapid degradation of primary volatile organic compounds such as aromatic compounds led to a continuous increase in both the O : C and H : C ratios. Overall, the share of polycyclic aromatic compounds (PACs) in particles degraded rapidly during ageing, although some oxygen-substituted PACs, most notably naphthaldehydic acid, increased, in particular during relatively short exposures. Similarly, the concentrations of particulate nitrophenols rose extensively during the first atmospheric equivalent day. During continuous photochemical ageing, the dominant transformation mechanisms shifted from the initial gas-phase functionalization/condensation to the transformation of the particulate OA by further oxidation reactions and fragmentation. The observed continuous transformation of OA composition throughout a broad range of OH exposures indicates that the entire atmospheric lifetime of the emission needs to be explored to fully assess the potential climate and health effects of RWC emissions.

Size-dependent influence of NOx on the growth rates of organic aerosol particles.

Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud condensation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore substantially influence the survival of newly formed particles to CCN. Nitrogen oxide (NOx) is known to suppress the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response of particle growth to the changes of HOM formation caused by NOx. We show that NOx suppresses particle growth in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained by the shifted HOM volatility after adding NOx. By illustrating how NOx affects the early growth of new particles, a critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects caused by the diverse changes of NOx level in forest regions around the globe.

Characteristics of Spatial and Temporal Evolution and Investigation of Air Pollution in Guangdong-Hong Kong-Macao Greater Bay Area Based on Ground-Space Observation Data

The temporal and spatial distribution characteristics, evolution trend and potential climatic effects of air pollution in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) were analyzed on different time scales and spatial spaces, based on ground environment observation data from June 2014 to December 2018 and satellite remote sensing inversion products from 2000 to 2018. The results show that:① From the in-situ observed daily average concentration of PM2.5, good or mild to moderate pollution occurred in January, February, October, November, and December every year, and the rest of the time was excellent. ② Based on the annual average PM2.5 concentration obtained by satellite for the past 20 years, the spatial characteristics showed that the external radiation is centered on Guangzhou and Foshan. The time evolution shows the characteristics of an Ω shape, which increases gradually from 2000 to 2009, is highest in 2008, and then gradually decreases. ③ The monthly average aerosol optical thickness (AOT) value from the Multi-angle Imaging Spectro Radiometer satellite reversion every 10 years for a period (2000-2009 for a period, 2010-2018 for a period) was used to see the monthly variation. The monthly average AOT value in the first period was larger than that in the second period of the same month, the maximum value was in March and April, and the minimum value was in November and December. It is envisaged to draw a line along the north-south direction of the Pearl River Port, which basically shows that the AOT value in the west is greater than that in the east. ④ According to the observed daily average concentration data of O3-8h, the main concentration level of O3-8h in the GBA is excellent. The cities with good ozone concentration were most numerous in 2014, with five cities, and least in 2018, with only one city. The highest ozone concentration was in September, followed by June and November, and then May and July. In the past 20 years, the spatial distribution of the average concentration of O3 monitored by satellite remote sensing showed a characteristic Ω shape, increasing initially and then decreasing. The maximum value was in May, and the north-south boundary line appeared in space. ⑤ There is a good linear relationship between the interannual variation of monthly mean temperature and radiation, whereas the relationship between AOT and radiation cannot be described by a simple linear relationship.

Fire history in Andean Araucaria–Nothofagus forests: coupled influences of past human land-use and climate on fire regimes in north-west Patagonia

Historical fire regimes are critical for understanding the potential effects of changing climate and human land-use on forest landscapes. Fire is a major disturbance process affecting the Andean Araucaria forest landscape in north-west Patagonia. The main goals of this study were to reconstruct the fire history of the Andean Araucaria–Nothofagus forests and to evaluate the coupled influences of climate and humans on fire regimes. Reconstructions of past fires indicated that the Araucaria forest landscape has been shaped by widespread, stand-replacing fires favoured by regional interannual climate variability related to major tropical and extratropical climate drivers in the southern hemisphere. Summer precipitation and streamflow reconstructions tended to be below average during fire years. Fire events were significantly related to positive phases of the Southern Annular Mode and to warm and dry summers following El Niño events. Although Euro-Chilean settlement (1883–1960) resulted in widespread burning, cattle ranching by Pehuenche Native Americans during the 18th and 19th centuries also appears to have changed the fire regime. In the context of climate change, two recent widespread wildfires (2002 and 2015) affecting Araucaria forests appear to be novel and an early indication of a climate change driven shift in fire regimes in north-west Patagonia.

Critical shifts on spatial traits and the risk of extinction of Andean anurans: an assessment of the combined effects of climate and land-use change in Colombia

Climate and land-use change, raise significant threats to biodiversity, affecting species ranges worldwide. Both factors operate on different scales, so including spatial traits that allow them to be appropriately evaluated is relevant to the early identification of extinction risks. We aimed to evaluate the potential effects of climate and land-use change on the extent of suitable habitat of a set of species of Andean anurans; to assess the loss of the area of occupancy (AOO); and to estimate the risk of extinction according to the percentages of loss of the extent of suitable habitat and AOO. We modeled the current and future potential distributions of 30 endemic anurans from the Colombian Andes. We calculated the change in current potential distributional ranges and in the extent of suitable habitat under two climatic regimes and land-use scenarios. We quantified the AOO using the 2×2km grid method and assessed its loss based on habitat availability in the combined scenarios. We used the percentage losses of the extent of suitable habitat and AOO to estimate and compare the extinction risks according to IUCN criteria. We found that climate and land-use change will cause a relative loss of 63.4 % to 79.4 % of the current extent of suitable habitat and 49.6 % to 72.6 % of AOO of the Andean anurans by the year 2050. The loss of AOO made it possible to detect twice as many species at high risk of extinction than the loss of the extent of suitable habitat. The effects of climate change and habitat loss could lead to potential extinction events in Andean frogs. Extent of suitable habitat, and especially the area of occupancy are appropriate spatial traits that could be used to assess extinction risks in species sensitive to local habitat modification by climate change and land-use change.

Comparing independent climate-sensitive models of aboveground biomass and diameter growth with their compatible simultaneous model system for three larch species in China

Accurate estimate of tree biomass is essential for forest management. In recent years, several climate-sensitive allometric biomass models with diameter at breast height [Formula: see text] as a predictor have been proposed for various tree species and climate zones to estimate tree aboveground biomass (AGB). But the allometric models only account for the potential effects of climate on tree biomass and do not simultaneously explain the influence of climate on [Formula: see text] growth. In this study, based on the AGB data from 256 destructively sampled trees of three larch species randomly distributed across the five secondary climate zones in northeastern and northern China, we first developed a climate-sensitive AGB base model and a climate-sensitive [Formula: see text] growth base model using a nonlinear least square regression separately. A compatible simultaneous model system was then developed with the climate-sensitive AGB and [Formula: see text] growth models using a nonlinear seemingly unrelated regression. The potential effects of several temperature and precipitation variables on AGB and [Formula: see text] growth were evaluated. The fitting results of climatic sensitive base models were compared against those of their compatible simultaneous model system. It was found that a decreased isothermality ([mean of monthly (maximum temperature-minimum temperature)]/(Maximum temperature of the warmest month-Minimum temperature of the coldest month)) and total growing season precipitation, and increased annual precipitation significantly increased the values of AGB; an increase of temperature seasonality (a standard deviation of the mean monthly temperature) and precipitation seasonality (a standard deviation of the mean monthly precipitation) could lead to the increase of [Formula: see text]. The differences of the model fitting results between the compatible simultaneous system with the consideration of climate effects on both AGB and [Formula: see text] growth and its corresponding climate-sensitive AGB and [Formula: see text] growth base models were very small and insignificant [Formula: see text]. Compared to the base models, the inherent correlation of AGB with [Formula: see text] was taken into account effectively by the proposed compatible model system developed with the climate-sensitive AGB and [Formula: see text] growth models. In addition, the compatible properties of the estimated AGB and [Formula: see text] were also addressed substantially in the proposed model system.

Using climate projections to assess ecosystem vulnerability at scales relevant to managers

AbstractLand managers require information about the ongoing and potential effects of future climate to coordinate responses for ecosystems, species, and human communities at scales that are operationally meaningful. Our study focused on the vulnerability for all upland ecosystem types of Arizona and New Mexico in the southwestern United States. Local vulnerability across the two‐state area was represented by the level of departure for late 21st‐century climate from the characteristic pre‐1990 climate envelope of the ecosystem type at each given location, resulting in a probability surface of climate impacts for the two‐state area and an uncertainty assessment based on agreement in results among multiple global climate models. Though the results varied from one ecosystem type to the next, the majority of lands were forecast as high vulnerability and low uncertainty, reflecting significant agreement among climate model projections for the southwestern United States. We then tested our results in relation to ongoing ecological processes that have both regional and global change implications and discovered significant relationships with wildfire severity, upward tree species recruitment, and the encroachment of scrub into semidesert grassland. The testing helped determine the efficacy of the vulnerability surface, as a product of relatively high spatial and thematic resolution, in supporting local planning and management decisions. Most important, this study links climate and changes in vegetation by ecosystem processes that are already ongoing. The results affirm the value of climate model downscaling and show that this portable approach to correlative modeling has value in determining the location and magnitude of potential climate‐related impacts.