Climate Warming Research Articles

Deploying human and non-human ecosystem engineers to rebuild nature for people

Protecting and rebuilding nature can deal with 30% of historic carbon dioxide emissions and prevent ecosystem collapse that will otherwise imperil human society. Our collective climate resilience can be increased by restoring bigger, more dynamic ecosystems. Traditional conservation approaches cannot do this. Human and non-human ‘ecosystem engineers’ need to work alongside one another to ensure that keystone species can range across our landscapes (‘re-animating’ them) to increase their long-term carbon dioxide lock-up value, maximise their ongoing biodiversity value and concurrently increase the other ecosystem services that they provide and on which people ultimately depend. However, ecosystem engineer species such as large herbivores cannot move across landscapes that have been severed by infrastructure many other species need to be enables to move as the climate warms. This implies the need for a strategic nature network, linking ecosystems under restoration by way of physical crossings that overcome barriers such as roads. Human engineers can play a leading role in enabling all these key elements of rebuilding nature – from working on individual structures and projects, to applying nature-positive systems-thinking in their day-to-day jobs and advocating for ambitious nature recovery. We can all help engineer a more nature-positive future. We need to all become ecosystem engineers.

Increasing phosphorus loss despite widespread concentration decline in US rivers

The loss of phosphorous (P) from the land to aquatic systems has polluted waters and threatened food production worldwide. Systematic trend analysis of P, a nonrenewable resource, has been challenging, primarily due to sparse and inconsistent historical data. Here, we leveraged intensive hydrometeorological data and the recent renaissance of deep learning approaches to fill data gaps and reconstruct temporal trends. We trained a multitask long short-term memory model for total P (TP) using data from 430 rivers across the contiguous United States (CONUS). Trend analysis of reconstructed daily records (1980–2019) shows widespread decline in concentrations, with declining, increasing, and insignificantly changing trends in 60%, 28%, and 12% of the rivers, respectively. Concentrations in urban rivers have declined the most despite rising urban population in the past decades; concentrations in agricultural rivers however have mostly increased, suggesting not-as-effective controls of nonpoint sources in agriculture lands compared to point sources in cities. TP loss, calculated as fluxes by multiplying concentration and discharge, however exhibited an overall increasing rate of 6.5% per decade at the CONUS scale over the past 40 y, largely due to increasing river discharge. Results highlight the challenge of reducing TP loss that is complicated by changing river discharge in a warming climate.

Evaluation of the Algerian Apricot Phenotypic and Genetic Diversity: Impact of Graft-Propagated Autochthonous and Introduced Cultivars in a Traditional Seed-Propagated System

AbstractDespite the apricot cultivars introduced from Spain and France are displacing the autochthonous Algerian cultivars in each area, there are a lot of local cultivars that still have a great interest and they are cultivated in the orchards from the Algerian arid agrosystem. This study addresses the phenotypical and molecular characterization of autochthonous (Algerian and Tunisian cultivars) and introduced (Spanish and French) graft-propagated apricot cultivars in a traditional seed-propagated system. Sixty-five apricot cultivated autochthonous and introduced accessions from the provinces of Batna (slightly arid area) and M’Sila (semi-arid area) in Algeria have been evaluated. These cultivated accessions included autochthonous Algerian cultivars (graft and seed propagated) selected over the years for its adaptation to warm Mediterranean climate and Spanish and French introduced cultivars (graft propagated). In these materials and agronomical evaluation of phenological (budburst, flowering and ripening date), pomological (fruit weight and yield per tree) and fruit quality (firmness and acidity), traits were performed together with a molecular characterization of the genetic diversity using simple sequence repeat (SSR) marks. Results showed the great diversity at agronomical and molecular level of this Algerian apricot germplasm. The seed-propagated autochthonous cultivars showed a lower yield per tree and fruit weight. Seed-propagated autochthonous also showed a longer fruit development and ripening cycle in comparison with the grafted cultivars with a later ripening date. Regarding fruit quality, seed-propagated autochthonous cultivars present low firmness and high acidity compared with the rest. Results also showed the effectiveness of the SSR markers by the correct identification, detecting some synonymies and suggesting the origin of some autochthonous cultivars. These results will provide more in-depth information to develop a strategy for in situ conservation of cultivars and to reduce gene flow from introduced material to ancient orchards. These materials would be interesting to modify some quality traits such as the acidity or firmness and drought resistance in apricot breeding programs.

Assessment of permafrost-related hazards in China: based on Chinese literature

Abstract. High Mountain Asia (HMA) is undergoing unprecedented warming, affecting the cryosphere – including permafrost (frozen ground) – and leading to various hazards. However, understanding the prevalence, distribution, and dynamics of these hazards and how they respond to a changing climate is challenging. Permafrost is extensive in HMA, and China makes up a significant portion of this. The permafrost area in China is about 1.6×106 km2, 66 % of which is on the Qinghai–Tibet Plateau. However, most of the scientific literature concerning permafrost in China is published in Chinese and, hence, remains largely unnoticed by the non-Chinese-speaking scientific communities. In this article, we used a systematic review to evaluate the Chinese scientific literature on permafrost-related hazards and found that the studied areas are concentrated in certain areas, especially on the Qinghai–Tibet Engineering Corridor (QTEC). The increasing amount of literature on permafrost hazards reflects the increased impact of climate warming on infrastructure built on permafrost. Not only is permafrost affecting infrastructure; these anthropogenic disturbances themselves also have amplified the occurrence of hazards around settlements and infrastructure. The literature shows the strong relationship between latitude and elevation with permafrost thickness. The permafrost classification system and nomenclature used by Chinese scientists is different to that used elsewhere, which is a potential source of confusion and deserves attention.

A First Assessment of Greenhouse Gas Emissions From Agricultural Peatlands in Canada: Evaluation of Climate Change Mitigation Potential

ABSTRACTCanada has a quarter of the world's peatlands accounting for an estimated 150 Gt of stored carbon. While over 98% of Canadian peatlands are intact, agriculture has been estimated as accounting for the greatest peatland disturbance by area. Greenhouse gas (GHG) emissions from peatland agriculture can contribute a large proportion of national anthropogenic emissions for some countries. In Canada, estimates of GHG emissions from cultivated peat soils are incomplete. Improved accounting of these GHG emissions is required to inform decisions about where to deploy ecological restoration projects and where to allow future agricultural expansion as climate warms. Compiled studies that measured GHG fluxes from agricultural peat fields in Canada resulted in mean emissions factors of 5.1 t CO2e ha−1 year−1, −0.12 kg CH4 ha−1 year−1, and 14.3 kg N2O‐N ha−1 year−1 for carbon dioxide, methane, and nitrous oxide, respectively. Combining these values with a compilation of estimates of agricultural peatland disturbance area in Canada, GHG emissions estimates in Canada arising from peatland converted to agriculture remain highly uncertain, ranging from 1.4 to 35 Mt CO2e year−1, with a median value near 18 Mt CO2e year−1. The largest contributor to this wide range of estimates is uncertainty peatland area affected, indicating an urgent need to improving mapping of organic soils under agriculture in Canada. To help guide decision‐making in Canada, we recommend a network of research stations across a range of agricultural management intensities and climate regions for monitoring hydrological conditions and GHG exchange on organic soils affected by agriculture.

Soil microfauna mediate multifunctionality under multilevel warming in a primary forest

Abstract Soil microfauna play a crucial role in maintaining multiple functions associated with soil phosphorous, nitrogen and carbon cycling. Although both soil microfauna diversity and multifunctionality are strongly affected by climate warming, it remains unclear how their relationships respond to different levels of warming. We conducted a 3‐year multilevel warming experiment with five warming treatments in a subtropical primary forest. Using infrared heating systems, the soil surface temperature in plots was maintained at 0.8, 1.5, 3.0 and 4.2°C above ambient temperature (control). Our findings indicated that low‐level warming (+0.8–1.5°C) increased soil multifunctionality, as well as nematode and protist diversity, compared with the control. In contrast, high‐level warming (+4.2°C) significantly reduced these variables. We also identified significant positive correlations between soil multifunctionality and nematode and protist diversity in the 0–10 cm soil layer. Notably, we found that soil multifunctionality and protist diversity did not change significantly under 3.0°C warming treatment. Our results imply that a temperature increase of around 3°C may represent a critical threshold in subtropical forests, which is of great importance for identifying response measures to global warming from the perspective of microfauna in the surface soil. Our findings provide new evidence on how soil microfauna regulate multifunctionality under varying degrees of warming in primary forests.

Extreme Events Contributing to Tipping Elements and Tipping Points

AbstractThis review article provides a synthesis and perspective on how weather and climate extreme events can play a role in influencing tipping elements and triggering tipping points in the Earth System. An example of a potential critical global tipping point, induced by climate extremes in an increasingly warmer climate, is Amazon rainforest dieback that could be driven by regional increases in droughts and exacerbated by fires, in addition to deforestation. A tipping element associated with the boreal forest might also be vulnerable to heat, drought and fire. An oceanic example is the potential collapse of the Atlantic meridional overturning circulation due to extreme variability in freshwater inputs, while marine heatwaves and high acidity extremes can lead to coral reef collapse. Extreme heat events may furthermore play an important role in ice sheet, glacier and permafrost stability. Regional severe extreme events could also lead to tipping in ecosystems, as well as in human systems, in response to climate drivers. However, substantial scientific uncertainty remains on mechanistic links between extreme events and tipping points. Earth observations are of high relevance to evaluate and constrain those links between extreme events and tipping elements, by determining conditions leading to delayed recovery with a potential for tipping in the atmosphere, on land, in vegetation, and in the ocean. In the subsurface ocean, there is a lack of consistent, synoptic and high frequency observations of changes in both ocean physics and biogeochemistry. This review article shows the importance of considering the interface between extreme events and tipping points, two topics usually addressed in isolation, and the need for continued monitoring to observe early warning signs and to evaluate Earth system response to extreme events as well as improving model skill in simulating extremes, compound extremes and tipping elements.

Contrasting Precipitation Variations over the Himalayas–Southeastern Tibetan Plateau in Winter: Insights from the Perspectives of Anthropogenic Warming and Arctic Sea Ice Variations

Abstract Climate warming has caused widespread glacier retreat across the Tibetan Plateau (TP), with notable impacts observed in both the western Himalayas and southeastern TP. Remarkably, over the past two decades, the rate of glacier mass loss has remained stable or even declined in the western Himalayas, whereas a contrasting trend of acceleration has been evident in the southeastern TP. Among various factors considered, the contrasting winter precipitation pattern across the Himalayas–southeastern TP stands out as an important contributor to the observed differences in glacier mass balances. However, the underlying mechanisms behind this phenomenon remain unclear. Here, we provide evidence of a noticeable shift in the climate regime due to anthropogenic warming, altering atmospheric circulation patterns. This, in turn, has led to a significant change in the dominant winter precipitation pattern, favoring the observed contrasting glacier mass balances trend in winter. Additionally, the Barents–Kara Sea ice has emerged as a plausible driver of the interannual variability of the contrasting precipitation pattern, acting by exerting force on the atmosphere and stimulating the Rossby wave propagation. Consequently, it led to the opposite vertical motion and alterations in the moisture budget between the western Himalayas and southeastern TP. Thus, it is crucial to consider the unprecedented anthropogenic warming and Arctic Sea ice variations as potential drivers shaping both past and future glacier behaviors within this domain.

Stronger Westerly Wind Bursts in a Warming Climate: The Effects of the Pacific Warming Pattern, the Madden–Julian Oscillation, and Tropical Cyclones

Abstract Westerly wind bursts (WWBs) in the western–central equatorial Pacific are critical in El Niño–Southern Oscillation (ENSO) dynamics. Understanding how they may change with global warming has important implications for future projections of El Niño. In this study, we investigate how the enhanced eastern equatorial Pacific warming pattern, emerging in future climate projections, can influence WWB characteristics in an atmospheric general circulation model, CAM6. Changes in three main factors affecting WWBs—El Niño-conditions mean westerly wind stress anomalies, the Madden–Julian oscillation (MJO), and tropical cyclones (TCs)—are analyzed. We find that during El Niño onset (December–April), the WWB wind stress intensity remains largely unchanged but WWBs shift westward by about 20° of longitude. In contrast, during El Niño development (May–November), the WWB intensity increases by 41% or 79% in two warming scenarios considered [shared socioeconomic pathways (SSP5-8.5) and SSP2-4.5, respectively], which is mainly caused by a higher frequency of TC occurrence in the central tropical Pacific within 15°N/S. Further, we find that westerly wind speed anomalies associated with El Niño and the MJO also increase during El Niño development. However, as trade winds weaken in the central-eastern equatorial Pacific, the mean strength of the resulting westerly wind stress anomalies does not change much, and no significant eastward shift of WWBs is observed. Thus, our atmospheric model simulations suggest a strong TC-driven increase in WWB wind stress anomalies during El Niño development and hence a more important role of TCs in WWB generation, which in a coupled system could lead to stronger ENSO events, enhanced TC–ENSO coupling, and even greater intensification of WWBs.

Tropical Cyclone Wind Shear-Relative Asymmetry in Reanalyses

Abstract While tropical cyclones (TCs) are axisymmetric vortices to the first order, they often exhibit noteworthy structural asymmetries. These often result from environmental vertical wind shear, which tilts the vortex and induces a wavenumber 1 pattern in the circulation and precipitation fields. Reanalyses and climate models have improved in representing the TC structure and climatology, but their relatively coarse resolution and dependence on parameterized physics cast doubt on their ability to capture the asymmetric TC structure. We perform the most comprehensive process-oriented assessment of TC asymmetry to date in reanalyses. Specifically, we analyze the composite shear-relative TC structure in ERA5 and Climate Forecast System Reanalysis (CFSR), which vary in their resolutions, physical parameterization suites, and data assimilation techniques. These structures are compared with aircraft reconnaissance radar observations. In agreement with the observations, the strongest tangential winds are usually found left-of-shear, while inner core rainfall, ascent, vortex tilt, and low-level inflow are favored directly downshear or in the downshear-left quadrant. Outer rainband convection generally peaks in the downshear-right quadrant. Thermodynamic asymmetries are also apparent, with anomalous low-level moisture right-of-shear, midlevel warmth in the upshear-right quadrant (uptilt), and cloud properties suggestive of a realistic precipitation life cycle from growth to fallout. We also decompose rainfall contributions from the convective parameterization and large-scale cloud schemes and highlight the roles of vorticity advection, buoyancy advection, and diabatic processes in driving asymmetric vertical motions in the inner core and outer rainband regions. Our results suggest that process-level studies of TC asymmetry and TC–wind shear interaction under future warming are viable using climate models. Significance Statement Asymmetries are common in tropical cyclones (TCs), influencing their intensity, track, and hazards. Vertical wind shear often plays a leading-order role in causing these asymmetries. It is uncertain how well asymmetric structures and processes are captured in reanalyses and global climate models (GCMs) with grid spacings of 0.25° and coarser. In this study, we first evaluate TC asymmetry in reanalyses, which have the benefit of being forced by observations. This helps to assess whether the resolutions associated with GCMs sufficiently capture asymmetric structures and processes and motivates upcoming work with free-running GCMs to study how TC asymmetry may change in a warming climate.

Classification Importance of Seed Morphology and Insights on Large-Scale Climate-Driven Strophiole Size Changes in the Iberian Endemic Chasmophytic Genus Petrocoptis (Caryophyllaceae)

Recruitment poses significant challenges for narrow endemic plant species inhabiting extreme environments like vertical cliffs. Investigating seed traits in these plants is crucial for understanding the adaptive properties of chasmophytes. Focusing on the Iberian endemic genus Petrocoptis A. Braun ex Endl., a strophiole-bearing Caryophyllaceae, this study explored the relationships between seed traits and climatic variables, aiming to shed light on the strophiole’s biological role and assess its classificatory power. We analysed 2773 seeds (557 individuals) from 84 populations spanning the genus’ entire distribution range. Employing cluster and machine learning algorithms, we delineated well-defined morphogroups based on seed traits and evaluated their recognizability. Linear mixed-effects models were utilized to investigate the relationship between climate predictors and strophiole area, seed area and the ratio between both. The combination of seed morphometric traits allows the division of the genus into three well-defined morphogroups. The subsequent validation of the algorithm allowed 87% of the seeds to be correctly classified. Part of the intra- and interpopulation variability found in strophiole raw and relative size could be explained by average annual rainfall and average annual maximum temperature. Strophiole size in Petrocoptis could have been potentially driven by adaptation to local climates through the investment of more resources in the production of bigger strophioles to increase the hydration ability of the seed in dry and warm climates. This reinforces the idea of the strophiole being involved in seed water uptake and germination regulation in Petrocoptis. Similar relationships have not been previously reported for strophioles or other analogous structures in Angiosperms.

The Influence of Waters of Lake Baikal on the Spatiotemporal Dynamics of Phytoplankton in the Irkutsk Reservoir

On a model natural object, the Lake Baikal–Angara River–Irkutsk Reservoir (IR), we studied changes in the qualitative and quantitative characteristics of phytoplankton communities over three seasons in 2023 depending on seasonal changes in habitat parameters. Of the 151 identified taxa, Chrysophyta (57), Chlorophyta (41) and Bacillariophyta (24) predominated in diversity. Over the entire observation period, the highest values of total biomass and total abundance were detected in the IR in June (hydrological spring) at a water temperature of 10.0–12.7 °C, and the lowest in August, despite the fact that the water warmed up to 20 °C. No mass blooms of Cyanobacteria were observed. Statistical analysis of species abundance profiles revealed that phytoplankton community structure varied across time and space. The direct effect of cold lake waters on the structure of phytoplankton in the reservoir was observed only in early June. In summer and autumn, the structures of phytoplankton in the lake and in the reservoir differed, even at the same water temperature. Low concentrations of phosphates and nitrates, high species diversity, the presence of cold-water species and species with a wide range of temperature preferences formed a dynamic spatiotemporal structure of IR phytoplankton, distinct from other temperate reservoirs, including Lake Baikal. The results obtained are important for understanding the mechanisms of formation of the flora of artificial reservoirs of temperate latitudes and for their monitoring, taking into account seasonal dynamics and the context of global climate warming.

Rubbery organic frameworks (ROFs) toward ultrapermeable CO2-selective membranes.

The capture of CO2 is of high interest in our society representing an essential tool to mitigate man-made climate warming. Membrane technology applied for CO2 capture offers several advantages in terms of energy savings, simple operation, and easy scale-up. Glassy membranes are associated with low gas permeability that negatively affect on their industrial implementation. Oppositely, rubbery membranes offer high permeability, but their selectivity is low. Here we report rubbery organic frameworks (ROFs) combining the high permeability of soft matrices with the high sieving selectivity of molecular frameworks. The best performing membranes provide a CO2/N2 selectivity up to 104 with a CO2 permeability up to 1000 Barrer, representing relevant performances for industrial implementation. Water vapors have a positive effect on CO2 permeability, and the CO2/N2 selectivity is higher than in dry conditions, as most of CO2 gas emissions are present in fully humidified gas streams. The synergetic high permeability/selectivity performances are superior to that observed with current state-of-the-art polymeric membranes.

A novel sustainable biocide against the fruit fly Drosophila suzukii made from orange peels.

Drosophila suzukii (D. suzukii), a pervasive pest originating from Southeast Asia, presents a substantial risk to global agriculture. The ability of the female flies to lay eggs within fruits of varying maturity stages, combined with the accelerated offspring development within warmer climates, results in rapid population growth. This poses significant challenges for fruit production and viticulture, exacerbated by the increasing prevalence of pesticide resistance. We propose a solution to this growing issue using an attract-and-kill approach by making use of upcycled organic waste materials made from orange peels. Specifically, we have tested an innovative salty orange peel product (OPP) in a choice experiment, in which OPP and hydrogel (control) were made available to fruit flies in Petri dishes situated beneath red wine grapes. The number of dead flies in both Petri dishes were counted each day and fly maggots inside berries were extracted after four days. Since Petri dishes were covered with a red lid, flies only selected on the basis of olfactory cues. Our results showed a higher number of captured flies in Petri dishes containing OPP compared to those with the hydrogel control. Furthermore, a notable reduction in the number of maggots was observed inside grapes located above OPP compared to the grapes closer to the hydrogel control. Dilution of OPP was followed by a lower count of dead flies. In additional choice experiments, the concentration of NaCl was found to be positively correlated with the number of dead flies. This suggests an important lethal effect caused by high salt concentrations. In a final experiment, OPP was also compared to the commercially-available attractant called Drosalure™, which resulted in a slightly higher attractiveness of OPP to D. suzukii. These findings suggest that OPP holds potential as a cost-efficient and eco-friendly biocide made from organic waste material. OPP offered in attract-and-kill traps equipped with small entry holes is safe for bees and may replace other less eco-friendly control measures for D. suzukii in organic vineyards.

Trends in extreme rainfall over the past 55 years suggest springtime subhourly rainfall extremes have intensified in Mahantango Creek, Pennsylvania.

Extreme short-duration rainfall is intensifying with climate warming, and growing evidence suggests that subhourly rainfall extremes are increasing faster than more widely studied durations at hourly and daily timescales. In this case study, we used 55 years (1968-2022) of 5-min precipitation data from Mahantango Creek, a long-term experimental agricultural watershed in east-central Pennsylvania, United States, to examine annual and seasonal changes in subhourly (15-min), hourly, and daily rainfall extremes. Specifically, we evaluated temporal trends in the magnitude and frequency of subhourly, hourly, and daily rainfall extremes. We then estimated apparent scaling rates between rainfall extremes and dew point temperature (Td) and compared these rates to the Clausius-Clapeyron (CC) rate (∼ 7% per °C). We also determined the coincidence of extreme rainfall trends with indicators of atmospheric instability and convective-type precipitation. Overall, we found the most significant changes in rainfall extremes at 15-min durations during the spring, with magnitudes of these subhourly extremes increasing by 0.6 to 0.9% per year, and frequencies rising by 3.4% per year. Apparent scaling rates in the spring showed that 15-min rainfall extremes transitioned from sub-CC scaling to greater than 2CC scaling when Td reached 11° C, implying a possible shift from stratiform rains to more intense convective rains above this Td threshold. Notably, trends in maximum hourly convective available potential energy (CAPE) increased during spring, as did the ratio of 15-min rainfall extremes to their corresponding daily rainfall totals. Findings indicate that convective-type precipitation may be playing an increasing role in the intensification of springtime 15-min rainfall extremes in Mahantango Creek.

Effect of Global Warming on the Fish Population Parameters in the Upper Volga Reservoirs

As a result of global warming, the average annual water temperature has significantly increased in the Upper Volga reservoirs. Warming and the subsequent deterioration of the oxygen regime had a significant effect on most of the fish populations inhabiting temperate waters. This led to changes in the population structure of many fish species. Such phenomena as the disappearance or a sharp decline in the abundance of cold-water species (European smelt, vendace, burbot and pike) in the Rybinsk reservoir coincided with the period of warming. The disappearance of European smelt in the Rybinsk Reservoir and the favorable temperature regime contributed to the appearance and rapid increase in the abundance of the Caspian invader, the Black Sea sprat, which occupied the empty niche of the European smelt and became instead the dominant species in the pelagic zone of the Upper Volga reservoirs. Warming resulted in a decrease in the abundance and the growth rate of burbot and pike. Climate warming had an indirect effect on many species through oxygen deficiency or transformation of the forage base (ruff, zander, perch, roach), which also led to a decrease in abundance and the growth rate.

Archives of cyanobacterial traits: insights from resurrected Nodularia spumigena from Baltic Sea sediments reveal a shift in temperature optima

Abstract Cyanobacterial blooms in the Baltic Sea proliferated in recent decades due to rising sea surface temperatures, resulting in significant ecological impacts. To elucidate their current success, we examined ecophysiological, biochemical and morphological traits of recent and ~ 33-year-old strains of Nodularia spumigena using a resurrection approach. The ability of many cyanobacteria to form dormant stages that can persist in anoxic sediments for decades provides a unique opportunity to study adaptive traits to past environmental conditions. A short sediment core from the Eastern Gotland Basin was processed to isolate strains of N. spumigena buried in 1987 ± 2 and 2020 ± 0.5 CE (Common Era). Sequencing was used for species identification, followed by characterisation of cell morphometry, carbon, nitrogen and chlorophyll a content. Photosynthetic performance was evaluated by using pulse-amplitude modulated fluorimetry and oxygen optodes to assess light and temperature requirements. Our results revealed trait changes in N. spumigena over the past 3 decades: Temperature optimum for photosynthesis shifted from 15.3°C to 21.1°C which is consistent with the past and present local SST. Recent strains exhibited increased carbon, nitrogen, and chlorophyll a content despite decreased cell volume. The demonstrated adaptability of N. spumigena to increasing temperature suggests that this species will thrive in a warmer climate in the future. These insights will aid modelling efforts aimed at understanding and managing consequences of future cyanobacterial blooms in the Baltic Sea ecosystem.

Persistent Trends and Geographic Traits of Heat Waves in a Changing Climate

Abstract By adopting a heatwave (HW) definition with a ~4-year recurrence frequency at world hot spots, we first examined the 1940-2022 HW climatology and trends in lifespan (duration), severity and recurrence frequency, by comparing the first and last 20-year periods of this 83- year record. Generally, HWs are becoming more frequent and more severe in the extra-tropic and mid-latitude regions. Increased HWs are not temporally uniform and tend to cluster together, posing a one-two punch for ecosystems. North America, regions affected by HWs in the early 21st Century expanded by ~47% relative to those in the mid-20th Century, contributed primarily by regions starting to be exposed to HWs in the early 21st Century. Mid-latitude basins are vulnerable areas. Geographic shifts can be attributed to adjustments in planetary wavelengths due to increased air viscosity (related to global warming). Polar amplified warming, leading to a reduced equator to pole temperature gradients and an overall reduction in zonal wind speeds across midlatitudes, promotes amplified planetary wave amplitudes, leading to more severe and persistent blockings and cutoffs, thus an increase in HW frequency, severity, and duration. Climate model simulations under a business-as-usual emission scenario corroborate trends in HW severity and lifespan increases, supported by a strong intermodal consensus. HW periods correspond to heightened planetary boundary layer (PBL) depths, which increase with eddy viscosity. The temperature-dependent nature of air viscosity underscores the similarity between trends in PBL depth and HW areal extent in a warming climate.

Sensitivity of the future evolution of the Wilkes Subglacial Basin ice sheet to grounding-line melt parameterizations

Abstract. Projections of Antarctic Ice Sheet mass loss and therefore global sea level rise are hugely uncertain, partly due to how mass loss of the ice sheet occurs at the grounding line. The Wilkes Subglacial Basin (WSB), a vast region of the East Antarctic Ice Sheet, is thought to be particularly vulnerable to deglaciation under future climate warming scenarios. However, future projections of ice loss, driven by grounding-line migration, are known to be sensitive to the parameterization of ocean-induced basal melt of the floating ice shelves and, specifically, to the adjacent grounding line – termed grounding-line melt parameterizations (GLMPs). This study investigates future ice sheet dynamics in the WSB with respect to four GLMPs under both the upper and lower bounds of climate warming scenarios from the present to 2500, with different model resolutions, ice shelf melt parameterizations (ISMPs) and choices of sliding relationships. The variation in these GLMPs determines the distribution and the amount of melt applied in the finite-element assembly procedure on partially grounded elements (i.e. elements containing the grounding line). Our findings indicate that the GLMPs significantly affect both the trigger timings of tipping points and the overall magnitude of ice mass loss. We conclude that applying full melting to the partially grounded elements, which causes melting on the grounded side of the grounding line, should be avoided under all circumstances due to its poor numerical convergence and substantial overestimation of ice mass loss. We recommend preferring options that depend on the specific model context, by either (1) not applying any melt immediately adjacent to the grounding line or (2) employing a sub-element parameterization.

Proteomic identification of potential biomarkers for heat tolerance in Caracu beef cattle using high and low thermotolerant groups.

Heat stress has deleterious effects on physiological and performance traits in livestock. Within this context, using tropically adapted cattle breeds in pure herds or terminal crossbreeding schemes to explore heterosis is attractive for increasing animal production in warmer climate regions. This study aimed to identify biological processes, pathways, and potential biomarkers related to thermotolerance in Caracu, a tropically adapted beef cattle breed, by proteomic analysis of blood plasma. To achieve this goal, 61 bulls had their thermotolerance evaluated through a heat tolerance index. A subset of 14 extreme animals, including the seven most thermotolerant (HIGH group) and the seven least thermotolerant (LOW group), had their blood plasma samples used for proteomic analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The differentially regulated proteins detected between HIGH and LOW groups were used to perform functional enrichment analysis and a protein-protein interaction network analysis. A total of 217 proteins were detected only in the HIGH thermotolerant group and 51 only in the LOW thermotolerant group. In addition, 81 and 87 proteins had significantly higher and lower abundancies in the HIGH group, respectively. Regarding proteins with the highest absolute log-fold change values, we highlighted those encoded by DUSP5, IGFALS, ROCK2, RTN4, IRAG1, and NNT genes based on their functions. The functional enrichment analysis detected several biological processes, molecular functions, and pathways related to cellular responses to stress, immune system, complement system, and hemostasis in both HIGH and LOW groups, in addition to terms and pathways related to lipids and calcium only in the HIGH group. Protein-protein interaction (PPI) network revealed as important nodes many proteins with roles in response to stress, hemostasis, immune system, inflammation, and homeostasis. Additionally, proteins with high absolute log-fold change values and proteins detected as essential nodes by PPI analysis highlighted herein are potential biomarkers for thermotolerance, such as ADRA1A, APOA1, APOB, APOC3, C4BPA, CAT, CFB, CFH, CLU, CXADR, DNAJB1, DNAJC13, DUSP5, FGA, FGB, FGG, HBA, HBB, HP, HSPD1, IGFALS, IRAG1, KNG1, NNT, OSGIN1, PROC, PROS1, ROCK2, RTN4, RYR1, TGFB2, VLDLR, VTN, and VWF. Identifying potential biomarkers, molecular mechanisms and pathways that act in response to heat stress in tropically adapted beef cattle contributes to developing strategies to improve performance and welfare traits in livestock under tropical climates.