Future Warming Research Articles

Increasing fluctuations in the Arctic summer sea ice cover are expected with future global warming

The loss of Arctic sea ice (ASI) represents a major transformation in the Arctic region, impacting regional and global climate, ecosystems, and socio-economic structures. Observational and reanalysis data have consistently shown a notable shift in polar environmental conditions over recent decades, marked by a substantial reduction in the ASI area and a rise in the variability in its coverage and distribution. Utilizing data from the latest Coupled Model Intercomparison Project phase, our study reveals a consistent pattern highlighting a fundamental shift in ASI dynamics preceding total loss. We observe increasing fluctuations in the September ASI area as the threshold for an ice-free Arctic is approached across various scenarios and models. This pattern is particularly concentrated in the Central Arctic (CA) sub-region. Spatial analyses reveal increasing variance along the CA’s northern coastlines, accompanied by a substantial increase in open water coverage, underscoring the shift from stable to highly variable ice conditions in this region. Additionally, our findings suggest a potential link between increased ASI fluctuations and variability in surface wind speeds. These specific results underscore the urgency of multidisciplinary approaches in addressing the challenges posed by ASI variability, with implications for marine ecosystems, Indigenous communities, and navigational safety.

Effects of warming on the seedling adaptation and growth of Machilus gamblei in a subtropical forest

Accurate predictions of community stability feedback to climate warming depend on an advanced understanding of responses of the key species. The transition from seed germination to seedling establishment is the most vulnerable stage of plants, which determines the maintenance of plant diversity and community resistance to climate change. To elucidate how the establishment and physiological characteristics of Machilus gamblei seedlings will respond to future global warming, artificial warming experiments (infrared warming, +0.75 ℃, +1.5 ℃, +3 ℃, +4 ℃) were conducted at the Ailao Mountain National Nature Reserve in Yunnan Province, China. The responses of seedling establishment and their physiological adaptation to different warming conditions were studied, and the contents of nutrients, chlorophyll, and nonstructural carbohydrate (NSC) in the leaves were measured. The results showed that: (1) increasing the temperature by 0.75 ℃ did not affect the survival rate or physiological characteristics of the seedlings, but increasing the temperature by 4 ℃ reduced the survival rate of the seedlings; (2) As the temperature increased from 1.5 ℃ to 3 ℃, the chlorophyll production in the seedling leaves improved, thus particularly promoting the accumulation of NSC by increasing the starch content. In summary, our work suggests that the temperature increase in 1.5 ℃ and 3 ℃ might be conducive to the establishment and growth of Machilus gamblei seedlings in the two-year experimental period, but increasing the temperature by 4 ℃ would threaten their survival and development.

Re-assessing thermal response of schistosomiasis transmission risk: Evidence for a higher thermal optimum than previously predicted.

The geographical range of schistosomiasis is affected by the ecology of schistosome parasites and their obligate host snails, including their response to temperature. Previous models predicted schistosomiasis' thermal optimum at 21.7°C, which is not compatible with the temperature in sub-Saharan Africa (SSA) regions where schistosomiasis is hyperendemic. We performed an extensive literature search for empirical data on the effect of temperature on physiological and epidemiological parameters regulating the free-living stages of S. mansoni and S. haematobium and their obligate host snails, i.e., Biomphalaria spp. and Bulinus spp., respectively. We derived nonlinear thermal responses fitted on these data to parameterize a mechanistic, process-based model of schistosomiasis. We then re-cast the basic reproduction number and the prevalence of schistosome infection as functions of temperature. We found that the thermal optima for transmission of S. mansoni and S. haematobium range between 23.1-27.3°C and 23.6-27.9°C (95% CI) respectively. We also found that the thermal optimum shifts toward higher temperatures as the human water contact rate increases with temperature. Our findings align with an extensive dataset of schistosomiasis prevalence in SSA. The refined nonlinear thermal-response model developed here suggests a more suitable current climate and a greater risk of increased transmission with future warming for more than half of the schistosomiasis suitable regions with mean annual temperature below the thermal optimum.

The ‘full-flowing stomach’: unwholesome food, climate, and colonialism in King Lear and Kristian Levring’s The King is Alive

Abstract This article considers Kristian Levring’s 2000 film The King is Alive from a radically open historicist methodology, analysing the film as a product of multiple interleaved archives. An adaptation of King Lear, the film’s relevant archive includes documents from the English Renaissance like the early modern recipe books and seventeenth-century medical treatises that this article uncovers. Yet because The King is Alive was filmed in an abandoned German mining colony in the Namib desert, the archive must also include accounts of the colonialist ‘Scramble for Africa’ more than two centuries after King Lear was written. The methodological deftness of history-as-adaptation allows us to see the film’s anxieties about food that rest at the nexus of these two archives. Shakespeare’s play worries about liminal foods—species-specific foods, foods that fail to nourish, and foods that become poison—but the film updates these concerns to implicate Western imperialism and global capitalism. Surrounded (and, in one instance, killed) by potentially botulistic cans of carrots that remain after the German occupation, the characters in the film must grapple with the toxic leftovers of colonialism, including Shakespeare’s playtext. The film thus asks its audience to consider further archives related to the imperialist roots of the invention of canning, the discovery of vitamins, and the export of Shakespeare as a ‘civilizing’ figure. Finally, the film gestures to the foodway challenges exacerbated by both capitalism and climate change, becoming a palimpsest of archives from across multiple temporalities: a Shakespearean past, a colonialist present, and a warming future.

Unique Temperature Trend Pattern Associated With Internally Driven Global Cooling and Arctic Warming During 1980–2022

AbstractDiagnosing the role of internal variability over recent decades is critically important for both model validation and projections of future warming. Recent research suggests that for 1980–2022 internal variability manifested as Global Cooling and Arctic Warming (i‐GCAW), leading to enhanced Arctic Amplification (AA), and suppressed global warming over this period. Here we show that such an i‐GCAW is rare in CMIP6 large ensembles, but simulations that do produce similar i‐GCAW exhibit a unique and robust internally driven global surface air temperature (SAT) trend pattern. This unique SAT trend pattern features enhanced warming in the Barents and Kara Sea and cooling in the Tropical Eastern Pacific and Southern Ocean. Given that these features are imprinted in the observed record over recent decades, this work suggests that internal variability makes a crucial contribution to the discrepancy between observations and model‐simulated forced SAT trend patterns.

Limited sensitivity of permafrost soils to heavy rainfall across Svalbard ecosystems

Together with warming air temperatures, Arctic ecosystems are expected to experience increases in heavy rainfall events. Recent studies report accelerated degradation of permafrost under heavy rainfall, which could put significant amounts of soil carbon and infrastructure at risk. However, controlled experimental evidence of rainfall effects on permafrost thaw is scarce. We experimentally tested the impact and legacy effect of heavy rainfall events in early and late summer for five sites varying in topography and soil type on the High Arctic archipelago of Svalbard. We found that effects of heavy rainfall on soil thermal regimes are small and limited to one season. Thaw rates increased under heavy rainfall in a loess terrace site, but not in polygonal tundra soils with higher organic matter content and water tables. End-of-season active layer thickness was not affected. Rainfall application did not affect soil temperature trends, which appeared driven by timing of snowmelt and organic layer thickness, particularly during early summer. Late summer rainfall was associated with slower freeze-up and colder soil temperatures the following winter. This implies that rainfall impacts on Svalbard permafrost are limited, locally variable and of short duration. Our findings diverge from earlier reports of sustained increases in permafrost thaw following extreme rainfall, but are consistent with observations that maritime permafrost regions such as Svalbard show lower rainfall sensitivity than continental regions. Based on our experiment, no substantial in-situ effects of heavy rainfall are anticipated for thawing of permafrost on Svalbard under future warming. However, further work is needed to quantify permafrost response to local redistribution of active layer flow under natural rainfall extremes. In addition, replication of experiments across variable Arctic regions as well as long-term monitoring of active layers, soil moisture and local climate will be essential to develop a panarctic perspective on rainfall sensitivity of permafrost.

Tibetan Plateau grasslands might increase sequestration of microbial necromass carbon under future warming

Microbial necromass carbon (MNC) can reflect soil carbon (C) sequestration capacity. However, changes in the reserves of MNC in response to warming in alpine grasslands across the Tibetan Plateau are currently unclear. Based on large-scale sampling and published observations, we divided eco-clusters based on dominant phylotypes, calculated their relative abundance, and found that their averaged importance to MNC was higher than most other environmental variables. With a deep learning model based on stacked autoencoder, we proved that using eco-cluster relative abundance as the input variable of the model can accurately predict the overall distribution of MNC under current and warming conditions. It implied that warming could lead to an overall increase in the MNC in grassland topsoil across the Tibetan Plateau, with an average increase of 7.49 mg/g, a 68.3% increase. Collectively, this study concludes that alpine grassland has the tendency to increase soil C sequestration capacity on the Tibetan Plateau under future warming.

Sensitivity of ocean circulation to warming during the Early Eocene greenhouse

Multiple abrupt warming events ("hyperthermals") punctuated the Early Eocene and were associated with deep-sea temperature increases of 2 to 4 °C, seafloor carbonate dissolution, and negative carbon isotope (δ13C) excursions. Whether hyperthermals were associated with changes in the global ocean overturning circulation is important for understanding their driving mechanisms and feedbacks and for gaining insight into the circulation's sensitivity to climatic warming. Here, we present high-resolution benthic foraminiferal stable isotope records (δ13C and δ18O) throughout the Early Eocene Climate Optimum (~53.26 to 49.14 Ma) from the deep equatorial and North Atlantic. Combined with existing records from the South Atlantic and Pacific, these indicate consistently amplified δ13C excursion sizes during hyperthermals in the deep equatorial Atlantic. We compare these observations with results from an intermediate complexity Earth system model to demonstrate that this spatial pattern of δ13C excursion size is a predictable consequence of global warming-induced changes in ocean overturning circulation. In our model, transient warming drives the weakening of Southern Ocean-sourced overturning circulation, strengthens Atlantic meridional water mass aging gradients, and amplifies the magnitude of negative δ13C excursions in the equatorial to North Atlantic. Based on model-data consistency, we conclude that Eocene hyperthermals coincided with repeated weakening of the global overturning circulation. Not accounting for ocean circulation impacts on δ13C excursions will lead to incorrect estimates of the magnitude of carbon release driving hyperthermals. Our finding of weakening overturning in response to past transient climatic warming is consistent with predictions of declining Atlantic Ocean overturning strength in our warm future.

The Growth and Carbon Sink of Tundra Peat Patches in Arctic Alaska

AbstractRecent amplified climate warming in the Arctic has caused profound changes in terrestrial ecosystems, with the potential for strong feedback on climate change. Arctic tundra landscapes have developed patchy and thin organic soil (peat) layers at the surface that may continue to grow into mature peatlands and become a larger carbon sink under future warming. Here we use paleoecological analyses of multiple soil and peat cores collected from the North Slope of Alaska to document and understand the formation and development histories of tundra peat patches and permafrost peatlands. We find a consistent peat development sequence for peat patches, first from mineral soils to sedge peat during the Little Ice Age, and then to Sphagnum peat during the recent warming with high carbon accumulation rates. These findings suggest that climate cooling is likely critical for the initial peat buildup on tundra soils due to reduced decomposition, whereas climate warming triggers the regime shift into an increased abundance of Sphagnum mosses that are likely central to enhancing their carbon sink capacity. Additionally, peat patches become similar to permafrost peatlands in the vicinity in terms of ecosystem processes and carbon dynamics, and therefore may have developed the same ecohydrological feedback system to maintain their long‐term stability. This study implies that the potential future expansion of peat patches into peatlands may strongly alter the carbon balance of Arctic tundra, supporting the new United Nations Environment Programme's report that calls for incorporating widespread shallow peat into understanding the peatland–carbon–climate nexus.

How Could Future Climate Conditions Reshape a Devastating Lake‐Effect Snow Storm?

AbstractLake‐effect snow (LES) storms, characterized by heavy convective precipitation downwind of large lakes, pose significant coastal hazards with severe socioeconomic consequences in vulnerable areas. In this study, we investigate how devastating LES storms could evolve in the future by employing a storyline approach, using the LES storm that occurred over Buffalo, New York, in November 2022 as an example. Using a Pseudo‐Global Warming method with a fully three‐dimensional two‐way coupled lake‐land‐atmosphere modeling system at a cloud‐resolving 4 km resolution, we show a 14% increase in storm precipitation under the end‐century warming. This increase in precipitation is accompanied by a transition in the precipitation form from predominantly snowfall to nearly equal parts snowfall and rainfall. Through additional simulations with isolated atmospheric and lake warming, we discerned that the warmer lake contributes to increased storm precipitation through enhanced evaporation while the warmer atmosphere contributes to the increase in the storm's rainfall, at the expense of snowfall. More importantly, this shift from snowfall to rainfall was found to nearly double the area experiencing another winter hazard, Rain‐on‐Snow. Our study provides a plausible future storyline for the Buffalo LES storm, focusing on understanding the intricate interplay between atmospheric and lake warming in shaping the future dynamics of LES storms. It emphasizes the importance of accurately capturing the changing lake‐atmosphere dynamics during LES storms under future warming.

North Atlantic Warming Hole Modulates Interhemispheric Asymmetry of Future Temperature and Precipitation

AbstractThe observed cooling in the subpolar North Atlantic, known as the warming hole, is receiving much attention because of its relationship with the climate sensitivity in the Earth System Models (ESMs). However, the impact of its future projection on the global climate remains unclear due to large uncertainties. Here, we show that the future warming hole changes will affect the interhemispheric asymmetry of temperature and precipitation by modulating the Northern Hemisphere (NH) warming. Models with a weaker warming hole in the future project stronger NH warming by injecting more non‐radiative fluxes to the atmosphere. This leads to an asymmetric warming contrast between the two hemispheres, resulting in a meridional shift of the Inter‐Tropical Convergence Zone and more precipitation increases in the NH. Our study implies that the future warming hole controls the interhemispheric heat exchanges and associated changes in the global temperature and precipitation, suggesting that its improved simulation is essential.

Latitudinal variation in thermal performance of the common coral Pocillopora spp.

Understanding how tropical corals respond to temperatures is important to evaluating their capacity to persist in a warmer future. We studied the common Pacific coral Pocillopora over 44° of latitude, and used populations at three islands with different thermal regimes to compare their responses to temperature using thermal performance curves (TPCs) for respiration and gross photosynthesis. Corals were sampled in the local autumn from Moorea, Guam and Okinawa, where mean±s.d. annual seawater temperature is 28.0±0.9°C, 28.9±0.7°C and 25.1±3.4°C, respectively. TPCs for respiration were similar among latitudes, the thermal optimum (Topt) was above the local maximum temperature at all three islands, and maximum respiration was lowest at Okinawa. TPCs for gross photosynthesis were wider, implying greater thermal eurytopy, with a higher Topt in Moorea versus Guam and Okinawa. Topt was above the maximum temperature in Moorea, but was similar to daily temperatures over 13% of the year in Okinawa and 53% of the year in Guam. There was greater annual variation in daily temperatures in Okinawa than Guam or Moorea, which translated to large variation in the supply of metabolic energy and photosynthetically fixed carbon at higher latitudes. Despite these trends, the differences in TPCs for Pocillopora spp. were not profoundly different across latitudes, reducing the likelihood that populations of these corals could better match their phenotypes to future more extreme temperatures through migration. Any such response would place a premium on high metabolic plasticity and tolerance of large seasonal variations in energy budgets.

Methodological approaches in the study of hydric stress in plants

Drought significantly affects plant growth and development, having a negative impact on the productivity of crops and, respectively, on food security worldwide. To predict the response of agricultural crops to future global warming and water deficit and to develop effective risk management strategies, there is a need to understand, at various levels of organization, the processes that determine tolerance to adverse environments. In this context it is important to use appropriate models of hydric stress induction and response assessment. The paper presents a brief description of the methodological approaches used in plant drought stress studies (field, greenhouse, laboratory experiments; experimental models using different types of substrates; distinct methods to induce water deficit), reflects their particularities, advantages and limitations and highlights the importance of combining and adapting methods of analysis according to the studied species, the environment and the research objectives.

Holocene hydroclimate variability of the Baltic region inferred from stable isotopes, d-excess and multi-proxy data at lake Nuudsaku, Estonia (NE Europe)

Long-term hydroclimate records provide an opportunity to understand potential drivers of the past, and give context to modern and future climate warming. A wide variety of proxy data now allow for reconstruction of climate variables that were not previously possible. Here we present a multi-proxy dataset including n-alkane δ2H (δ2Hn-alk) values from an open-basin lake in Estonia to reconstruct past hydroclimate conditions for the eastern Baltic region. We complement our sedimentary δ2Hn-alk data with existing carbonate-based oxygen stable isotope (δ18O) data to derive deuterium (d-) excess. We present multiple isotopic records and reconstructed relative humidity (ΔRH) values over the Holocene, and link these with modern precipitation δ2H and δ18O values to guide the interpretation of the paleo-proxies. Fossil pollen and chironomid-based temperature reconstructions, as well as biogeochemical data provide additional information for inferring past environmental changes. Our results indicate that the middle Holocene in Estonia had on average 6 ± 3% higher RH values than the late Holocene. The δ18O and δ2H values were also higher during the middle Holocene, which we interpret as increased warm season precipitation. Our reconstructed d-excess values were relatively higher during the middle Holocene, indicating a more northerly or cold source water origin, in comparison to the late Holocene. In addition to the paleoclimatic significance, our results show how multiple quantitative proxies can be combined to characterize hydroclimate sensitivity to changes in relative humidity, temperature and moisture source.

Proton-pumping rhodopsin of the coral symbiont Breviolum minutum and its potential role in coping with phosphorus deficiency in future warmer ocean

Proton-pumping rhodopsin of the coral symbiont Breviolum minutum and its potential role in coping with phosphorus deficiency in future warmer ocean

Emergence of decadal linkage between Western Australian coast and Western–central tropical Pacific

The impact of interbasin linkage on the weather/climate and ecosystems is significantly broader and profounder than that of only appearing in an individual basin. Here, we reveal that a decadal linkage of sea surface temperature (SST) has emerged between western Australian coast and western–central tropical Pacific since 1985, associated with continuous intensification of decadal variabilities (8–16 years). The rapid SST changes in both tropical Indian Ocean and Indo-Pacific warm pool in association to greenhouse gases and volcanoes are emerging factors resulting in enhanced decadal co-variabilities between these two regions since 1985. These SST changes induce enhanced convection variability over the Maritime Continent, leading to stronger easterlies in the western–central tropical Pacific during the warm phase off western Australian coast. The above changes bring about cooling in the western–central tropical Pacific and strengthened Leeuwin Current and anomalous cyclonic wind off western Australian coast, and ultimately resulting in enhanced coupling between these two regions. Our results suggest that enhanced decadal interbasin connections can offer further understanding of decadal changes under future warmer conditions.

Central-Pacific El Niño-Southern Oscillation less predictable under greenhouse warming

El Niño-Southern Oscillation (ENSO) is the dominant mode of interannual climate variability in the tropical Pacific, whose nature nevertheless may change significantly in a warming climate. Here, we show that the predictability of ENSO may decrease in the future. Across the models in the Coupled Model Intercomparison Project Phase 6 (CMIP6), we find a robust decrease of the persistence and predictability for the Central Pacific (CP) ENSO under global warming, notably in passing through the boreal spring. The strength of spring predictability barrier will be increased by 25% in the future. The reduced predictability of CP ENSO is caused by the faster warming over surface ocean in tropical Pacific and, in turn, the enhanced thermodynamical damping rate on CP ENSO in response to global warming. In contrast, the predictability of Eastern Pacific ENSO will not change. Our results suggest that future greenhouse warming will make the prediction of CP ENSO more challenging, with far-reaching implications on future climate predictions.

Permafrost melting enhances growth but leads to less intra-annual density fluctuations in boreal Larix gmelinii forests at its southernmost limit in northeast China

Permafrost melting due to climate warming in recent decades has produced significant effects on forest ecosystems, especially the boreal biome at its southernmost limit in Asia. How this warming affects wood formation of trees at intra-annual resolution is unclear, yet is crucial for assessing the impact of permafrost melting on boreal forest growth. In this study, we compared the radial growth and intra-annual wood density fluctuations (IADFs) of Dahurian larch (Larix gmelinii Rupr.) at a permafrost (PF) and a non-permafrost (NPF) site at the southernmost permafrost limit in northeast China and quantified their relationships with climate factors. Drought in early summer was the main factor limiting growth of Dahurian larch. The basal area increment (BAI) of trees at both sites increased initially and then decreased in the 1980s, probably in response to warm-dry climate conditions. Earlywood IADFs (IADF-E) occurred in 14.0% and 9.3% of dated rings at the NPF and PF sites, while the frequency of latewood IADFs (IADF-L) was 6.8% and 2.7% at these two sites. The frequency of IADF-E in trees at both sites was positively and negatively related to June temperatures (and vapor pressure deficit) and precipitation, respectively, suggesting drought stress in June triggered the formation of IADF-E. The IADF-Ls were probably formed in response to warm temperatures in the late growing season. A higher BAI and a lower frequency of IADF-Es of trees at the PF site than at the NPF site indicated that permafrost melting could alleviate drought stress in early summer and promote radial growth of Dahurian larch. This greatly improved forest carbon sequestration and wood quality of some northeastern Asian boreal forests may offset to some extent the adverse effects of warming-drying climates at some sites of northeast Asia. Larch IADF-Es recorded extreme droughts in early summer, giving us a new sight for reconstructing high-frequency extreme climate events. If climate warming continues, the benefits of permafrost melting will gradually disappear and even turn negative due to warmer-dryer climate conditions. Our findings provide valuable information for boreal forest management and conservation under future global warming.

High‐Resolution Climate Simulations Over the Eastern Mediterranean Black Sea Region Using the Pseudo‐Global Warming Method With a CMIP6 Ensemble

AbstractThe strong drying expected in the Eastern Mediterranean with climate change could cause mass migration of people already living under water shortages. On the other hand, precipitation is expected to increase toward the region’s north, particularly those along the interior of the eastern Black Sea coasts, which could worsen existing floods. However, this double‐sided adverse phenomenon and its underlying reasons have been investigated by relatively low‐resolution models in the Eastern Mediterranean Black Sea (EMBS) region, where orographic precipitation prevails. This study performs 4 km resolution Weather Research and Forecasting (WRF) model simulations with and without climate change signals retrieved from a CMIP6 GCM ensemble via pseudo‐global‐warming (PGW). The WRF simulations captured the large‐scale dynamics affecting the EMBS fairly well: an anticyclonic low‐level circulation and enhancing subsidence stem from anomalous ridge development over the central Mediterranean in winter (DJF), and a cyclonic low‐level circulation and weakening subsidence rise from heat‐low development over the Eastern Mediterranean in summer (JJA). The resulting picture of future warming and drying over the area generally supports the literature, although new insights emerge in anomalous precipitation increase, especially in the summer season over the Greater Caucasus and nearby regions. Most likely, the warmer‐than‐expected Caspian Sea induces a large increase in specific humidity and, thus, a large moisture source in the lower troposphere and an extension of the heat‐low effect in the mid‐troposphere. In addition, the high‐resolution WRF simulations provide added value over the complex topography of the Caucasian Mountain range for new insights into this region.

Future extreme and compound events in Angola: CORDEX-Africa regional climate modelling projections

Angola is exceptionally vulnerable to climate change, and sectors such as health, agricultural, water resources and ecosystems may endure severe impacts. Here, an extensive analysis of the signal of climate change on temperature, precipitation, extremes and compound events, for the end of the 21st century, is presented. The analysis is based on a CORDEX-Africa multi-model ensemble at 0.44° resolution built with 19 individual simulations, which allows a robust study of climate change future projections and depict model's uncertainty. For the RCP8.5, the end of the century future warming can reach maxima values ∼ 7 °C for maximum temperature in south-eastern Angola, and 6 °C for minimum temperature. The extreme temperatures (90th percentile) is projected to rise more than 7 °C in southern areas. In general, projections display a rainfall reduction in the drier seasons and a rise in the wet seasons, leading to sharper annual cycles; it is also projected a growth on extreme precipitation (95th percentile), as much as plus ∼ 50 % in some coastal regions. Angola is projected to endure in the future more frequent and longer heatwaves and droughts. In agreement with the RCP8.5, up to 10 heatwaves and more 4 moderate droughts will occur, respectively in coastal and interior areas. Finally, the number of days when a compound of heatwave and moderate drought occurs is projected to growth immensely, around +30 % for many regions, which corresponds to multiply by 10 these events in the future. For the RCP4.5, changes are projected to be smaller but significant in what regards especially extremes and compound events. The magnitude of the projected changes for vulnerable countries as Angola constitute an urgent call for global mitigation and national to regional adaptation strategies, and ultimately to a constant effort of updating and deepen the quality of climate information produced.