Effects Of Climate Extremes Research Articles

Drought intensity and post-drought precipitation determine vegetation recovery in a desert steppe in Inner Mongolia, China

Extreme drought events are expected to increase in frequency and severity, posing significant threats to ecosystems worldwide. While considerable research has been concentrated on the effects of climate extremes on the stability of grasslands, the process by which grassland productivity may recover after extreme drought events are still not well understood. Here, we conducted a four-year (2019–2022) recovery investigation after four-year's (2015–2018) extreme drought treatments of different intensities (control, press and pulse) to explore the vegetation recovery of desert-grassland ecosystems Inner Mongolia, China. Press drought involved a 66 % reduction in natural precipitation from May to August, while pulse drought reduced it by 100 % during June and July. We found that both press and pulse droughts led to a sharp decrease in aboveground net primary productivity (ANPP) after four years, primarily due to reduced growth, density, and productivity of annual and perennial plants. However, ANPP under pulse drought could recover fully after four years of stopping of drought treatment, and it could not under press drought. Additionally, community structure (i.e., species richness, plant density, and height) fully recovered within 1 year after the end of the two extreme drought treatments. Both plant density and height contributed to the ANPP recovery after press and pulse droughts. Structural equation modeling (SEM) results further revealed that the reduction in ANPP during the extreme drought was primarily due to a decrease in plant density caused by reduced soil water content. The recovery of ANPP in pulse drought was directly caused by increased soil water content in the post-extreme drought. These results suggest that drought intensity and precipitation determine ANPP recovery in a degraded desert steppe. Our findings are crucial for deepening understanding of the processes and mechanisms of ecosystem recovery after extreme drought, as well as for the successful management and protection of grassland ecosystems.

Forest edge effects on moss growth are amplified by drought.

Forest fragmentation increases the amount of edges in the landscape. Differences in wind, radiation, and vegetation structure create edge-to-interior gradients in forest microclimate, and these gradients are likely to be more pronounced during droughts and heatwaves. Although the effects of climate extremes on edge influences have potentially strong and long-lasting impacts on forest understory biodiversity, they are not well understood and are not often considered in management and landscape planning. Here we used a novel method of retrospectively quantifying growth to assess biologically relevant edge influences likely caused by microclimate using Hylocomium splendens, a moss with annual segments. We examined how spatio-temporal variation in drought across 3 years and 46 sites in central Sweden, affected the depth and magnitude of edge influences. We also investigated whether edge effects during drought were influenced by differences in forest structure. Edge effects were almost twice as strong in the drought year compared to the non-drought years, but we did not find clear evidence that they penetrated deeper into the forest in the drought year. Edge influences were also greater in areas that had fewer days with rain during the drought year. Higher levels of forest canopy cover and tree height buffered the magnitude of edge influence in times of drought. Our results demonstrate that edge effects are amplified by drought, suggesting that fragmentation effects are aggravated when droughts become more frequent and severe. Our results suggest that dense edges and buffer zones with high canopy cover can be important ways to mitigate negative drought impacts in forest edges.

The expansion of rainfed grain production can generate spontaneous hydrological changes that reduce climate sensitivity

As global warming intensifies climatic extremes, the need to understand their effects on farming systems, particularly under rainfed conditions, grows. During the last three decades the Argentine Pampas, a major global grain exporter, hosted an unprecedented expansion of cultivation under unirrigated and undrained conditions. Simultaneously, the extreme flatness and lack of water infrastructure favored groundwater level raises where agriculture expanded. However, the effect of climate extremes and elevated water tables buffering droughts but increasing flooding risk on the sensitivity of regional grain production remains unknown. Based on agronomic, weather, water table, and remote sensing data, we analyzed the production response to dry, wet, and flooded periods over the last 35 years, and to the ongoing water table raises during the last 15 years, focusing on sown and effective harvested area (harvested/sown area) and yield. Soybean and maize production increased 5.9 and 3.3-fold, respectively, as a result of area and yield growths. On average, droughts decreased production (−25 % for soybean and −14 % for maize) and wet periods increased it (+14 % for soybean and +17 % for maize) through their effects on yields and effective harvested area. Floods reduced production (−8 % for soybean and −10 % for maize) by decreasing sown and effective harvested area, leaving yields unaffected. As water tables rose, a positive yield effect during drought was detected, with counties with shallow water tables (< 3 m depth) halving yield cuts during dry years. Lacking water infrastructure, this South American grain belt is currently matching the annual production variability levels observed under intense irrigation and drainage in North America. The unexpected water table level raises of the Pampas had an overall positive effect on grain production, with flood disruptions being more than compensated by drought buffering. This balance may change in the future, calling for a deeper understanding of these complex relationships between climate, hydrology and agriculture.

Effects of Climate Extremes on Spring Phenology of Temperate Vegetation in China

The response of vegetation spring phenology to climate warming has received extensive attention. However, there are few studies on the response of vegetation spring phenology to extreme climate events. In this study, we determined the start of the growing season (SOS) for three vegetation types in temperate China from 1982 to 2015 using the Global Inventory Modeling and Mapping Study’s third-generation normalized difference vegetation index and estimated 25 extreme climate events. We analyzed the temporal trends of the SOS and extreme climate events and quantified the relationships between the SOS and extreme climate events using all-subsets regression methods. We found that the SOS was significantly advanced, with an average rate of 0.97 days per decade in China over the study period. Interestingly, we found that the SOS was mainly associated with temperature extremes rather than extreme precipitation events. The SOS was mainly influenced by the frost days (FD, r = 0.83) and mean daily minimum temperature (TMINMEAN, r = 0.34) for all three vegetation types. However, the dominant influencing factors were vegetation-type-specific. For mixed forests, the SOS was most influenced by TMINMEAN (r = 0.32), while for grasslands and barren or sparsely vegetated land, the SOS was most influenced by FD (r &gt; 0.8). Our results show that spring phenology was substantially affected by extreme climate events but mainly by extreme temperature events rather than precipitation events, and that low temperature extremes likely drive spring phenology.

Climate Change and Diurnal Warming: Impacts on the Growth of Different Vegetation Types in the North–South Transition Zone of China

Since land use/cover change profoundly impacts climate change and global warming has become an irreversible trend in the Anthropocene, there have been numerous global studies on the impact of climate change on vegetation growth (VG). However, the effects of climate extremes on the growth and direction of various vegetation types need to be better investigated, especially in the climate transition zones. In this paper, we examined the effect of diurnal warming on the growth of various types of vegetation in China’s north–south transition zone. Based on the daily observation data of 92 meteorological stations in the Qinling-Daba (Qinba) mountainous area from 1982 to 2015, coupled with the Normalized Difference Vegetation Index (NDVI) and data on the type of vegetation. This research examined the temporal changes in the highest and lowest temperatures during the last 33 years using trend analysis. Second-order correlation analysis was used to investigate vegetation NDVI response characteristics to diurnal warming and to examine the effect of diurnal warming on the growth of different vegetation types. Our results showed that maximum temperature (Tmax) and minimum temperature (Tmin) showed an obvious upward trend, with the daytime temperature increase rate 1.2 times that at night, but failing the t-test. In addition, diurnal warming promoted vegetation growth, with NDVI associated positively correlated with Tmax at approximately 91.2% of the sites and 3492 rasters and with Tmin at roughly 53.25% of the sites and 2864 rasters. Spatial significance analysis showed an apparent difference, but few areas passed the t-test. Furthermore, daytime warming enhanced the growth of grasses, shrubs, deciduous broad-leaved forests, crops, and conifers, while the effect of nighttime warming on VG had a positive effect only on the growth of evergreen broad-leaved forest vegetation. These findings reveal the mechanisms of the impact of climate extremes on VG under global change, particularly the extent to which different vegetation types in climatic transitional zones respond to climate extremes.

Interactive effects of drought and edge exposure on old-growth forest understory species

ContextBoth climatic extremes and land-use change constitute severe threats to biodiversity, but their interactive effects remain poorly understood. In forest ecosystems, the effects of climatic extremes can be exacerbated at forest edges.ObjectivesWe explored the hypothesis that an extreme summer drought reduced the richness and coverage of old-growth forest species, particularly in forest patches with high edge exposure.MethodsUsing a high-resolution spatially explicit precipitation dataset, we could detect variability in drought intensity during the summer drought of 2018. We selected 60 old-growth boreal forest patches in central Sweden that differed in their level of drought intensity and amount of edge exposure. The year after the drought, we surveyed red-listed and old-growth forest indicator species of vascular plants, lichens and bryophytes. We assessed if species richness, composition, and coverage were related to drought intensity, edge exposure, and their interaction.ResultsSpecies richness was negatively related to drought intensity in forest patches with a high edge exposure, but not in patches with less edge exposure. Patterns differed among organism groups and were strongest for cyanolichens, epiphytes associated with high-pH bark, and species occurring on convex substrates such as trees and logs.ConclusionsOur results show that the effects of an extreme climatic event on forest species can vary strongly across a landscape. Edge exposed old-growth forest patches are more at risk under extreme climatic events than those in continuous forests. This suggest that maintaining buffer zones around forest patches with high conservation values should be an important conservation measure.

Effects of Climate Extremes on Cereal Production in the North China Plain During 1950–2015

The North China Plain (NCP) is a cereal production base in China. However, the understanding of how climate extremes affect cereal production during past decades in the region is limited. Based on the statistical data of climate disasters and cultivated areas during 1950-2015, the relationship between regional cereal production and four meteorological disasters was examined. The results showed that during 1950-1980, the cultivated area for cereal production increased, accounting for 80-85% of the total cultivated area, but gradually decreased in the second 30 years after 1980. Flood disaster was the greatest in intensity compared with the other three meteorological disasters; drought was the most widespread and impactful. The effects of the four disasters became more noteworthy after 1980, and the spatiotemporal trend in the NCP was similar. Flood and drought had significant effects (P < 0.01) on cereal yield with path coefficients of -0.355 and -0.344, respectively. The harvest areas declined slowly and the yield increased slightly during the 7 disaster window years, suggesting that technology advancement offset the decline in cultivated areas and increased the yield. The effect of climate extremes on cereal production could be addressed through technology improvement and the implementation of preventive measures in the NCP.

Impact of climatic extremes on Alpine ecosystems during MIS 3

The effects of climatic extremes on Alpine ecosystems, such as in the last glacial period, are poorly understood. The recently discovered Nesseltalgraben site is currently the best dated and most complete high-resolution sedimentary sequence in the northern Alps covering the Marine Isotope Stage (MIS) 3 around 59-28 calibrated kiloyears before present (ka cal BP). The MIS 3 is a period with frequent climatic fluctuations known as Dansgaard-Oeschger cycles or Greenland interstadials-stadials. Here, we present pollen assemblages, bryophyte macrofossils, and stable isotopes (δ2H, δ13C, δ18O) from the Nesseltalgraben to elucidate palaeoenvironments and palaeoclimatic variability during that period. In addition to bulk sedimentary cellulose, also cellulose extracted from fossil wood, monocots, and bryophytes was analysed isotopically. Among the terrestrial pollen, Poaceae and arboreal pollen show an antithetic behaviour reflecting interstadial-stadial variations. Arboreal pollen are dominated by Pinus sylvestris-type, with admixtures of Picea, Betula, Alnus, and Salix. The arboreal pollen record exhibits several maxima indicating milder climatic conditions tentatively assigned to Greenland interstadials 17–14, 12/11, 8, and 6. During Heinrich events 5 and 4, the arboreal pollen record shows distinct minima underlining a severe impact of these events on regional climate and vegetation. Bryophyte assemblages show predominant wetland conditions at the site during the entire MIS 3. The sudden occurrence of the bryophyte Drepanocladus turgescens after 31.6 ka cal BP indicates a change from a fen to a frequently drying wetland environment. This habitat change is presumably linked to enhanced glaciofluvial action caused by glaciers approaching the site. Carbon, hydrogen, and oxygen stable isotope records of bulk sedimentary cellulose exhibit comparably stable conditions from 59 until 52 ka cal BP and increased values around 51 ka cal BP followed by a period of almost absent cellulose until 39 ka cal BP. Thereafter, and lasting until 30 ka cal BP, bulk sedimentary cellulose isotope records (δ2H, δ13C, and δ18O) reveal strongly fluctuating values. These isotope variations are interpreted as variable mixtures between terrestrial lignified plants and monocots on the one, and wetland bryophyte sources on the other hand. A strong negative isotope excursion in the bulk sedimentary and the bryophyte cellulose records around 36.4 ka cal BP is contemporaneous with maximum Cyperaceae pollen and best explained by progressively waterlogged soils due to permafrost. The rise in the bryophyte δ18O record thereafter, accompanied by likewise increasing δ13C values, most likely indicates an enhanced evaporation of source waters.

The Different Effects of Climate Extremes on Physiological Health Among Agroecology and Conventional Smallholder Rice Farmers

As climate change increases temperatures and the frequency of extreme heat events, farm workers are among the most affected. Because of the nature of the work, farmers working at hot temperatures m...

Spatiotemporal Consistency of Four Gross Primary Production Products and Solar‐Induced Chlorophyll Fluorescence in Response to Climate Extremes Across CONUS in 2012

AbstractLarge spatial‐scale effects of climate extremes on gross primary production (GPP), the largest terrestrial carbon flux, are highly uncertain even as these extremes increase in frequency and extent. Here we report the impacts of spring warming and summer drought in 2012 on GPP across the contiguous United States (CONUS) using estimates from four GPP models: Vegetation Photosynthesis Model (VPM), MOD17A2H V006, Carnegie‐Ames‐Stanford Approach, and Simple Biosphere/Carnegie‐Ames‐Stanford Approach. VPM simulations are driven by Moderate Resolution Imaging Spectroradiometer, North American Regional Reanalysis climate data, and C3 and C4 cropland maps from the United States Department of Agriculture Cropland Data Layer data set. Across 25 eddy covariance flux tower sites, GPP estimates from VPM (GPPVPM) showed better accuracy in terms of cross‐site variability and interannual variability (R2 = 0.84 and 0.46, respectively) when compared to MOD17 GPP. We further assessed the spatial and temporal (seasonal) consistency between GPP products and the Global Ozone Monitoring Experiment‐2 solar‐induced chlorophyll fluorescence over CONUS during 2008–2014. The results suggested that GPPVPM agrees best with solar‐induced chlorophyll fluorescence across space and time, capturing seasonal dynamics and interannual variations. Anomaly analyses showed that increased GPP during the spring compensated for the reduced GPP during the summer, resulting in near‐neutral changes in annual GPP for the CONUS. This study demonstrates the importance of assessing the impacts of different types and timing of climate extremes on GPP and the need to improve light use efficiency models by incorporating C3 and C4 plant functional types.

Assessing vegetation response to multi-time-scale drought across inner Mongolia plateau

This study assessed the impacts of climate change in IMP by investigating vegetation responses droughtin multiple timescales. Methods used included the Normalized Difference Vegetation Index (NDVI) andStandardized Precipitation Evapotranspiration Index (SPEI), by annual maximum Pearson correlation(Rmax) and the corresponding month (Rmonth) of drought. Results showed that: (1) It is necessary tozone IMP when analyzing the vegetation responses to drought. (2) Rmax is significantly positive cor-relation in IMP, indicating that vegetation was largely in fl uenced by drought; the most seriously affectedareas are in the north-eastern part of typical steppe, south-western parts of steppe desert and southernpart of desert steppe, while light seriously are distributed in the south-eastern of typical steppe andforest steppe. (3) Vegetation in typical steppe, steppe desert and desert steppe are sensitive to shortertime-scales of droughts, while in the forest, forest steppe and sand desert, vegetation shows a closerelationship with the longer drought time-scales. (4) The effects of drought related climate extremes canalso contr ibute to Rmax and Rmo nth between SPEI and NDVI. Vegetation in forest and sand desert areas,have lower sensitivity to drought under the effect of climate extremes. Adaptation measures, such asbuilding drought resilience vegetation types, applying biochar and monitoring and forecasting drought,must be timely and effectively initiated, especially, in the typical steppe, steppe desert and desert steppein IMP since vegetation in these four areas is affected seriously, once drought occur. The results from thisstudy may provide useful infor mation about appropriate adaptation and mitigation strategies against theinverse effects of drought on vegetation, and even alleviate the losses caused by drought.

Climate Change Impacts on Faidherbia albida (Delile) A. Chev. Distribution in Dry Lands of Ethiopia

AbstractGiven recent and projected climate change, the study of adaptation and mitigation strategies which involve ecologically and economically important plant species is urgently needed. Faidherbia albida (Delile) A. Chev. is a species of both economic and ecological importance. We use 229 locational records gathered in the dry highlands of Ethiopia, nineteen environmental variables and the modelling program MaxEnt to model both the present and possible future distributions of this species. To model future distributions, we used two emission scenarios (Representative Concentration Pathways 2.6 and 8.5) for two time slices (2050 and 2070). Mean temperature of wettest quarter was the major factor which determines the species' potential distribution. Suitable habitat for F. albida under the current climatic conditions is the mid‐highlands. However, its future distributions would shift upwards in elevation and will likely lead to some decrease in suitable areas, especially towards the end of the century. At the same time, however, other areas would become suitable for colonization, so that, overall, the species does not appear to face a significant reduction in distribution within our study region. Future studies should consider the possible effects of climate extremes, further environmental factors and of evolutionary adaptation of the species to new conditions.

Effects of climate extremes on the terrestrial carbon cycle: concepts, processes and potential future impacts.

Extreme droughts, heat waves, frosts, precipitation, wind storms and other climate extremes may impact the structure, composition and functioning of terrestrial ecosystems, and thus carbon cycling and its feedbacks to the climate system. Yet, the interconnected avenues through which climate extremes drive ecological and physiological processes and alter the carbon balance are poorly understood. Here, we review the literature on carbon cycle relevant responses of ecosystems to extreme climatic events. Given that impacts of climate extremes are considered disturbances, we assume the respective general disturbance-induced mechanisms and processes to also operate in an extreme context. The paucity of well-defined studies currently renders a quantitative meta-analysis impossible, but permits us to develop a deductive framework for identifying the main mechanisms (and coupling thereof) through which climate extremes may act on the carbon cycle. We find that ecosystem responses can exceed the duration of the climate impacts via lagged effects on the carbon cycle. The expected regional impacts of future climate extremes will depend on changes in the probability and severity of their occurrence, on the compound effects and timing of different climate extremes, and on the vulnerability of each land-cover type modulated by management. Although processes and sensitivities differ among biomes, based on expert opinion, we expect forests to exhibit the largest net effect of extremes due to their large carbon pools and fluxes, potentially large indirect and lagged impacts, and long recovery time to regain previous stocks. At the global scale, we presume that droughts have the strongest and most widespread effects on terrestrial carbon cycling. Comparing impacts of climate extremes identified via remote sensing vs. ground-based observational case studies reveals that many regions in the (sub-)tropics are understudied. Hence, regional investigations are needed to allow a global upscaling of the impacts of climate extremes on global carbon–climate feedbacks.

Simulating the Effect of Climate Extremes on Groundwater Flow Through a Lakebed

Groundwater exchanges with lakes resulting from cyclical wet and dry climate extremes maintain lake levels in the environment in ways that are not well understood, in part because they remain difficult to simulate. To better understand the atypical groundwater interactions with lakes caused by climatic extremes, an original conceptual approach is introduced using MODFLOW-2005 and a kinematic-wave approximation to variably saturated flow that allows lake size and position in the basin to change while accurately representing the daily lake volume and three-dimensional variably saturated groundwater flow responses in the basin. Daily groundwater interactions are simulated for a calibrated lake basin in Florida over a decade that included historic wet and dry departures from the average rainfall. The divergent climate extremes subjected nearly 70% of the maximum lakebed area and 75% of the maximum shoreline perimeter to both groundwater inflow and lake leakage. About half of the lakebed area subject to flow reversals also went dry. A flow-through pattern present for 73% of the decade caused net leakage from the lake 80% of the time. Runoff from the saturated lake margin offset the groundwater deficit only about half of that time. A centripetal flow pattern present for 6% of the decade was important for maintaining the lake stage and generated 30% of all net groundwater inflow. Pumping effects superimposed on dry climate extremes induced the least frequent but most cautionary flow pattern with leakage from over 90% of the actual lakebed area.

Effect of climate extremes on the grain yield and quality of cereals

A long-term experiment was started in 2005 in the Agricultural Research Institute to monitor the effects of extreme climatic events on the grain yield, quality and disease resistance of cereals. The yield was poor in 2007 due to the long dry period from autumn till spring, while it was high in 2006 and 2008 when there was more precipitation. The grain quality was the highest in 2007, however, despite the extreme weather events. Fungicide treatment generally resulted in higher yield potential and better grain quality in every year.

Comparing approaches for studying the effects of climate extremes – a case study of hospital admissions in Sweden during an extremely warm summer

Background: Health effects induced by climate, weather and climatic change may act directly or indirectly on human physiology. The future total burden of global warming is uncertain, but in some areas and for specific outcomes, mortality and morbidity are likely to increase. One likely effect of global warming is an increasing number of extreme weather events, such as floods, storms and heat waves. The excess numbers of specific health outcomes attributable to climate-induced events can be estimated. This paper compares approaches for estimating excess numbers of outcomes associated with climate extremes, exemplified by a case study of hospital admissions during the extremely warm summer of 2006 in southern Sweden.Materials and methods: Daily hospital admission data were obtained from the Swedish National Board of Health and Welfare for six hospitals in the Skåne region of southern Sweden for the period 1998 to 2006. Daily temperature data for the region were obtained from the meteorological station in the city of Malmö. We used four established approaches for estimating the daily excess numbers associated with extreme heat. Time series of daily event rates were assumed to follow a Poisson distribution. Excess event rates were compared by using several approaches, such as standardised event ratios and generalised additive models to estimate the health risks attributable to the extreme climate event.Results: The four approaches yielded vastly different results. The estimates of excess were considerably biased when not accounting for time trends in previous years’ data. Three of four approaches showed a significant increase in excess hospitalisation rates attributable to the heat episode in Skåne in 2006. However, modelling the effect of temperature failed to describe the risks induced by the extreme heat.Conclusion: Estimates of excess events depend greatly on the approach used. Further research is needed to identify which method yielded the most accurate estimates. However, one of the approaches used generally performed better than the others in estimating the excess rates associated with the heat episode. Further on, estimating relative risks of temperature or other determinants of disease may fail to incorporate the unique characteristics of particular weather events, such as the effect caused by very persistent heat exposure. Unless this can be incorporated into predictive models, such models may be less appropriate to use when predicting the future burden of heat waves on human health.

The Attributed Effect of Climate Extremes, Climate Related Epidemics or Outbreaks on Health Is Largely Dependent on the Choice of Approach – A Case Study Comparing Four Approaches for Estimating Excess Hospital Admissions During a Record Warm Summer in South Sweden

The Attributed Effect of Climate Extremes, Climate Related Epidemics or Outbreaks on Health Is Largely Dependent on the Choice of Approach – A Case Study Comparing Four Approaches for Estimating Excess Hospital Admissions During a Record Warm Summer in South Sweden

Effects of Climatic Extremes: Critical Review

Effects of Climatic Extremes: Critical Review