Increase In Temperature Variability Research Articles

Tree height-diameter allometry across the United States.

The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height–diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales.

Structure of trophic and mutualistic networks across broad environmental gradients.

This study aims to understand how inherent ecological network structures of nestedness and modularity vary over large geographic scales with implications for community stability. Bipartite networks from previous research from 68 locations globally were analyzed. Using a meta-analysis approach, we examine relationships between the structure of 22 trophic and 46 mutualistic bipartite networks in response to extensive gradients of temperature and precipitation. Network structures varied significantly across temperature gradients. Trophic networks showed decreasing modularity with increasing variation in temperature within years. Nestedness of mutualistic networks decreased with increasing temperature variability between years. Mean annual precipitation and variability of precipitation were not found to have significant influence on the structure of either trophic or mutualistic networks. By examining changes in ecological networks across large-scale abiotic gradients, this study identifies temperature variability as a potential environmental mediator of community stability. Understanding these relationships contributes to our ability to predict responses of biodiversity to climate change at the community level.

Predation Life History Responses to Increased Temperature Variability

The evolution of life history traits is regulated by energy expenditure, which is, in turn, governed by temperature. The forecasted increase in temperature variability is expected to impose greater stress to organisms, in turn influencing the balance of energy expenditure and consequently life history responses. Here we examine how increased temperature variability affects life history responses to predation. Individuals reared under constant temperatures responded to different levels of predation risk as appropriate: namely, by producing greater number of neonates of smaller sizes and reducing the time to first brood. In contrast, we detected no response to predation regime when temperature was more variable. In addition, population growth rate was slowest among individuals reared under variable temperatures. Increased temperature variability also affected the development of inducible defenses. The combined effects of failing to respond to predation risk, slower growth rate and the miss-match development of morphological defenses supports suggestions that increased variability in temperature poses a greater risk for species adaptation than that posed by a mean shift in temperature.

Topography influences the distribution of autumn frost damage on trees in a Mediterranean-type Eucalyptus forest

Extreme temperatures are causing forest dieback in a Mediterranean-type forest. Topography and cold-air pooling explain the geographic distribution of frost dieback in susceptible tree species. Alterations to the frequency and intensity of extreme temperatures, predicted with climate change, pose a threat to the health of many forests. Some Mediterranean climate regions are experiencing higher temperature variability, including more extreme low and high temperature events. Following one such low-temperature event in autumn 2012, we conducted landscape- and site-level studies to examine the impact of frost on trees and the interaction between topography, temperature, and dieback in a forest ecosystem in the Mediterranean climate region of southwest Australia. Canopy damage was widespread across the survey area and occurred in distinct patches, with sizes ranging between 4.1 and 2,518.0 ha. In affected forest, Eucalyptus marginata and Corymbia calophylla experienced nearly complete crown dieback, while E. patens and E. wandoo were undamaged. Canopy damage was found more frequently in valleys and lower to mid-slope positions, and site-level studies confirmed that crown dieback generally increased with decreasing elevation. Low temperatures were strongly correlated with elevation along damaged forest transects and cold-air pooling explained the pattern of forest damage. By regressing temperatures from damaged sites against those collected from the nearest meteorological station, projected minimum air temperatures ranged from −0.1 to −2.7 °C at valley bottom when the dieback occurred. Insufficient tissue hardening is suspected to have predisposed trees to this autumn frost. The interaction between shifting temperature regimes with climate change and frost damage is discussed. With continued increases in temperature variability, we can expect to see more temperature-driven disturbance events and associated reductions in forest health.

Recent increases in extreme temperature occurrence over land

AbstractRecently observed global and U.S. temperature increases are probed from the perspective of several hundred climate realizations afforded by the availability of reforecast climate model runs from the NCEP Climate Forecast System Version 2. The large number of seasonal realizations with the observed time‐varying CO2 affords a unique opportunity to explore the role of greenhouse gas changes on 3 month seasonal mean temperature increases, and specifically, whether they are the result of a shift in the mean temperature distribution or an increase in its variability. It is found that significant positive shifts in the temperature probability density function (PDF) occur primarily as the result of the time‐varying CO2 included in the historical model runs, although a contribution from natural climate variability modes cannot be categorically excluded. The temperature PDF comparison further indicates that the increasing global and U.S. temperatures over the last 30 years are predominantly the result of shifts in the mean temperature distribution and not increasing temperature variability. As such, the likelihood of increases in the occurrence of warm temperature extremes will likely continue to increase worldwide, leading to significant impacts on many socioeconomic sectors such as agriculture and public health.

The Impact of Temperature Variability on Years of Life Lost

To the Editor: The relationship between temperature and mortality is generally found to be bathtub shaped (rising at both extremes).1,2 However, there are limited data on the potential health effects of temperature variability3–5 and on temperature itself.6 We used a quasi-Poisson linear regression combined with a distributed lag nonlinear model to examine the relationship between temperature variability and years of life lost in Brisbane, Australia, from 1996 to 2004 (additional details in the eAppendix, https://links.lww.com/EDE/A764). Temperature variability refers to the standard deviation (SD) of minimum temperature within a given week. We found that years of life lost increased with a rise in the variability of weekly minimum temperature (Figure). Women (eFigure 2, https://links.lww.com/EDE/A764) and persons younger than 65 years (eFigure 3, https://links.lww.com/EDE/A764) were more sensitive to this variability. Years of life lost due to cardiovascular illnesses increased strongly with increases in variability of weekly minimum temperature, while years of life lost due to respiratory-related illnesses were not as sensitive to variations in minimum temperature (eFigure 4, https://links.lww.com/EDE/A764).FIGURE: The association between temperature variability (standard deviation of minimum temperature within 1 week) and years of life lost. (No reference value was set.)eTable 2 (https://links.lww.com/EDE/A764) shows the impact of a 1°C increase in weekly minimum temperature SD on years of life lost. Years of life lost increased by 8% (95% confidence interval = 1%–15%), with a 1°C increment of weekly minimum temperature SD. For each 1°C increase in the variability of weekly minimum temperature, annual health care costs were projected to increase by more than AUD$255 million. Increased temperature variability may stress the ability of the thermoregulation system to adapt to sudden and extreme temperature changes, especially when those changes happen frequently in a relatively short time period. Such adaptive ability may be reduced in the presence of other illness. Recently, Zanobetti et al5 found that summer temperature variability was associated with reduced long-term survival among people over 65 years with preexisting diseases. Bull7 has suggested that sudden changes in weather conditions may affect humoral or cellular immunity. Some researchers have reported sudden temperature changes associated with increases in blood cholesterol levels, blood pressure, and heart rate.8 In total, temperature variability should be considered as a factor in addition to temperature change when assessing possible health effects of climate change. ACKNOWLEDGMENTS We thank Adrian G. Barnett for his valuable comments on the manuscript revision. Zhiwei Xu Wenbiao Hu School of Public Health and Social Work Queensland University of Technology Brisbane, Australia Xiaoming Wang CSIRO Climate Adaptation Flagship and CSIRO Ecosystem Sciences Commonwealth, Scientific and Industrial Research Organisation Melbourne, Australia Cunrui Huang Centre for Environment and Population Health School of Environment Griffith University Brisbane, Australia Shilu Tong School of Public Health and Social Work Queensland University of Technology Brisbane, Australia Institute of Health and Biomedical Innovation Queensland University of Technology Brisbane, Australia [email protected]

Major declines of woody plant species ranges under climate change in Yunnan, China

AbstractAimA wide range of forests distributed across steep environmental gradients are found in Yunnan, southwest China. Climate change could profoundly change these forests by affecting species ranges. We produce predictions about species suitable habitat shifts and use these to (1) evaluate species range size change, loss and turn‐over under no‐ and full‐dispersal and nine climate change scenarios and (2) identify environmental variables responsible for current species richness and future local species losses.LocationYunnan Province, Southwest China.MethodsUsing MaxEnt, we modelled current distributions of 2319 woody plant species, corrected for collecting bias and found that 1996 had significant spatial association with environmental factors. Using three General Circulation Models (GCMs: CGCM, CSIRO and HADCM3) for the years 2070–2099 (2080s), based on three emission scenarios for each GCM (A1b, A2a and B2a), we predicted the future geographic position of suitable habitat for each species.ResultsAlthough most species were predicted to persist within Yunnan, with a maximum extinction rate of c. 6% under the most extreme climate change scenario, up to 1400 species (of the 1996 tested) are expected to lose more than 30% of their current range under the most extreme climate change scenario. Assuming no‐ or unlimited dispersal minimally affected these outcomes. Species losses were associated with increasing temperature variability and declining precipitation during the dry season.Main conclusionsTo conserve Yunnan's woody flora, management efforts should focus on providing elevational migration routes at local scales, with priority for those areas located within previously identified conservation hotspots. As almost all species show range contractions, storage of genetic diversity in seed banks and botanical gardens would be sensible. A change in Yunnan's conservation policy will be needed to counter the predicted negative impacts of climate change on its flora.

Climatic factors controlling plant sensitivity to warming

Plant sensitivity to warming can be expressed as β or the number of days of advance in leafing or flowering events per 1 °C of Mean Annual Temperature (MAT) change. Many local studies demonstrate that β estimates for spring flowering species are usually larger than estimates for plants flowering in summer or fall. Until now, however, neither observa- tional nor experimental estimates of this parameter were considered to be climate or geograph- ically dependent. Here we question this paradigm through reanalysis of observational β estimates and mathematical modeling of the seasonal warming signal. Statistical analysis of a large number of bulk (averaged over species) estimates of β derived from the Pan European Phenology Data network (PEP725) revealed a positive spatial correlation with MAT, as well as a negative correlation with the Seasonal Temperature Range (STR). These spatial correlations of bulk β values as well as interseasonal variability in β were explained using a simple deterministic model of the Thermal Growing Season (TGS). More specifically, we found that the geographic distribution of bulk plant sensitivity to warming as well as the seasonal decline of β were controlled by the seasonal patterns in the warming signal and by average soil thermal properties. Thus, until recently, plants managed to keep pace with climate warming by shifting their leafing and flowering events by the same number of days as the length of the period of weather suitable for their growth. Our model predicts, however, an even greater increase in the TGS for subsequent increases in MAT. Depending on how they interact with other factors such as changes in precipitation and increased temperature variability, these longer thermal growing seasons may not be beneficial for plant growth.

Multi-GCM projections of future drought and climate variability indicators for the Mediterranean region

Future climate conditions for the Mediterranean region based on an ensemble of 16 Global Climate Models are expressed and mapped using three approaches, giving special attention to the intermodel uncertainty. (1) The scenarios of mean seasonal temperature and precipitation agree with the projections published previously by other authors. The results show an increase in temperature in all seasons and for all parts of the Mediterranean with good intermodel agreement. Precipitation is projected to decrease in all parts and all seasons (most significantly in summer) except for the northernmost parts in winter. The intermodel agreement for the precipitation changes is lower than for temperature. (2) Changes in drought conditions are represented using the Palmer Drought Severity Index and its intermediate Z-index product. The results indicate a significant decrease in soil moisture in all seasons, with the most significant decrease occurring in summer. The displayed changes exhibit high intermodel agreement. (3) The climate change scenarios are defined in terms of the changes in parameters of the stochastic daily weather generator calibrated with the modeled daily data; the emphasis is put on the parameters, which affect the diurnal and interdiurnal variability in weather series. These scenarios indicate a trend toward more extreme weather in the Mediterranean. Temperature maxima will increase not only because of an overall rise in temperature means, but partly (in some areas) because of increases in temperature variability and daily temperature range. Increased mean daily precipitation sums on wet days occurring in some seasons, and some parts of the Mediterranean may imply higher daily precipitation extremes, and decreased probability of wet day occurrence will imply longer drought spells all across the Mediterranean.

Delirium in ICU patients is associated with increased temperature variability

Delirium is an acute disturbance of consciousness and cognition. It is a common disorder in the ICU and associated with impaired long-term outcome [1,2]. Despite its frequency and impact, delirium is poorly recognized by ICU physicians and nurses using delirium screening tools [3]. A completely new approach to detect delirium is to use monitoring of physiological alterations. Temperature variability, a measure for temperature regulation, could be an interesting parameter for monitoring of ICU delirium, but this has never been investigated before. The aim of this study was to investigate whether temperature variability is affected during ICU delirium.

Nestling corticosterone response to microclimate in an altricial bird

Although altricial young are dependent on their parents during early life, they must respond to environmental variation to maintain homeostasis. The hormone corticosterone (CORT) may be an important link between environment and phenotype during early life; however, no previous study has experimentally assessed the sensitivity of CORT to nest microclimate in altricial birds beginning to thermoregulate. We tested the hypothesis that microclimate influences CORT by cross-fostering nestling Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) between thicker-walled “aspen” nest boxes and thinner-walled “plywood” nest boxes. Quantification of CORT in nestling feathers allowed us to consider hormone secreted over days, rather than instantaneously from blood samples. In agreement with our hypothesis, we detected significant positive relationships between feather CORT and increased temperature variability and maximum, but not minimum, nest box temperatures. This could reflect the energetic challenge of warmer temperatures or positive developmental effects on the nestling hypothalamic–pituitary–adrenal axis. Feather CORT was significantly lower in chicks hatched in aspen nest boxes compared with plywood ones, but cross-fostering did not influence nestling CORT. This suggests that the influence of natal nest box environment on feather CORT was likely greater than the influence of the foster nest box environment. The relationships we detected highlight the sensitivity of feather CORT to environmental variation and contribute insight into nestling responses to environmental change.

Modeling the response of rice phenology to climate change and variability in different climatic zones: Comparisons of five models

Crop models have been widely used in simulating and predicting changes in rice phenology in the major rice production regions of China, however the uncertainties in simulating crop phenology at a large scale and from different models were rarely investigated. In the present study, five rice phenological models/modules (i.e., CERES-Rice, ORYZA2000, RCM, Beta Model, SIMRIW) were firstly calibrated and validated based on a large number of rice phenological observations across China during 1981–2009. The inner workings of the models, as well as the simulated phenological response to climate change/variability, were compared to determine if the models adequately handled climatic changes and climatic variability. Results showed these models simulated rice phenological development over a large area fairly well after calibration, although the relative performance of the models varied in different regions. The simulated changes in rice phenology were generally consistent when temperatures were below the optimum; however varied largely when temperatures were above the optimum. The simulated rice growing season under future climate scenarios was shortened by about 0.45–5.78 days; but in northeastern China, increased temperature variability may prolong the growing season of rice. We concluded more modeling and experimental studies should be conducted to accelerate understanding of rice phenology development under extreme temperatures.

Summer temperature variability and long-term survival among elderly people with chronic disease

Time series studies show that hot temperatures are associated with increased death rates in the short term. In light of evidence of adaptation to usual temperature but higher deaths at unusual temperatures, a long-term exposure relevant to mortality might be summertime temperature variability, which is expected to increase with climate change. We investigated whether the standard deviation (SD) of summer (June-August) temperatures was associated with survival in four cohorts of persons over age 65 y with predisposing diseases in 135 US cities. Using Medicare data (1985-2006), we constructed cohorts of persons hospitalized with chronic obstructive pulmonary disease, diabetes, congestive heart failure, and myocardial infarction. City-specific yearly summer temperature variance was linked to the individuals during follow-up in each city and was treated as a time-varying exposure. We applied a Cox proportional hazard model for each cohort within each city, adjusting for individual risk factors, wintertime temperature variance, yearly ozone levels, and long-term trends, to estimate the chronic effects on mortality of long-term exposure to summer temperature SD, and then pooled results across cities. Mortality hazard ratios ranged from 1.028 (95% confidence interval, 1.013- 1.042) per 1 °C increase in summer temperature SD for persons with congestive heart failure to 1.040 (95% confidence interval, 1.022-1.059) per 1 °C increase for those with diabetes. Associations were higher in elderly persons and lower in cities with a higher percentage of land with green surface. Our data suggest that long-term increases in temperature variability may increase the risk of mortality in different subgroups of susceptible older populations.

Extreme summer temperatures in Western Europe

Abstract. We discuss the evolution of summer temperature extremes over Western Europe during 1961–2004 in the context of current climate warming. Using a parametric approach, we investigate the role of properties and changes in probability density functions of daily temperatures in modifying the frequency of severe, isolated events. In this perspective, the recent intensification of extremely warm events over Europe turns out to be well consistent with a pure, nonuniform shift of mean values, with no room for conjectures about increasing temperature variability.

TEMPERATURE VARIABILITY AND LONG-TERM SURVIVAL

Background and Aims: Time series studies show that cold and hot temperatures, and their extremes, are associated with increased death rates. Few if any studies have evaluated longer-term temperature associations with deaths. Because there is evidence of adaptation to usual temperature, but higher deaths at unusual temperatures, we hypothesized that a long-term exposure relevant to mortality might be temperature variability. We investigated whether the variance of summer (June-August) and winter (December-February) temperatures were associated with survival in four cohorts of persons with predisposing diseases in 135 US cities. Rather than modeling exposure cross-sectionally, as typical in cohort studies, we treated temperature variance as a time varying exposure. Methods: We used Medicare data (1985-2006), and constructed cohorts of persons hospitalized with: chronic obstructive pulmonary disease (COPD), diabetes, congestive heart failure (CHF), and myocardial infarction (MI). Yearly summer and winter temperature variance were linked to the individuals during follow up in each city. We applied Cox’s proportional hazard model for each cohort within each city, adjusting for individual risk factors, and long term trends, and pooled results across cities. Results: Significant summer hazard ratios for mortality, ranged from 1.038 (95% Confidence Interval (CI): 1.024, 1.052) per an IQR increase in summer variance for persons with CHF, to 1.055 (95% CI: 1.035, 1.076) for persons with an MI. Associations during winter were also significant, with a hazard ratio of 1.017 (95% CI: 1.009, 1.025) for CHF, and 1.018 (95% CI: 1.008, 1.028) for persons with MI, per IQR increase in winter variance. Associations were higher in the elderly and lower in cities with a higher percent of green space. Conclusions: Increases in temperature variability in the cold and warm seasons were associated with increased mortality of the elderly. Some adaptation measures, such as green space, may ameliorate this effect.

Evolution of extreme temperatures in a warming climate

[1] The ongoing increase in extremely warm temperature events across large areas of the globe is generally thought to be a signature of a more extreme climate. However, it is still unclear whether global warming is accompanied by changes in statistical properties beyond the mean, such as an increasing temperature variability. Here we shed light on this issue by uncovering the way probabilities of extremes are being influenced by temperature evolution. Focusing on Europe, we show how the behavior of warm and cold extremes can be determined to a high accuracy by statistically modeling daily temperatures and their changes. Detailed comparison with observations over the past decades puts forward the dominant role of the mean in explaining exceptionally hot events, and rules out contributions from potential changes in second and higher moments.

Influence of Climate on Emergency Department Visits for Syncope: Role of Air Temperature Variability

BackgroundSyncope is a clinical event characterized by a transient loss of consciousness, estimated to affect 6.2/1000 person-years, resulting in remarkable health care and social costs. Human pathophysiology suggests that heat may promote syncope during standing. We tested the hypothesis that the increase of air temperatures from January to July would be accompanied by an increased rate of syncope resulting in a higher frequency of Emergency Department (ED) visits. We also evaluated the role of maximal temperature variability in affecting ED visits for syncope.Methodology/Principal FindingsWe included 770 of 2775 consecutive subjects who were seen for syncope at four EDs between January and July 2004. This period was subdivided into three epochs of similar length: 23 January–31 March, 1 April–31 May and 1 June–31 July. Spectral techniques were used to analyze oscillatory components of day by day maximal temperature and syncope variability and assess their linear relationship.There was no correlation between daily maximum temperatures and number of syncope. ED visits for syncope were lower in June and July when maximal temperature variability declined although the maximal temperatures themselves were higher. Frequency analysis of day by day maximal temperature variability showed a major non-random fluctuation characterized by a ∼23-day period and two minor oscillations with ∼3- and ∼7-day periods. This latter oscillation was correlated with a similar ∼7-day fluctuation in ED visits for syncope.Conclusions/SignificanceWe conclude that ED visits for syncope were not predicted by daily maximal temperature but were associated with increased temperature variability. A ∼7-day rhythm characterized both maximal temperatures and ED visits for syncope variability suggesting that climate changes may have a significant effect on the mode of syncope occurrence.

Preparing a People: Climate Change and Public Health

Almost 700 people died from heat-related stress during the catastrophic 1995 heat wave in Chicago, Illinois.1 The three-day weather event saw 24-hour mean average temperatures of 87.2°F; the heat reached triple digits on two days, and there was little relief at night.2 Many people succumbed to heart attack and dehydration, while others collapsed during severe episodes of existing respiratory conditions.3 The death toll in the summer of 1995 gave Chicagoans a clear picture of how a surge in hot weather can affect human health. A decade later, Mayor Richard Daley launched an extensive program that brought together city agencies, academics, and scientists to develop a Climate Change Action Plan to help reduce the city’s contribution to climate change.4 Much of the plan focuses on sustainable mitigation actions such as planting trees and training workers to install renewable energy technologies. Within that plan, however, is a climate change adaptation strategy with a goal of preparing the city and its residents for future unusual weather events associated with climate change.5 Chicago is one of several large cities with climate action plans in place—others include New York City, San Francisco, Sydney, and Mexico City.6 Like Chicago’s, these plans promote mitigation and sustainability. Much of the adaptation portion of these initiatives is aimed at the built environment—buildings, highways, and facilities. But officials in these cities are beginning to talk about the public health cobenefits from their action plans, and public health advocates are speaking up and pushing for programs designed to prepare for or prevent climate-sensitive disease and illness.

An experimental test of the role of environmental temperature variability on ectotherm molecular, physiological and life-history traits: Implications for global warming

Global climate change is one of the greatest threats to biodiversity; one of the most important effects is the increase in the mean earth surface temperature. However, another but poorly studied main characteristic of global change appears to be an increase in temperature variability. Most of the current analyses of global change have focused on mean values, paying less attention to the role of the fluctuations of environmental variables. We experimentally tested the effects of environmental temperature variability on characteristics associated to the fitness (body mass balance, growth rate, and survival), metabolic rate (VCO 2) and molecular traits (heat shock protein expression, Hsp70), in an ectotherm, the terrestrial woodlouse Porcellio laevis. Our general hypotheses are that higher values of thermal amplitude may directly affect life-history traits, increasing metabolic cost and stress responses. At first, results supported our hypotheses showing a diversity of responses among characters to the experimental thermal treatments. We emphasize that knowledge about the cellular and physiological mechanisms by which animals cope with environmental changes is essential to understand the impact of mean climatic change and variability. Also, we consider that the studies that only incorporate only mean temperatures to predict the life-history, ecological and evolutionary impact of global temperature changes present important problems to predict the diversity of responses of the organism. This is because the analysis ignores the complexity and details of the molecular and physiological processes by which animals cope with environmental variability, as well as the life-history and demographic consequences of such variability.

Thermal variability alters climatic stress resistance and plastic responses in a globally invasive pest, the Mediterranean fruit fly (Ceratitis capitata)

AbstractClimatic means with different degrees of variability (δ) may change in the future and could significantly impact ectotherm species fitness. Thus, there is an increased interest in understanding the effects of changes in means and variances of temperature on traits of climatic stress resistance. Here, we examined short‐term (within‐generation) variation in mean temperature (23, 25, and 27 °C) at three levels of diel thermal fluctuations (δ = 1, 3, or 5 °C) on an invasive pest insect, the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Using the adult flies, we address the hypothesis that temperature variability may affect the climatic stress resistance over and above changes in mean temperature at constant variability levels. We scored the traits of high‐ and low‐thermal tolerance, high‐ and low‐temperature acute hardening ability, water balance, and egg production under benign conditions after exposure to each of the nine experimental scenarios. Most importantly, results showed that temperature variance may have significant effects in addition to the changes in mean temperature for most traits scored. Although typical acclimation responses were detected for most of the traits under low variance conditions, high variance scenarios dramatically altered the outcomes, with poorer climatic stress resistance detected in some, but not all, traits. These results suggest that large temperature fluctuations might limit plastic responses which in turn could reduce the insect fitness. Increased mean temperatures in conjunction with increased temperature variability may therefore have stronger negative effects on this agricultural pest than elevated temperatures alone. The results of this study therefore have significant implications for understanding insect responses to climate change and suggest that analyses or simulations of only mean temperature variation may be inappropriate for predicting population‐level responses under future climate change scenarios despite their widespread use.