Magnitude Of Extreme Weather Events Research Articles

Flooding disturbances increase resource availability and productivity but reduce stability in diverse plant communities.

The natural world is increasingly defined by change. Within the next 100 years, rising atmospheric CO₂ concentrations will continue to increase the frequency and magnitude of extreme weather events. Simultaneously, human activities are reducing global biodiversity, with current extinction rates at ~1,000 × what they were before human domination of Earth's ecosystems. The co-occurrence of these trends may be of particular concern, as greater biological diversity could help ecosystems resist change during large perturbations. We use data from a 200-year flood event to show that when a disturbance is associated with an increase in resource availability, the opposite may occur. Flooding was associated with increases in productivity and decreases in stability, particularly in the highest diversity communities. Our results undermine the utility of the biodiversity-stability hypothesis during a large number of disturbances where resource availability increases. We propose a conceptual framework that can be widely applied during natural disturbances.

Health care facilities resilient to climate change impacts.

Climate change will increase the frequency and magnitude of extreme weather events and create risks that will impact health care facilities. Health care facilities will need to assess climate change risks and adopt adaptive management strategies to be resilient, but guidance tools are lacking. In this study, a toolkit was developed for health care facility officials to assess the resiliency of their facility to climate change impacts. A mixed methods approach was used to develop climate change resiliency indicators to inform the development of the toolkit. The toolkit consists of a checklist for officials who work in areas of emergency management, facilities management and health care services and supply chain management, a facilitator’s guide for administering the checklist, and a resource guidebook to inform adaptation. Six health care facilities representing three provinces in Canada piloted the checklist. Senior level officials with expertise in the aforementioned areas were invited to review the checklist, provide feedback during qualitative interviews and review the final toolkit at a stakeholder workshop. The toolkit helps health care facility officials identify gaps in climate change preparedness, direct allocation of adaptation resources and inform strategic planning to increase resiliency to climate change.

Effects of high temperature on the chlorophyll a fluorescence of Alhagi sparsifolia at the southern Taklamakan Desert

Climate change is expected to result in an increase in the frequency and magnitude of extreme weather events. Alhagi sparsifolia is an important factor for wind prevention and sand fixation in the forelands of the Taklamakan Desert. The effects of high temperature on desert plants remain widely unknown. In this work, chlorophyll a fluorescence induction kinetics were investigated at different time stresses of 5, 20, 40, and 60 min at temperature gradients of 38–44 °C at 2 °C intervals. A pronounced K-step was found, and the values of the maximum quantum yield for primary photochemistry, the quantum yield of electron transport, the density of reaction centers and the performance index on absorption basis were lowest after 60 min at 44 °C, thus indicating that the oxygen-evolving complex was damaged, the inactivated reaction centers increased, and the activity of the photosystem II (PSII) reaction center in leaves was seriously limited. Therefore, we suggest that under normal temperature (below 42 °C), the PSII of A. sparsifolia would be unaffected. When such temperature is maintained for 40 min, the activity of PSII would be limited, and when retained for 60 min, PSII may be severely damaged.

Anomalous, extreme weather disrupts obligate seed dispersal mutualism: snow in a subtropical forest ecosystem

Ongoing global climate change is predicted to increase the frequency and magnitude of extreme weather events, impacting population dynamics and community structure. There is, however, a critical lack of case studies considering how climatic perturbations affect biotic interactions. Here, we document how an obligate seed dispersal mutualism was disrupted by a temporally anomalous and meteorologically extreme interlude of unseasonably frigid weather, with accompanying snowstorms, in subtropical China, during January-February 2008. Based on the analysis of 5892 fecal samples (representing six mammalian seed dispersers), this event caused a substantial disruption to the relative seed dispersal function for the raisin tree Hovenia dulcis from prestorm 6.29 (2006) and 11.47 (2007), down to 0.35 during the storm (2008). Crucially, this was due to impacts on mammalian seed dispersers and not due to a paucity of fruit, where 4.63 fruit per branch were available in January 2008, vs. 3.73 in 2006 and 3.58 in 2007. An induced dietary shift occurred among omnivorous carnivores during this event, from the consumption fruit to small mammals and birds, reducing their role in seed dispersal substantially. Induced range shift extinguished the functionality of herbivorous mammals completely, however, seed dispersal function was compensated in part by three omnivorous carnivores during poststorm years, and thus while the mutualism remained intact it was enacted by a narrower assemblage of species, rendering the system more vulnerable to extrinsic perturbations. The storm's extended effects also had anthropogenic corollaries - migrating ungulates becoming exposed to heightened levels of illegal hunting - causing long-term modification to the seed dispersal community and mutualism dynamics. Furthermore, degraded forests proved especially vulnerable to the storm's effects. Considering increasing climate variability and anthropogenic disturbance, the impacts of such massive, aberrant events warrant conservation concern, while affording unique insights into the stability of mutualisms and the processes that structure biodiversity and mediate ecosystem dynamics.

Air temperature and winter mortality: Implications for the persistence of the invasive mussel, Perna viridis in the intertidal zone of the south-eastern United States

Global climate change and invasive species represent two of the biggest threats to the environment. Biological communities are responding to global climate change through poleward shifts in distribution, and changes in abundance and phenology of both native and non-native species. An increase in the frequency and magnitude of extreme weather events is predicted with global climate change. Much is known about mortality events of marine organisms in relation to warm thermal stress with relatively little known about cold thermal stress, particularly in the tropics. Intertidal species are particularly susceptible to fluctuations in aerial conditions and many are considered indicators of climate change. Perna viridis is a recent invader to the United States where it fouls hard substrates and soft sediment habitats. During winter 2007/08, a mortality event was observed for P. viridis across Tampa Bay, Florida. This mortality event coincided with extreme weather conditions when air temperatures dropped below 2 °C for a period of 6 h during low water. The minimum air temperature recorded was 0.53 °C. During this period water temperature remained relatively constant (~ 20 °C). We provide strong evidence supporting the hypothesis that thermal stress relating to exposure to cold air temperatures during emersion was the primary factor underpinning the mortality event. Similar mortality events occurred in 2009 and 2010, also coinciding with prolonged exposure to low air temperatures. In the short term, weather may be responsible for the temporary trimming back of populations at the edge of their geographic range but in the longer-term, it is expected that climate warming will trigger the poleward movement of both native and non-native species potentially facilitating biotic homogenisation of marine communities. The challenge now is to devise adaptive management strategies in order to mitigate any potential negative impacts to native biodiversity.

Identifying target traits and molecular mechanisms for wheat breeding under a changing climate

Global warming is causing changes in temperature at a rate unmatched by any temperature change over the last 50 million years. Crop cultivars have been selected for optimal performance under the current climatic conditions. With global warming, characterized by shifts in weather patterns and increases in frequency and magnitude of extreme weather events, new ideotypes will be required with a different set of physiological traits. Severe pressure has been placed on breeders to produce new crop cultivars for a future, rapidly-changing environment that can only be predicted with a great degree of uncertainty and is not available in the present day for direct experiments or field trials. Mathematical modelling, therefore, in conjunction with crop genetics, represents a powerful tool to assist in the breeding process. In this review, drought and high temperature are considered as key stress factors with a high potential impact on crop yield that are associated with global warming, focusing on their effects on wheat. Modelling techniques are described which can help to quantify future threats to wheat growth under climate change and simple component traits that are amenable to genetic analysis are identified. This approach could be used to support breeding programmes for new wheat cultivars suitable for future environments brought about by the changing climate.

A single drought event of 100‐year recurrence enhances subsequent carbon uptake and changes carbon allocation in experimental grassland communities

AbstractEvidence suggests that the expected increase in frequency and magnitude of extreme weather events during climate change will alter plant productivity. Therefore, extreme weather events might also be capable of changing C sequestration and allocation. Here, experimental grassland communities of two species compositions, differing in their diversity, were exposed either to a simulated single drought or to a heavy‐rainfall event. The magnitude of these manipulations imitated the local 100‐year weather extreme according to extreme‐value statistics. Effects on Net Ecosystem CO2 Exchange (NEE in µmol m–2 s–1) as well as aboveground biomass production and leaf‐area index (LAI) were recorded from prior to the manipulations until two months after the manipulations ended. Initial light utilization efficiency and maximum NEE increased after the drought. No change in the respiration was detected and maximum uptake capacity (GPPmax) was 15% higher for the drought‐manipulated plots compared to controls, which indicates an enhanced CO2 uptake into the systems. The level of diversity was also found to alter the light‐response curves, increasing respiration and maximum NEE to a higher degree than drought in the more diverse compared to the less diverse community. This resulted in an increase of GPPmax by 55%. No significant interactions between species composition and weather manipulations were detected. Interestingly, aboveground biomass production was not significantly affected by weather manipulations, even though LAI increased due to drought. This increase was caused by a decrease in the ratio between reproductive and vegetative growth. The heavy‐rainfall manipulation resulted in no significant effects. Our data suggest that C sequestration can be enhanced by a single weather event. However the importance, long‐term duration, and thresholds or turning points of such effects need to be investigated further as intensification of weather extremes is currently emerging as one of the most important facets of climate change.

Research frontiers in climate change: Effects of extreme meteorological events on ecosystems

Climate change will increase the recurrence of extreme weather events such as drought and heavy rainfall. Evidence suggests that modifications in extreme weather events pose stronger threats to ecosystem functioning than global trends and shifts in average conditions. As ecosystem functioning is connected with ecological services, this has far-reaching effects on societies in the 21st century. Here, we: (i) present the rationale for the increasing frequency and magnitude of extreme weather events in the near future; (ii) discuss recent findings on meteorological extremes and summarize their effects on ecosystems and (iii) identify gaps in current ecological climate change research.

Impacts of climate change on wheat in England and Wales

The frequency and magnitude of extreme weather events are likely to increase with global warming. However, it is not clear how these events might affect agricultural crops and whether yield losses resulting from severe droughts or heat stress will increase in the future. The aim of this paper is to analyse changes in the magnitude and spatial patterns of two impact indices for wheat: the probability of heat stress around flowering and the severity of drought stress. To compute these indices, we used a wheat simulation model combined with high-resolution climate scenarios based on the output from the Hadley Centre regional climate model at 18 sites in England and Wales. Despite higher temperature and lower summer precipitation predicted in the UK for the 2050s, the impact of drought stress on simulated wheat yield is predicted to be smaller than that at present, because wheat will mature earlier in a warmer climate and avoid severe summer drought. However, the probability of heat stress around flowering that might result in considerable yield losses is predicted to increase significantly. Breeding strategies for the future climate might need to focus on wheat varieties tolerant to high temperature rather than to drought.

Simulation of extreme weather events by a stochastic weather generator

A stochastic weather generator is a model capable of generating daily weather patterns that are statistically similar to the observed patterns. Weather generators are commonly used in climate change studies as a computationally inexpensive tool to generate high resolution climate change scenarios based on the output from global climate models. Considering that the frequency and the magnitude of extreme weather events are likely to increase under climate change, there is a growing need to investigate how well weather extremes are simulated by weather generators. The aim of this study was to test the skill of the LARS-WG stochastic weather generator to simulate extreme weather events at 20 locations with diverse climates. Yearly maxima of daily precipitation, maximum temperature and length of heat waves, and their 10 and 20 yr return values were compared for observed and synthetic data by fitting the generalized extreme value distribution and computing confidence intervals. Means of yearly maxima and return values of daily synthetic precipitation were within the 95% confidence intervals (CI 95 ) of observed data for all sites. Daily maximum temperature extremes were reproduced less accurately. Although the root mean squared error (RMSE) calculated for the means of maxima of maximum temperature was <1°C, synthetic means for approximately half of the sites were outside the CI 95 for observed values. This indicates that the assumption used in LARS-WG, that daily temperature could be approximated by the normal distribution, is inadequate. Means of yearly maxima for length of heat waves and 10 and 20 yr return values were within the CI 95 for all sites except 3. For those sites where LARS-WG performance was inadequate, daily maximum temperature was not normally distributed but was skewed.