Source Of Climate Variability Research Articles

Physiology of gamma-aminobutyric acid treated Capsicum annuum L. (Sweet pepper) under induced drought stress.

There is now widespread agreement that global warming is the source of climate variability and is a global danger that poses a significant challenge for the 21st century. Climate crisis has exacerbated water deficit stress and restricts plant's growth and output by limiting nutrient absorption and raising osmotic strains. Worldwide, Sweet pepper is among the most important vegetable crops due to its medicinal and nutritional benefits. Drought stress poses negative impacts on sweet pepper (Capsicum annuum L.) growth and production. Although, γ aminobutyric acid (GABA) being an endogenous signaling molecule and metabolite has high physio-molecular activity in plant's cells and could induce tolerance to water stress regimes, but little is known about its influence on sweet pepper development when applied exogenously. The current study sought to comprehend the effects of foliar GABA application on vegetative development, as well as physiological and biochemical constituents of Capsicum annuum L. A Field experiment was carried out during the 2021 pepper growing season and GABA (0, 2, and 4mM) concentrated solutions were sprayed on two Capsicum annuum L. genotypes including Scope F1 and Mercury, under drought stress of 50% and 30% field capacity. Results of the study showed that exogenous GABA supplementation significantly improved vegetative growth attributes such as, shoot and root length, fresh and dry weight, as well as root shoot ratio (RSR), and relative water content (RWC) while decreasing electrolyte leakage (EL). Furthermore, a positive and significant effect on chlorophyll a, b, a/b ratio and total chlorophyll content (TCC), carotenoids content (CC), soluble protein content (SPC), soluble sugars content (SSC), total proline content (TPC), catalase (CAT), and ascorbate peroxidase (APX) activity was observed. The application of GABA at 2mM yielded the highest values for these variables. In both genotypes, peroxidase (POD) and superoxide dismutase (SOD) content increased with growing activity of those antioxidant enzymes in treated plants compared to non-treated plants. In comparison with the rest of GABA treatments, 2mM GABA solution had the highest improvement in morphological traits, and biochemical composition. In conclusion, GABA application can improve development and productivity of Capsicum annuum L. under drought stress regimes. In addition, foliar applied GABA ameliorated the levels of osmolytes and the activities of antioxidant enzymes involved in defense mechanism.

Understanding drivers of glacier-length variability over the last millennium

Abstract. Changes in glacier length reflect the integrated response to local fluctuations in temperature and precipitation resulting from both external forcing (e.g., volcanic eruptions or anthropogenic CO2) and internal climate variability. In order to interpret the climate history reflected in the glacier moraine record, the influence of both sources of climate variability must therefore be considered. Here we study the last millennium of glacier-length variability across the globe using a simple dynamic glacier model, which we force with temperature and precipitation time series from a 13-member ensemble of simulations from a global climate model. The ensemble allows us to quantify the contributions to glacier-length variability from external forcing (given by the ensemble mean) and internal variability (given by the ensemble spread). Within this framework, we find that internal variability is the predominant source of length fluctuations for glaciers with a shorter response time (less than a few decades). However, for glaciers with longer response timescales (more than a few decades) external forcing has a greater influence than internal variability. We further find that external forcing also dominates when the response of glaciers from widely separated regions is averaged. Single-forcing simulations indicate that, for this climate model, most of the forced response over the last millennium, pre-anthropogenic warming, has been driven by global-scale temperature change associated with volcanic aerosols.

Quantifying the influence of natural climate variability on in situ measurements of seasonal total and extreme daily precipitation

While various studies explore the relationship between individual sources of climate variability and extreme precipitation, there is a need for improved understanding of how these physical phenomena simultaneously influence precipitation in the observational record across the contiguous United States. In this work, we introduce a single framework for characterizing the historical signal (anthropogenic forcing) and noise (natural variability) in seasonal mean and extreme precipitation. An important aspect of our analysis is that we simultaneously isolate the individual effects of seven modes of variability while explicitly controlling for joint inter-mode relationships. Our method utilizes a spatial statistical component that uses in situ measurements to resolve relationships to their native scales; furthermore, we use a data-driven procedure to robustly determine statistical significance. In Part I of this work we focus on natural climate variability: detection is mostly limited to DJF and SON for the modes of variability considered, with the El Niño/Southern Oscillation, the Pacific–North American pattern, and the North Atlantic Oscillation exhibiting the largest influence. Across all climate indices considered, the signals are larger and can be detected more clearly for seasonal total versus extreme precipitation. We are able to detect at least some significant relationships in all seasons in spite of extremely large (> 95%) background variability in both mean and extreme precipitation. Furthermore, we specifically quantify how the spatial aspect of our analysis reduces uncertainty and increases detection of statistical significance while also discovering results that quantify the complex interconnected relationships between climate drivers and seasonal precipitation.

Análisis de eventos fríos y cálidos por medio de datos de buceo: un enfoque de ciencia ciudadana en el Golfo de Papagayo, Costa Rica

Introduction: In January 2011 and as a Citizen Science initiative, the owners of the Deep Blue Diving Shop in Playa del Coco, Guanacaste, Costa Rica, began to collect daily temperature data in the seawater column during their diving activities, to inform tourists before traveling to Costa Rica and help them properly select their diving equipment and thus maximize the enjoyment of the experience in the Gulf of Papagayo. This data collection remained constant until January 2020 due to the COVID-19 pandemic. Objective: Identify cold and warm events of the sub-surface temperature of the sea in the Gulf of Papagayo, Guanacaste, Costa Rica and their relationship with known sources of climate variability as El Nino-Southern Oscillation (ENSO) and synoptic systems such as incursions of cold fronts in the Caribbean Sea. Methods: Sea Subsurface Temperature data corresponding to the lowest temperature of the seawater column were used, at an approximate depth of 25-35m. Observations were made daily, from 01/01/2011 to 01/31/2020. Results: The mean temperature was 25.7 degrees C. Cooler temperatures were observed in February-March, below 22.5 degrees C with a secondary minimum in July. There were two peaks in May and August with temperatures above 27.4 degrees C. The drops during cold events reached 16-17 degrees C. All cold events were associated with the passage of cold fronts through the Caribbean Sea, due to reinforcement in the intensity of the trade winds, with a zonal component from the East, which causes seasonal upwelling. The warm events presented temperatures at their maximum of 30-31 degrees C. The latter events were associated with the development and maturity of warm El Nino-type ENSO events. ENSO is an important modulator of sea temperature variability in the Gulf of Papagayo, since El Nino events are related to positive anomalies in sea temperature in the Eastern Tropical Pacific. Conclusions: The Citizen Science initiative presented in this study proved to be very useful for monitoring sea temperature in the Gulf of Papagayo. The results of this study indicate that Dive Masters can provide data on sea temperature of sufficient quality and with high temporal resolution. Divers can profitably support monitoring and Citizen Science can contribute positively to social well-being by influencing the questions that are being addressed and by giving people a voice in local environmental decision-making. The information generated in this study returns to the tour operators and enhance the understanding of the variability observed in the data collected by them, a knowledge that is later transmitted to their clients to improve their experience.

Climate impacts on tree growth in a Neotropical high mountain forest of the Peruvian Andes

Global warming can jeopardize important ecosystem functions and services in sensitive Neotropical mountain areas. However, untangling the relative roles of natural climate variability pattern from current global warming trends still represent a major challenge. Here, we propose a novel analytical approach based on Structural Equation Models to evaluate the relative roles of different sources of climate variability on tree growth. Specifically, we investigate direct and indirect linkages between Basal Area Increments (BAI) and a set of different climatic sources of variability, such as: (i) large-scale atmospheric oscillation patterns (i.e., the El Niño Southern Oscillation, ENSO and the Pacific Decadal Oscillation, PDO); and (ii) local meteorology in terms of temperature and precipitation. Additionally, we included in the SEM framework other important variables such as: (iii) calendar year (representative of temporal linear trends); and (iv) tree size (representative of main biological trends). Results indicate that the ENSO and PDO modulate minimum temperatures (Tmin) in the study area. These indices describe the oscillating behavior of the climatic modes (i.e., South Oscillation Index and PDO index) and are negatively correlated with Tmin. As such, they also influence tree growth (represented here by BAI) indirectly. Furthermore, through its direct impact on Tmin increase, ongoing climate warming has an indirect negative effect on BAI, thereby implying that the ongoing temperature rise could exert control on productivity in high mountain forests of the Andes, and that this influence could become more important with continued temperature increase.

Tornado-days in the United States by phase of the Madden–Julian oscillation and global wind oscillation

Tornado activity in the United States varies over multiple time scales. The Madden–Julian oscillation (MJO) and global wind oscillation (GWO) are sources of climate variability at the seasonal and subseasonal scales. The univariate distributions of tornado-days across the phases of these oscillations have been documented, but the bivariate distribution of tornado-days across both oscillations has not been. Here, the bivariate distribution of tornado-days across the phases of the MJO and GWO is documented and analyzed. Results herein refine the previously reported univariate distributions and highlight variability across the phases of one of the oscillations while holding the phase of the other constant (e.g., tornado-days are more likely during phase 2 of the GWO, but the likelihood varies across the phase of MJO).

Lower Tropospheric Temperatures 1978-2016: The Role Played By Anthropogenic Global Warming

The slowdown in tropospheric temperature increase between 1997-2016 led some commentators in Australia (and elsewhere) to repeat earlier assertions that there is an absence of any relationship between anthropogenic carbon dioxide increase and global air temperature. Here we test the null hypothesis that anthropogenic greenhouse forcing makes no contribution to global mean tropospheric temperature by analysing a satellite-derived lower tropospheric temperature record since 1978. A well-known heuristic model that separates variance in air temperature into components from different sources of climate variability is employed to determine what contribution anthropogenic greenhouse gases made to satellite-measured lower tropospheric temperature. Over the satellite record from December 1978 to the January 2016 the anthropogenic contribution to lower tropospheric temperature is estimated to be between +0.29 and +0.34K. Over the shorter segment of the record from December 1997 to January 2016 an anthropogenic contribution of +0.15K to the satellite-derived lower tropospheric air temperature was found. The slowdown in rate of temperature increase in that period is found simply to be a consequence of internal climate system variability that at other times has the opposite effect. The null hypothesis of no relationship between lower troposphere temperature and greenhouse gas increase is rejected.

Lower Tropospheric Temperatures 1978-2016: The Role Played By Anthropogenic Global Warming

The slowdown in tropospheric temperature increase between 1997-2016 led some commentators in Australia (and elsewhere) to repeat earlier assertions that there is an absence of any relationship between anthropogenic carbon dioxide increase and global air temperature. Here we test the null hypothesis that anthropogenic greenhouse forcing makes no contribution to global mean tropospheric temperature by analysing a satellite-derived lower tropospheric temperature record since 1978. A well-known heuristic model that separates variance in air temperature into components from different sources of climate variability is employed to determine what contribution anthropogenic greenhouse gases made to satellite-measured lower tropospheric temperature. Over the satellite record from December 1978 to the January 2016 the anthropogenic contribution to lower tropospheric temperature is estimated to be between +0.29 and +0.34K. Over the shorter segment of the record from December 1997 to January 2016 an anthropogenic contribution of +0.15K to the satellite-derived lower tropospheric air temperature was found. The slowdown in rate of temperature increase in that period is found simply to be a consequence of internal climate system variability that at other times has the opposite effect. The null hypothesis of no relationship between lower troposphere temperature and greenhouse gas increase is rejected.

The effect of the wintertime Arctic Oscillation on springtime vegetation over the northern high latitude region

The winter Arctic Oscillation (AO), a major source of climate variability in the Northern Hemisphere, affects winter and the subsequent spring climate over northern high latitude. Such effects are evident even in the 1st eigenmode of the normalized difference vegetation index (NDVI). The impacts of the winter AO is a dipole pattern between Eurasia and North America; positive (negative) values of the winter AO induce warmer (cooler) and high (low) vegetation activity in the following spring over Eurasia (North America). Regarding the time-lagged response of vegetation, the sea surface temperature (SST) and snow cover contribute to maintaining the large-scale circulation anomaly associated with the AO.

Vegetation patterns in South America associated with rising CO2: uncertainties related to sea surface temperatures

Spatially precise forecasts of the impacts of climate change on the distribution of major vegetation types are essential for the implementation of effective conservation and land use policy. However, existing studies frequently omit major sources of climate variability that can significantly increase the uncertainty of projections. In this study we demonstrate how different predictions for sea surface temperature (SST) for the first half of the twenty-first century increase the uncertainty associated with forecasts of the future distribution of major ecosystems in South America. This is demonstrated through a numerical experiment using a coupled climate–vegetation model (CCM3-IBIS) for IPCC emission scenario A2 that incorporates the SST data from ten different models. The study reveals an increasing uncertainty in the ability to forecast future vegetation patterns, such that by 2050 the simulation is unable to robustly forecast the vegetation cover in an area equivalent to 28 % in South America (5 × 106 km2). The future of the central and northeastern regions of Brazil is especially uncertain, with outcomes, ranging from savanna, and open shrubland to grassland. Recognizing and managing such uncertainty should be a priority for decision makers.

Circumglobal Teleconnection in the Northern Hemisphere Summer*

AbstractAnalysis of the 56-yr NCEP–NCAR reanalysis data reveals a recurrent circumglobal teleconnection (CGT) pattern in the summertime midlatitude circulation of the Northern Hemisphere. This pattern represents the second leading empirical orthogonal function of interannual variability of the upper-tropospheric circulation. The CGT, having a zonal wavenumber-5 structure, is primarily positioned within a waveguide that is associated with the westerly jet stream. The spatial phases of CGT tend to lock to preferred longitudes. The geographically phase-locked patterns bear close similarity during June, August, and September, but the pattern in July shows shorter wavelengths in the North Pacific–North America sector. The CGT is accompanied by significant rainfall and surface air temperature anomalies in the continental regions of western Europe, European Russia, India, east Asia, and North America. This implies that the CGT may be a source of climate variability and predictability in the above-mentioned midlatitude regions.The CGT has significant correlations with the Indian summer monsoon (ISM) and El Niño–Southern Oscillation (ENSO). However, in normal ISM years the CGT–ENSO correlation disappears; on the other hand, in the absence of El Niño or La Niña, the CGT–ISM correlation remains significant. It is suggested that the ISM acts as a “conductor” connecting the CGT and ENSO. When the interaction between the ISM and ENSO is active, ENSO may influence northern China via the ISM and the CGT. Additionally, the variability of the CGT has no significant association with the Arctic Oscillation and the variability of the western North Pacific summer monsoon. The circulation of the wave train shows a barotropic structure everywhere except the cell located to the northwest of India, where a baroclinic circulation structure dominates. Two possible scenarios are proposed. The abnormal ISM may excite an anomalous west-central Asian high and downstream Rossby wave train extending to the North Pacific and North America. On the other hand, a wave train that is excited in the jet exit region of the North Atlantic may affect the west-central Asian high and, thus, the intensity of the ISM. It is hypothesized that the interaction between the global wave train and the ISM heat source may be instrumental in maintaining the boreal summer CGT.