Seasonal Climate Patterns Research Articles

Coccidioidomycosis seasonality in California: a longitudinal surveillance study of the climate determinants and spatiotemporal variability of seasonal dynamics, 2000–2021

Coccidioidomycosis, an emerging fungal disease in the western USA, exhibits seasonal patterns that are poorly understood, including periods of strong cyclicity, aseasonal intervals, and variation in seasonal timing that have been minimally characterized, and unexplained as to their causal factors. Coccidioidomycosis incidence has increased markedly in recent years, and our limited understanding of intra- and inter-annual seasonality has hindered the identification of important drivers of disease transmission, including climate conditions. In this study, we aim to characterize coccidioidomycosis seasonality in endemic regions of California and to estimate the relationship between drought conditions and coccidioidomycosis seasonal periodicity and timing. We analysed data on all reported incident cases of coccidioidomycosis in California from 2000 to 2021 to characterize seasonal patterns in incidence, and conducted wavelet analyses to assess the dominant periodicity, power, and timing of incidence for 17 counties with consistently high incidence rates. We assessed associations between seasonality parameters and measures of drought in California using a distributed lag nonlinear modelling framework. All counties exhibited annual cyclicity in incidence (i.e., a dominant wavelet periodicity of 12 months), but there was considerable heterogeneity in seasonal strength and timing across regions and years. On average, 12-month periodicity was most pronounced in the Southern San Joaquin Valley and Central Coast. Further, the annual seasonal cycles in the Southern San Joaquin Valley and the Southern Inland regions occurred earlier than those in coastal and northern counties, yet the timing of annual cycles became more aligned among counties by the end of the study period. Drought conditions were associated with a strong attenuation of the annual seasonal cycle, and seasonal peaks became more pronounced in the 1-2 years after a drought ended. We conclude that drought conditions do not increase the risk of coccidioidomycosis onset uniformly across the year, but instead promote increased risk concentrated within a specific calendar period (September to December). The findings have important implications for public health preparedness, and for how future shifts in seasonal climate patterns and extreme events may impact spatial and temporal coccidioidomycosis risk. National Institutes of Health.

Morphologic, Atmospheric, and Oceanic Drivers Cause Multi‐Temporal Saltwater Intrusion on a Remote, Sand Island

AbstractSmall‐island populations disproportionately rely on fresh groundwater resources, which are increasingly threatened by salinization from changing ocean and climate conditions. This study investigates island groundwater dynamics and salinization over multiple timescales in response to marine, atmospheric, and morphologic drivers. New geophysical and hydrological data sets were collected on a remote sand island in the Northwest Atlantic Ocean between 2020 and 2022 and compared to historical baseline data from the 1970s. Data reveal saltwater intrusion due to multi‐decadal erosion, seasonal climate patterns, tidal forcing, and episodic flooding from Atlantic hurricanes. Long‐term dune erosion has caused the freshwater lens to thin and become asymmetrical; however, a lagged groundwater response causes the freshwater lens to be in disequilibrium with present island morphology. The maximum vertical lens thickness is seasonally constant, but the lateral transition zone along the coast thickens and moves seaward in spring when the water table is high from precipitation and frequent beach flooding. Groundwater level and electrical conductivity along low‐lying beaches significantly increase following Atlantic hurricanes due to seawater flooding, and reach a maximum of 1.93 m above sea level and 38 mS/cm, respectively. While groundwater levels recover quickly, conductivity (salinity) remains elevated due to the short intervals between winter flood events that outpace freshening from meteoric recharge. Results emphasize the importance of multi‐temporal groundwater dynamics and feedbacks between coastal flooding, erosion, and salinization. Field‐based studies considering multiple drivers and timescales of saltwater intrusion are critical for understanding and managing coastal freshwater resources in an age of rapid environmental change.

Soil properties zoning of agricultural fields based on a climate-driven spatial clustering of remote sensing time series data

The identification of zones within an agricultural field that respond differently to environmental factors and agronomic management is a key requirement for the adoption of more precise and sustainable agricultural practices. Several approaches based on spatial clustering methods applied to different data sources, e.g. yield maps, proximal sensors and soil surveys, have been proposed in the last decades. The current availability of a huge amount of free remote sensing data allows to apply these approaches to agricultural areas where ground or proximal data are not available. However, in order to provide useful agronomic management information, it is essential that the zoning obtained by clustering is linked to the underlying spatial variability of soil properties. In this work we explore the hypothesis that the response of crop vigor to temporal climate variability, assessed by remote sensing data time series, selected to correspond to specific growth phases and seasonal climate patterns, provides indications on the variability of soil properties within agricultural fields, for both herbaceous and tree crops. NDVI time-series for 38 years (1984–2021) were obtained for fourteen non-irrigated herbaceous and tree crop fields in Central Italy, from multispectral satellites data (Landsat 5/7/8, Sentinel 2). The Standardized Precipitation-Evapotranspiration Index (SPEI) was used to classify time series into three climatic classes (dry/normal/wet) for five different periods of the growth season, covering the main phenological phases. K-means clustering was used to identify patterns of crop growth from climatically classified image sets, as well as for all the bulked images for comparison (bulk clustering). Clustering results were compared with soil maps obtained from spatialized ground data, for soil texture (clay, silt and sand), soil organic matter and available soil water (ASW). The agreement between the different clustering results and soil maps was assessed by the Adjusted Rand Index. Agreement with soil maps varied depending on the field, the phenological phase considered and the soil property considered. Climate driven clustering from long, late growth season periods best matched soil properties, both for herbaceous and tree crops, despite being based on a limited number of images. The clustering from images spanning a longer growth period for dry years systematically outpaced the bulk clustering for silt, sand and ASW, while the clustering for normal climatic conditions was the best for organic matter. The performance of the matching between clustering and soil maps increased with soil variability significantly more (P < 0.05) than in the bulk clustering (mean slopes respectively 0.468 ± 0.167; 0.113 ± 0.270). The integration of the SPEI climatic index into the clustering procedure systematically improved the identification of zones with homogeneous soil properties, highlighting that a greater attention should be posed to the climate-crop-field interactions when using remotely sensed images.

Spatio-temporal Assessment of Changing Annual and Seasonal Climate Patterns over the Major Climatic Zones of Pakistan

The extensive impacts of climate change on the ecology and the environment have made it one of the biggest challenges being faced by the humanity today. Apart from the temporal scale, the climate patterns also vary on the spatial scale due to the different spatial features and the latitudinal location. This necessitates investigating the changing climate patterns over the different locales to formulate a holistic climate change adaptation and mitigation strategy. Therefore, this study was conducted to briefly investigate the annual and seasonal climate trends over the major climatic zones of Pakistan during the period 1990-2022 using the MK test and Sen’s slope estimator method. The results obtained from the study showed an annual mean temperature rise of about 0.1 to 1.0 °C over the Greater Himalayas and sub-Montane region, and about 0.15 to 1.2 °C over the central, southern, and the coastal parts of the country, while a declining trend was found over the Western Highlands during the study period. Seasonally, the spring season was found to be the warmest among all seasons in the country. For the summer season, a declining trend was found over the Greater Himalayas and Western Highlands, while warming increased over the other climatic zones. For the winter season, the temperature rose by about 0.1 to 1.0 °C over the Greater Himalayas and northern Balochistan, and by about 0.1 to 0.2 °C over the coastal zones. For annual precipitation, an increasing trend was found over the majority of the selected stations, whereas for the summer monsoon, a declining trend was found over the Greater Himalayas, while the other zones witnessed a significant rising trend, with the highest increment noted over the Western Highlands (100-300 mm), and about 50-150 mm in central Punjab and the lower Indus plain. For winter precipitation, the Greater Himalayas observed an upward trend (0.3-0.9 mm/year), while the southern and coastal parts of the country witnessed a declining pattern. Based on the findings, it was established that the climate patterns have varied greatly on the spatial scale over Pakistan, which necessitates the formulation of an integrated and effective climate change adaptation and mitigation strategy for the conservation of natural resources in the country.

Spatio-temporal patterns of different tree species response to climatic factors in south Kyrgyzstan

Understanding forest phenology is essential for monitoring global carbon budgets and managing vegetation resources in a changing climate. In southern Kyrgyzstan, walnut and wild apple trees dominate the forest landscape. These forests contain unique genetic diversity and offer potential for the development of climate-resilient crop varieties. They also support local communities through activities such as grazing, firewood collection, and fruit harvesting. However, these practices pose a threat to natural regeneration. Climate change exacerbates these challenges by altering their ecological niche. Despite this, few studies have examined forest phenology and its relationship to climate in Kyrgyzstan. To address this gap, we collected ecological data from forest plots in several protected areas and one forestry unit. This included tree species coordinates and landscape. Time series of vegetation indices, land surface temperature and precipitation were generated from remote sensing data. Regression analyses showed that temperature trends had limited predictive power for vegetation, while seasonal temperature variations had a positive effect on vegetation until excessive heat was reached, which had a negative effect. Precipitation trends and seasons had the most significant effects on vegetation, with lagged effects. Regression models were developed for Juglans regia L. (R2=0.8) and Malus spp. (R2=0.75) to predict vegetation index from temperature and precipitation data with high accuracy. Spatial heterogeneity in species response to climatic factors was evident within a small area. The study highlights the influence of landscape and climatic diversity on forest dynamics and emphasizes the importance of seasonal climate patterns over interannual trends.

UV index and climate seasonality explain fungal community turnover in global drylands

AbstractAimFungi are major drivers of ecosystem functioning. Increases in aridity are known to negatively impact fungal community composition in dryland ecosystems globally; yet, much less is known on the potential influence of other environmental drivers, and whether these relationships are linear or nonlinear.Time period2017–2021.LocationGlobal.Major taxa studiedFungi.MethodsWe re‐analysed multiple datasets from different dryland biogeographical regions, for a total of 912 samples and 1,483 taxa. We examined geographical patterns in community diversity and composition, and spatial, edaphic and climatic factors driving them.ResultsUV index, climate seasonality, and sand content were the most important environmental predictors of community shifts, showing the strongest association with the richness of putative plant pathogens and saprobes. Important nonlinear relationships existed with each of these fungal guilds, with increases in UV and temperature seasonality above 7.5 and 900 SD (standard deviation x 100 of the mean monthly temperature), respectively, being associated with an increased probability of plant pathogen and unspecified saprotroph occurrence. Conversely, these environmental parameters had a negative relationship with litter and soil saprotroph richness. Consequently, these ecological groups might be particularly sensitive to shifts in UV radiation and climate seasonality, which is likely to disturb current plant–soil dynamics in drylands.Main conclusionsOur synthesis integrates fungal community data from drylands across the globe, allowing the investigation of fungal distribution and providing the first evidence of shifts in fungal diversity and composition of key fungal ecological groups along diverse spatial, climatic and edaphic gradients in these widely distributed ecosystems. Our findings imply that shifts in soil structure and seasonal climatic patterns induced by global change will have disproportionate consequences for the distribution of fungal groups linked to vegetation and biogeochemical cycling in drylands, with implications for plant–soil interactions in drylands.

Seasonal rainfall trends of a key Mediterranean area in relation to large-scale atmospheric circulation: How does current global change affect the rainfall regime?

Current global warming causes a change in atmospheric dynamics, with consequent variations in the rainfall regimes. Understanding the relationship between global climate patterns, global warming, and rainfall regimes is crucial for the creation of future scenarios and for the relative modification of water management. The aim of this study is to improve knowledge of the relationship between North Atlantic Oscillation (NAO), East Atlantic (EA), and Western Mediterranean Oscillation (WeMO) with the seasonal rainfalls in Tuscany, Italy. The study area occupies a strategic position since it lies in a transition zone between the wet area of northern Europe and the dry area of the northern coast of Africa. This research, based on a statistical correlation method and on linear models, is designed to understand the relationship between seasonal rainfalls and climate patterns. The results of this study demonstrate that the use of linear models can yield more information than traditional statistical correlations. The results show a decrease in rainfall in the warm period of the year, namely in the summer, when its expression is most visible. This phenomenon is ascribable to current global warming, which causes an increase in sea-surface temperatures. An increase in the Northern Atlantic Sea Surface Temperature and in the Mediterranean Sea Surface Temperature causes a reduction of the Iceland Low, with an extension of the Azores High. Moreover, an increase in the Genoa Gulf SST induces a weakening of the Genoa Gulf Low, one of the main cyclogenetic systems of the Mediterranean.

Designing Climate Information Services to Enhance Resilient Farming Activities: Lessons From Papua New Guinea

Anthropogenically-driven changes in seasonal climate patterns are already jeopardizing traditional farming practices all around the world. These climatic changes increasingly expose farmers to challenging conditions, reducing the efficacy of existing farm practices and productivity. There is a plethora of information, tools, and practices that could be useful for farmers trying to respond to climate variability and change, including climate projections, horticultural advances, and agricultural management best practices. Whilst these tools and knowledge exist, they are often not contextualized in ways that equitably facilitate decision-making and action. To ensure weather and climate information services are accessible and useful to farmers, it is critical to understand and integrate considerations for the desired types, timing, and uses of the information. The one-size-fits-all information services that are often available don't account for regional or social differences, local physical conditions, or the needs of different populations. In order to improve our understanding of how weather and climate information services can better cater to farmers' needs when modifying and adapting their goals, risk management, and farm practices, we carried out a household survey in communities across three provinces in Papua New Guinea. The survey was developed to draw out key design considerations for seasonal climate forecasts in terms of timing, type of information, and applications. Based on the clustering and associations of these variables, this study identifies different profiles of information services content. It then examines whether specific profiles are associated with demographic groups or geographic locations. The findings demonstrate gender and geographic differences in the desired bundles of weather and climate information, and therefore can help to pinpoint specific components that would be beneficial to incorporate into extension and outreach programmes in different contexts within Papua New Guinea. This study highlights the value of tailoring weather and climate information services with specific groups of farmers, thereby enabling more equitable access to and use of critical knowledge for smallholders to build the capacity, knowledge, and systems to strategically adapt to climate change. At the same time, this study illustrates areas to gain efficiency and potentially scale up the provision of climate information services.

Gravity fingering control on evaporation and deep drainage in a 3D porous medium

Water infiltration in soils is a fundamental hydrologic process that determines the water availability for plant roots and the rate of recharge to deep groundwater bodies. When both the initial water saturation of the soil and the water infiltration rate is low, the infiltration front becomes unstable, resulting in gravity fingers that act as preferential flow channels. Preferential flow may allow for the rapid bypass of water through the evaporation zone, thereby promoting deep drainage of water into the subsoil even in arid and semi-arid regions, where the potential evapotranspiration (PET) is high and the mean annual precipitation (MAP) is low. Here, we investigate experimentally the impact of gravity fingering on deep drainage coupled with surface evaporation in a 3D porous medium. We use a cylindrical vessel packed with dry glass beads, and reproduce seasonal climatic patterns consisting of relatively short rainfall events alternating with periods of intense evaporation. We vary the volume of rainfall events and the interval between rainfall events to replicate climate conditions. We record the mass of water in the system throughout the experiment, and determine the partition between evaporation and deep drainage before and after the onset of fingering. We find that in semi-arid conditions, the fraction of water that bypasses the evaporation zone increases fourfold after gravity fingering starts. This finding has potentially important implications for understanding infiltration dynamics in arid environments and ecosystems’ response in regions susceptible to desertification.

Distribution of the SARS-CoV-2 Pandemic and Its Monthly Forecast Based on Seasonal Climate Patterns.

This paper investigates whether the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) pandemic could have been favored by specific weather conditions and other factors. It is found that the 2020 winter weather in the region of Wuhan (Hubei, Central China)—where the virus first broke out in December and spread widely from January to February 2020—was strikingly similar to that of the Northern Italian provinces of Milan, Brescia and Bergamo, where the pandemic broke out from February to March. The statistical analysis was extended to cover the United States of America, which overtook Italy and China as the country with the highest number of confirmed COronaVIrus Disease 19 (COVID-19) cases, and then to the entire world. The found correlation patterns suggest that the COVID-19 lethality significantly worsens (4 times on average) under weather temperatures between 4 °C and 12 °C and relative humidity between 60% and 80%. Possible co-factors such as median population age and air pollution were also investigated suggesting an important influence of the former but not of the latter, at least, on a synoptic scale. Based on these results, specific isotherm world maps were generated to locate, month by month, the world regions that share similar temperature ranges. From February to March, the 4–12 °C isotherm zone extended mostly from Central China toward Iran, Turkey, West-Mediterranean Europe (Italy, Spain and France) up to the United State of America, optimally coinciding with the geographic regions most affected by the pandemic from February to March. It is predicted that in the spring, as the weather gets warm, the pandemic will likely worsen in northern regions (United Kingdom, Germany, East Europe, Russia and North America) while the situation will likely improve in the southern regions (Italy and Spain). However, in autumn, the pandemic could come back and affect the same regions again. The Tropical Zone and the entire Southern Hemisphere, but in restricted colder southern regions, could avoid a strong pandemic because of the sufficiently warm weather during the entire year and because of the lower median age of their population. Google-Earth-Pro interactive-maps covering the entire world are provided as supplementary files.

Shift in seasonal climate patterns likely to impact residential energy consumption in the United States

We develop a highly-resolved ensemble of climate simulations and empirical relationships between weather and household energy consumption to provide one of the most detailed estimates to date for potential climate-driven changes in the United States residential energy demand under the highest greenhouse gas emissions pathway. Our results indicate that more intense and prolonged warm conditions will drive an increase in electricity demand while a shorter and milder cold season will reduce natural gas demand by the mid 21st century. The environmental conditions that favor more cooling degree days in summer and reduced heating degree days in winter are driven by changes in daily maximum temperatures and daily minimum temperatures in the respective seasons. Our results also indicate that climate-driven change can potentially reverse impacts of a projected decrease in rural population on residential energy demand. These projected changes in climate-driven energy demand have implications for future energy planning and management.

Differential use of winter precipitation by upper and lower elevation Douglas fir in the Northern Rockies.

In temperate regions such as the American west, forest trees often exhibit growth sensitivity to climatic conditions of a particular season. For example, annual tree ring growth increments may correlate well with winter precipitation, but not with summer rainfall, suggesting that trees rely more on winter snow than summer rain. Because both the timing and character of seasonal western climate patterns are expected to change considerably over coming decades, variation in the importance of different seasonal moisture sources for trees can be expected to influence how different forest trees respond to climate change as a whole, with shifts in seasonality potentially benefitting some trees while challenging others. In this study, we inferred patterns of tree water use in Douglas fir trees from the Northern Rockies for 2years using stable water isotopes, while simultaneously quantifying and tracking precipitation inputs to soil moisture across a vertical soil profile. We then coupled water source use with daily measurements of radial growth to demonstrate that soil moisture from winter precipitation accounted for 87.5% and 84% of tree growth at low and high elevations, respectively. We found that prevailing soil moisture conditions drive variation in the depth at which trees access soil water, which in turn determines which seasonal precipitation inputs are available to support tree growth and function. In general, trees at lower elevations relied more on winter precipitation sourced from deep soils while trees at higher elevations made better use of summer rains sourced from near-surface soil layers. As both the timing of seasons and phase of precipitation (rain vs. snow) are likely to change considerably across much of the west, such patterns in tree water use are likely to play a role in determining the evolution of forest composition and structure in a warming climate.

Species-specific phenological trends in shallow Pampean lakes' (Argentina) zooplankton driven by contemporary climate change in the Southern Hemisphere.

The relationship between the timing of recurrent biological events and seasonal climatic patterns (i.e., phenology) is a crucial ecological process. Changes in phenology are increasingly linked to global climate change. However, current evidence of phenological responses to recent climate change is subjected to substantial regional and seasonal biases. Most available evidence on climate-driven phenological changes comes from Northern Hemisphere (NH) ecosystems and typically involves increases in spring and summer temperatures, which translate into earlier onsets of spring population developments. In the Argentine Pampa region, warming has occurred at a much slower pace than in the NH, and trends are mostly restricted to increases in the minimum temperatures. We used zooplankton abundance data from Lake Chascomús (recorded every two weeks from 2005 to 2015) to evaluate potential changes in phenology. We adopted a sequential screening approach to identify taxa displaying phenological trends and evaluated whether such trends could be associated to observe long-term changes in water temperature. Two zooplankton species displayed significant later shifts in phenology metrics (end date of Brachionus havanaensis seasonal distribution: 31day/decade, onset and end dates of Keratella americana seasonal distribution: 59day/decade and 82day/decade, respectively). The timing of the observed shift in B.havanaensis phenology was coincident with a warming trend in the May lake water temperature (4.7°C per decade). Analysis of abundance versus temperature patterns from six additional shallow Pampean lakes, and evaluation of previous experimental results, provided further evidence that the lake water warming trend in May was responsible for the delayed decline of B. havanaensis populations in autumn. This study is the first report of freshwater zooplankton phenology changes in the Southern Hemisphere (SH).

Understanding coastal wetland hydrology with a new regional‐scale, process‐based hydrological model

AbstractCoastal wetlands represent an ecotone between ocean and terrestrial ecosystems, providing important services, including flood mitigation, fresh water supply, erosion control, carbon sequestration, and wildlife habitat. The environmental setting of a wetland and the hydrological connectivity between a wetland and adjacent terrestrial and aquatic systems together determine wetland hydrology. Yet little is known about regional‐scale hydrological interactions among uplands, coastal wetlands, and coastal processes, such as tides, sea level rise, and saltwater intrusion, which together control the dynamics of wetland hydrology. This study presents a new regional‐scale, physically based, distributed wetland hydrological model, PIHM‐Wetland, which integrates the surface and subsurface hydrology with coastal processes and accounts for the influence of wetland inundation on energy budgets and evapotranspiration (ET). The model was validated using in situ hydro‐meteorological measurements and Moderate Resolution Imaging Spectroradiometer (MODIS) ET data for a forested and herbaceous wetland in North Carolina, USA, which confirmed that the model accurately represents the major wetland hydrological behaviours. Modelling results indicate that topographic gradient is a primary control of groundwater flow direction in adjacent uplands. However, seasonal climate patterns become the dominant control of groundwater flow at lower coastal plain and land–ocean interface. We found that coastal processes largely influence groundwater table (GWT) dynamics in the coastal zone, 300 to 800 m from the coastline in our study area. Among all the coastal processes, tides are the dominant control on GWT variation. Because of inundation, forested and herbaceous wetlands absorb an additional 6% and 10%, respectively, of shortwave radiation annually, resulting in a significant increase in ET. Inundation alters ET partitioning through canopy evaporation, transpiration, and soil evaporation, the effect of which is stronger in cool seasons than in warm seasons. The PIHM‐Wetland model provides a new tool that improves the understanding of wetland hydrological processes on a regional scale. Insights from this modelling study provide benchmarks for future research on the effects of sea level rise and climate change on coastal wetland functions and services.

Seasonal Pattern In the High-Elevation Fluvial Travertine From the Jiuzhaigou National Nature Reserve, Sichuan, Southwestern China

Abstract: The Jiuzhaigou National Nature Reserve on the Tibetan Plateau (Sichuan, southwestern China) is characterized by the deposition of fluvial travertine in a spectacular array of shoals, waterfalls, pool dams, and multicolored lakes. This is possibly the highest vegetated travertine setting of the world, from 2200 to 2900 m above sea level, an environment sensitive to minimal changes in temperature and precipitation regime. The evolution of the system is driven by two seasonal monsoon climate patterns with a wet spring–summer travertine deposition and then a dry fall–winter characterized by no precipitation or erosion. Spring and phreatic–vadose deposits transition from laminated columnar calcite to clotted micrite encrustation, possibly correlated with a mid-Holocene peak in precipitation and high lake levels in the northeastern Tibetan area connected to glacial advance. The most peculiar features are the fluvial shoals, a rather uncommon travertine surface consisting of two main superimposed facies of alternating weak- and strong-turbulence water flow. The low-turbulence facies consists of clotted micrite encrustation of mosses and cyanobacteria filaments, and platy calcite crystals covering algal filaments. The high-water-turbulence facies show seasonal alternation of diatom-rich bundles of Phormidium sp. (late spring) with algal Oocardium stratum levels (summer–fall). Upslope and downslope of the shoals, the precipitation of calcium carbonate results in the formation of prograding waterfalls and dam–pool systems that encrust macrophytes with microspar and clotted micrite. Encrusted chironomids larvae tubes are present in the waterfall walls up to an elevation of 2860 m, possibly the highest ever recorded. Early diagenetic processes such as dissolution of diatom frustules take place over the span of several years, a slower phenomenon compared to other travertine occurrences. In this high-elevation extreme setting, travertine sand and gravel bar deposits are produced by the exposure to severe weathering of a section of the valley that is bypassed through an underground karst system during the winter dry season. High-elevation travertine probably has a low preservation potential, but it appears to be more sensitive to climate changes than other depositional settings, especially in the Himalayan–Tibetan area, where the extent of the Quaternary glacial advances and retreats is still a matter of debate.

A Review on Causes of Climate Change: Challenges and Opportunities for Livestock Production in the Tropics

The growth in demand for livestock products will probably still play a dominant role over the next decades and lead to a net increase in the area dedicated to livestock, despite the intensification trend. It is estimated that the world food requirement by the year 2050 will be double that of 2010. A significant part of this requirement will emanate from the developing countries, on account of increased human populations, disposable incomes and urbanization. To the contrary, climate change poses the threat of serious social upheaval, population displacement; economic hardships and environmental degradation were it has been caused both by natural phenomenon and man-made activities. Livestock established their current geographic ranges through long-term adaptation to seasonal climate patterns. Anthropogenic climate change is likely to alter those seasonal patterns on a timescale far more rapid than has occurred naturally over past millennia. It is this rapid rate of climate change which challenges the natural adaptive capacity of livestock. The faster the changes, the greater will be the risk of damage exceeding ability to cope with the consequences. Significant negative consequences including loss of livestock through heat stress, loss of land to agricultural encroachment, an increase in frequency of flooding and the spread of human and livestock diseases were some the problems. Since, livestock are an irreplaceable source of livelihoods for the poor community and there is a chance to give attention for the sector. Because, it is the fastest growing sector and in some countries accounts for 80% of the GDP, in particular in dry lands. As to livestock products, about two-thirds of the increased demand needs to be met by improving the production efficiency of feeds (forages and concentrates). Balanced nutrition contributes to improve animal output as well as to reduce both the cost of production and the emission of greenhouse gases per animal. Ultimately large scale implementation of such programs can help to improve the productivity of livestock in developing countries. Therefore, livestock management system-efficient and affordable adaptation practices have to be developed for producers not able to buy expensive adaptation technologies.

Seasonal climate patterns and their influence on calibration of the Hargreaves-Samani equation

Annual patterns in climate parameters were studied to evaluate how these influence the quality of reference evapotranspiration (ETo) estimates obtained from the Hargreaves-Samani (HS) equation, since the method only uses the measured temperature directly. The work evaluates how these patterns can be used to improve the HS ETo estimates. Ten-year moving averages from a set of California Irrigation Management Information System (CIMIS) stations were used to evaluate the relationships between solar radiation (Rs), temperature (T) and ETo. The results indicate that T treads behind solar radiation and its value peaks some 25 days later. Thus, the main irrigation season in the Mediterranean climate (1 May–30 September) can be divided into three phases: increasing Rs and T; decreasing Rs with increasing T; and decreasing Rs and T. Non-univocal annual cycles were observed between Rs and T, ETo and Rs, and ETo and T. These annual patterns result in important seasonal changes in the ratio between the HS and Penman-Monteith (FAO PM) ETo estimates. The changes are particularly important during the irrigation season, where the FAO PM initially calculates greater ETo values than the HS methodology, and from the end of May to early September, where the HS equation overestimates the ETo values (by 17 mm, or 3%). These patterns obtained from 2000–2009 data were used to calibrate and improve HS ETo estimates at new sites for the 2010–2011 period. Calibration based on the proposed seasonal region-wide FAO PM/HS ETo ratios improved both the bias (decreased from 0.40 to 0.36 mm d-1) and r2 (increased from 0.67 to 0.87) of the ETo estimates for the irrigation season. The proposed methodology can be easily applied to other regions, even when the existing weather stations are sparse.Editor Z.W. Kundzewicz

Climate and CO2 effects on the vegetation of southern tropical Africa over the last 37,000 years

The savanna vegetation of southern tropical Africa is characterized by co-dominance of C4 grasslands and C3 woodlands. Long-term variations in the tropical savanna vegetation in arid and semi-arid climates are commonly considered to be primarily sensitive to precipitation and atmospheric CO2 concentrations. The sensitivity of tropical vegetation to temperature, however, is often considered as secondary or negligible, particularly in paleostudies due to difficulties of reconstructing terrestrial temperature in the tropics. In this study, we use the terrestrial vegetation model BIOME4, which was forced by climate simulations from the Kiel Climate Model (KCM) for the Holocene and by climate reconstructions for the most recent glacial period to understand reconstructed vegetation changes in southern tropical Africa of the past 37,000 yr. We focus on these two periods because vegetation reconstructions from a marine sediment core near the Zambezi River mouth cannot be explained by precipitation changes and changes of atmospheric CO2 alone. For the Holocene, we force BIOME4 simulations with reconstructed atmospheric CO2 concentrations, and spatial and seasonal climate patterns from the early- and mid-Holocene (9.5 and 6 ka BP) simulations with the KCM. For the glacial period, we analyze idealized experiments based upon reconstructed temperature, precipitation and CO2 at 31, 28 and 21 ka BP. Our study shows that both Holocene and glacial simulations of vegetation cover exhibit good agreement with reconstructed C4:C3 ratios when temperature changes are taken into account. While both precipitation and temperature control the C4:C3 ratio during the Holocene atmospheric CO2 and temperature variations are major factors controlling vegetation changes during the glacial period. In our simulations, variations in temperature along with precipitation and atmospheric CO2 reconcile the evolution of vegetation observed in the Zambezi catchment during the last 37,000 yr. In consequence, the effect of temperature variations on tropical savanna vegetation should be taken into account with respect to modeling past or future climates.

Pyrolysis kinetics of algal consortia grown using swine manure wastewater

In this study, pyrolysis kinetics of periphytic microalgae consortia grown using swine manure slurry in two seasonal climatic patterns in northwest Arkansas were investigated. Four heating rates (5, 10, 20 and 40°Cmin−1) were used to determine the pyrolysis kinetics. Differences in proximate, ultimate, and heating value analyses reflected variability in growing substrate conditions, i.e., flocculant use, manure slurry dilution, and differences in diurnal solar radiation and air temperature regimes. Peak decomposition temperature in algal harvests varied with changing the heating rate. Analyzing pyrolysis kinetics using differential and integral isoconversional methods (Friedman, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose) showed strong dependency of apparent activation energy on the degree of conversion suggesting parallel reaction scheme. Consequently, the weight loss data in each thermogravimetric test was modeled using independent parallel reactions (IPR). The quality of fit (QOF) for the model ranged between 2.09% and 3.31% indicating a good agreement with the experimental data.

Governance of Arctic expedition cruise ships in a time of rapid environmental and economic change

Changes in seasonal climate patterns and decreasing sea ice cover have facilitated an increase in navigable waters throughout Arctic Canada and resulted in the urgent need for new approaches to ocean, coastal, and vessel management. Increased access has resulted in a significant expansion of Arctic shipping activity over the past decade with one of the fastest growing sectors being expedition cruising. This paper presents an assessment of the existing marine regulations and governance structures that manage the cruise sector in Arctic Canada and provides a critical evaluation of its effectiveness considering recent and rapid growth. Using a variety of sources, including interviews with community residents and key informant stakeholders, analysis of changing ship volumes over the past decade, and an inventory of institutional governance for the sector, the major governance challenges for the industry were identified. Also identified are potential strategies for mitigating these challenges. Results of the analysis raise concerns that there is no central authority to govern the growth of the industry, no specific sector or operator management plan, and no site guidelines for highly visited shore locations (other than in protected areas). Instead, governance occurs within the complex multi-jurisdictional regulatory frameworks that exist for all shipping in the region. The paper concludes that under current conditions there are significant barriers to supporting development of this sector while avoiding human, environmental and security problems in the near-to medium-term future.