NDVI variation and its relation to climate in Canadian ecozones

Parks Canada began the Northern Satellite Monitoring Program in 1997, with the objective of tracking large‐scale vegetation variation in Canadian ecosystems and helping land managers to develop appropriate management practices in response to climate change. Under this program, a sequence of 10‐day composite Advanced Very High Resolution Radiometer (AVHRR)‐derived Normalized Difference Vegetation Index (NDVI) data from 1985 to 2007 was examined to study seasonal and inter‐annual relationships between vegetation and climate data over Canadian ecosystems using statistical and wavelet analysis. Statistical analysis showed that temperature was the principal driver for seasonal variability in greenness, explaining more than 70 percent of seasonal variation in vegetation for most Canadian ecozones. In comparison with temperature, the relationships between NDVI and precipitation were weaker but still significant. Maximum annual NDVI showed increasing trends in Canadian ecozones during the study period, although increasing rates were spatially heterogeneous. Wavelet analysis confirmed that inter‐annual variation in NDVI was different at two ecozones in Canada. NDVI variation in the Northern Arctic was significant at scales of 3–4 years from 1997 to 2001, which was associated with temperature and precipitation variation. Comparatively, NDVI variation in the Boreal Shield was significant at scales of 5–8 years from 1991 to 1999, but did not correspond with climate variation.     

Assessment of Relationships Between Precipitation and Satellite Derived Vegetation Condition Within South Australia

The normalised difference vegetation index (NDVI) has evolved as a primary tool for monitoring continental‐scale vegetation changes and interpreting the impact of short to long‐term climatic events on the biosphere. The objective of this research was to assess the nature of relationships between precipitation and vegetation condition, as measured by the satellite‐derived NDVI within South Australia. The correlation, timing and magnitude of the NDVI response to precipitation were examined for different vegetation formations within the State (forest, scrubland, shrubland, woodland and grassland). Results from this study indicate that there are strong relationships between precipitation and NDVI both spatially and temporally within South Australia. Differences in the timing of the NDVI response to precipitation were evident among the five vegetation formations. The most significant relationship between rainfall and NDVI was within the forest formation. Negative correlations between NDVI and precipitation events indicated that vegetation green‐up is a result of seasonal patterns in precipitation. Spatial patterns in the average NDVI over the study period closely resembled the boundaries of the five classified vegetation formations within South Australia. Spatial variability within the NDVI data set over the study period differed greatly between and within the vegetation formations examined depending on the location within the state. ACRONYMS AVHRR Advanced Very High Resolution Radiometer ENVSAEnvironments of South Australia EOS Terra‐Earth Observing System EVIEnhanced Vegetation Index MODIS Moderate Resolution Imaging Spectro‐radiometer MVC Maximum Value Composite NDVINormalised Difference Vegetation Index NIRNear Infra‐Red NOAANational Oceanic and Atmospheric Administration SPOT Systeme Pour l’Observation de la Terre     

An exploration of regional climate change scenarios for Scotland

Based on a high resolution regional climate model (RCM) experiment, a climate change scenario for Scotland for the end of this century is constructed with the aim of exploring the added value of utilising a regional rather than a global model (GCM) for climate change scenario construction. Spatial variations in regional seasonal average temperature and precipitation change are analysed and the local response of ‘extreme’ weather events to climate warming is assessed using daily model output. The analyses suggest that in comparison with the GCM, the RCM does not provide fundamentally different patterns of seasonal climate change and daily weather response over Scotland, although it does capture more subtle spatial variations in these changes. The RCM also simulates more realistic daily weather events than the GCM, although the relative changes in the frequencies of daily extremes are not greatly different. However, with the limited length of the single model simulation analysed here, it is not easy to establish how robust and significant are the sub‐national patterns of climate response across Scotland. To improve the quality and comprehensiveness of regional climate change scenario information, a number of research issues remain to be addressed.     

Quaternary Organic Deposit from Newton Creek Valley,Western Tasmania

Pollen and macrofossils from an organic deposit probably 44 ka BP in age record subalpine heath with abundant local Athrotaxis cupressoides. This was succeeded by subalpine heath that included Casuarina, Phyllocladus and Eucalyptus. The pollen/vegetation assemblages are comparable with present subalpine vegetation located between 850–1050 m, though the site is at 550 m and potentially below the limit of temperate rainforest (620 m). It is inferred that the vegetation altered from upper to lower subalpine heath and that the climate became warmer and wetter. The mean temperature is estimated to have been at least 3.2°C to 1.7°C colder than today. The trend of vegetation and climate change compares closely with Late Glacial changes but does not compare with changes recorded from sites of Middle Last Glacial age in the West Coast Ranges. A radiocarbon date of 34 ka BP and a trend towards warming suggests that the deposit may represent the onset of an interstadial during the Early Last Glacial Stage.     

The micromammalian fauna from Border Cave,Kwazulu, South Africa

The micromammalian fauna from Border Cave is analysed in terms of community composition and structure. Changes in these aspects are interpreted as indicative of changes in vegetation and climate in the vicinity of the cave during the period of deposition. It would appear that vegetation comprised relatively extensive forest or thick bush and dense grass during wetter phases and fairly open savanna woodland, even open grassland, during drier periods. Variation through time in mean mandibular size in two species of Crocidura (musk shrew) was different both in the two species and from what was expected. It now seems likely that the size change constitutes a response to complex phenomena and not simply to changes in temperature. Comparison with the Boomplaas A sequence indicates that the same general pattern of change is reflected at both sites but that there was a greater amplitude of change at Boomplaas A and that ¹⁸O stage 4 was dry at this site but wet at Border Cave. Evidence for periodic changes in the distribution of various species, and in some cases the mutually exclusive occurrence of ecologically equivalent species, has implications for the zoogeography of the species involved. In particular, the occurrence of Pelomys fallax (creek rat) in the lower half of the sequence is of interest in view of its present distribution 600 + km north of Border Cave.     

Environmental influences on pastoral conflict in the Horn of Africa

This paper seeks to discern the influence of environmental variability on pastoral conflict in the Horn of Africa. While the literature on environmental factors in civil wars is rich in empirical research and explanatory power, the dearth of data is an obstacle to the study of other important forms of violence such as pastoral conflict. If environmental factors are associated with pastoral conflict then what are they, and can they be used as early warning indicators to prevent its escalation or mitigate its effects? These questions are increasingly important given the expected impact of climate change on pastoral societies worldwide. To help answer these questions we draw on data collected by field monitors with the Inter-Governmental Authority on Development's (IGAD) Conflict Early Warning and Response Network (CEWARN) and environmental data for the same region. Field monitors collect incident and situation reports from more than two dozen areas of reporting along the borders of Ethiopia, Kenya and Uganda collectively known at the Karamoja Cluster. We compare these conflict data with three environmental indicators: precipitation, vegetation and forage. Preliminary statistical analyses of the data suggest that aggravating behavior, along with a reduction in peace initiatives and reciprocal exchanges, is associated with an escalation in pastoral conflict, particularly when coupled with an increase in vegetation that may provide cover for organized raids. We therefore recommend that conflict early warning systems integrate both response options and salient environmental indicators into their analyses to better deal with the complexity of the relationships between pastoral conflict and the environment in an era of climate change.     

Good for glaciers,bad for people? Archaeologically relevant climate models developed from reconstructions of glacier mass balance

We present a new climate and vegetation model, and discuss applications with a study of medieval land degradation and settlement abandonment in þórsmörk, Iceland. Existing meteorological data are used as the starting point for modelling glacier snowlines (equilibrium lines), and this is developed to model seasonal snowcover, potential vegetation and growing season. The current status and past fluctuations of glaciers across Iceland provide independent spatial and temporal constraints to the model. In þórsmörk, there was extensive landscape degradation and settlement abandonment in the late Medieval period, with an unclear role for climate change. Modelling of the landscape impacts of a 1 °C fall in temperatures shows that climatically induced degradation through reduced vegetation, growing season, and increased snowcover had limited effects on the once settled area, highlighting the importance of anthropogenically driven change. High resolution modelling offers a significant potential for assessing ‘what if’ questions, and identifying key empirical tests.     

Shifts Along a Spectrum: A Longitudinal Study of the Western Eurasian Realized Climate Niche

ABSTRACT

Climate niches that modern humans and earlier hominin ancestors occupied have changed dramatically over time, but the extent of those changes has gone largely undocumented. This study investigates the manner in which the realised hominin climate niche has expanded, contracted, or stayed stationary across four time periods (Last Interglacial, Last Glacial Maximum, Mid-Holocene, and 1950–2000) in Western Eurasia. Using spatially gridded general circulation model data and site locations this study examines climate variables from archaeological sites and current Western Eurasian cities to describe both the regional Western Eurasian fundamental and realised climate niches. Changes between the three prehistoric periods and modern-day time period are analysed by calculating each realised niche breadth, overlap, position, and variance. Results indicate that as global temperatures cooled from the Last Interglacial to Last Glacial Maximum, populations expanded their climate niche breadth beyond that of earlier Neanderthal groups, shifting toward regions with less seasonal variation. Conversely, Mid-Holocene humans, who saw the proliferation of both agriculture and population, contracted their realised climate niche space. The contraction and expansion of realised climate niche space illustrates how hominins have evolved the capacity to shift their niche through changes to their subsistence strategy and adaptations to overall climatic conditions.     

Bronze Age landscape dynamics: spatially detailed pollen analysis from a ceremonial complex

The late Neolithic and early Bronze Age are periods marked by the construction of conspicuous concentrations of ‘ritual’ complexes, used for funerary rituals, seasonal gatherings and communal activities. Understanding the environmental context of monuments may provide detailed insights into relationships between the physical environment and the activities undertaken at individual monuments. Raised burial mounds (barrows) are generally assumed to have been constructed in open landscapes (the so-called ‘landscape openness’ hypothesis) thus rendering them highly visible in the surrounding landscape. This paper seeks to test to what extent vegetation (and in particular openness) around a dense concentration of barrows was actively managed, using three pollen sequences in close spatial juxtaposition to the archaeology. The local vegetation histories, supported by radiocarbon dating, demonstrate spatial differences in vegetation pattern both during the time of monument construction and use (c. 2000–1500 cal BC) and during subsequent periods. They do not support the ‘landscape openness’ hypothesis. This suggests that there is no single ‘blueprint’ for vegetation structure on and around these types of monument complexes. There is no evidence for major restructuring of the landscape during the early Bronze Age. The data describe a major transformation of the vegetation around 1500 cal BC (the Middle Bronze Age) in an area not known for archaeology of this date. This serves to emphasize the role of palaeoecology in augmenting the archaeological record of landscape re-organisation and transformation in prehistory.     

Climate,vegetation and ecology during Harappan period: excavations at Kanjetar and Kaj,mid-Saurashtra coast,Gujarat

A multi-proxy study was carried out to address climate–culture relationship from two trenches one each from Kaj and Kanjetar (mid-Saurashtra coast) deposited in a lacustrine setting, since ∼1960 Cal BC and ∼2230 Cal BC, respectively. The salinity of aqueous soil solution (0.1 ppt) and fresh water thecamoebians in both the sites indicate fresh water depositional environment. But, an increase in salinity (0.2 ppt) in the top clayey sediment in Kanjetar is attributed to water evaporation through upward capillary action from moisture deficit exposed land. The fragments of ancient potteries and other artefacts recovered from the bottom sediment provide evidences of Sorath-Harappan colonization in the vicinity which was not an urban site. The abundant cyanobacterium remains, low terrigenous organic matter, aquatic pollen and low thecamoebians in bottom sediment indicates low precipitation and arid climatic conditions ∼2000 BC. During this period the dominance of evergreen and moist deciduous arboreals from both the sites do not show equilibrium with the prevailing dry/arid climate and therefore, the pollen assemblage here represents the remnants of wetter middle Holocene vegetation in the region. Phytoliths of drought-tolerant summer season crops also reflects here changes made in the agricultural strategy by Harappans in response to climate. The increase in deciduous arboreal pollen since the last ∼2000 years represents equilibrium with the dry/arid climate. But, enhanced limnic conditions recorded with the help of thecamoebians during this period is attributed to changes in wetland configuration induced by hydrostatic changes in the river mouth that was largely defined by the dynamics of sediment deposition through rain-fed rivers/streams in the region.     

The environmental context of a prehistoric rock carving on the Bjäre Peninsula,Scania, southern Sweden

Palaeoecological analysis of peat deposits from a small bog at Lingården, southern Sweden, have been used to examine the nature and timing of vegetation changes and anthropogenic activity associated with a nearby rock carving located close to the edge of the wetland. This study is the first of its type to investigate the environmental context of rock carvings in southern Sweden. Debate has tended to focus on chronology and iconography, with little consideration of the environmental relationships of rock carvings and how vegetation may help construct a site within its surrounding landscape. The pollen evidence from Lingården demonstrates that the rock carving was located in an isolated semi-wooded setting during the late Bronze Age. This is in stark contrast to several other pollen studies from the Bjäre Peninsula that record widespread woodland clearance and agricultural activity from the late Neolithic–Bronze Age transition. The results of this study support hypotheses that suggest complex rock carvings, such as Lingården, were separated from settled areas. This sense of separation and isolation is reinforced by the vegetation surrounding the rock carving. This paper also discusses the relationship between charcoal in the pollen sequence and evidence that the decorated outcrop had been burnt.     

历史文化村镇旅游流季节性特征比较研究——以西递、周庄为例

本文以西递和周庄为例,对历史文化村镇旅游流季节性特征进行比较。研究表明,两地在旅游流季节分布不均匀性、季节分布模式和季节划分方面均存在一定差异。对基尼系数和季节性强度指数的分析表明,两者在描述旅游流的季节性变动特征方面具有可替代性,且前者在一定程度上优于后者。另外,旅游地发展阶段也会对旅游流季节性特征有一定影响。论文建议旅游流季节性特征可作为旅游地发展阶段的一项评估指标。     

The unequal geographies of climate finance: Climate injustice and dependency in the world system

Central to climate justice is the question of who will pay for the mitigation and adaptation efforts needed as the climate crisis worsens, particularly in countries that bear little responsibility for global greenhouse gas emissions. Climate finance is a complex set of mechanisms intended to address this concern. World-systems theory has long understood international development assistance as a tool that reproduces spatial dependency between states. In this paper, we ask whether climate finance follows the expectations of world-systems theory and reproduces relationships of dependency, or if it instead advances climate justice and challenges spatial dependency in the world-system. Through this analysis, we consider the implications of climate finance for world-systems theory. We use recent empirical data to ask whether climate finance follows or challenges world-systems theory expectations, focusing on five areas: (1) spatial flows of climate finance between the core, semi-periphery, and periphery; (2) the governance of climate finance institutions; (3) the types of projects supported by climate finance; (4) the relationship of projects to dominant systems of extraction, production, and consumption; and (5) the agency of peripheral state and non-state actors in shaping climate finance in relation to their interests. Taken together, we argue that climate finance in many ways reproduces relationships of dependency, though potential avenues exist for contesting this unequal balance of power and for advocating for climate justice. This case illustrates the need to approach analyses of dependency in a nuanced way, interrogating specific processes through which dependency is produced and contested across scales.     

Study of the Impact of Urban Development on Surface Temperature Using Remote Sensing in Ho Chi Minh City,Southern Vietnam

Rapid urbanisation and industrialisation have resulted in sharp land cover changes. Urban change not only impacts on land cover but also on urban climate. Land surface and atmospheric modifications due to urbanisation generally lead to a modified thermal climate that is warmer than the surrounding, non-urbanised areas. In this research remote sensing technology was used to evaluate urban growth patterns and its thermal characteristics through mapping impervious surfaces and evaluating thermal infrared images. The case study was carried out in the northern part of Ho Chi Minh City, which has experienced accelerated urban development since the late 1980s. Landsat and Aster images were used to calculate variations in urban impervious surfaces from 1989 to 2006. Thermal bands were processed to obtain radiant surface temperatures for investigating the urban heat island effect associated with increasing impervious surfaces, both spatially and temporally. Impacts of urban development on surface temperature were shown by investigating the surface urban heat island effect intensity. The results show that the built-up area in the northern part of Ho Chi Minh City expanded by 6.5 times between 1989 and 2006. Urban development has altered the magnitude and pattern of the surface urban heat island, with the highest land surface temperature cores found in the industrial (greater than 45^oC) and urban areas (within 36^oC and 40^oC). In suburban and rural areas, where agricultural land still remains with full vegetation cover, the land surface temperature is usually lower. Using remote sensing, the impervious surface was extracted with overall accuracy and a Kappa coefficient for all three years greater than 96%, and the retrieved land surface temperatures with variations from in-situ measurements of less than 2^oC. The results presented here indicate that remote sensing can help to spatially monitor urban development and land surface temperature changes over the whole area and over a long period of time.     

Holocene later stone age hunter-gatherers south of the Limpopo River, Ca. 10,000-2000 B.P.

Encouraged by new, ethnographically grounded interpretations of San rock art, Holocene hunter-gatherer research south of the Limpopo has undergone a partial paradigm shift over the last decade, away from ecological issues and in favor of questions of social organization and ideology. Earlier models relating changes in regional demography to environmental shifts now need revision, as do long-standing studies of seasonal mobility. New research emphasizes instead identification of exchange and alliance networks and patterns of seasonal aggregation and dispersal. However, several of the assumptions of these models remain untested, while dating problems make it difficult to integrate rock art with other components of the archaeological record. Critical use of a more diverse set of ethnographic data, from both within and beyond the Kalahari, is also needed. These points are emphasized in discussing evidence for social and economic intensification between 5000 and 2000 B.P. in several areas of the subcontinent (KwaZulu-Natal, the southern, eastern, and far western Cape).     

Monitoring the Near‐surface Urban Heat Island in Beijing,China by Satellite Remote Sensing

Urban heat island (UHI) effect is an important impact factor of the regional climate and ecological environment. How to observe and analyse the spatial distribution of UHI has become an important issue of urban environmental research. In this paper, the near‐surface air temperature of Beijing was derived based on the Landsat/TM satellite imagery on 26 July 2011 to study the near‐surface UHI. A statistical model at 195‐m window size was established to estimate the air temperature, using land surface temperature, normalized difference vegetation index, altitude, and surface albedo as independent variables. The mean absolute error (MAE) of the model was 0.87°C, and the R² was 0.66, indicating that the method can be used to effectively estimate the air temperature. The air temperature distribution obtained from remote sensing revealed that the UHI effect in Beijing was very significant and showed a concentrated pattern. The heat island intensity was stronger in the southern part than in the northern part of the city. In addition, the relationship between the air temperature and impervious surfaces was analysed. The air temperature increased with increasing impervious surface coverage, and the rate of change depended on the impervious surface coverage. When the impervious surface coverage was below 40 per cent, the temperature increased rapidly with increasing impervious surface coverage, and when the impervious surface coverage was above 40 per cent, the temperature increased slowly. This study provides a new approach to monitor near‐surface UHI and reveals its relationship with impervious surface, providing a scientific reference for urban planning and environmental assessment.     

Phenology of Six Ficus L., Moraceae,Species and its Effects on Pollinator Survival,in Brisbane,Queensland, Australia

The biogeography and historical distribution of various plants often depend as much on the environmental tolerance of their pollinators as they do on the tolerance of the plant. A four year, phenological study of 35 trees from six Ficus species was carried out in Brisbane's Central Business District. The presence of syconia (figs) and their sexual phases was recorded monthly for each tree. All six species bore ‘female’ phase syconia randomly in any month. The presence of ‘male’ phase syconia was seasonal for Ficus benjamina, Ficus microcarpa and Ficus virens. It was less seasonal for Ficus obliqua and Ficus rubiginosa. Ficus macrophylla exhibited aseasonal distribution of ‘male’ phase syconia. Symbiont pollinator wasp mortality was the cause of the skew in the seasonal distribution of ‘male’ phase syconia. Ficus benjamina, F. microcarpa and F. virens seldom had ‘male’ and ‘female’ phase syconia concurrently on an individual tree, while F. macrophylla and F. obliqua often did. Ficus rubiginosa was intermediate between the two groups. Intra‐tree overlap of syconia in both sexual phases permits short dispersal flights by pollinators and is advantageous to their survival during the cooler months. The pollinators of F. benjamina, F. microcarpa and F. virens, historically tropical and tropical/subtropical species, are unlikely to establish in temperate areas due to high winter mortality rates. The other three Ficus species historically occurred in temperate climates and the pollinators of two, F. macrophylla and F. rubiginosa, are extending their range into temperate Australia and New Zealand. The pollination biology of Ficus spp. will thus be a determining factor in whether a species is able to naturalise or become invasive in a location that experiences a particular climate, or if it is safe to use as a horticultural amenity species.     

DIGITAL CEMENTUM LUMINANCE ANALYSIS AND THE HAUA FTEAH HOMININS: HOW SEASONALITY AND SEASON OF USE CHANGED THROUGH TIME*

The importance of environmental seasonality and the seasonal cycling of resources to human populations make studies of human responses to seasonality useful to test hypotheses about short‐ and long‐term changes in human behaviour. This paper utilizes digital dental cementum luminance analysis in order to better understand patterns of the seasons of death of Ammotragus lervia at Haua Fteah, Cyrenaica, and to test whether long‐term climatic changes can be detected in dental cement. The overall pattern of the season of death of A. lervia at Haua Fteah is that of year‐round utilization, with a slight increase over time in A. lervia use during the growth period/summer time. The use of digital cementum luminance analysis (DCLA) to detect changes in the seasonal differences between temperatures indicates a trend for increased seasonality in temperature over the past 40 000 years at Haua Fteah. Furthermore, DCLA patterns in the more recent assemblages indicate a shift to a warmer climate from Marine Oxygen Isotope Stage (MIS) 3 to MIS 1.     

Climate change,human security and violent conflict

Climate change is increasingly been called a ‘security’ problem, and there has been speculation that climate change may increase the risk of violent conflict. This paper integrates three disparate but well-founded bodies of research – on the vulnerability of local places and social groups to climate change, on livelihoods and violent conflict, and the role of the state in development and peacemaking, to offer new insights into the relationships between climate change, human security, and violent conflict. It explains that climate change increasingly undermines human security in the present day, and will increasingly do so in the future, by reducing access to, and the quality of, natural resources that are important to sustain livelihoods. Climate change is also likely to undermine the capacity of states to provide the opportunities and services that help people to sustain their livelihoods. We argue that in certain circumstances these direct and indirect impacts of climate change on human security may in turn increase the risk of violent conflict. The paper then outlines the broad contours of a research programme to guide empirical investigations into the risks climate change poses to human security and peace.     

Climate change, uncertainty and prehistoric hunter–gatherer mobility

The onset of Little Ice Age conditions in California’s Sierra Nevada mountains resulted in increased temporal and spatial variability, and hence uncertainty regarding the distribution and production of resources targeted by its inhabitants, the Western Mono. The Mono responded with a risk-averse strategy composed of lowland winter population aggregation supported by logistical forays and seasonal residential dispersals to the high country, both ways of averaging variance in environmental productivity. These patterns were reconstructed using surface archaeology, GIS, and two straightforward spatial statistics, nearest-neighbor and variance-to-mean ratios, that combined provide a robust, objective picture of population aggregation and dispersal and the scale of these phenomena in different environments and seasons. These diverse strategies conform to expectations regarding the best ways for hunter–gatherers to cope with uncertainty, particularly in mountain environments. Despite this, the residentially mobile aspect of the pattern is rare in mountains and probably the result of historical connections between the Mono and Great Basin groups employing similar behaviors. Ultimately, this research suggests that climate change and environmental variability condition risk-averse, satisficing economic behaviors focused more on security than optimization, implying that pronounced environmental variability runs counter to economic intensification and its association with the evolution of more complex societies.