Search results for "Climate variability"
showing 9 items of 19 documents
How do tropical temperate troughs form and develop over southern Africa?
2014
16 pages ; Corrigendum Figure (Macron C, B Pohl, Y Richard & M Bessafi (2014) CORRIGENDUM. Journal of Climate, 27, 5198-5199. doi:10.1175/JCLI-D-14-00319.1); International audience; This paper aims at separating the respective influences of tropical and midlatitude variability on the development and life cycle of tropical temperate troughs (TTTs) over southern Africa in austral summer (November-February). Cluster analysis is applied to 1971-2000 40-yr ECMWF Re-Analysis (ERA-40) daily outgoing longwave radiation (OLR) anomalies to identify TTTs and monitor tropical convection. The same analysis applied to the zonal wind stretching deformation at 200 hPa (ZDEF) characterizes midlatitude trans…
Simulation of the effects of climate change on barley yields in rural Italy
2009
The Greenhouse effect is considered to be one of the most influential factors on climate change today, especially where temperature and rainfall levels/distribution are concerned, making it of considerable importance in the field of Agronomy. Crop growth and development simulation models are a valuable cognitive tool in understanding water and nutrient dynamics in soil/plant systems. This paper looks at the direct and indirect effects of climatic changes on average barley yields. The complex nature of the study rendered the use of mathematical simulation models essential, both for predicting future climate conditions and for the simulation of crop growth and development. Of the different si…
Cropping system dynamics, climate variability, and seed losses among East African smallholder farmers: a retrospective survey.
2014
Abstract Climate variability directly affects traditional low input and rain-fed farming systems, but few studies have paid attention retrospectively to the cropping system’s ability to mitigate climate risk. This study analyzes the impacts of rainfall variability on farmers’ seed variety losses over time, considering changes in smallholder farming systems. The cropping system dynamics, in favoring maize at the expense of sorghum and pearl millet, have induced an increasing risk of seed loss during drought. Combining ecological anthropology and climatology, a retrospective survey asking farmers about the period 1961–2006 was carried out at three altitudinal levels (750, 950, and 1100 m) on …
Changes in Climate and Land Use Over the Amazon Region: Current and Future Variability and Trends
2018
This paper shows recent progress in our understanding of climate variability and trends in the Amazon region, and how these interact with land use change. The review includes an overview of up-to-date information on climate and hydrological variability, and on warming trends in Amazonia, which reached 0.6-0.7 °C over the last 40 years, with 2016 as the warmest year since at least 1950 (0.9 °C +0.3°C). We focus on local and remote drivers of climate variability and change. We review the impacts of these drivers on the length of dry season, the role of the forest in climate and carbon cycles, the resilience of the forest, the risk of fires and biomass burning, and the potential “die back” of …
Multiscale variation in drought controlled historical forest fire activity in the boreal forests of eastern Fennoscandia
2017
Forest fires are a key disturbance in boreal forests, and characteristics of fire regimes are among the most important factors explaining the variation in forest structure and species composition. The occurrence of fire is connected with climate, but earlier, mostly local-scale studies in the northern European boreal forests have provided little insight into fire-climate relationship before the modern fire suppression period. Here, we compiled annually resolved fire history, temperature, and precipitation reconstructions from eastern Fennoscandia from the mid-16th century to the end of the 19th century, a period of strong human influence on fires. We used synchrony of fires over the network…
Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years
2021
Significance The variability of the Asian summer monsoon (ASM) is important for the functioning of ecological and societal systems at regional to continental scales, but the long-term evolution and interannual variability of this system is not well understood. Here, we present a stable isotope–based reconstruction of ASM variability covering 4680 BCE to 2011 CE. Superimposed on a gradual drying trend, a rapid drop in mean annual precipitation (>40%) toward persistently drier conditions occurred in ∼1675 BCE. This megadrought caused regional forest deterioration and enhanced aeolian activity affecting Chinese ecosystems. We argue that this abrupt aridification starting ∼2000 BCE triggered wa…
Climate variability, innovation and firm performance: evidence from the European agricultural sector
2021
Abstract It is generally accepted that adaptation to climate variability requires a technological advancement strategy. However, the innovation process has received little explicit consideration in this framework. We employ a panel endogenous switching regression model to explore whether and to what extent climate variability affects firm performance through the ability to induce the development of adaptation innovations in key resource-based sectors in Europe during the period 2007–2017. Our findings confirm that the knowledge generation process at the heart of climate change adaptation technologies enhances firm performance, especially for firms in the aquaculture and fishing sub-sectors …
Evidence for a link between the Atlantic Multidecadal Oscillation and annual asthma mortality rates in the US
2019
AbstractAn association between climatic conditions and asthma mortality has been widely assumed. However, it is unclear whether climatic variations have a fingerprint on asthma dynamics over long time intervals. The aim of this study is to detect a possible correlation between climatic indices, namely the Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation, and asthma mortality rates over the period from 1950 to 2015 in the contiguous US. To this aim, an analysis of non-stationary and non-linear signals was performed on time series of US annual asthma mortality rates, AMO and PDO indices to search for characteristic periodicities. Results revealed that asthma death rates evalu…
Atmospheric circulation modulates the spatial variability of temperature in the Atlantic-Arctic region
2019
International audience; The Arctic region has experienced significant warming during the past two decades with major implications on the cryosphere. The causes of Arctic amplification are still an open question within the scientific community, attracting recent interest. The goal of this study is to quantify the contribution of atmospheric circulation on temperature variability in the Atlantic–Arctic region at decadal to intra‐annual timescales from 1951 to 2014. Daily 20th Century reanalyses geopotential height anomalies at 500 hPa were clustered into different weather regimes to assess their contribution to observed temperature variability. The results show that in winter, 25% of the warm…