Trends In Climate Variables Research Articles

Research on Climate – Grapevine Yield Relationship and the Impact of Global Warming

Trends of climate variables were studied for the latest 41 years (1973-2013) and their effects on the quantity and quality of the grape production for Feteasca regala variety, clone 21 Bl, grafted on Kober 5 BB, in the plantation of the University of Agricultural Sciences and Veterinary Medicine, Bucharest, for the latest 16 years (1998-2013). Following the trend of main climate variables, there was a highly significant heating, especially in the summer. Some significant correlations were established between climate variables and production, sugar accumulation in the berries and titratable acidity in the must. Significant results were obtained with bioclimatic indices Huglin and Winkler. It also increased the number of hot days (with maximum temperature above 30°C) and very hot days (with maximum temperature above 35°C), which adversely affects the metabolism of vines, producing unbalanced wines. Since it is expected that this trend of temperature rising continues in the future and that the ripening period of the grapes takes place in warmer conditions, there are necessary adjustments of viticulture development strategies under the new conditions.

Sensitivity of Reference Crop Evapotranspiration in Shaanxi Province

Reference crop evapotranspiration (ET0) is a key to estimate crop water requirements, and also an important component of irrigation schedule and water resources planning, sensitivity analysis are crucial in assessing the impact of climate changes inET0estimations. In this study, based on the daily meteorological data of 18 meteorological stations in Shanxi Province from 1961 to 2000, the dailyET0values were calculated using Penman-Monteith equation recommended by FAO-56. The trends of climate variables were detected by using Mann-Kendall test. Sensitivity coefficients were employed to predict responses ofET0to five climatic variables, combined with annual of meteorological factors quantitative analysis ofET0changes. The results show that statistically significant decreasing trends are observed in wind and daily sunshine hours in Guanzhong and southern Shaanxi. Relative humidity has a significant decreasing trend in northern Shaanxi. In general,ET0value is on the decline; relative humidity is the most sensitive variable, followed by solar radiation, daily sunshine hour, wind speed and mean temperature. The change ofET0is primarily attributed to the significantly decreasing in wind speed and sunshine hour.

Spatial variability of the trends in climatic variables across China during 1961–2010

Distribution of meteorological stations is not uniform in many regions of the world, especially in developing countries like China. To eliminate the effect of uneven stations, this study produced a data set of areal average precipitation, air temperature, solar radiation, and wind speed from 736 meteorological station observations during 1961–2010 using an inverse-distance weighted technique. Based on the data set, this study detected the trends in climatic variables. Precipitation has a slight but no significant (p = 0.78) trend for the whole of China and has a significant increase trend in northwest China. Surface air temperature has a significant (p < 0.001) accelerating warming trend of 0.032 °C/a for the whole of China, and spatially larger in northern China than that in southern China. Solar radiation has a significant (p < 0.001) dimming trend of −0.14 W/(m2 · a) for the whole of China, and the largest dimming trend appears in eastern China, the possible cause for which is a high-aerosol concentration. Surface wind speed has a significant (p < 0.001) stilling trend of −0.012 m/(s·a) for the whole of China, the causes for which were speculated the changes in atmospheric circulation and surface roughness, as well as increases in aerosol concentration and the decrease in the south-north temperature gradient in China. In addition, three large-scale instrument replacements increase uncertainties of the trend analysis.

Subseasonal climate variability for North Carolina, United States

Subseasonal trends in climate variability for maximum temperature (Tmax), minimum temperature (Tmin) and precipitation were evaluated for 249 ground-based stations in North Carolina for 1950–2009. The magnitude and significance of the trends at all stations were determined using the non-parametric Theil–Sen Approach (TSA) and the Mann–Kendall (MK) test, respectively. The Sequential Mann–Kendall (SQMK) test was also applied to find the initiation of abrupt trend changes. The lag-1 serial correlation and double mass curve were employed to address the data independency and homogeneity. Using the MK trend test, statistically significant (confidence level≥95% in two-tailed test) decreasing (increasing) trends by 44% (45%) of stations were found in May (June). In general, trends were decreased in Tmax and increased in Tmin data series in subseasonal scale. Using the TSA method, the magnitude of lowest (highest) decreasing (increasing) trend in Tmax is −0.050°C/year (+0.052°C/year) in the monthly series for May (March) and for Tmin is −0.055°C/year (+0.075°C/year) in February (December). For the precipitation time series using the TSA method, it was found that the highest (lowest) magnitude of 1.00mm/year (−1.20mm/year) is in September (February). The overall trends in precipitation data series were not significant at the 95% confidence level except that 17% of stations were found to have significant (confidence level≥95% in two-tailed test) decreasing trends in February. The statistically significant trend test results were used to develop a spatial distribution of trends: May for Tmax, June for Tmin, and February for precipitation. A correlative analysis of significant temperature and precipitation trend results was examined with respect to large scale circulation modes (North Atlantic Oscillation (NAO) and Southern Oscillation Index (SOI)). A negative NAO index (positive-El Niño Southern Oscillation (ENSO) index) was found to be associated with the decreasing precipitation in February during 1960–1980 (2000–2009). The incremental trend in Tmin in the inter-seasonal (April–October) time scale can be associated with the positive NAO index during 1970–2000.

Changing Trends of Climatic Variables of Agro-Climatic Zones of Rice in South Korea

1986년 농촌진흥청에서는 벼 작물을 기준으로 전국의 기온, 강수량, 일조시간 등 기후요소의 분석과 평가를 통해, 전국을 19개 농업기후지대로 구분하였고(제주도 제외), 현재까지 벼의 안전재배기준과 기상재해 대책 등에 활용되고 있다. 본 연구에서는 최근 40년 동안 벼 작물 기준 19개 농업기후지대와 제주지역을 포함한 총 20개 농업기후지대의 연대별 기후요소의 변화 양상과 특징을 비교?분석하였다. 기상청 방재기상정보포탈시스템에서 서비스하는 1971년부터 2010년까지 40년 동안의 일별 기상자료를 바탕으로 연대별(1970년대, 1980년대, 1990년대, 2000년대)로 구분하여 분석하였다. 기간별 연평균기온은 1970년대의 12.0±0.14℃에서, 1980년대의 11.9±0.13℃와 1990년대의 12.2±0.14℃를 거쳐 2000년대의 12.6±0.13℃로 높아졌고, 기간별 연평균강수량은 1970년대의 1,270.3±20.05 mm에서 1980년대의 1,343.0±26.01와 1990년대의 1,350.6±27.13 mm를 거쳐 2000년대의 1,416.8±24.87 mm로 증가한 것으로 분석된 반면에, 기간별 연평균 일조시간은 1970년대의 2,421.7±18.37시간에서 1980년대의 2,352.4±15.01시간과 1990년대의 2,196.3±12.32시간을 거쳐 2000년대의 2,146.8± 15.37시간으로 크게 줄어든 것으로 조사되었다. 이들 기후요소를 농업기후지대별로 재분석하면, 연간 평균기온의 상승률은 중부 내륙지대(+1.2℃)와 동해안 남부지대(+1.1℃)에서 가장 높았고, 연간 누적강수량의 증가율은 태백고냉지대(+364 mm)와 태백준고냉지대(+326 mm)에서 가장 컸으며, 연간 누적일조시간은 중부 내륙지대(-995시간)에서 가장 많이 줄어든 것으로 평가되었다. 통계적으로 연간 평균기온(F=2.708, df=3, p=0.046)과 연간 누적강수량(F=5.037, df=3, p=0.002)은 유의하게 높아지거나 증가하였고, 연간 누적일조시간(F=26.181, df=3, p<0.0001)은 유의하게 감소하였다. 향후 벼 작물 농업기후지대 재구분을 통하여 각 농업기후지대별 기후특성에 적합한 벼 재배 안전작기, 벼 생육특성 및 작부체계 등에 대한 연구가 필요하다

Attribution of temperature and precipitation changes to greenhouse gases in northwest Iran

Increase of the greenhouse gases has a considerable effect on climatic variables changes such as temperature and precipitation. Three-dimensional models of coupled ocean–atmosphere general circulation, AOGCMs, under all emissions scenarios, are able to simulate past and future climate periods. The present study investigates the possible attribution of climate change to the increase of the greenhouse gases in northwest Iran. Interannual variability range for the long-term (1000 years) of temperature and precipitation, resulting from control run (greenhouse gas constant) CGCM3 model used for the study area in northwest Iran. Then, the range of natural climate variables was determined from two-dimensional graphs of temperature and precipitation based on two-variant normal distribution. Ultimately, the detected trends of climate variables can be compared with the natural climate variability range of the region. The results showed that in different parts of the study area, the range of natural climate variables for temperature and precipitation changes (95% probability) in the west of the study area are less than 1.8 C° and 40%, respectively. These values are less than 4 C° and 40% respectively, in the east of the study area. However, the climate variables in the most regions of the west are almost outside the range of natural climate variables in the recent years (1998–2008). The result indicates the effect of climate changes on the climatic variables for the case study in recent years.

Climatic indices for determining risks to the distribution and maintenance of Quercus emoryi Torr. (Fagaceae) in Mexico

Mexico is one of the two centres of diversification of oaks (Quercus spp.) in the world, with 161 species, 66% of which are endemic. The local-scale analysis of trends in climate variables, using climate indices, can be useful in estimating both the potential benefits and risks presented by climate to oak populations. Since the minimum January temperature is an important limiting factor in the distribution of Quercus emoryi Torr. in Mexico, this study analysed trends in this variable in the area of distribution of the species and identified the populations likely to be affected by them. The RClimDex 1.0 software was used to analyse trends of nine climate indices related to minimum temperature recorded in 14 weather stations in the area of the species’ potential distribution in Mexico. Data from five stations showed significant trends related to an increase in minimum January temperature, whereas data from seven stations showed trends of a decrease in this variable. Populations of the species, mainly in the ecoregion containing piedmonts and plains with grassland, scrubland and forests in the Cuauhtemoc region in Chihuahua state, and Cuencame and Canatlan regions in Durango state, could be affected by these trends. The information on at-risk populations may be used for in situ and ex situ species conservation programs.

Are climate model simulations useful for forecasting precipitation trends? Hindcast and synthetic-data experiments

Water scientists and managers currently face the question of whether trends in climate variables that affect water supplies and hazards can be anticipated. We investigate to what extent climate model simulations may provide accurate forecasts of future hydrologic nonstationarity in the form of changes in precipitation amount. We compare gridded station observations (GPCC Full Data Product, 1901–2010) and climate model outputs (CMIP5 Historical and RCP8.5 simulations, 1901–2100) in real and synthetic-data hindcast experiments. The hindcast experiments show that imputing precipitation trends based on the climate model mean reduced the root mean square error of precipitation trend estimates for 1961–2010 by 9% compared to making the assumption (implied by hydrologic stationarity) of no trend in precipitation. Given the accelerating pace of climate change, the benefits of incorporating climate model assessments of precipitation trends in water resource planning are projected to increase for future decades. The distribution of climate models’ simulated precipitation trends shows substantial spatially coherent biases, suggesting that there may be room for further improvement in how climate models are parametrized and used for precipitation estimation. Linear extrapolation of observed trends in long precipitation records may also be useful, particularly for lead times shorter than about 25 years. Overall, our findings suggest that simulations by current global climate models, combined with the continued maintenance of in situ hydrologic observations, can provide useful information on future changes in the hydrologic cycle.

Temporal and Spatial Trend of Climate Variability in Vietnam

Vietnam’s long coastline, geographic location, and diverse topography and climates contribute to its being one of the most hazard-prone countries of the Asia-Pacific region. Given that a high proportion of the country’s population and economic assets are located in coastal lowlands and deltas, Vietnam has been ranked among the five countries likely to be most affected by global climate change. This paper aims at providing a short overview on the temporal and spatial trends of climate variability in Vietnam which affected by global climate change.

Analysis of climatic variability and snow cover in the Kaligandaki River Basin, Himalaya, Nepal

Various remote sensing products and observed data sets were used to determine spatial and temporal trends in climatic variables and their relationship with snow cover area in the higher Himalayas, Nepal. The remote sensing techniques can detect spatial as well as temporal patterns in temperature and snow cover across the inaccessible terrain. Non-parametric methods (i.e. the Mann–Kendall method and Sen's slope) were used to identify trends in climatic variables. Increasing trends in temperature, approximately by 0.03 to 0.08 °C year−1 based on the station data in different season, and mixed trends in seasonal precipitation were found for the studied basin. The accuracy of MOD10A1 snow cover and fractional snow cover in the Kaligandaki Basin was assessed with respect to the Advanced Spaceborne Thermal Emission and Reflection Radiometer-based snow cover area. With increasing trends in winter and spring temperature and decreasing trends in precipitation, a significant negative trend in snow cover area during these seasons was also identified. Results indicate the possible impact of global warming on precipitation and snow cover area in the higher mountainous area. Similar investigations in other regions of Himalayas are warranted to further strengthen the understanding of impact of climate change on hydrology and water resources and extreme hydrologic events.

Institutional perceptions, adaptive capacity and climate change response in a post-conflict country: a case study from Central African Republic

The Central African Republic (CAR) faces increased vulnerability to climate change because it is a low-income country with low adaptive capacity; a situation that is exacerbated by recent civil conflict. This research analysed the perceptions of decision-makers within, and the response of diverse national, regional and international institutions to the complex challenges of climate change. Results indicate that while awareness of climate change is high, a concrete response is only in the beginning stages. There was a widespread recognition that the poor who depend on subsistence agriculture, and who constitute the majority of the population, would be most affected. Although CAR has low adaptive capacity, networking and connectivity among different institutions increased through the development of its National Adaptation Programme of Action and the REDD+ (Reducing Emissions from Deforestation and Forest Degradation) documents. In order to mitigate climate change and adapt agriculture and natural resource management to long-term trends in climate variability, such linkages need to be strengthened to build capacity within government institutions, within local communities and within non-governmental organizations that work with those communities. Building adaptive capacity to climate change can also contribute to the process of reconstruction, reconciliation and peace building in the country.

Effects of climate variability and climate change on crop production in southern Mali

In West Africa predictions of future changes in climate and especially rainfall are highly uncertain, and up to now no long-term analyses are available of the effects of climate on crop production. This study analyses long-term trends in climate variability at N’Tarla and Sikasso in southern Mali using a weather dataset from 1965 to 2005. Climatic variables and crop productivity were analysed using data from an experiment conducted from 1965 to 1993 at N’Tarla and from a crop yield database from ten cotton growing districts of southern Mali. Minimum daily air temperature increased on average by 0.05°C per year during the period from 1965 to 2005 while maximum daily air temperature remained constant. Seasonal rainfall showed large inter-annual variability with no significant change over the 1965–2005 period. However, the total number of dry days within the growing season increased significantly at N’Tarla, indicating a change in rainfall distribution. Yields of cotton, sorghum and groundnut at the N’Tarla experiment varied (30%) without any clear trend over the years. There was a negative effect of maximum temperature, number of dry days and total seasonal rainfall on cotton yield. The variation in cotton yields was related to the rainfall distribution within the rainfall season, with dry spells and seasonal dry days being key determinants of crop yield. In the driest districts, maize yields were positively correlated with rainfall. Our study shows that cotton production in southern Mali is affected by climate change, in particular through changes in the rainfall distribution.

Climate‐induced changes in biome distribution, NPP, and hydrology in the Upper Midwest U.S.: A case study for potential vegetation

AbstractWe investigated the impacts of recent climate change on potential vegetation distributions and carbon and water cycling across the Upper Midwest from 1948 to 2007. We used the Agro‐IBIS dynamic vegetation model driven by a newly developed gridded daily climate data set at 5 min × 5 min spatial resolution. Trends in climate variables were spatially heterogeneous over the study period and were associated with an overall increase in net primary productivity (NPP). We observed an average regional change in total NPP of 41 ± 30 g C m−2 (8%). Increased summer relative humidity and increased annual precipitation were key variables contributing to the positive trends. Mechanisms for increased productivity included a reduction in soil moisture stress as well as increased stomatal conductance resulting from an increase in summertime humidity. Model simulations also showed an average total increase in annual groundwater recharge throughout the region of 39 ± 35 mm (45%) driven by increases in annual precipitation. Evapotranspiration had a highly variable spatial trend over the 60 year period, with an average total change of 5 ± 21 mm (1%) across all grid cells. The location of the Tension Zone, a broad ecotone dividing northern mixed forests and southern hardwood forests and prairies, was not observed to migrate using analysis of meteorological variables.

Distribution and abundance of foliage‐arthropods across elevational gradients in the east and west Himalayas

AbstractElevational gradients are ideal for studying geographic variation in the distribution and abundance of organisms corresponding to predictable variation in climatic factors. This study provides a broad‐scale assessment of variation in distribution patterns of foliage‐dwelling arthropod orders along elevational gradients located across an extensive precipitation gradient in the Himalayas. Relative abundances of foliage‐dwelling arthropods were estimated from 16 sites during the summer months. Abundances declined significantly from east to west and peaked at intermediate elevations along elevational gradients, corresponding with trends in climatic variables.

Evidence of Recent Climate Change within the Historic Range of Rio Grande Cutthroat Trout: Implications for Management and Future Persistence

AbstractEvidence of anthropogenically influenced climate change has motivated natural resource managers to incorporate adaptive measures to minimize risks to sensitive and threatened species. Detecting trends in climate variables (i.e., air temperature and hydrology) can serve as a valuable management tool for protecting vulnerable species by increasing our understanding of localized conditions and trends. The Rio Grande cutthroat trout Oncorhynchus clarkii virginalis has suffered a severe decline in its historical distribution, with the majority of current populations persisting in isolated headwater streams. To evaluate recent climate change within the subspecies’ historical range, we examined trends in average air temperatures, biologically important hydrological variables (timing of snowmelt and seasonal flows), and the April 1 snow water equivalent over the last 45 years (1963–2007). While rates of change in all three metrics were variable across sites, rangewide patterns were evident. Across the subspecies’ historical range, average annual air temperatures increased (0.29°C per decade) and the timing of snowmelt shifted 10.6 d earlier in the year (2.3 d/decade). Flows increased during biologically important periods, including winter (January 1–March 31; 6.6% increase per decade), prespawning (April 1–May 14; 6.9% increase per decade), and spawning (May 15–June 15; 4.2% increase per decade) and decreased in summer (June 16–September 15; 1.9% decrease per decade). Evidence of decreasing April 1 snow water equivalent (5.3% per decade) was also observed. While the impacts of these changes at the population level are equivocal, it is likely that negative effects would influence the subspecies by altering its distribution, decreasing available habitat, and altering the timing of important life history components. Continued monitoring and proactive management will be required to increase the resiliency of remaining populations to ensure long‐term persistence and protection in a changing climate.

Evaluation of the impact of climatic trends and variability in rice–wheat system productivity using Cropping System Model DSSAT over the Indo-Gangetic Plains of India

Indo-Gangetic Plains (IGP), accountable for the region's food security, has undergone climatic fluctuations and variability during the last three decades under the influence of natural or fast trend of population growth, urbanization and industrial development. The objective of this study is to understand the trends of climatic variables over 5 selected locations during the last 25–30 years and the variability of recorded and simulated rice–wheat system yield using DSSAT-CSMv4.5. There was no significant change in rainfall over the years in both the rice and the wheat growing seasons at all the sites except Hisar. The annual change in the rainfall trend was −28.9mm/year (P<0.05) and during the rice season it was −20.5mm/year (P<0.01) for Hisar. Incidentally, higher coefficient of variation of 79% has been noticed in annual rainfall. The district average yields of rice varied from 0.9t/ha at Samastipur to 3.8t/ha at Ludhiana. Rice yields decreased from the west to east IGP. The time trend of rice yield ranged from −0.023t/ha per year at Samastipur to 0.055t/ha per year in Faizabad. Negative trends were observed in Samastipur and was statistically significant (P<0.05). In wheat, the yield trend ranged from 0.01t/ha per year at Samastipur to 0.096t/ha per year in Hisar. All the sites had a positive yield trend and at three stations (Hisar, Faizabad and Kanpur) have significant positive trends (P<0.05). Wheat yields appeared to be increasing throughout the IGP. The comparison of observed and simulated rice and wheat yield shows that there is very good agreement between them based on Spearman correlation coefficient (rs), significant at P<0.05 level for all the sites except Samastipur. Thus DSSAT-CSMv4.5 can be used for determining the impact of climatic variability on rice–wheat productivity.

On the attribution of changing pan evaporation in a nature reserve in SW China

AbstractNegative trends of measured pan evaporation are widely reported. Studies of the factors that underlie this reduction in pan evaporation have not reached a consensus about the controlling factors. Most studies employ statistical analysis (correlation analysis or stepwise regression) to identify the controlling climatic variables; in contrast, few studies have employed physical‐based theories. In addition, observations of pan evaporation and related climatic variables are reported to be influenced by anthropogenic activities. Consequently, the observed trends of climatic variables in a nature reserve would be useful for understanding regional climate change. The present study site is located in Ailaoshan National Nature Reserve, SW China, which is free of anthropogenic activity. In this study, we firstly applied the adjusted PenPan model to estimate the pan evaporation. Then, using this physical‐based model, we identified a positive trend in pan evaporation, with a much larger increase in the dry season than in the wet season. The model results indicate that the change in the aerodynamic component is larger than that in the radiative component. In contrast to the reduction in wind speed and sunshine hours that has been reported in previous studies at various sites, we found that wind speed and sunshine hours have increased in recent decades, thereby explaining the increase of the pan evaporation rate. Wind speed made the greatest contribution to the change in pan evaporation, followed by sunshine duration. This study indicates that the potential evaporation has increased at this site despite the widely reported reduction in measured pan evaporation. During the dry season, the availability of water for agriculture and agroforestry could be threatened. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Climatic trends in Gujarat and its likely impact on different crops

Maximum temperature, minimum temperature and rainfall of Anand, Junagadh, Mahuva, Navsari and SK Nagar stations of Gujarat were analyzed on seasonal (winter, summer, monsoon and postmonsoon) and annual time scales using long period data. Linear regression/least squares time series slope (parameteric) and Theil-Sen slope (non-parameteric) were used to investigate the trends of climate va riability. Parametric and non-parametric trend analysis showed fair agreement in result except some cases where the non-parametric approach revealed very high magnitude in slope. During winter season minimum temperature is increasing and maximum temperature is decreasing at Junagadh. At Mahuva minimum temperature is decreasing and maximum temperature is increasing during summer. Only Anand station showed statistically significant increasing annual trend for minimum and maximum temperatures. There was no significant trend for any temperature time series of SK Nagar station. The rainfall of Saurashtra region (Junagadh and Mahuva) showed increasing trend. The impact of increasing temperature on different crops was found negative while decreasing temperature was found positive in most of crop studied.

Trends in climate variability over Himachal Pradesh

The study indicates warming signals in all the study sites except Shimla during 1969 to 87. The study indicated of higher than average signals of warming in Himachal Pradesh upland than lowland regions viz. Fatehpur and Palam Valley in recent decades. The data analyzed in terms of day and night temperature indicated that the warming was predominantly due to an increase in maximum temperature. The annual rainfall in all the regions experienced decreasing trends. The rainfall during rabi season found to be increased by 1.0 to 7.44 mm y-1in the regions receiving snowfall during winter months.. The Palam and Kullu valley experienced decreasing trends in evaporation whereas relative humidity showed increasing trends at all elevations.

Trends and variability in pan evaporation and other climatic variables at Ibadan, Nigeria, 1973–2008

AbstractUnderstanding changes in evaporation rates is expected to be of great importance for water resource planning and management. This paper examines pan evaporation data as an example of the detection and attribution of trends in climate variables. Records of pan evaporation (Epan), rainfall (R), radiation (SR), wind speed (WS), temperature (Ta) and humidity (RH) for the period 1973–2008 were collected from the International Institute of Tropical Agriculture (IITA) in Ibadan, Nigeria. Mann–Kendall trend and Sen's slope tests were performed on the respective meteorological variables and a variability index (VI) was also computed for these. The results showed that annually Epan, SR and WS significantly decrease (P &lt; 0.001) while R, Ta, and RH showed insignificant increasing trends in the last four decades. Epan and SR decrease at the rate of 8.3 mm year−2 and 37.8 MJ m−2 year−1, respectively. Similar to Epan, SR decreased significantly in all the months (P &lt; 0.01) and the reduction ranged from 5.1% per decade in March to 9.3% per decade in August. The result of VI showed that the decrease in Epan and other explanatory variables is rather recent. Regression between Epan and other variables indicates that about 30, 15 and 6% of its variance can be explained by SR, WS and VPD (vapour pressure deficit), respectively. The possible roles of dust‐haze known as ‘harmattan’ winds and monsoon clouds in attenuating SR and hence reducing Epan are discussed. Copyright © 2011 Royal Meteorological Society