The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly...The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly affects the local land ecosystem and could consequently lead to notable vegetation changes. In this paper, the interannual variations of the plateau vegetation are investigated using a 21-year normalized difference vegetation index （NDVI） dataset to quantify the consequences of climate warming for the regional ecosystem and its interactions. The results show that vegetation coverage is best in the eastern and southern plateau regions and deteriorates toward the west and north. On the whole, vegetation activity demonstrates a gradual enhancement in an oscillatory manner during 1982-2002. The temporal variation also exhibits striking regional differences： an increasing trend is most apparent in the west, south, north and southeast, whereas a decreasing trend is present along the southern plateau boundary and in the central-east region. Covariance analysis between the NDVI and surface temperature/precipitation suggests that vegetation change is closely related to climate change. However, the controlling physical processes vary geographically. In the west and east, vegetation variability is found to be driven predominantly by temperature, with the impact of precipitation being of secondary importance. In the central plateau, however, temperature and precipitation factors are equally important in modulating the interannual vegetation variability.展开更多
Studies indicate that the climate has experienced a dramatic change in the Heihe River Basin with scope of temperature rise reaching 0.5-1.1 o C in the 1990s compared to the mean value of the per...Studies indicate that the climate has experienced a dramatic change in the Heihe River Basin with scope of temperature rise reaching 0.5-1.1 o C in the 1990s compared to the mean value of the period 1960-1990, precipitation increased 18.5 mm in the 1990s compared to the 1950s, and 6.5 mm in the 1990s compared to the mean value of the period 1960-1990, water resources decreased 2.6×10 8 m 3 in the 1990s compared to the 1950s, and 0.4×10 8 m 3 in the 1990s compared to the mean value of the period 1960-1990. These changes have exerted a greater effect on the local environment and socio-economy, and also made the condition worsening in water resources utilizations in the Heihe Rver Basin.展开更多
Global warming and climate change is one of the most extensively researched and discussed topical issues affecting the environment.Although there are enough historical evidence to support the theory that climate chang...Global warming and climate change is one of the most extensively researched and discussed topical issues affecting the environment.Although there are enough historical evidence to support the theory that climate change is a natural phenomenon,many research scientists are widely in agreement that the increase in temperature in the 20 th century is anthropologically related.The associated effects are the variability of rainfall and cyclonic patterns that are being observed globally.In Southeast Asia the link between global warming and the seasonal atmospheric flow during the monsoon seasons shows varying degree of fuzziness.This study investigates the impact of climate change on the seasonality of monsoon Asia and its effect on the variability of monsoon rainfall in Southeast Asia.The comparison of decadal variation of precipitation and temperature anomalies before the 1970 s found general increases which were mostly varying.But beyond the 1970 s,global precipitation anomalous showed increases that almost corresponded with increases in global temperature anomalies for the same period.There are frequent changes and a shift westward of the Indian summer monsoon.Although precipitation is observed to be 70%below normal levels,in some areas the topography affects the intensity of rainfall.These shifting phenomenon of other monsoon season in the region are impacting on the variability of rainfall and the onset of monsoons in Southeast Asia and is predicted to delay for 15 days the onset of the monsoon in the future.The variability of monsoon rainfall in the SEA region is observed to be decadal and the frequency and intensity of intermittent flooding of some areas during the monsoon season have serious consequences on the human,financial,infrastructure and food security of the region.展开更多
This paper investigated spatiotemporal dynamic pattern of vegetation,climate factor,and their complex relationships from seasonal to inter-annual scale in China during the period 1982–1998 through wavelet transform m...This paper investigated spatiotemporal dynamic pattern of vegetation,climate factor,and their complex relationships from seasonal to inter-annual scale in China during the period 1982–1998 through wavelet transform method based on GIMMS data-sets.First,most vegetation canopies demonstrated obvious seasonality,increasing with latitudinal gradient.Second,obvious dynamic trends were observed in both vegetation and climate change,especially the positive trends.Over 70%areas were observed with obvious vegetation greening up,with vegetation degradation principally in the Pearl River Delta,Yangtze River Delta,and desert.Overall warming trend was observed across the whole country(>98%area),stronger in Northern China.Although over half of area(58.2%)obtained increasing rainfall trend,around a quarter of area(24.5%),especially the Central China and most northern portion of China,exhibited significantly negative rainfall trend.Third,significantly positive normalized difference vegetation index(NDVI)–climate relationship was generally observed on the de-noised time series in most vegetated regions,corresponding to their synchronous stronger seasonal pattern.Finally,at inter-annual level,the NDVI–climate relationship differed with climatic regions and their long-term trends:in humid regions,positive coefficients were observed except in regions with vegetation degradation;in arid,semiarid,and semihumid regions,positive relationships would be examined on the condition that increasing rainfall could compensate the increasing water requirement along with increasing temperature.This study provided valuable insights into the long-term vegetation–climate relationship in China with consideration of their spatiotemporal variability and overall trend in the global change process.展开更多
A lot of researches have been done on the negative impacts and challenges caused by extreme weather conditions due to climate change and variability. Not many researches have been focused on the positive side in form ...A lot of researches have been done on the negative impacts and challenges caused by extreme weather conditions due to climate change and variability. Not many researches have been focused on the positive side in form of opportunities presented due to climate change. The study aimed to show the climate change scenarios and explore possible opportunities that could be derived from such scenarios in the southeastern region of Zimbabwe. The research used climate data records from three Zimbabwe Meteorological Services Department run weather stations in the region. The time series data were analyzed to show trends of rainfall and temperature over time. A questionnaire survey was also carried out to enquire from the farmers if they perceived climate change to have any opportunities. The rainfall trend analysis showed that rainfall amounts have declined at two of the three stations used. Rainfall total was also shown to be variable from year to year at all the stations. Ambient temperatures at all the stations were shown to have increased for both winter and summer. Opportunities that could be derived from climate change in the region were identified as the hydrological, agricultural and industrial. The research concludes that taking advantages of opportunities offered by climate change and variability provides the quickest way of embracing climate change adaptation.展开更多
In recent decades,large ensemble simulation(LENS)or super-large ensemble simulation(SLENS)experiments with climate models,including the simulation of both the historical and future climate,have been increasingly explo...In recent decades,large ensemble simulation(LENS)or super-large ensemble simulation(SLENS)experiments with climate models,including the simulation of both the historical and future climate,have been increasingly exploited in the fields of climate change,climate variability,climate projection,and beyond.This paper provides an overview of LENS in climate systems.It delves into its definition,initialization,significance,and scientific concerns.Additionally,its development history and relevant theories,methods,and primary fields of application are also reviewed.Conclusions obtained from single-model LENS can be more robust compared with those from ensemble simulations with smaller numbers of members.The interactions among model biases,forced responses,and internal variabilities,which serve as the added value in LENS,are highlighted.Finally,we put forward the future trajectory of LENS with climate or Earth system models(ESMs).Super-large ensemble simulation,high-resolution LENS,LENS employing ESMs,and combining LENS with artificial intelligence,will greatly promote the study of climate and related applications.展开更多
Climate change poses a significant threat to Nigeria's agricultural sector,which is a cornerstone of its economy and food security.The increasing frequency of extreme weather events,erratic rainfall patterns,and r...Climate change poses a significant threat to Nigeria's agricultural sector,which is a cornerstone of its economy and food security.The increasing frequency of extreme weather events,erratic rainfall patterns,and rising temperatures have disrupted agricultural productivity,threatening the livelihoods of millions of Nigerians.Through a comprehensive literature review,synthesizing data from peer-reviewed journals,institutional reports,and credible online sources from 2000 to 2023,this study aims to explore the multi-faceted impacts of climate variability on agricultural production,livestock,fisheries,and food security in Nigeria,and to identify effective adaptation strategies to mitigate these impacts.The findings reveal that climate change has significantly disrupted agricultural productivity in Nigeria,with erratic rainfall,rising temperatures,and extreme weather events leading to reduced crop yields,increased pest and disease pressure,and land degradation.Vulnerable crops such as maize,cassava,and rice are particularly affected,while livestock production faces challenges such as heat stress and reduced feed availability.The fisheries sector is also impacted,with shrinking water resources and increasing contamination levels threatening livelihoods.Adaptation strategies,including crop diversification,improved irrigation,and indigenous knowledge practices,offer some resilience but require substantial policy and financial support.The study highlights the urgency of implementing climate-smart agricultural practices,enhancing infrastructure,and promoting public-private partnerships to mitigate climate-induced risks.Recommendations align with the United Nations Sustainable Development Goals(SDGs)2(Zero Hunger),13(Climate Action),and 15(Life on Land),emphasizing the need for sustainable agricultural practices,ecosystem preservation,and adaptive policy frameworks to ensure food security and economic stability in Nigeria.This study provides valuable insights into the impacts of climate change on Nigeria's agricultural sector and offers practical recommendations for building resilience and ensuring sustainable food systems.It reveals the importance of collaborative efforts at all levels to address the challenges posed by climate change and safeguard the nation's agricultural heritage for future generations.展开更多
Forests all over the world have been dramatically impacted by climate change,which has contributed to an increase in the number of pathogen invasions and the rise in the prevalence of forest diseases.This article pres...Forests all over the world have been dramatically impacted by climate change,which has contributed to an increase in the number of pathogen invasions and the rise in the prevalence of forest diseases.This article presents a systematic review that investigates the intricate relationship between climate change and the prevalence of forest diseases.The study identifies climate-related factors that drive the rising incidence of these forest diseases.Following the PRISMA guidelines,73 studies were selected and analyzed from a pool of 3,510 articles,focusing on their spatial and temporal patterns,contextual drivers,and linkages to climate change.The findings underscore the critical role of extended drought periods and rising temperatures as key factors exacerbating forest disease outbreaks.Methodologically,only 3%of the studies utilized field sampling,indicating a predominance of laboratory analysis methods at 45%.Geographically,temperate forests accounted for 78%of the studies,forest plantations 20%,and boreal forests 2%.This review highlights the pressing need for sustainable forest management practices to counteract the adverse impacts of climate change on forest ecosystems.By identifying critical climate drivers and ecological vulnerabilities,this research provides a foundation for adaptive silviculture and pathogen management strategies.展开更多
The Songhua River Basin(SRB),ranking third largest in China in terms of both runoff volume and basin area,has experi-enced frequent disasters and drastic changes in runoff since the early 20th century.Many studies hav...The Songhua River Basin(SRB),ranking third largest in China in terms of both runoff volume and basin area,has experi-enced frequent disasters and drastic changes in runoff since the early 20th century.Many studies have analyzed the causes of runoff re-duction;however,the spatiotemporal differences in runoff contributions and their underlying mechanisms remain poorly understood,which are crucial for regional water resources management and effective utilization.This study used the Mann-Kendall rank correlation trend test,continuous wavelet analysis,cumulative anomaly,and the slope change ratio of cumulative quantities(SCRCQ)method to explore the runoff changes characteristics and spatiotemporal differences of the contributions of climate change and human activities to runoff changes across three sub-basins of the SRB.The results show that:1)runoff from 1955 to 2022 in all the three sub-basins exhibit a statistically significant decreasing trend at 0.05 significant level.2)Four abrupt change points in runoff were detected in Nenjiang River Basin(NRB)and the mainstream of the SRB(MSRB),whereas only two change points in the Second Songhua River(SSRB).3)Runoff and precipitation series of the NRB and MSRB exhibit similar multi-timescale cycle characteristics with the most dominated cycles of 45-58 yr.In contrast,it is 12-18 yr for SSRB.4)Anthropogenic activities are the primary factor leading to in the reduction of runoff in NRB(74.33%-91.67%)and MSRB(50.11%-102.12%),whereas it is only 5.38%-33.12%in SSRB.This is attributed to the uneven distribution of regional climate and human activities in the entire SRB.5)With the growing demand for water diversion for agri-cultural irrigation,anthropogenic activities in the NRB and MSRB have increased.However,the opposite is found in SSR,where the in-creased influence of precipitation on runoff and water conservation policies are identified.展开更多
Understanding changes in land surface processes over the past several decades requires knowledge of trends and interannual variability in surface energy fluxes in response to climate change. In our study, the Communit...Understanding changes in land surface processes over the past several decades requires knowledge of trends and interannual variability in surface energy fluxes in response to climate change. In our study, the Community Land Model version 3.5 （CLM3.5）, driven by the latest updated hybrid reanalysis-observational surface climate data from Princeton University, is used to obtain global distributions of surface energy fluxes during 1948 to 2000. Based on the climate data and simulation results, long-term trends and interannual variability （IAV） of both climatic variables and surface energy fluxes for this span of 50＋ years are derived and analyzed. Regions with strong long-term trends and large IAV for both climatic variables and surface energy fluxes are identified. These analyses reveal seasonal variations in the spatial patterns of climate and surface fluxes; however, spatial patterns in trends and IAV for surface energy fluxes over the past ～50 years do not fully correspond to those for climatic variables, indicating complex responses of land surfaces to changes in the climatic forcings.展开更多
Comparing the perception of farmers to climate change and variability in Bako Tibe, Ethiopia and Abeokuta, Nigeria is important in promoting sustainable agriculture and in understanding the impact of climate change an...Comparing the perception of farmers to climate change and variability in Bako Tibe, Ethiopia and Abeokuta, Nigeria is important in promoting sustainable agriculture and in understanding the impact of climate change and variability on agriculture in Africa. A total of 153 farmers were interviewed in both study areas using well structure questionnaire. The study describes the socioeconomic characteristics of farmers using descriptive statistics and thereafter the perception of Bako Tibe and Abeokuta farmers to climate change and variability was examined using Likert type scale. The binary logistics regression was later used to ascertain the effect of socioeconomic characteristics on perception of the farmers in both study areas. The farmers in both study areas believed that there have been changes in the amount of rainfall and temperature in the past thirty years. The farmers in Bako agreed that there have been increased temperature and decreased rainfall, contrary to the farmer’s perception in Abeokuta. The binary logistic regression results showed that socioeconomic characteristics of farmers in Bako Tibe, have no effect on the perception of farmers on climate change and variability. However, in Abeokuta, age, land ownership, and distance to market had an effect on the perception on the farmers on climate change and variability. The adaptation strategies to climate change and variability commonly used by Bako Tibe farmers was, improved seed (drought resistance) adaptation method, while most farmers in Abeokuta used soil moisture conservation adaptation method. The study recommends that government and Non-Governmental Organization of both countries should promote more adaptation and mitigation practices to climate change and variability through policy interventions to help curb the impact of climate change and variability to agriculture.展开更多
The magnitude and trend of temperature and rainfall extremes as indicators of climate variability and change were investigated in the Arid and Semi-Arid Lands (ASALs) of Kenya using in-situ measurements and gridded cl...The magnitude and trend of temperature and rainfall extremes as indicators of climate variability and change were investigated in the Arid and Semi-Arid Lands (ASALs) of Kenya using in-situ measurements and gridded climate proxy datasets, and analysed using the Gaussian-Kernel analysis and the Mann-Kendall statistics. The results show that the maximum and minimum temperatures have been increasing, with warmer temperatures being experienced mostly at night time. The average change in the mean maximum and minimum seasonal surface air temperature for the region were 0.74°C and 0.60°C, respectively between the 1961-1990 and 1991-2013 periods. Decreasing but statistically insignificant trends in the seasonal rainfall were noted in the area, but with mixed patterns in variability. The March-April-May rainfall season indicated the highest decrease in the seasonal rainfall amounts. The southern parts of the region had a decreasing trend in rainfall that was greater than that of the northern areas. The results of this study are expected to support sustainable pastoralism system prevalent with the local communities in the ASALs.展开更多
This paper presents the lessons learnt from a research project titled “Improving Beef Cattle Productivity for Enhanced Food Security and Efficient Utilization of Natural Resources in the Lake Victoria Basin” which i...This paper presents the lessons learnt from a research project titled “Improving Beef Cattle Productivity for Enhanced Food Security and Efficient Utilization of Natural Resources in the Lake Victoria Basin” which includes Tanzania, Uganda and Rwanda. The key focus is on the implications of land use land cover change and climate variability on the future prospects of beef cattle production in this region. The study utilizes information and data from natural resources and climate components to deduce the impact of land use and land cover changes on climate variability. Additional analysis is conducted to summarize the land use and land cover data to carry out analysis on climate data using the Mann-Kendal test, linear regression and moving averages to reveal patterns of change and trends in annual and seasonal rainfall and temperature. The findings reveal that the study areas of Rwanda, Uganda and Tanzania in the Lake Victoria Basin (LVB) have changed over time following land cover manipulations and land use change, coupled with climate variability. The grazing land has been converted to agriculture and settlements, thereby reducing cattle grazing land which is the cheapest and major feed source for ruminant livestock production. Although the cattle population has been on the increase in the same period, it has been largely attributed to the fact that the carrying capacity of available grazing areas had not been attained. The current stocking rates in the LVB reveal that the rangelands are greatly overstocked and overgrazed with land degradation already evidenced in some areas. Climate variability coupled with a decrease in grazing resources is driving unprecedented forage scarcity which is now a major limiting factor to cattle production. Crop cultivation and settlement expansion are major land use types overtaking grazing lands;therefore the incorporation of crop residues into ruminant feeding systems could be a feasible way to curtail rangeland degradation and increase beef cattle production.展开更多
This study aimed at assessing perception of Fogera cattle farmers on climate change and variability in selected districts of Awi zone. The zone was classified as lowland (<1500), midland (1500 - 2500), and highland...This study aimed at assessing perception of Fogera cattle farmers on climate change and variability in selected districts of Awi zone. The zone was classified as lowland (<1500), midland (1500 - 2500), and highland (>2500 m.a.s.l) based on altitudinal variation from which a total of three districts one per cluster were selected through random sampling. 150 households were selected through systematic random sampling targeting Fogera cattle owners for primary data collection. Over 36 years (from 1983-2019) of meteorological data were taken from the National Meteorological Agency. Meteorological data result confirmed that climate was changing across all the agro-ecological zones. Both the mean annual maximum and minimum temperature was considerably increasing for all agro-ecological zones whereas the mean annual rainfall was decreasing which is consistent with the farmers’ perception. Meteorological data result also showed that the short rainy and dry season rainfall indicated high interannual variability at all agro-ecological zones. Survey result revealed that 97.13% of the farmers recognized climate change and variability impact in all agro-ecological zones. About 80.91% of Fogera cattle farmers reported the incidence of negative impacts of climate change and variability on cattle. Chi-square test values of survey results show that in all agro-ecological zones frequency of drought, duration of dry spell, wind, and floods were ever-increasing (p < 0.001). Moreover, about 84.48%, 65.3%, and 60.47% of farmers owning Fogera cattle in the lowland, midland, and highland, respectively perceived the prevalence of increasing (p < 0.001) cattle mortality. In response to climate change and variability, farmers were reducing number of livestock, diversification of livestock species, and replacing Fogera cattle with small ruminants as adaptation strategies. Thus, regular prediction of climate change and variability and designing pertinent response strategies is essential to reduce the adverse impacts of climate change for enhancing resilience capacity of the Fogera cattle farmers in the study areas.展开更多
Forty years ago, Klaus Wyrtki （1975） of University of Hawaii discovered that E1 Nifio warming off South America is not a result of local wind change but a response to the relaxed equatorial trade winds some 10 000 k...Forty years ago, Klaus Wyrtki （1975） of University of Hawaii discovered that E1 Nifio warming off South America is not a result of local wind change but a response to the relaxed equatorial trade winds some 10 000 km away near the international dateline. The Kelvin wave mechanism was quickly verified from wind-forced ocean model simulations. Consequent develop- ments show that the dance between the fast-reacting atmosphere and slow-evolving ocean sets the pace of E1 Nifio-Southern Oscillation （ENSO; Philander, 1990）. The concept of ocean-atmosphere interaction has revolutionized our view of the climate system and led to operational climate prediction.展开更多
The Boreal forest is a terrestrial ecosystem highly vulnerable to the impacts of short-term climate and weather variabilities. Detecting abrupt, rapid climate-induced changes in fire weather and related changes in fir...The Boreal forest is a terrestrial ecosystem highly vulnerable to the impacts of short-term climate and weather variabilities. Detecting abrupt, rapid climate-induced changes in fire weather and related changes in fire seasonality can provide important insights to assessing impacts of climate change on forestry. This paper, taking the Sakha Republic of Russia as study area, aims to suggest an approach for detecting signals indicating climate-induced changes in fire weather to express recent fire weather variability by using short-term ranks of major meteorological parameters such as air temperature and atmospheric precipitation. Climate data from the “Global Summary of the Day Product” of NOAA (the United States National Oceanic and Atmospheric Administration) for 1996 to 2018 were used to investigate meteorological parameters that drive fire activity. The detection of the climate change signals is made through a 4-step analysis. First, we used descriptive statistics to grasp monthly, annual, seasonal and peak fire period characteristics of fire weather. Then we computed historical normals for WMO reference period, 1961-1990, and the most recent 30-year period for comparison with the current means. The variability of fire weather is analyzed using standard deviation, coefficient of variation, percentage departures from historical normals, percentage departures from the mean, and precipitation concentration index. Inconsistency and abrupt changes in the evolution of fire weather are assessed using homogeneity analysis whilst a Mann-Kendall test is used to detect significant trends in the time series. The results indicate a significant increase of temperature during spring and fall months, which extends the fire season and potentially contributes to increase of burned areas. We again detected a significant rainfall shortage in September which extended the fire season. Furthermore, this study suggests a new approach in statistical methods appropriate for the detection of climate change signals on fire weather variability using short-term climate ranks and evaluation of its impact on fire seasonality and activity.展开更多
Climate change has resulted in serious social-economic ramifications and extremely catastrophic weather events in the world, Tanzania and Zanzibar in particular, with adaptation being the only option to reduce impacts...Climate change has resulted in serious social-economic ramifications and extremely catastrophic weather events in the world, Tanzania and Zanzibar in particular, with adaptation being the only option to reduce impacts. The study focuses on the influence of climate change and variability on spatio-temporal rainfall and temperature variability and distribution in Zanzibar. The station observation datasets of rainfall, T<sub>max</sub> and T<sub>min</sub> acquired from Tanzania Meteorological Authority (TMA) and the Coordinated Regional Climate Downscaling Experiment program (CORDEX) projected datasets from the Regional climate model HIRHAM5 under driving model ICHEC-EC-EARH, for the three periods of 1991-2020 used as baseline (HS), 2021-2050 as near future (NF) and 2051-2080 far future (FF), under two representative concentration pathways (RCP) of 4.5 and 8.5, were used. The long-term observed T<sub>max</sub> and T<sub>min</sub> were used to produce time series for observing the nature and trends, while the observed rainfall data was used for understanding wet and dry periods, trends and slope (at p ≤ 0.05) using the Standardized Precipitation Index (SPI) and the Mann Kendall test (MK). Moreover, the Quantum Geographic Information System (QGIS) under the Inverse Distance Weighting (IDW) interpolation techniques were used for mapping the three decades of 1991-2000 (hereafter D1), 2001-2010 (hereafter D2) and 2011-2020 (hereafter D3) to analyze periodical spatial rainfall distribution in Zanzibar. As for the projected datasets the Climate Data Operator Commands (CDO), python scripts and Grid analysis and Display System (GrADS) soft-wares were used to process and display the results of the projected datasets of rainfall, T<sub>max</sub> and T<sub>min</sub> for the HS, NF and FF, respectively. The results show that the observed T<sub>max</sub> increased by the rates of 0.035℃ yr<sup>-</sup><sup>1</sup> and 0.0169℃ yr<sup>-</sup><sup>1</sup>, while the T<sub>min</sub> was increased by a rate of 0.064℃ yr<sup>-</sup><sup>1</sup> and 0.104℃ yr<sup>-</sup><sup>1</sup> for Unguja and Pemba, respectively. The temporal distribution of wetness and dryness indices showed a climate shift from near normal to moderate wet during 2005 at Zanzibar Airport, while normal to moderately dry conditions, were observed in Pemba at Matangatuani. The decadal rainfall variability and distributions revealed higher rainfall intensity with an increasing trend and good spatial distribution in D3 from March to May (MAM) and October to December (OND). The projected results for T<sub>max</sub> during MAM and OND depicted higher values ranging from 1.7℃ - 1.8℃ to 1.9℃ - 2.0℃ and 1.5℃ to 2.0℃ in FF compared to NF under both RCPs. Also, higher T<sub>min</sub> values of 1.12℃ - 1.16℃ was projected in FF for MAM and OND under both RCPs. Besides, the rainfall projection generally revealed increased rainfall intensity in the range of 0 - 25 mm for Pemba and declined rainfall in the range of 25 - 50 mm in Unguja under both RCPs in perspectives of both NF and FF. Conclusively the study has shown that the undergoing climate change has posed a significant impact on both rainfall and temperature spatial and temporal distributions in Zanzibar (Unguja and Pemba), with Unguja being projected to have higher rainfall deficits while increasing rainfall strengths in Pemba. Thus, the study calls for more studies and formulation of effective adaptation, strategies and resilience mechanisms to combat the projected climate change impacts especially in the agricultural sector, water and food security.展开更多
This study presents the work commenced in northern Thailand on spatial and temporal variability of rainfall. Thirty years (1988-2017) rainfall data of eight meteorological stations were used for assessing temporal var...This study presents the work commenced in northern Thailand on spatial and temporal variability of rainfall. Thirty years (1988-2017) rainfall data of eight meteorological stations were used for assessing temporal variability and trend analysis. The results showed decreasing trend in rainfall from its first half of the observed study period (1988-2002) to last half of the time period (2003-2017) in total average annual as well as monsoonal average rainfall by 14.92% and 15.50% respectively. It was predicted from linear regression results that by 2030 the average annual and monsoonal rainfall will drop by 35% and 34.10% respectively. All stations showed negative trend except Fakara met-station in annual rainfall. In the seasonal trend analysis, the results showed decreasing trend almost in all met-stations. Mann-Kendall trend test was applied to assess the trend. All met-stations show significant negative trend. To assess drought in the study area, Standardized Precipitation Index (SPI) was applied to 12-month temporal time period. The results predicted meteorological drought in the near future. The spatial distribution of rainfall presented changing phenomena in average annual, monsoonal, winter, and summer seasons in both analyzed periods.展开更多
Under the impacts of climate change and human activities, great uncertainties still exist in the response of climate extremes, especially in Central Asia (CA). In this study, we investigated spatial-temporal variation...Under the impacts of climate change and human activities, great uncertainties still exist in the response of climate extremes, especially in Central Asia (CA). In this study, we investigated spatial-temporal variation trends and abrupt changes in 17 indices of climate extremes, based on daily climate observations from 55 meteorological stations in CA during 1957-2005. We also speculated as to which atmospheric circulation factors had the greatest impacts on climate extremes. Our results indicated that the annual mean temperature (Tav), mean maximum and minimum temperature significantly increased at a rate of 0.32ºC/10a, 0.24ºC/10a and 0.41ºC/10a, respectively, which was far higher than the increasing rates either globally or across the Northern Hemisphere. Other temperature extremes showed widespread significant warming trends, especially for those indices derived from daily minimum temperature. All temperature extremes exhibited spatially widespread rising trends. Compared to temperature changes, precipitation extremes showed higher spatial and temporal variabilities. The annual total precipitation significantly increased at a rate of 4.76 mm/10a, and all precipitation extremes showed rising trends except for annual maximum consecutive dry days (CDD), which significantly decreased at a rate of -3.17 days/10a. On the whole, precipitation extremes experienced slight wetter trends in the Tianshan Mountains, Kazakhskiy Melkosopochnik (Hill), the Kyzylkum Desert and most of Xinjiang. The results of Cumulative Deviation showed that Tav and Txav had a significant abrupt change around 1987, and all precipitation indices experienced abrupt changes in 1986. Spearman’s correlation analysis pointed to Siberian High and Tibetan Plateau Index_B as possibly being the most important atmospheric circulation factors affecting climate extremes in CA. A full quantitative understanding of these changes is crucial for the management and mitigation of natural hazards in this region.展开更多
℃ Climate change is likely to affect hydrological cycle through precipitation, evapotranspiration, soil moisture etc. In the present study, an attempt has been made to study the climate change and the sensitivity of...℃ Climate change is likely to affect hydrological cycle through precipitation, evapotranspiration, soil moisture etc. In the present study, an attempt has been made to study the climate change and the sensitivity of estimated evapotranspiration to each climatic variable for a semi-arid region of Beijing in North China using data set from 1951 to 2010. Penman-Monteith method was used to calculate reference crop evapotranspiration （ETo）. Changes of ETo to each climatic variable was estimated using a sensitivity analysis method proposed in this study. Results show that in the past 60 years, mean temperature and vapor pressure deficit （VPD） were significantly increasing, relative humidity and sunshine hours were significantly decreasing, and wind speed greatly oscillated without a significant trend. Total precipitation was significantly decreasing in corn season （from June to September）, but it was increasing in wheat season （from October to next May）. The change rates of tem- perature, relative humidity, VPD, wind speed, annual total precipitation, sunshine hours and solar radiation were 0.42℃, 1.47%, 0.04 kPa, 0.05 m.s-1, 25.0 mm, 74.0 hours and 90.7 MJ.m-2 per decade, respectively. In the past 60 years, yearly ETo was increasing with a rate of 19.5 mm per decade, and total ETos in wheat and corn seasons were increasing with rates of 13.1 and 5.3 mm per decade, respectively. Sensitivity analysis showed that mean air temperature was the first key factor for ETo change in the past 60 years, causing an annual total ETo increase of 7.4%, followed by relative humidity （5.5%） and sunshine hours （-3.1%）; the less sensitivity factors were wind speed （0.7%）, minimum temperature （-0.3%） and maximum temperature （-0.2%）. A greater reduction of total ETo （12.3%） in the past 60 years was found in wheat season, mainly because of mean temperature （8.6%） and relative hu- midity （5.4%）, as compared to a reduction of 6.0% in ETo during corn season due to sunshinehours （-6.9%）, relative humidity （4.7%） and temperature （4.5%）. Increasing precipitation in the wheat season will improve crop growth, while decreasing precipitation and increasing ETo in the corn season induces a great pressure for local government and farmers to use water more efficiently by widely adopting water-saving technologies in the future.展开更多
基金supported by the foundation from:the program of the National Natural Science Foundation of China(40675037)the key program of the Sichuan Province Youth Science and Technology Fund(05ZQ026-023)the opening project of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences.
文摘The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly affects the local land ecosystem and could consequently lead to notable vegetation changes. In this paper, the interannual variations of the plateau vegetation are investigated using a 21-year normalized difference vegetation index （NDVI） dataset to quantify the consequences of climate warming for the regional ecosystem and its interactions. The results show that vegetation coverage is best in the eastern and southern plateau regions and deteriorates toward the west and north. On the whole, vegetation activity demonstrates a gradual enhancement in an oscillatory manner during 1982-2002. The temporal variation also exhibits striking regional differences： an increasing trend is most apparent in the west, south, north and southeast, whereas a decreasing trend is present along the southern plateau boundary and in the central-east region. Covariance analysis between the NDVI and surface temperature/precipitation suggests that vegetation change is closely related to climate change. However, the controlling physical processes vary geographically. In the west and east, vegetation variability is found to be driven predominantly by temperature, with the impact of precipitation being of secondary importance. In the central plateau, however, temperature and precipitation factors are equally important in modulating the interannual vegetation variability.
基金National Natural Science Foundation of China , No.40235053 Knowledge Innovation Project of CAS+1 种基金 No.KZCX3-SW-329 No.KZCX1-10-03-01
文摘Studies indicate that the climate has experienced a dramatic change in the Heihe River Basin with scope of temperature rise reaching 0.5-1.1 o C in the 1990s compared to the mean value of the period 1960-1990, precipitation increased 18.5 mm in the 1990s compared to the 1950s, and 6.5 mm in the 1990s compared to the mean value of the period 1960-1990, water resources decreased 2.6×10 8 m 3 in the 1990s compared to the 1950s, and 0.4×10 8 m 3 in the 1990s compared to the mean value of the period 1960-1990. These changes have exerted a greater effect on the local environment and socio-economy, and also made the condition worsening in water resources utilizations in the Heihe Rver Basin.
文摘Global warming and climate change is one of the most extensively researched and discussed topical issues affecting the environment.Although there are enough historical evidence to support the theory that climate change is a natural phenomenon,many research scientists are widely in agreement that the increase in temperature in the 20 th century is anthropologically related.The associated effects are the variability of rainfall and cyclonic patterns that are being observed globally.In Southeast Asia the link between global warming and the seasonal atmospheric flow during the monsoon seasons shows varying degree of fuzziness.This study investigates the impact of climate change on the seasonality of monsoon Asia and its effect on the variability of monsoon rainfall in Southeast Asia.The comparison of decadal variation of precipitation and temperature anomalies before the 1970 s found general increases which were mostly varying.But beyond the 1970 s,global precipitation anomalous showed increases that almost corresponded with increases in global temperature anomalies for the same period.There are frequent changes and a shift westward of the Indian summer monsoon.Although precipitation is observed to be 70%below normal levels,in some areas the topography affects the intensity of rainfall.These shifting phenomenon of other monsoon season in the region are impacting on the variability of rainfall and the onset of monsoons in Southeast Asia and is predicted to delay for 15 days the onset of the monsoon in the future.The variability of monsoon rainfall in the SEA region is observed to be decadal and the frequency and intensity of intermittent flooding of some areas during the monsoon season have serious consequences on the human,financial,infrastructure and food security of the region.
基金The authors gratefully acknowledge the financial support received for this work from the National Natural Science Foundation of China(grant number 41071267)the Scientific Research Foundation for Returned Scholars,Ministry of Education of China(grant number[2012]940)the Science Foundation of Fujian Province(grant numbers 2012I0005 and 2012J01167)。
文摘This paper investigated spatiotemporal dynamic pattern of vegetation,climate factor,and their complex relationships from seasonal to inter-annual scale in China during the period 1982–1998 through wavelet transform method based on GIMMS data-sets.First,most vegetation canopies demonstrated obvious seasonality,increasing with latitudinal gradient.Second,obvious dynamic trends were observed in both vegetation and climate change,especially the positive trends.Over 70%areas were observed with obvious vegetation greening up,with vegetation degradation principally in the Pearl River Delta,Yangtze River Delta,and desert.Overall warming trend was observed across the whole country(>98%area),stronger in Northern China.Although over half of area(58.2%)obtained increasing rainfall trend,around a quarter of area(24.5%),especially the Central China and most northern portion of China,exhibited significantly negative rainfall trend.Third,significantly positive normalized difference vegetation index(NDVI)–climate relationship was generally observed on the de-noised time series in most vegetated regions,corresponding to their synchronous stronger seasonal pattern.Finally,at inter-annual level,the NDVI–climate relationship differed with climatic regions and their long-term trends:in humid regions,positive coefficients were observed except in regions with vegetation degradation;in arid,semiarid,and semihumid regions,positive relationships would be examined on the condition that increasing rainfall could compensate the increasing water requirement along with increasing temperature.This study provided valuable insights into the long-term vegetation–climate relationship in China with consideration of their spatiotemporal variability and overall trend in the global change process.
文摘A lot of researches have been done on the negative impacts and challenges caused by extreme weather conditions due to climate change and variability. Not many researches have been focused on the positive side in form of opportunities presented due to climate change. The study aimed to show the climate change scenarios and explore possible opportunities that could be derived from such scenarios in the southeastern region of Zimbabwe. The research used climate data records from three Zimbabwe Meteorological Services Department run weather stations in the region. The time series data were analyzed to show trends of rainfall and temperature over time. A questionnaire survey was also carried out to enquire from the farmers if they perceived climate change to have any opportunities. The rainfall trend analysis showed that rainfall amounts have declined at two of the three stations used. Rainfall total was also shown to be variable from year to year at all the stations. Ambient temperatures at all the stations were shown to have increased for both winter and summer. Opportunities that could be derived from climate change in the region were identified as the hydrological, agricultural and industrial. The research concludes that taking advantages of opportunities offered by climate change and variability provides the quickest way of embracing climate change adaptation.
基金This study was supported by the National Natural Science Foundation of China(Grant No.U2342228)the National Key Program for Developing Basic Sciences(Grant No.2020YFA0608902)+1 种基金the National Natural Science Foundation of China(Grant Nos.92358302,and 42242018)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0500303).
文摘In recent decades,large ensemble simulation(LENS)or super-large ensemble simulation(SLENS)experiments with climate models,including the simulation of both the historical and future climate,have been increasingly exploited in the fields of climate change,climate variability,climate projection,and beyond.This paper provides an overview of LENS in climate systems.It delves into its definition,initialization,significance,and scientific concerns.Additionally,its development history and relevant theories,methods,and primary fields of application are also reviewed.Conclusions obtained from single-model LENS can be more robust compared with those from ensemble simulations with smaller numbers of members.The interactions among model biases,forced responses,and internal variabilities,which serve as the added value in LENS,are highlighted.Finally,we put forward the future trajectory of LENS with climate or Earth system models(ESMs).Super-large ensemble simulation,high-resolution LENS,LENS employing ESMs,and combining LENS with artificial intelligence,will greatly promote the study of climate and related applications.
文摘Climate change poses a significant threat to Nigeria's agricultural sector,which is a cornerstone of its economy and food security.The increasing frequency of extreme weather events,erratic rainfall patterns,and rising temperatures have disrupted agricultural productivity,threatening the livelihoods of millions of Nigerians.Through a comprehensive literature review,synthesizing data from peer-reviewed journals,institutional reports,and credible online sources from 2000 to 2023,this study aims to explore the multi-faceted impacts of climate variability on agricultural production,livestock,fisheries,and food security in Nigeria,and to identify effective adaptation strategies to mitigate these impacts.The findings reveal that climate change has significantly disrupted agricultural productivity in Nigeria,with erratic rainfall,rising temperatures,and extreme weather events leading to reduced crop yields,increased pest and disease pressure,and land degradation.Vulnerable crops such as maize,cassava,and rice are particularly affected,while livestock production faces challenges such as heat stress and reduced feed availability.The fisheries sector is also impacted,with shrinking water resources and increasing contamination levels threatening livelihoods.Adaptation strategies,including crop diversification,improved irrigation,and indigenous knowledge practices,offer some resilience but require substantial policy and financial support.The study highlights the urgency of implementing climate-smart agricultural practices,enhancing infrastructure,and promoting public-private partnerships to mitigate climate-induced risks.Recommendations align with the United Nations Sustainable Development Goals(SDGs)2(Zero Hunger),13(Climate Action),and 15(Life on Land),emphasizing the need for sustainable agricultural practices,ecosystem preservation,and adaptive policy frameworks to ensure food security and economic stability in Nigeria.This study provides valuable insights into the impacts of climate change on Nigeria's agricultural sector and offers practical recommendations for building resilience and ensuring sustainable food systems.It reveals the importance of collaborative efforts at all levels to address the challenges posed by climate change and safeguard the nation's agricultural heritage for future generations.
基金supported by the UKM research grant no,SK-2022-015the Peninsular Malaysia Forestry Department through the research project titled‘Prediction of Bio-Climatic Habitat Adaptation of Diseases and Pests in Selected Forest Plantation Species in Peninsular Malaysia’,grant No.PHSB-08-2020.
文摘Forests all over the world have been dramatically impacted by climate change,which has contributed to an increase in the number of pathogen invasions and the rise in the prevalence of forest diseases.This article presents a systematic review that investigates the intricate relationship between climate change and the prevalence of forest diseases.The study identifies climate-related factors that drive the rising incidence of these forest diseases.Following the PRISMA guidelines,73 studies were selected and analyzed from a pool of 3,510 articles,focusing on their spatial and temporal patterns,contextual drivers,and linkages to climate change.The findings underscore the critical role of extended drought periods and rising temperatures as key factors exacerbating forest disease outbreaks.Methodologically,only 3%of the studies utilized field sampling,indicating a predominance of laboratory analysis methods at 45%.Geographically,temperate forests accounted for 78%of the studies,forest plantations 20%,and boreal forests 2%.This review highlights the pressing need for sustainable forest management practices to counteract the adverse impacts of climate change on forest ecosystems.By identifying critical climate drivers and ecological vulnerabilities,this research provides a foundation for adaptive silviculture and pathogen management strategies.
基金Under the auspices of National Natural Science Foundation of China(No.42271125)Jilin Province Foreign Expert Project(No.L202322)Doctoral Research Initiation Project of Jilin Normal University(No.0420237)。
文摘The Songhua River Basin(SRB),ranking third largest in China in terms of both runoff volume and basin area,has experi-enced frequent disasters and drastic changes in runoff since the early 20th century.Many studies have analyzed the causes of runoff re-duction;however,the spatiotemporal differences in runoff contributions and their underlying mechanisms remain poorly understood,which are crucial for regional water resources management and effective utilization.This study used the Mann-Kendall rank correlation trend test,continuous wavelet analysis,cumulative anomaly,and the slope change ratio of cumulative quantities(SCRCQ)method to explore the runoff changes characteristics and spatiotemporal differences of the contributions of climate change and human activities to runoff changes across three sub-basins of the SRB.The results show that:1)runoff from 1955 to 2022 in all the three sub-basins exhibit a statistically significant decreasing trend at 0.05 significant level.2)Four abrupt change points in runoff were detected in Nenjiang River Basin(NRB)and the mainstream of the SRB(MSRB),whereas only two change points in the Second Songhua River(SSRB).3)Runoff and precipitation series of the NRB and MSRB exhibit similar multi-timescale cycle characteristics with the most dominated cycles of 45-58 yr.In contrast,it is 12-18 yr for SSRB.4)Anthropogenic activities are the primary factor leading to in the reduction of runoff in NRB(74.33%-91.67%)and MSRB(50.11%-102.12%),whereas it is only 5.38%-33.12%in SSRB.This is attributed to the uneven distribution of regional climate and human activities in the entire SRB.5)With the growing demand for water diversion for agri-cultural irrigation,anthropogenic activities in the NRB and MSRB have increased.However,the opposite is found in SSR,where the in-creased influence of precipitation on runoff and water conservation policies are identified.
基金supported inpart by the National Basic Research Program of China(973 program2009CB421402)the NOAA Center for Atmospheric Sciences (NCAS) at Howard University(NA06OAR4810172)
文摘Understanding changes in land surface processes over the past several decades requires knowledge of trends and interannual variability in surface energy fluxes in response to climate change. In our study, the Community Land Model version 3.5 （CLM3.5）, driven by the latest updated hybrid reanalysis-observational surface climate data from Princeton University, is used to obtain global distributions of surface energy fluxes during 1948 to 2000. Based on the climate data and simulation results, long-term trends and interannual variability （IAV） of both climatic variables and surface energy fluxes for this span of 50＋ years are derived and analyzed. Regions with strong long-term trends and large IAV for both climatic variables and surface energy fluxes are identified. These analyses reveal seasonal variations in the spatial patterns of climate and surface fluxes; however, spatial patterns in trends and IAV for surface energy fluxes over the past ～50 years do not fully correspond to those for climatic variables, indicating complex responses of land surfaces to changes in the climatic forcings.
文摘Comparing the perception of farmers to climate change and variability in Bako Tibe, Ethiopia and Abeokuta, Nigeria is important in promoting sustainable agriculture and in understanding the impact of climate change and variability on agriculture in Africa. A total of 153 farmers were interviewed in both study areas using well structure questionnaire. The study describes the socioeconomic characteristics of farmers using descriptive statistics and thereafter the perception of Bako Tibe and Abeokuta farmers to climate change and variability was examined using Likert type scale. The binary logistics regression was later used to ascertain the effect of socioeconomic characteristics on perception of the farmers in both study areas. The farmers in both study areas believed that there have been changes in the amount of rainfall and temperature in the past thirty years. The farmers in Bako agreed that there have been increased temperature and decreased rainfall, contrary to the farmer’s perception in Abeokuta. The binary logistic regression results showed that socioeconomic characteristics of farmers in Bako Tibe, have no effect on the perception of farmers on climate change and variability. However, in Abeokuta, age, land ownership, and distance to market had an effect on the perception on the farmers on climate change and variability. The adaptation strategies to climate change and variability commonly used by Bako Tibe farmers was, improved seed (drought resistance) adaptation method, while most farmers in Abeokuta used soil moisture conservation adaptation method. The study recommends that government and Non-Governmental Organization of both countries should promote more adaptation and mitigation practices to climate change and variability through policy interventions to help curb the impact of climate change and variability to agriculture.
文摘The magnitude and trend of temperature and rainfall extremes as indicators of climate variability and change were investigated in the Arid and Semi-Arid Lands (ASALs) of Kenya using in-situ measurements and gridded climate proxy datasets, and analysed using the Gaussian-Kernel analysis and the Mann-Kendall statistics. The results show that the maximum and minimum temperatures have been increasing, with warmer temperatures being experienced mostly at night time. The average change in the mean maximum and minimum seasonal surface air temperature for the region were 0.74°C and 0.60°C, respectively between the 1961-1990 and 1991-2013 periods. Decreasing but statistically insignificant trends in the seasonal rainfall were noted in the area, but with mixed patterns in variability. The March-April-May rainfall season indicated the highest decrease in the seasonal rainfall amounts. The southern parts of the region had a decreasing trend in rainfall that was greater than that of the northern areas. The results of this study are expected to support sustainable pastoralism system prevalent with the local communities in the ASALs.
文摘This paper presents the lessons learnt from a research project titled “Improving Beef Cattle Productivity for Enhanced Food Security and Efficient Utilization of Natural Resources in the Lake Victoria Basin” which includes Tanzania, Uganda and Rwanda. The key focus is on the implications of land use land cover change and climate variability on the future prospects of beef cattle production in this region. The study utilizes information and data from natural resources and climate components to deduce the impact of land use and land cover changes on climate variability. Additional analysis is conducted to summarize the land use and land cover data to carry out analysis on climate data using the Mann-Kendal test, linear regression and moving averages to reveal patterns of change and trends in annual and seasonal rainfall and temperature. The findings reveal that the study areas of Rwanda, Uganda and Tanzania in the Lake Victoria Basin (LVB) have changed over time following land cover manipulations and land use change, coupled with climate variability. The grazing land has been converted to agriculture and settlements, thereby reducing cattle grazing land which is the cheapest and major feed source for ruminant livestock production. Although the cattle population has been on the increase in the same period, it has been largely attributed to the fact that the carrying capacity of available grazing areas had not been attained. The current stocking rates in the LVB reveal that the rangelands are greatly overstocked and overgrazed with land degradation already evidenced in some areas. Climate variability coupled with a decrease in grazing resources is driving unprecedented forage scarcity which is now a major limiting factor to cattle production. Crop cultivation and settlement expansion are major land use types overtaking grazing lands;therefore the incorporation of crop residues into ruminant feeding systems could be a feasible way to curtail rangeland degradation and increase beef cattle production.
文摘This study aimed at assessing perception of Fogera cattle farmers on climate change and variability in selected districts of Awi zone. The zone was classified as lowland (<1500), midland (1500 - 2500), and highland (>2500 m.a.s.l) based on altitudinal variation from which a total of three districts one per cluster were selected through random sampling. 150 households were selected through systematic random sampling targeting Fogera cattle owners for primary data collection. Over 36 years (from 1983-2019) of meteorological data were taken from the National Meteorological Agency. Meteorological data result confirmed that climate was changing across all the agro-ecological zones. Both the mean annual maximum and minimum temperature was considerably increasing for all agro-ecological zones whereas the mean annual rainfall was decreasing which is consistent with the farmers’ perception. Meteorological data result also showed that the short rainy and dry season rainfall indicated high interannual variability at all agro-ecological zones. Survey result revealed that 97.13% of the farmers recognized climate change and variability impact in all agro-ecological zones. About 80.91% of Fogera cattle farmers reported the incidence of negative impacts of climate change and variability on cattle. Chi-square test values of survey results show that in all agro-ecological zones frequency of drought, duration of dry spell, wind, and floods were ever-increasing (p < 0.001). Moreover, about 84.48%, 65.3%, and 60.47% of farmers owning Fogera cattle in the lowland, midland, and highland, respectively perceived the prevalence of increasing (p < 0.001) cattle mortality. In response to climate change and variability, farmers were reducing number of livestock, diversification of livestock species, and replacing Fogera cattle with small ruminants as adaptation strategies. Thus, regular prediction of climate change and variability and designing pertinent response strategies is essential to reduce the adverse impacts of climate change for enhancing resilience capacity of the Fogera cattle farmers in the study areas.
文摘Forty years ago, Klaus Wyrtki （1975） of University of Hawaii discovered that E1 Nifio warming off South America is not a result of local wind change but a response to the relaxed equatorial trade winds some 10 000 km away near the international dateline. The Kelvin wave mechanism was quickly verified from wind-forced ocean model simulations. Consequent develop- ments show that the dance between the fast-reacting atmosphere and slow-evolving ocean sets the pace of E1 Nifio-Southern Oscillation （ENSO; Philander, 1990）. The concept of ocean-atmosphere interaction has revolutionized our view of the climate system and led to operational climate prediction.
文摘The Boreal forest is a terrestrial ecosystem highly vulnerable to the impacts of short-term climate and weather variabilities. Detecting abrupt, rapid climate-induced changes in fire weather and related changes in fire seasonality can provide important insights to assessing impacts of climate change on forestry. This paper, taking the Sakha Republic of Russia as study area, aims to suggest an approach for detecting signals indicating climate-induced changes in fire weather to express recent fire weather variability by using short-term ranks of major meteorological parameters such as air temperature and atmospheric precipitation. Climate data from the “Global Summary of the Day Product” of NOAA (the United States National Oceanic and Atmospheric Administration) for 1996 to 2018 were used to investigate meteorological parameters that drive fire activity. The detection of the climate change signals is made through a 4-step analysis. First, we used descriptive statistics to grasp monthly, annual, seasonal and peak fire period characteristics of fire weather. Then we computed historical normals for WMO reference period, 1961-1990, and the most recent 30-year period for comparison with the current means. The variability of fire weather is analyzed using standard deviation, coefficient of variation, percentage departures from historical normals, percentage departures from the mean, and precipitation concentration index. Inconsistency and abrupt changes in the evolution of fire weather are assessed using homogeneity analysis whilst a Mann-Kendall test is used to detect significant trends in the time series. The results indicate a significant increase of temperature during spring and fall months, which extends the fire season and potentially contributes to increase of burned areas. We again detected a significant rainfall shortage in September which extended the fire season. Furthermore, this study suggests a new approach in statistical methods appropriate for the detection of climate change signals on fire weather variability using short-term climate ranks and evaluation of its impact on fire seasonality and activity.
文摘Climate change has resulted in serious social-economic ramifications and extremely catastrophic weather events in the world, Tanzania and Zanzibar in particular, with adaptation being the only option to reduce impacts. The study focuses on the influence of climate change and variability on spatio-temporal rainfall and temperature variability and distribution in Zanzibar. The station observation datasets of rainfall, T<sub>max</sub> and T<sub>min</sub> acquired from Tanzania Meteorological Authority (TMA) and the Coordinated Regional Climate Downscaling Experiment program (CORDEX) projected datasets from the Regional climate model HIRHAM5 under driving model ICHEC-EC-EARH, for the three periods of 1991-2020 used as baseline (HS), 2021-2050 as near future (NF) and 2051-2080 far future (FF), under two representative concentration pathways (RCP) of 4.5 and 8.5, were used. The long-term observed T<sub>max</sub> and T<sub>min</sub> were used to produce time series for observing the nature and trends, while the observed rainfall data was used for understanding wet and dry periods, trends and slope (at p ≤ 0.05) using the Standardized Precipitation Index (SPI) and the Mann Kendall test (MK). Moreover, the Quantum Geographic Information System (QGIS) under the Inverse Distance Weighting (IDW) interpolation techniques were used for mapping the three decades of 1991-2000 (hereafter D1), 2001-2010 (hereafter D2) and 2011-2020 (hereafter D3) to analyze periodical spatial rainfall distribution in Zanzibar. As for the projected datasets the Climate Data Operator Commands (CDO), python scripts and Grid analysis and Display System (GrADS) soft-wares were used to process and display the results of the projected datasets of rainfall, T<sub>max</sub> and T<sub>min</sub> for the HS, NF and FF, respectively. The results show that the observed T<sub>max</sub> increased by the rates of 0.035℃ yr<sup>-</sup><sup>1</sup> and 0.0169℃ yr<sup>-</sup><sup>1</sup>, while the T<sub>min</sub> was increased by a rate of 0.064℃ yr<sup>-</sup><sup>1</sup> and 0.104℃ yr<sup>-</sup><sup>1</sup> for Unguja and Pemba, respectively. The temporal distribution of wetness and dryness indices showed a climate shift from near normal to moderate wet during 2005 at Zanzibar Airport, while normal to moderately dry conditions, were observed in Pemba at Matangatuani. The decadal rainfall variability and distributions revealed higher rainfall intensity with an increasing trend and good spatial distribution in D3 from March to May (MAM) and October to December (OND). The projected results for T<sub>max</sub> during MAM and OND depicted higher values ranging from 1.7℃ - 1.8℃ to 1.9℃ - 2.0℃ and 1.5℃ to 2.0℃ in FF compared to NF under both RCPs. Also, higher T<sub>min</sub> values of 1.12℃ - 1.16℃ was projected in FF for MAM and OND under both RCPs. Besides, the rainfall projection generally revealed increased rainfall intensity in the range of 0 - 25 mm for Pemba and declined rainfall in the range of 25 - 50 mm in Unguja under both RCPs in perspectives of both NF and FF. Conclusively the study has shown that the undergoing climate change has posed a significant impact on both rainfall and temperature spatial and temporal distributions in Zanzibar (Unguja and Pemba), with Unguja being projected to have higher rainfall deficits while increasing rainfall strengths in Pemba. Thus, the study calls for more studies and formulation of effective adaptation, strategies and resilience mechanisms to combat the projected climate change impacts especially in the agricultural sector, water and food security.
文摘This study presents the work commenced in northern Thailand on spatial and temporal variability of rainfall. Thirty years (1988-2017) rainfall data of eight meteorological stations were used for assessing temporal variability and trend analysis. The results showed decreasing trend in rainfall from its first half of the observed study period (1988-2002) to last half of the time period (2003-2017) in total average annual as well as monsoonal average rainfall by 14.92% and 15.50% respectively. It was predicted from linear regression results that by 2030 the average annual and monsoonal rainfall will drop by 35% and 34.10% respectively. All stations showed negative trend except Fakara met-station in annual rainfall. In the seasonal trend analysis, the results showed decreasing trend almost in all met-stations. Mann-Kendall trend test was applied to assess the trend. All met-stations show significant negative trend. To assess drought in the study area, Standardized Precipitation Index (SPI) was applied to 12-month temporal time period. The results predicted meteorological drought in the near future. The spatial distribution of rainfall presented changing phenomena in average annual, monsoonal, winter, and summer seasons in both analyzed periods.
基金National Natural Science Foundation of China,No.41630859The CAS "Light of West China" Program,No.2015-XBQN-B-17
文摘Under the impacts of climate change and human activities, great uncertainties still exist in the response of climate extremes, especially in Central Asia (CA). In this study, we investigated spatial-temporal variation trends and abrupt changes in 17 indices of climate extremes, based on daily climate observations from 55 meteorological stations in CA during 1957-2005. We also speculated as to which atmospheric circulation factors had the greatest impacts on climate extremes. Our results indicated that the annual mean temperature (Tav), mean maximum and minimum temperature significantly increased at a rate of 0.32ºC/10a, 0.24ºC/10a and 0.41ºC/10a, respectively, which was far higher than the increasing rates either globally or across the Northern Hemisphere. Other temperature extremes showed widespread significant warming trends, especially for those indices derived from daily minimum temperature. All temperature extremes exhibited spatially widespread rising trends. Compared to temperature changes, precipitation extremes showed higher spatial and temporal variabilities. The annual total precipitation significantly increased at a rate of 4.76 mm/10a, and all precipitation extremes showed rising trends except for annual maximum consecutive dry days (CDD), which significantly decreased at a rate of -3.17 days/10a. On the whole, precipitation extremes experienced slight wetter trends in the Tianshan Mountains, Kazakhskiy Melkosopochnik (Hill), the Kyzylkum Desert and most of Xinjiang. The results of Cumulative Deviation showed that Tav and Txav had a significant abrupt change around 1987, and all precipitation indices experienced abrupt changes in 1986. Spearman’s correlation analysis pointed to Siberian High and Tibetan Plateau Index_B as possibly being the most important atmospheric circulation factors affecting climate extremes in CA. A full quantitative understanding of these changes is crucial for the management and mitigation of natural hazards in this region.
基金Open Research Funds of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, No.IWHR-SKL-201105 National Natural Science Foundation of China, No.51179005 Fundamental Re- search Funds for the Central Universities, No.2009SD-10
文摘℃ Climate change is likely to affect hydrological cycle through precipitation, evapotranspiration, soil moisture etc. In the present study, an attempt has been made to study the climate change and the sensitivity of estimated evapotranspiration to each climatic variable for a semi-arid region of Beijing in North China using data set from 1951 to 2010. Penman-Monteith method was used to calculate reference crop evapotranspiration （ETo）. Changes of ETo to each climatic variable was estimated using a sensitivity analysis method proposed in this study. Results show that in the past 60 years, mean temperature and vapor pressure deficit （VPD） were significantly increasing, relative humidity and sunshine hours were significantly decreasing, and wind speed greatly oscillated without a significant trend. Total precipitation was significantly decreasing in corn season （from June to September）, but it was increasing in wheat season （from October to next May）. The change rates of tem- perature, relative humidity, VPD, wind speed, annual total precipitation, sunshine hours and solar radiation were 0.42℃, 1.47%, 0.04 kPa, 0.05 m.s-1, 25.0 mm, 74.0 hours and 90.7 MJ.m-2 per decade, respectively. In the past 60 years, yearly ETo was increasing with a rate of 19.5 mm per decade, and total ETos in wheat and corn seasons were increasing with rates of 13.1 and 5.3 mm per decade, respectively. Sensitivity analysis showed that mean air temperature was the first key factor for ETo change in the past 60 years, causing an annual total ETo increase of 7.4%, followed by relative humidity （5.5%） and sunshine hours （-3.1%）; the less sensitivity factors were wind speed （0.7%）, minimum temperature （-0.3%） and maximum temperature （-0.2%）. A greater reduction of total ETo （12.3%） in the past 60 years was found in wheat season, mainly because of mean temperature （8.6%） and relative hu- midity （5.4%）, as compared to a reduction of 6.0% in ETo during corn season due to sunshinehours （-6.9%）, relative humidity （4.7%） and temperature （4.5%）. Increasing precipitation in the wheat season will improve crop growth, while decreasing precipitation and increasing ETo in the corn season induces a great pressure for local government and farmers to use water more efficiently by widely adopting water-saving technologies in the future.
