Spatial-temporal variability of thermohaline intrusions in the northwestern tropical Pacific Ocean

Using repeated hydrographic measurements at 137°E,spatial-temporal variability of thermohaline intrusions in the northwestern tropical Pacific are investigated.Intrusions can be found in the main thermocline throughout the section,with their strength decreasing rapidly poleward.The strongest intrusions exist at the North Equatorial Countercurrent(NECC) where North/South Pacific thermocline water converges.These intrusions also exhibit temporal variations in strength which are closely associated with the meridional displacement of the NECC.Intrusion strength peaks in boreal winter when the NECC reaches its northernmost position of the year.At interannual time scale,intrusions tend to be weak(strong) during El Ni o(La Ni a) episodes.Variations in intrusion strength also lead to prominent fluctuation of lateral diffusivity K L and cross-front temperature flux F Θ.F Θ exhibits significant year-to-year changes which are well correlated with ENSO index,suggesting a possible role of intrusions in the low-latitude Pacific climate variability.     

气候变化对RC结构碳化侵蚀可靠度的影响

气候变化引起的全球大气中CO2浓度的升高,加速了钢筋混凝土(RC)结构的劣化.针对《混凝土耐久性设计规范》中规定的碳化环境(Ⅰ类环境),评估了未来气候变化对中国RC结构在正常使用极限状态下时变可靠度的影响.研究显示:未来气候变化使中国RC结构的平均碳化深度增大20％～40％,降低了RC结构的碳化侵蚀可靠度.到2100年,混凝土结构耐久性设计规范中Ⅰ类环境下Ⅰ-A、Ⅰ-B环境作用等级的耐久性规定不能够适应气候变化对中国钢筋混凝土结构的耐久性影响.     

Prediction of a global climate change on Jupiter

Jupiter's atmosphere, as observed in the 1979 Voyager space craft images, is characterized by 12 zonal jet streams and about 80 vortices, the largest of which are the Great Red Spot and three White Ovals that had formed in the 1930s. The Great Red Spot has been observed continuously since 1665 and, given the dynamical similarities between the Great Red Spot and the White Ovals, the disappearance of two White Ovals in 1997-2000 was unexpected. Their longevity and sudden demise has been explained however, by the trapping of anticyclonic vortices in the troughs of Rossby waves, forcing them to merge. Here I propose that the disappearance of the White Ovals was not an isolated event, but part of a recurring climate cycle which will cause most of Jupiter's vortices to disappear within the next decade. In my numerical simulations, the loss of the vortices results in a global temperature change of about 10 K, which destabilizes the atmosphere and thereby leads to the formation of new vortices. After formation, the large vortices are eroded by turbulence over a time of approximately 60 years--consistent with observations of the White Ovals-until they disappear and the cycle begins again.     

Influence of the carbon cycle on the attribution of responsibility for climate change

The carbon cycle is one of the fundamental climate change issues.Its long-term evolution largely affects the amplitude and trend of human-induced climate change,as well as the formulation and implementation of emission reduction policy and technology for stabilizing the atmospheric CO2concentration.Two earth system models incorporating the global carbon cycle,the Community Earth System Model and the Beijing Normal University-Earth System Model,were used to investigate the effect of the carbon cycle on the attribution of the historical responsibility for climate change.The simulations show that when compared with the criterion based on cumulative emissions,the developed(developing)countries’responsibility is reduced(increased)by 6%–10%using atmospheric CO2concentration as the criterion.This discrepancy is attributed to the fact that the developed world contributed approximately61%–68%(61%–64%)to the change in global oceanic(terrestrial)carbon sequestration for the period from 1850 to2005,whereas the developing world contributed approximately 32%–49%(36%–39%).Under a developed world emissions scenario,the relatively larger uptake of global carbon sinks reduced the developed countries’responsibility for carbon emissions but increased their responsibility for global ocean acidification(68%).In addition,the large emissions from the developed world reduced the efficiency of the global carbon sinks,which may affect the long-term carbon sequestration and exacerbate global warming in the future.Therefore,it is necessary to further consider the interaction between carbon emissions and the carbon cycle when formulating emission reduction policy.     

Constraints on radiative forcing and future climate change from observations and climate model ensembles

The assessment of uncertainties in global warming projections is often based on expert judgement, because a number of key variables in climate change are poorly quantified. In particular, the sensitivity of climate to changing greenhouse-gas concentrations in the atmosphere and the radiative forcing effects by aerosols are not well constrained, leading to large uncertainties in global warming simulations. Here we present a Monte Carlo approach to produce probabilistic climate projections, using a climate model of reduced complexity. The uncertainties in the input parameters and in the model itself are taken into account, and past observations of oceanic and atmospheric warming are used to constrain the range of realistic model responses. We obtain a probability density function for the present-day total radiative forcing, giving 1.4 to 2.4 W m-2 for the 5-95 per cent confidence range, narrowing the global-mean indirect aerosol effect to the range of 0 to -1.2 W m-2. Ensemble simulations for two illustrative emission scenarios suggest a 40 per cent probability that global-mean surface temperature increase will exceed the range predicted by the Intergovernmental Panel on Climate Change (IPCC), but only a 5 per cent probability that warming will fall below that range.     

Effects of climate change on biodiversity

1 Rise of studies on climate change＇s effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America＇s annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].     

Orbit-related long-term climate cycles revealed in a 12-Myr continental record from Lake Baikal

Quaternary records of climate change from terrestrial sources, such as lake sediments and aeolian sediments, in general agree well with marine records. But continuous records that cover more than the past one million years were essentially unavailable until recently, when the high-sedimentation-rate site of Lake Baikal was exploited. Because of its location in the middle latitudes, Lake Baikal is highly sensitive to insolation changes and the entire lake remained uncovered by ice sheets throughout the Pleistocene epoch, making it a valuable archive for past climate. Here we examine long sediment cores from Lake Baikal that cover the past 12 million years. Our record reveals a gradual cooling of the Asian continental interior, with some fluctuations. Spectral analyses reveal periods of about 400 kyr, 600 kyr and 1,000 kyr, which may correspond to Milankovitch periods (reflecting orbital cycles). Our results indicate that changes in insolation were closely related to long-term environmental variations in the deep continental interior, over the past 12 million years.     

泥炭记录的近2 200年吉林省敦化盆地的气候变化

根据典型泥炭剖面孢粉图示、粒度分布(纤维含量)、pH、沉积速率、吸湿水、C/ N、有机质含量等指标的综合分析,结合地层特征,研究了2 200 a B.P.以来的晚全新世敦化盆地植被和气候的变化.结果表明:敦化大桥泥炭地是从山地森林演替为草甸,继而经沼泽化形成;周围植被经历了以松林(Pinus)为主的温带山地针叶林,桦(Betula)、榛(Corylus)、胡桃(Juglans)等阔叶树和松林共生的针阔混交林,以榛、鹅耳枥(Carpinus)、松为主的针阔混交林和松、桦为主的针阔混交林之后,渐渐进入现代景观;相应地,该区气候经历了四个时期,即冷干((2 045±70)B.P.)～(2 195±70)a B.P.)、暖湿((1 745±70)a B.P.～(2 045±70)a B.P.)、温湿((705±70)a B.P.～1 745±70)a B.P.)和冷湿(公元1245-1950年)时期.     

北太平洋海温对阜新气候变暖的影响

为了揭示阜新气候变暖的影响因素及变化规律,利用近50年北太平洋海温资料、历年阜新地区气温资料,在太阳黑子谷值年活动周期内,采用数理统计分析方法,对阜新年、季、月气温变化进行了深入的分析和研究,找出了阜新气候变暖与海温之间的一些重要规律.结果证明了阜新气候变暖与海温有着密切的关系及海温对气温影响的长期效应.通过海温与气温的研究,对气候变暖、冷暖冬、高温、低温冷害、干旱、洪涝等方面的气候预测有着重要的帮助作用.     

Impact of urbanization and land-use change on climate

The most important anthropogenic influences on climate are the emission of greenhouse gases and changes in land use, such as urbanization and agriculture. But it has been difficult to separate these two influences because both tend to increase the daily mean surface temperature. The impact of urbanization has been estimated by comparing observations in cities with those in surrounding rural areas, but the results differ significantly depending on whether population data or satellite measurements of night light are used to classify urban and rural areas. Here we use the difference between trends in observed surface temperatures in the continental United States and the corresponding trends in a reconstruction of surface temperatures determined from a reanalysis of global weather over the past 50 years, which is insensitive to surface observations, to estimate the impact of land-use changes on surface warming. Our results suggest that half of the observed decrease in diurnal temperature range is due to urban and other land-use changes. Moreover, our estimate of 0.27 degrees C mean surface warming per century due to land-use changes is at least twice as high as previous estimates based on urbanization alone.     

Impact of regional climate change on human health

The World Health Organisation estimates that the warming and precipitation trends due to anthropogenic climate change of the past 30 years already claim over 150,000 lives annually. Many prevalent human diseases are linked to climate fluctuations, from cardiovascular mortality and respiratory illnesses due to heatwaves, to altered transmission of infectious diseases and malnutrition from crop failures. Uncertainty remains in attributing the expansion or resurgence of diseases to climate change, owing to lack of long-term, high-quality data sets as well as the large influence of socio-economic factors and changes in immunity and drug resistance. Here we review the growing evidence that climate-health relationships pose increasing health risks under future projections of climate change and that the warming trend over recent decades has already contributed to increased morbidity and mortality in many regions of the world. Potentially vulnerable regions include the temperate latitudes, which are projected to warm disproportionately, the regions around the Pacific and Indian oceans that are currently subjected to large rainfall variability due to the El Ni?o/Southern Oscillation sub-Saharan Africa and sprawling cities where the urban heat island effect could intensify extreme climatic events.     

关于股票数据波动性的多变点研究

目前对金融时间序列模型结构变化问题主要集中于对单变点的研究,但在许多情况下,金融数据可能出现多个变点,因此,对实际问题的研究需要检验多变点的存在,需要对变点的个数以及变点发生的时刻作出估计.本文讨论了股票数据均值的多变点检验问题.在原假设下给出统计量的极限分布及渐近临界值的解析表达式.并且在递归检验的过程中同时得到变点时刻与变点个数估计.最后用实例分析说明了方法的有效性.     

气候变化对沿海城市的影响(英文)

海岸及海洋综合管理模式是目前普遍认可的可持续发展管理方式.分析海岸及海洋综合管理中最重要的两个因素,防止海洋污染及协调管理冲突,提出建议,以促进海岸及海洋综合管理的发展.     

气候变化对主要沿海城市的影响(英文)

气候变化给人类以及人类赖以生存的环境带来了诸多问题,例如风暴潮、飓风和台风.分析气候变化对沿海主要城市的影响具有重大意义.上海作为一个主要的沿海城市,正受到海平面上升的威胁,针对此问题,提出减小海平面上升对其影响的几个建议.     

东北太平洋热带气旋活动特征分析

为使船舶驾驶人员对东北太平洋海域热带风暴或飓风的活动规律有所了解,利用1980～1997年的资料对该海域的热带气旋进行了综合统计分析．给出了热带气旋天气气候特征和移动规律,为该海域航行的船舶提供了有用的资料,以期达到预防和避离飓风的目的．     

全球气候变化下的半干旱区相对湿度变化研究

为揭示全球气候变化下半干旱区空气相对湿度的变化规律,利用线性回归分析、多元线性相关分析以及M-K检验法对吉林省西部5个站点的1953年以来的相对湿度、气温、降水和风速资料进行了研究.结果表明:相对湿度的年变化曲线呈双峰型,相对湿度的最大值出现在8月,次大值出现在1月,最小值出现在4月,次小值出现在10月.夏、秋季的相对湿度较大,而春、冬季的相对湿度较小.近50年,年平均相对湿度及春、夏、秋、冬四季的相对湿度在波动中下降,下降趋势不显著;但是9月和10月的平均相对湿度下降显著.影响相对湿度变化的主要因子是温度和降水,风速也起一定的作用.相对湿度的变化与温度和风速变化呈负相关关系,与降水变化呈正相关关系.     

Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability

Systematic climate shifts have been linked to multidecadal variability in observed sea surface temperatures in the North Atlantic Ocean. These links are extensive, influencing a range of climate processes such as hurricane activity and African Sahel and Amazonian droughts. The variability is distinct from historical global-mean temperature changes and is commonly attributed to natural ocean oscillations. A number of studies have provided evidence that aerosols can influence long-term changes in sea surface temperatures, but climate models have so far failed to reproduce these interactions and the role of aerosols in decadal variability remains unclear. Here we use a state-of-the-art Earth system climate model to show that aerosol emissions and periods of volcanic activity explain 76 per cent of the simulated multidecadal variance in detrended 1860-2005 North Atlantic sea surface temperatures. After 1950, simulated variability is within observational estimates; our estimates for 1910-1940 capture twice the warming of previous generation models but do not explain the entire observed trend. Other processes, such as ocean circulation, may also have contributed to variability in the early twentieth century. Mechanistically, we find that inclusion of aerosol-cloud microphysical effects, which were included in few previous multimodel ensembles, dominates the magnitude (80 per cent) and the spatial pattern of the total surface aerosol forcing in the North Atlantic. Our findings suggest that anthropogenic aerosol emissions influenced a range of societally important historical climate events such as peaks in hurricane activity and Sahel drought. Decadal-scale model predictions of regional Atlantic climate will probably be improved by incorporating aerosol-cloud microphysical interactions and estimates of future concentrations of aerosols, emissions of which are directly addressable by policy actions.     

Evidence for recent climate change on Mars from the identification of youthful near-surface ground ice

Ground ice in the crust and soil may be one of the largest reservoirs of water on Mars. Near-surface ground ice is predicted to be stable at latitudes higher than 40 degrees (ref. 4), where a number of geomorphologic features indicative of viscous creep and hence ground ice have been observed. Mid-latitude soils have also been implicated as a water-ice reservoir, the capacity of which is predicted to vary on a 100,000-year timescale owing to orbitally driven variations in climate. It is uncertain, however, whether near-surface ground ice currently exists at these latitudes, and how it is changing with time. Here we report observational evidence for a mid-latitude reservoir of near-surface water ice occupying the pore space of soils. The thickness of the ice-occupied soil reservoir (1-10 m) and its distribution in the 30 degrees to 60 degrees latitude bands indicate a reservoir of (1.5-6.0) x 104 km3, equivalent to a global layer of water 10-40 cm thick. We infer that the reservoir was created during the last phase of high orbital obliquity less than 100,000 years ago, and is now being diminished.     

基于判别分析探析气候变化对国家脆弱性的影响

气候变化作为21世纪人类面临的最严峻挑战之一,加剧许多国家的脆弱性。针对气候变化如何影响国家不稳问题,使用判别分析、时间列分析、Holt-Winters无季节指数平滑拟合等方法,建立气候变化下的国家脆弱性评价模型和国家瘫痪的预测模型,并运用MATLAB,SPSS等软件对问题进行求解。通过研究影响因素,对防止国家成为脆弱的国家提供政策建议。