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1.
观测表明近百年全球在变暖,特别是自1970年以来更加明显,相应海平面上升、冰雪融化、异常与极端天气以及气候事件频发,给社会与经济造成极大影响。值得注意的是,在21世纪的未来80年是否会继续保持增暖的趋势,以及这种变暖在历史上的地位和从古气候暖期所获得的启示,本文将集中在这个问题上。 相似文献
2.
The magnitude and even direction of recent Antarctic climate change is still debated because the paucity of long and complete
instrumental data records. While along Antarctic Peninsula a strong warming coupled with large retreat of glaciers occurred,
in continental Antarctica a cooling was recently detected. Here, the first existing permafrost data set longer than 10 years
recorded in continental Antarctica is presented. Since 1997 summer ground surface temperature showed a strong warming trend
(0.31°C per year) although the air temperature was almost stable. The summer ground surface temperature increase seemed to
be influenced mainly by the increase of the total summer radiation as confirmed also by the increase of the summer thawing
degree days. In the same period the active layer exhibited a thickening trend (1 cm per year) comparable with the thickening
rates observed in several Arctic locations where air warming occurred. At all the investigated depths permafrost exhibited
an increase of mean annual temperature of approximately 0.1°C per year. The dichotomy between active layer thickness and air
temperature trends can produce large unexepected and unmodelled impacts on ecosystems and CO2 balance. 相似文献
3.
《Global Environmental Change》1999,9(3):179-201
Anthropogenic sources of methane emissions are thought to be nearly twice as high as emissions from natural sources. As the second most important anthropogenic greenhouse gas after carbon dioxide, methane ought to be addressed by policy makers when they consider reductions of national greenhouse-gas inventories. This article first comprehensively reviews source and sink estimates of methane by natural and anthropogenic sectors (wetlands, wet-paddy rice farming, livestock farming, biomass burning, landfills, coal mining, and venting of natural gas or natural-gas pipeline leaks), then proceeds to suggest where different mitigation strategies might be applied. The final section considers how the scenario of a warmer planet may affect the methane biogeochemical cycle. 相似文献
4.
Assessing the strength of regional changes in near-surface climate associated with a global warming of 2°C 总被引：2，自引：1，他引：1
Wilhelm May 《Climatic change》2012,110(3-4):619-644
In this study, the strength of the regional changes in near-surface climate associated with a global warming of 2°C with respect to pre-industrial times is assessed, distinguishing between 26 different regions. Also, the strength of these regional climate changes is compared to the strength of the respective changes associated with a markedly stronger global warming of 4.5°C. The magnitude of the regional changes in climate is estimated by means of a normalized regional climate change index, which considers changes in the mean as well as changes in the interannual variability of both near-surface temperature and precipitation. The study is based on two sets of four ensemble simulations with the ECHAM5/MPI-OM coupled climate model, each starting from different initial conditions. In one set of simulations (1860–2200), the greenhouse gas concentrations and sulphate aerosol load have been prescribed according to observations until 2000 and according to the SRES A1B scenario after 2000. In the other set of simulations (2020–2200), the greenhouse gas concentrations and sulphate aerosol load have been prescribed in such a way that the simulated global warming does not exceed 2°C with respect to pre-industrial times. The study reveals the strongest changes in near-surface climate in the same regions for both scenarios, i.e., the Sahara, Northern Australia, Southern Australia and Amazonia. The regions with the weakest changes in near-surface climate, on the other hand, vary somewhat between the two scenarios except for Western North America and Southern South America, where both scenarios show rather weak changes. The comparison between the magnitude of the regional changes in near-surface climate for the two scenarios reveals relatively strong changes in the 2°C-stabilization scenario at high northern latitudes, i.e., Northeastern Europe, Alaska and Greenland, and in Amazonia. Relatively weak regional climate changes in this scenario, on the other hand, are found for Eastern Asia, Central America, Central South America and Southern South America. The ratios between the regional changes in the near-surface climate for the two scenarios vary considerably between different regions. This illustrates a limitation of obtaining regional changes in near-surface climate associated with a particular scenario by means of scaling the regional changes obtained from a widely used “standard” scenario with the ratio of the changes in the global mean temperature projected by these two scenarios. 相似文献
5.
[No abstract available] 相似文献
6.
The possible change in the characteristics of weather in the future should be considered as important as the mean climate change because the increasing risk of extremes is related to the variability on daily time scales. The weather characteristics can be represented by the climatological mean interdiurnal (day-to-day) variability (MIDV). This paper first assessed the phase five of the Coupled Model Intercomparison Project coupled climate models’ capability to represent MIDV for the surface maximum and minimum temperature, surface wind speed and precipitation under the present climate condition. Based on the assessment, we selected three best models for projecting future change. We found that the future changes in MIDV are characterized by: (a) a marked reduction in surface maximum and minimum temperature over high latitudes during the cold season; (b) a stronger reduction in the surface minimum temperature than in the maximum temperature; (c) a reduction in surface wind speed over large parts of lands in Northern Hemisphere (NH) during NH spring; (d) a noticeable increase in precipitation in NH mid-high latitudes in NH spring and winter, and in particular over East Asia throughout most of the year. 相似文献
7.
Near-term increase in frequency of seasonal temperature extremes prior to the 2°C global warming target 总被引：2，自引：1，他引：1
Given current international efforts to reduce greenhouse gas emissions and limit human-induced global-mean near-surface temperature
increases to 2°C, relative to the pre-industrial era, we seek to determine the impact such a temperature increase might have
upon the frequency of seasonal-mean temperature extremes; further we seek to determine what global-mean temperature increase
would prevent extreme temperature values from becoming the norm. Results indicate that given a 2°C global mean temperature
increase it is expected that for 70–80% of the land surface maximum seasonal-mean temperatures will exceed historical extremes
(as determined from the 95th percentile threshold value over the second half of the 20th Century) in at least half of all
years, i.e. the current historical extreme values will effectively become the norm. Many regions of the globe—including much
of Africa, the southeastern and central portions of Asia, Indonesia, and the Amazon—will reach this point given the “committed”
future global-mean temperature increase of 0.6°C (1.4°C relative to the pre-industrial era) and 50% of the land surface will
reach it given a future global-mean temperature increase of between 0.8 and 0.95°C (1.6–1.75°C relative to the pre-industrial
era). These results suggest substantial fractions of the globe could experience seasonal-mean temperature extremes with high
regularity, even if the global-mean temperature increase remains below the 2°C target. 相似文献
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The epochal changes in the seasonal evolution of El Niño induced tropical Indian Ocean (TIO) warming in the context of mid-1970s regime shift is investigated in this study. El Niño induced warming is delayed by one season in the northern TIO during epoch-2 (post mid-1970) and southern TIO during epoch-1 (pre mid-1970). Significant spatiotemporal changes in TIO (especially in the north) warming are apparent during the developing phase of El Niño. The ocean dynamics is the major driver in the basin wide warming during epoch-2 whereas heat fluxes are the dominant processes during epoch-1. Strong coupling between thermocline and sea surface temperature (SST) in epoch-2 indicates that El Niño induced oceanic changes are very significant in the seasonal evolution of basin-wide warming. The thermocline-SST coupling is strengthened by the upward propagating subsurface warming in epoch-2. The westward propagating barrier layer over southern TIO supports persistence of warm SST (over southwest TIO in epoch-2), which in turn induce spring asymmetric mode in winds and precipitation. The asymmetric wind pattern and persistent subsidence over maritime continent are primarily responsible for stronger spring warming in epoch-2. The strong east equatorial Indian Ocean cooling in epoch-2 is mainly driven by coastal upwelling over Java–Sumatra coast, whereas in epoch-1 the weak cooling is controlled by the latent heat flux. The spatiotemporal changes in TIO SST warming and their evolution have strong impact on atmospheric circulation and rainfall distribution over the Indian Oceanic rim through local air–sea interaction. 相似文献
11.
Youichi Kamae Masahiro Watanabe Masahide Kimoto Hideo Shiogama 《Climate Dynamics》2014,43(9-10):2569-2583
In this the second of a two-part study, we examine the physical mechanisms responsible for the increasing contrast of the land–sea surface air temperature (SAT) in summertime over the Far East, as observed in recent decades and revealed in future climate projections obtained from a series of transient warming and sensitivity experiments conducted under the umbrella of the Coupled Model Intercomparison Project phase 5. On a global perspective, a strengthening of land–sea SAT contrast in the transient warming simulations of coupled atmosphere–ocean general circulation models is attributed to an increase in sea surface temperature (SST). However, in boreal summer, the strengthened contrast over the Far East is reproduced only by increasing atmospheric CO2 concentration. In response to SST increase alone, the tropospheric warming over the interior of the mid- to high-latitude continents including Eurasia are weaker than those over the surrounding oceans, leading to a weakening of the land–sea SAT contrast over the Far East. Thus, the increasing contrast and associated change in atmospheric circulation over East Asia is explained by CO2-induced continental warming. The degree of strengthening of the land–sea SAT contrast varies in different transient warming scenarios, but is reproduced through a combination of the CO2-induced positive and SST-induced negative contributions to the land–sea contrast. These results imply that changes of climate patterns over the land–ocean boundary regions are sensitive to future scenarios of CO2 concentration pathways including extreme cases. 相似文献
12.
California’s hydropower system is composed of high and low elevation power plants. There are more than 150 high-elevation power plants, at elevations above 1,000 feet (300 m). Most have modest reservoir storage capacities, but supply roughly 74% of California’s in-state hydropower. The expected shift of runoff peak from spring to winter due to climate warming, resulting in snowpack reduction and increased snowmelt, might have important effects on power generation and revenues in California. The large storage capacities at low-elevation power plants provide flexibility to operations of these units under climate warming. However, with climate warming, the adaptability of the high-elevation hydropower system is in question as this system was designed to take advantage of snowpack, a natural reservoir. With so many high-elevation hydropower plants in California, estimation of climate warming effects by conventional simulation or optimization methods would be tedious and expensive. An Energy-Based Hydropower Optimization Model (EBHOM) was developed to facilitate practical climate change and other low-resolution system-wide hydropower studies, based on the historical generation data of 137 high-elevation hydropower plants for which the data were complete for 14 years. Employing recent historical hourly energy prices, the model was used to explore energy generation in California for three climate warming scenarios (dry warming, wet warming, and warming-only) over 14 years, representing a range of hydrologic conditions. The system is sensitive to the quantity and timing of inflows. While dry warming and warming-only climate changes reduce average hydropower revenues, wet warming could increase revenue. Re-operation of available storage and generation capacities help compensate for snowpack losses to some extent. Storage capacity expansion and to a lesser extent generation capacity expansion both increase revenues, although such expansions might not be cost-effective. 相似文献
13.
The radiative impacts of the stratosphere in global warming simulations are investigated using abrupt CO2 quadrupling experiments of the Coupled Model Inter-comparison Project phase 5 (CMIP5), with a focus on stratospheric temperature and water vapor. It is found that the stratospheric temperature change has a robust bullhorn-like zonal-mean pattern due to a strengthening of the stratospheric overturning circulation. This temperature change modifies the zonal mean top-of-the-atmosphere energy balance, but the compensation of the regional effects leads to an insignificant global-mean radiative feedback (?0.02 ± 0.04 W m?2 K?1). The stratospheric water vapor concentration generally increases, which leads to a weak positive global-mean radiative feedback (0.02 ± 0.01 W m?2 K?1). The stratospheric moistening is related to mixing of elevated upper-tropospheric humidity, and, to a lesser extent, to change in tropical tropopause temperature. Our results indicate that the strength of the stratospheric water vapor feedback is noticeably larger in high-top models than in low-top ones. The results here indicate that although its radiative impact as a forcing adjustment is significant, the stratosphere makes a minor contribution to the overall climate feedback in CMIP5 models. 相似文献
14.
V. V. Popova 《Russian Meteorology and Hydrology》2014,39(3):159-167
Considered is a relationship between long-term variations of the surface air temperature and of the field of geopotential at the level of 500 hPa in the middle of summer in the European part of Russia and the variations of large-scale atmospheric circulation described by the indices of North Atlantic and North Pacific centers of atmospheric action. The considerable inhomogeneity in the course of average temperature in the European part of Russia in July divides it into two periods, before and after the 1980s. Unlike stationary fluctuations of temperature before the 1980s, the 6–10-year fluctuations are typical of the period of 1981–2010 against a background of its considerable rise by 0.8°C per 10 years with the contribution of 20% to the total variance. During this period, about 80% of temperature variability are caused by the circulation variations, and 55% of them are associated with the North Pacific centers of atmospheric action, in particular, with the WP index in July, May, and April. Revealed regression dependences between circulation indices and the air temperature in the European part of Russia explain rather accurately the linear trend, the fluctuations with the period of 6–10 years, and the extremes in 1988, 2001–2003, and 2010. The analysis of the time series (1950–2012) of WP, PDO, and SOI indices demonstrates that changes in the atmospheric circulation took place in the extratropical zone of the Northern Hemisphere at the turn of the 1980s and this caused the formation of blocking situations and, hence, steady heat and drought in summer in the mid-latitude zone including the European part of Russia. These variations can be interpreted as a change in the regimes of strong (1950–1980) and weak (1981–2012) circulation. The heat in July 2010 was an extreme display of weak circulation, and this is indicated by the unprecedented low values of the WP index in July and May. 相似文献
15.
J. Fasullo 《Climate Dynamics》2012,39(5):1137-1147
A central paradox of the global monsoon record involves reported decreases in rainfall over land during an era in which the global hydrologic cycle is both expected and observed to intensify. It is within this context that this work develops a physical basis for both interpreting the observed record and anticipating changes in the monsoons in a warming climate while bolstering the concept of the global monsoon in the context of shared feedbacks. The global-land monsoon record across multiple reanalyses is first assessed. Trends that in other studies have been taken as real are shown to likely be spurious as a result of changes in the assimilated data streams both prior to and during the satellite era. Nonetheless, based on satellite estimates, robust increases in monsoon rainfall over ocean do exist and a physical basis for this land–ocean contrast remains lacking. To address the contrast’s causes, simulated trends are therefore assessed. While projections of total rainfall are inconsistent across models, the robust land–ocean contrast identified in observations is confirmed. A feedback mechanism is proposed rooted in the facts that land areas warm disproportionately relative to ocean, and onshore flow is the chief source of monsoonal moisture. Reductions in lower tropospheric relative humidity over land domains are therefore inevitable and these have direct consequences for the monsoonal convective environment including an increase in the lifting condensation level and a shift in the distribution of convection generally towards less frequent and potentially more intense events. The mechanism is interpreted as an important modulating influence on the “rich-get-richer” mechanism. Caveats for regional monsoons exist and are discussed. 相似文献
16.
Bruce T. Anderson 《Climatic change》2012,112(2):325-337
Current international efforts to reduce greenhouse gas emissions and limit human-induced global-mean near-surface temperature increases to 2°C, relative to the pre-industrial era, are intended to avoid possibly significant and dangerous impacts to physical, biological, and socio-economic systems. However, it is unknown how these various systems will respond to such a temperature increase because their relevant spatial scales are much different than those represented by numerical global climate models—the standard tool for climate change studies. This deficiency can be addressed by using higher-resolution regional climate models, but at great computational expense. The research presented here seeks to determine how a 2°C global-mean temperature increase might change the frequency of seasonal temperature extremes, both in the United States and around the globe, without necessarily resorting to these computationally-intensive model experiments. Results indicate that in many locations the regional temperature increases that accompany a 2°C increase in global mean temperatures are significantly larger than the interannual-to-decadal variations in seasonal-mean temperatures; in these locations a 2°C global mean temperature increase results in seasonal-mean temperatures that consistently exceed the most extreme values experienced during the second half of the 20th Century. Further, results indicate that many tropical regions, despite having relatively modest overall temperature increases, will have the most substantial increase in number of hot extremes. These results highlight that extremes very well could become the norm, even given the 2°C temperature increase target. 相似文献
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As a typical inland arid and semiarid region, Central Asia (CA) is vulnerable to the forced global warming (FGW) due to anthropogenic activity. Aiming at the interdecadal variation of the FGW-forced aridity pattern (FAP) in CA, we try to extract the associated oceanic and atmospheric modes by analyzing observations, reanalysis data and multi-model simulations during 1950–2016. The FAP in CA features a tripolar pattern with wetting–drying-wetting responses arranging from southeast to northwest and shows strong interdecadal-to-interannual amplitude variations. It is found that the sea surface temperature (SST) in the tropical South Atlantic (TSA) well correlates with the amplitude variation of FAP on interdecadal time scale, possibly through modulating the interannual SST modes characterized by the North Atlantic horseshoe-like dipole (NAHD) and the El Ninõ and South Oscillation (ENSO). Corresponding to the enhancing FAP from the middle 1970s to early 2000s, the TSA-modulated NAHD and ENSO, together with the Pacific Decadal Oscillation-modulated Indian Ocean Dipole-like mode, show connections with an Eurasian middle-latitude wave train coupled with the North Arctic Oscillation and equatorial low, which favors the moisture transport to strengthen the tripolar FAP by forming a local circulation dipole with positive/negative anomaly over the northwest/southeast CA. But after the early 2000s, the increasing FAP amplitude is decelerated due to the interdecadal decline of TSA accompanied by the weakened/reversed relationship between FAP and the NAHD/ENSO. Because of the corresponding breakdown of the wave train, the favorable local circulation is unavailable to support the sustained enhancement of FAP. Therefore, the multiscale coupling between the above oceanic and atmospheric modes is significantly related to the characteristic of stage of the forced aridity change in CA under the background of global warming.
相似文献20.
In accordance with numerous investigations, global climate warming due to the increased greenhouse gas content in the atmosphere can significantly influence the environment already in the near decades. In order to mitigate or prevent possible adverse consequences of this warming the technologies on reducing greenhouse gas emissions as well as a deliberate interference with climate, including its control, are under consideration. Let us analyze the present investigations on the estimate of the influence of a simultaneous increase in the atmospheric CO2 concentration and in the stratospheric aerosol on the global and regional climate, ozone layer, and World Ocean acidification. It is noted that the production and subsequent maintenance of the artificial aerosol layer in the stratosphere could, in principle, eliminate or retard climate warming, but it would be accompanied by a decrease in the global precipitation, especially in the tropical zone. Furthermore, the stratospheric aerosol screen does not solve the problem of the atmospheric CO2 increase, which in turn results in the further World Ocean acidification, and thus has an adverse effect on the marine part of the biosphere. Political and ethic issues connected with the deliberate global man interference with the natural environment are also under considerations. 相似文献