Widespread amphibian extinctions from epidemic disease driven by global warming

As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with 'very high confidence' (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.     

Eocene global warming events driven by ventilation of oceanic dissolved organic carbon

'Hyperthermals' are intervals of rapid, pronounced global warming known from six episodes within the Palaeocene and Eocene epochs (～65-34 million years (Myr) ago). The most extreme hyperthermal was the ～170 thousand year (kyr) interval of 5-7 °C global warming during the Palaeocene-Eocene Thermal Maximum (PETM, 56?Myr ago). The PETM is widely attributed to massive release of greenhouse gases from buried sedimentary carbon reservoirs, and other, comparatively modest, hyperthermals have also been linked to the release of sedimentary carbon. Here we show, using new 2.4-Myr-long Eocene deep ocean records, that the comparatively modest hyperthermals are much more numerous than previously documented, paced by the eccentricity of Earth's orbit and have shorter durations (～40?kyr) and more rapid recovery phases than the PETM. These findings point to the operation of fundamentally different forcing and feedback mechanisms than for the PETM, involving redistribution of carbon among Earth's readily exchangeable surface reservoirs rather than carbon exhumation from, and subsequent burial back into, the sedimentary reservoir. Specifically, we interpret our records to indicate repeated, large-scale releases of dissolved organic carbon (at least 1,600 gigatonnes) from the ocean by ventilation (strengthened oxidation) of the ocean interior. The rapid recovery of the carbon cycle following each Eocene hyperthermal strongly suggests that carbon was re-sequestered by the ocean, rather than the much slower process of silicate rock weathering proposed for the PETM. Our findings suggest that these pronounced climate warming events were driven not by repeated releases of carbon from buried sedimentary sources, but, rather, by patterns of surficial carbon redistribution familiar from younger intervals of Earth history.     

Origins and estimates of uncertainty in predictions of twenty-first century temperature rise

Predictions of temperature rise over the twenty-first century are necessarily uncertain, both because the sensitivity of the climate system to changing atmospheric greenhouse-gas concentrations, as well as the rate of ocean heat uptake, is poorly quantified and because future influences on climate-of anthropogenic as well as natural origin-are difficult to predict. Past observations have been used to help constrain the range of uncertainties in future warming rates, but under the assumption of a particular scenario of future emissions. Here we investigate the relative importance of the uncertainty in climate response to a particular emissions scenario versus the uncertainty caused by the differences between future emissions scenarios for our estimates of future change. We present probabilistic forecasts of global-mean temperatures for four representative scenarios for future emissions, obtained with a comprehensive climate model. We find that, in the absence of policies to mitigate climate change, global-mean temperature rise is insensitive to the differences in the emissions scenarios over the next four decades. We also show that in the future, as the signal of climate change emerges further, the predictions will become better constrained.     

湖北地区气温变化对全球变暖的响应

选用湖北省77个代表站1960-2003年逐日气温观测资料,分析了湖北省气温的年、季节变化规律及其地域分布特征．结果表明：湖北省近44年气温呈上升趋势,至2003年气温上升了0．5℃,增温速率约为0．12℃／10a,和近50年来的全球平均增温速率相当．20世纪90年代升温最剧烈．春季、秋季和冬季气温均呈上升趋势,冬季增温最明显,而夏季气温却呈下降趋势．夏季平均日最高气温也呈下降趋势,冬季平均日最低气温上升趋势显著．气温变化不同的地区差异较大,西部地区变化趋势不明显,有微弱的下降趋势,而中东部地区则有较明显的升温趋势．     

Fingerprints of global warming on wild animals and plants

Over the past 100 years, the global average temperature has increased by approximately 0.6 degrees C and is projected to continue to rise at a rapid rate. Although species have responded to climatic changes throughout their evolutionary history, a primary concern for wild species and their ecosystems is this rapid rate of change. We gathered information on species and global warming from 143 studies for our meta-analyses. These analyses reveal a consistent temperature-related shift, or 'fingerprint', in species ranging from molluscs to mammals and from grasses to trees. Indeed, more than 80% of the species that show changes are shifting in the direction expected on the basis of known physiological constraints of species. Consequently, the balance of evidence from these studies strongly suggests that a significant impact of global warming is already discernible in animal and plant populations. The synergism of rapid temperature rise and other stresses, in particular habitat destruction, could easily disrupt the connectedness among species and lead to a reformulation of species communities, reflecting differential changes in species, and to numerous extirpations and possibly extinctions.     

全球变暖背景下大连地区寒潮活动的气候变化

利用1961~2005年大连地区6个气象观测站的逐日平均气温、最低气温和最大平均风力资料,分析近45年大连地区寒潮活动的气候特征,着重研究大连地区寒潮的年代际、年际变化.结果表明:大连地区寒潮活动各地差异较大,南部开始早,结束晚;东部开始晚,结束早.大连地区寒潮主要出现在11、12月和1月.近45年来,大连地区寒潮异常具有三次跃变,跃变发生在20世纪70年代中期、80年代中后期和21世纪初期.大连的寒潮活动也可以分为四个阶段:活跃期—沉寂期—正负振荡期—沉寂期.近45年来,大连地区寒潮活动具有减少的趋势,从1961~2005年,趋势性寒潮频数减少为0.7次/10年.     

Multimodel projections and uncertainties of net ecosystem production in China over the twenty-first century

Ecosystems in China have been absorbing anthropogenic CO2 over the last three decades. Here, we assess future carbon uptake in China using models from phase 5 of Coupled Model Intercomparison Project under four socio-economic scenarios. The average of China＇s carbon sink from 2006 to 2100 represented by multimodel mean net ecosystem production （NEP） is projected to increase （relative to averaged NEP from 1976 to 2005） in the range of 0.137 and 0.891 PgC a^-1 across different scenarios. Increases in NEP are driven by increases in net primary production exceeding increases in heterotrophic respiration, and future carbon sink is mainly attributed to areas located in eastern China. However, there exists a considerable model spread in the magnitude of carbon sink and model spread tends to be larger when future climate change becomes more intense. The model spread may result from intermodel discrepancy in the magnitude of CO2 fertilization effect on photosynthesis, soil carbon turnover time, presence of carbon-nitrogen cycle and interpretation of land-use changes. For better quantifying future carbon cycle, a research priority toward improving model representation of these processes is recommended.     

Astronomical pacing of late Palaeocene to early Eocene global warming events

At the boundary between the Palaeocene and Eocene epochs, about 55 million years ago, the Earth experienced a strong global warming event, the Palaeocene-Eocene thermal maximum. The leading hypothesis to explain the extreme greenhouse conditions prevalent during this period is the dissociation of 1,400 to 2,800 gigatonnes of methane from ocean clathrates, resulting in a large negative carbon isotope excursion and severe carbonate dissolution in marine sediments. Possible triggering mechanisms for this event include crossing a threshold temperature as the Earth warmed gradually, comet impact, explosive volcanism or ocean current reorganization and erosion at continental slopes, whereas orbital forcing has been excluded. Here we report a distinct carbonate-poor red clay layer in deep-sea cores from Walvis ridge, which we term the Elmo horizon. Using orbital tuning, we estimate deposition of the Elmo horizon at about 2 million years after the Palaeocene-Eocene thermal maximum. The Elmo horizon has similar geochemical and biotic characteristics as the Palaeocene-Eocene thermal maximum, but of smaller magnitude. It is coincident with carbon isotope depletion events in other ocean basins, suggesting that it represents a second global thermal maximum. We show that both events correspond to maxima in the approximately 405-kyr and approximately 100-kyr eccentricity cycles that post-date prolonged minima in the 2.25-Myr eccentricity cycle, implying that they are indeed astronomically paced.     

Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model

The continued increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being absorbed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO2 concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon-climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a 'business as usual' scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C yr(-1) is balanced by the terrestrial carbon source, and atmospheric CO2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback.     

Recognition of climatic effects of land use/land cover change under global warming

Greenhouse gas emissions and land use/land cover change (LUCC) are two human activities notably affecting climate change. Will temperature and precipitation increase significantly during global warming resulting in more pronounced LUCC climatic effects? Considering the interannual forcing of these two factors, the NCAR Community Atmosphere Model (CAM4.0) was used in this study to investigate the importance of climatological background to LUCC impacts. Experiments based on the difference in the background climate, the greenhouse gas concentrations in 1850 and in the present age indicate contrary changes in climate sensitivity through estimations of the radiative forcing associated with LUCC, which are 0.54°C/(W/m²) and ?0.26°C/(W/m²), respectively. Therefore, the background climate appears to play an important role in the regional impact of LUCC, especially at higher latitudes. In addition, global warming predominantly influences snow-albedo feedback in the mid-latitudes, thus determining the impact of LUCC, whereas the regional difference in precipitation caused by global warming is responsible for the differing climate response to LUCC in the tropics and subtropics.     

Release of methane from a volcanic basin as a mechanism for initial Eocene global warming

A 200,000-yr interval of extreme global warming marked the start of the Eocene epoch about 55 million years ago. Negative carbon- and oxygen-isotope excursions in marine and terrestrial sediments show that this event was linked to a massive and rapid (approximately 10,000 yr) input of isotopically depleted carbon. It has been suggested previously that extensive melting of gas hydrates buried in marine sediments may represent the carbon source and has caused the global climate change. Large-scale hydrate melting, however, requires a hitherto unknown triggering mechanism. Here we present evidence for the presence of thousands of hydrothermal vent complexes identified on seismic reflection profiles from the V?ring and M?re basins in the Norwegian Sea. We propose that intrusion of voluminous mantle-derived melts in carbon-rich sedimentary strata in the northeast Atlantic may have caused an explosive release of methane--transported to the ocean or atmosphere through the vent complexes--close to the Palaeocene/Eocene boundary. Similar volcanic and metamorphic processes may explain climate events associated with other large igneous provinces such as the Siberian Traps (approximately 250 million years ago) and the Karoo Igneous Province (approximately 183 million years ago).     

施用氮肥与生物炭对菜地净综合温室效应的影响

采用静态暗箱-气相色谱法,研究施用氮肥与生物炭对菜地周年净综合温室效应(net GWP)的影响。结果表明:施用氮肥可以显著增加菜地N2O累积排放量和净综合温室效应,增幅分别为31.2%~116.4%和38.9%~308.5%,对蔬菜产量和CH4累积排放量无显著影响,增加菜地温室气体强度(GHGI)52.1%~293.8%;施用生物炭能够显著减少菜地N2O的累积排放量和净综合温室效应,减幅分别为1.6%~24.4%和89.5%~701.1%,显著增加蔬菜总产量2.4%~34.5%,降低菜地温室气体强度。因此,在菜地施用生物炭既能保证蔬菜产量又能减少温室气体排放,是合适的增产减排措施。     

A comparison of the Medieval Warm Period, Little Ice Age and 20th century warming simulated by the FGOALS climate system model

To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-l...     

Decadal co-variability of the summer surface air temperature and soil moisture in China under global warming

The self-calibrating Palmer Drought Severity Index (PDSI) is calculated using newly updated ground observations of monthly surface air temperature (SAT) and precipitation in China. The co-variabilities of PDSI and SAT are examined for summer for the period 1961-2004. The results show that there exist decadal climate co-variabilities and strong nonlinear interactions between SAT and soil moisture in many regions of China. Some of the co-variabilities can be linked to global warming. In summer,sig-nificant decadal co-variabilities from cool-wet to warm-dry conditions are found in the east region of Northwest China,North China,and Northeast China. An important finding is that in the west region of Northwest China and Southeast China,pronounced decadal co-variabilities take place from warm-dry to cool-wet conditions. Because significant warming was observed over most areas of the global land surface during the past 20-30 years,the shift to cool-wet conditions is a unique phenomenon which may deserve much scientific attention. The nonlinear interactions between SAT and soil moisture may partly account for the observed decadal co-variabilities. It is shown that anomalies of SAT will greatly affect the climatic co-variabilities,and changes of SAT may bring notable influence on the PDSI in China. These results provide observational evidence for increasing risks of decadal drought and wet-ness as anthropogenic global warming progresses.     

A comparison of the Medieval Warm Period, Little Ice Age and 20th century warming simulated by the FGOALS climate system model

To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-latitudes of the North Pacific. However, the magnitude of the warming is weaker than that in the 20th century. The warming in the high latitudes of the Northern Hemisphere is stronger than that in the Southern Hemisphere. The LIA cooling is also evident on a global scale, with a strong cooling over the high Eurasian continent, while the cooling center is over the Arctic domain. Both the MWP and the 20CW experiments exhibit the strongest warming anomalies in the middle troposphere around 200?C300 hPa, but the cooling center of the LIA experiment is seen in the polar surface of the Northern Hemisphere. A comparison of model simulation against the reconstruction indicates that model??s performance in simulating the surface air temperature changes during the warm periods is better than that during the cold periods. The consistencies between model and reconstruction in lower latitudes are better than those in high latitudes. Comparison of the inter-annual variability mode of East Asian summer monsoon (EASM) rainfall during the MWP, LIA and 20CW reveals a similar rainfall anomalies pattern. However, the time spectra of the principal component during the three typical periods of the last millennium are different, and the quasi-biannual oscillation is more evident during the two warm periods. At a centennial time scale, the external mode of the EASM variability driven by the changes of effective solar radiation is determined by the changes of large scale land-sea thermal contrast. The rainfall anomalies over the east of 110°E exhibit a meridional homogeneous change pattern, which is different from the meridional out-of-phase change of rainfall anomalies associated with the internal mode.     

Comparisons of grain size characteristics of red earth from southern China with that of loess and dune sand from Bering region

The comparisons of grain size distributions among eolian deposits along the monsoon wind trajectory are a fundamental task for the reconstruction of the past wind regimes. Here the authors sampled the dune sands in Hunsandak desert, loess deposits in Beijing region and red earth in southern China. Grain size analyses show that the distribution models of the loess and dune sand samples are unimodal whereas the red earth and paleosol are polymodal. The red earth, paleosol, loess and dune samples are distinguished and closely related to one another in grain size parameter diagrams. Moreover, the grain size distributions and parameters of the red earth and paleosol are similar, implying that the red earth in southern China and the paleosol in northern China had the same origin.     

气候变暖条件下中国西北地区地理环境演变趋势初探

在预测分析的基础上,探讨了因气温升高而引起的气候、植被、土壤、水文、地貌等自然地理要素的变化趋势