东亚夏季海陆热力对比对全球变暖的响应

利用耦合模式比较20世纪气候模拟试验和21世纪SRES(Special Report on Emissions Scenarios)A1B情景气候预估试验结果,探讨了东亚区域海陆热力对比对全球变暖的响应。首先通过超级集合方法,重建了20世纪40a(1960—1999年)和预估了21世纪40 a(2020—2059年)东亚地区的海陆热力对比;在此基础上,分析了东亚夏季海陆热力对比的过去40 a的变化特征及其未来的可能变化趋势。结果表明,超级集合的方法能够有效地降低单个模式存在的不确定性,其结果优于多模式的算术平均结果。利用超级集合方法能够很好地再现1960—1999年间海陆热力差指数的变化特征,并且有效地降低与再分析资料的均方根误差。进一步分析发现,陆面温度在全球变暖背景下变化较明显,尤其在华南地区存在显著增温;而东亚大陆季风区,存在明显的降温趋势。利用超级集合方法预估未来海陆热力对比的结果表明,在2040年前存在较强的海陆热力差,而2050后海陆热力对比有减弱趋势。     

Ocean change around Greenland under a warming climate

Climate Dynamics - The impact of climate warming on the ocean near Greenland is investigated with a high resolution coupled global climate model. The ocean around Greenland exhibits a strong...     

Mechanisms for the land/sea warming contrast exhibited by simulations of climate change

The land/sea warming contrast is a phenomenon of both equilibrium and transient simulations of climate change: large areas of the land surface at most latitudes undergo temperature changes whose amplitude is more than those of the surrounding oceans. Using idealised GCM experiments with perturbed SSTs, we show that the land/sea contrast in equilibrium simulations is associated with local feedbacks and the hydrological cycle over land, rather than with externally imposed radiative forcing. This mechanism also explains a large component of the land/sea contrast in transient simulations as well. We propose a conceptual model with three elements: (1) there is a spatially variable level in the lower troposphere at which temperature change is the same over land and sea; (2) the dependence of lapse rate on moisture and temperature causes different changes in lapse rate upon warming over land and sea, and hence a surface land/sea temperature contrast; (3) moisture convergence over land predominantly takes place at levels significantly colder than the surface; wherever moisture supply over land is limited, the increase of evaporation over land upon warming is limited, reducing the relative humidity in the boundary layer over land, and hence also enhancing the land/sea contrast. The non-linearity of the Clausius–Clapeyron relationship of saturation specific humidity to temperature is critical in (2) and (3). We examine the sensitivity of the land/sea contrast to model representations of different physical processes using a large ensemble of climate model integrations with perturbed parameters, and find that it is most sensitive to representation of large-scale cloud and stomatal closure. We discuss our results in the context of high-resolution and Earth-system modelling of climate change.     

全球变暖与地球“三极”气候变化

北极、南极和青藏高原分别是地球的最北端、最南端和海拔最高的高原,被称为地球“三极”。地球三极是全球气候变化的关键区与敏感区,在区域及全球气候系统中的重要性日益凸显。本文回顾了该领域的最新研究成果,重点阐述了地球三极气候年代际变化的基本特征及其对区域气候的影响,探究了在全球气候变暖背景下地球三极气候变化之间的潜在联系,讨论并展望了未来地球三极气候变化研究所面临的挑战。     

The ratio of land to ocean temperature change under global warming

The result in climate simulations, supported in the observation-based record, is that the ratio $\phi = T_{L} /T_{O} $ of land-average to ocean-average temperature change is greater than one and varies comparatively modestly as climate changes. This is investigated in results from the CMIP3 data archive of climate change simulations following the B1 and more strongly forced A1B scenarios as well as in 2×CO₂ integrations. The associated precipitation ratio $ \psi = P_{L} /P_{O} $ is also considered briefly. The behaviour of ? is analyzed in terms of a forcing-response view of the energy balance over land and ocean regions. The analysis indicates that the value of ??>?1 is not maintained by separate local balances over land and ocean but by an energetic balance that also involves a change in transport between the regions. The transport change does not restrain the land warming by exporting energy to the ocean region but, rather, the reverse. The anomalous transport is from the ocean to the land region even though the ocean warms less than the land does. Feedbacks in the ocean region, especially in the equatorial Pacific, do not sufficiently counteract the forcing and the result is an excess of energy that is transported to the land. The land warms in order to radiate away both the energy from the forcing over land but also the extra energy imported from the ocean region, thereby maintaining ??>?1. This situation can be understood to parallel the SST-forced case in model studies where ??>?1 despite the forcing being confined to the ocean area. The climate system is effective in redistributing forcing so that it is the local feedbacks, rather than the pattern of the forcing, that determine the temperature response. Land and ocean averaged quantities and budgets behave in a consistent manner to provide a simplified representation of the changes in temperature and energetic processes that are occurring. The geographical distributions of the terms do not, however, display a strong land/ocean demarcation. The land/ocean average budgets and balances are the residual of processes that vary considerably within the land and ocean boundaries.     

Temporal change of climate zones in China in the context of climate warming

In China, ten climate types were classified using the K-means cluster analysis based on monthly temperature and precipitation data from 753 national meteorological stations for the period 1966–2005. However, 11 mountain climate stations, which are located in southeast China, were classified as one type due to their distinct climate characteristic that differentiated them from other stations. This type could not represent the climate characteristic of this region because all climate stations in this type were located at high-elevation mountains. Thus, it was eliminated when defining climate zones based on climate types. Therefore, nine climate zones were defined in China. Moreover, the temporal change of climate zones was detected in 20-year intervals (1966–1985 and 1986–2005). Although 48 stations changed their climate zones between these two periods, the whole pattern of all climate zones remained stable in these two periods. However, the boundaries between some climate zones changed slightly due to inconsistent variation of regional temperature and precipitation. The most obvious change was the eastern movement of the boundary between an arid temperate zone and a sub-humid temperate zone. There was also a northern shift of the boundary between a tropic zone and a southern subtropic zone. All these changes were probably connected with the climate change in recent 40 years.     

Spatiotemporal change in geographical distribution of global climate types in the context of climate warming

After standardizing global land climate gridded data from the Climatic Research Unit TS (time-series) 3.1 dataset for the period 1901–2009, cluster analysis is used to objectively classify world climates into 14 climate types. These climate types establish a baseline classification map and the types are named according to Köppen–Geiger climate classifications. Although the cluster analysis and Köppen classification methods are very different, the distributions of climate types obtained by the two methods are similar. Moreover, the climate types we identify also coincide well with their corresponding vegetation types. Thus, cluster analysis can be used as an effective alternative to the Köppen classification method for classifying world climate types. The spatial and temporal changes in geographical distribution of global climate types were investigated in 25-year intervals, and Cohen’s kappa coefficient is used to detect agreement between the periods. Globally, although an obvious trend in increasing global temperature is found, distribution of climate types overall show no distinct changes over the periods. However, at the regional scale, spatial change in distribution of climate types is evident in South America and Africa. In South America, larger areas of the “fully humid equatorial rainforest” (Af) and “equatorial savannah with dry winter” (Aw) climate types have changed types. In Africa, changes mainly occurred in the Af, “equatorial savannah with dry summer” (As), Aw, “steppe climate” (BS), and “desert climate” (BW) climate types. Moreover, some climate types, including Af, “equatorial monsoon” (Am), BS, BW, and “tundra climate” (ET), were susceptible to temporal climate changes, especially in the period 1976–2009.     

The impact of perturbations to ocean-model parameters on climate and climate change in a coupled model

Assessments of the impacts of uncertainties in parameters on mean climate and climate change in complex climate models have, to date, largely focussed on perturbations to parameters in the atmosphere component of the model. Here we expand on a previously published study which found the global impacts of perturbed ocean parameters on the rate of transient climate change to be small compared to perturbed atmosphere parameters. By separating the climate-change-induced ocean vertical heat transport in each perturbed member into components associated with the resolved flow and each parameterisation scheme, we show that variations in global mean heat uptake in different perturbed versions are an order of magnitude smaller than the average heat uptake. The lack of impact of the perturbations is attributed to (1) the relatively small impact of the perturbation on the direct vertical heat transport associated with the perturbed process and (2) a compensation between those direct changes and indirect changes in heat transport from other processes. Interactions between processes and changes appear to combine in complex ways to limit ensemble spread and uncertainty in the rate of warming. We also investigate regional impacts of the perturbations that may be important for climate change predictions. We find variations across the ensemble that are significant when measured against natural variability. In terms of the experimental set-up used here (models without flux adjustments) we conclude that perturbed physics ensembles with ocean parameter perturbations are an important component of any probabilistic estimate of future climate change, despite the low spread in global mean quantities. Hence, careful consideration should be given to assessing uncertainty in ocean processes in future probabilistic assessments of regional climate change.     

Dividing climate change: global warming in the Indian mass media

Much research has now been conducted into the representation of climate change in the media. Specifically, the communication of climate change from scientists and policy-makers to the public via the mass media has been a subject of major interest because of its implications for creating national variation in public understanding of a global environmental issue. However, to date, no study has assessed the situation in India. As one of the major emerging economies, and so one of the major greenhouse gas emitters, India is a key actor in the climate change story. This study analyses the four major, national circulation English-language newspapers to quantify and qualify the frames through which climate change is represented in India. The results strongly contrast with previous studies from developed countries; by framing climate change along a ‘risk-responsibility divide’, the Indian national press set up a strongly nationalistic position on climate change that divides the issue along both developmental and postcolonial lines.     

黑龙江省1981-2010年气候平均值的变化及对气候评价的影响

利用黑龙江省气候评价业务使用的71个气象台站的气温、降水和日照时数资料,对1981-2010年气候平均值和1971-2000年气候平均值进行比较。结果表明:黑龙江省大部地区年平均气温升高,冬季偏暖突出;年降水量大部地区增多,春季、夏季、冬季降水量增多,秋季减少,7月降水量增幅最大;年日照时数大部地区减少。     

Making decisions to conserve species under climate change

Severe impacts on biodiversity are predicted to arise from climate change. These impacts may not be adequately addressed by conventional approaches to conservation. As a result, additional management actions are now being considered. However, there is currently limited guidance to help decision makers choose which set of actions (and in what order) is most appropriate for species that are considered to be vulnerable. Here, we provide a decision framework for the full complement of actions aimed at conserving species under climate change from ongoing conservation in existing refugia through various forms of mobility enhancement to ex situ conservation outside the natural environment. We explicitly recognize that allocation of conservation resources toward particular actions may be governed by factors such as the likelihood of success, cost and likely co-benefits to non-target species in addition to perceived vulnerability of individual species. As such, we use expert judgment of probable tradeoffs in resource allocation to inform the sequential evaluation of proposed management interventions.     

气候变暖下干旱对森林生态系统的影响

人类活动显著影响着全球大气循环格局,全球平均温度升高导致干旱事件发生幅度、频度和持续时间增加,这对森林生态系统带来更多的是负面影响.本文基于已有研究,系统总结了干旱事件对森林生态系统地理分布格局、群落结构重建、植物生长和生理特性、死亡和灭绝、植物生产力以及碳循环功能的影响及其机理,并对未来干旱事件对森林生态系统长期效应以及在不同时间尺度上作用机理的研究提出建议.本研究对开展全球变化背景下森林生态系统对干旱事件响应机制的研究具有重要指导意义.     

Modelling the response of glaciers to climate warming

 Dynamic ice-flow models for 12 glaciers and ice caps have been forced with various climate change scenarios. The volume of this sample spans three orders of magnitude. Six climate scenarios were considered: from 1990 onwards linear warming rates of 0.01, 0.02 and 0.04 K a^-1, with and without concurrent changes in precipitation. The models, calibrated against the historic record of glacier length where possible, were integrated until 2100. The differences in individual glacier responses are very large. No straightforward relationship between glacier size and fractional change of ice volume emerges for any given climate scenario. The hypsometry of individual glaciers and ice caps plays an important role in their response, thus making it difficult to generalize results. For a warming rate of 0.04 K a^-1, without increase in precipitation, results indicate that few glaciers would survive until 2100. On the other hand, if the warming rate were to be limited to 0.01 K a^-1 with an increase in precipitation of 10% per degree warming, we predict that overall loss would be restricted to 10 to 20% of the 1990 volume. Received: 30 June 1997/Accepted: 21 October 1997     

Heat budget of the upper Arctic Ocean under a warming climate

The heat budget of the upper Arctic Ocean is examined in an ensemble of coupled climate models under idealised increasing CO₂ scenarios. All of the experiments show a strong amplification of surface air temperatures but a smaller increase in sea surface temperature than the rest of the world as heat is lost to the atmosphere as the sea-ice cover is reduced. We carry out a heat budget analysis of the Arctic Ocean in an ensemble of model runs to understand the changes that occur as the Arctic becomes ice free in summer. We find that as sea-ice retreats heat is lost from the ocean surface to the atmosphere contributing to the amplification of Arctic surface temperatures. Furthermore, heat is mixed upwards into the mixed layer as a result of increased upper ocean mixing and there is increased advection of heat into the Arctic as the ice edge retreats. Heat lost from the upper Arctic Ocean to the atmosphere is therefore replenished by mixing of warmer water from below and by increased advection of warm water from lower latitudes. The ocean is therefore able to contribute more to Arctic amplification.     

A co-evolutionary approach to climate change impact assessment: Part I. Integrating socio-economic and climate change scenarios

Climate change policies currently pay disproportionately greater attention to the mitigation of climate change through emission reductions strategies than to adaptation measures. Realising that the world is already committed to some global warming, policy makers are beginning to turn their attention to the challenge of preparing society to adapt to the unfolding impacts at the local level. This two-part article presents an integrated, or `co-evolutionary', approach to using scenarios in adaptation and vulnerability assessment. Part I explains how climate and social scenarios can be integrated to better understand the inter-relationships between a changing climate and the dynamic evolution of social, economic and political systems. The integrated scenarios are then calibrated so that they can be applied `bottom up’ to local stakeholders in vulnerable sectors of the economy. Part I concludes that a co-evolutionary approach (1) produces a more sophisticated and dynamic account of the potential feedbacks between natural and human systems; (2) suggests that sustainability indicators are both a potentially valuable input to and an output of integrated scenario formulation and application. Part II describes how a broadly representative sample of public, private and voluntary organisations in the East Anglian region of the UK responded to the scenarios, and identifies future research priorities.     

气候变暖背景下修水县春茶气候品质等级变化趋势分析

基于1961—2019年修水县气象观测资料,运用气候倾向率方法分析了近59 a春茶采摘期间（3月1日—5月10日）主要气象要素、春霜冻灾害和基于气候品质指数的春茶气候品质等级的变化趋势。结果表明：在气候变暖背景下,1961—2019年修水县春茶采摘期间平均气温呈明显上升趋势,平均相对湿度呈减小趋势,日照时数呈显著增加趋势;春霜日数呈明显减少趋势,春霜冻发生概率在下降;近59 a来修水县春茶气候品质等级为特优、优和良的总日数呈增加趋势;春茶采摘期间,气候品质特优等级的概率随时间呈先增加后减小的趋势,等级为优和良的概率呈增加趋势。综合考虑平均气温、平均相对湿度、日照时数等气象条件,以及春霜冻和春茶气候品质等级变化特征,认为气候变暖有利于修水县春茶品质趋好。     

The impact of spatial resolution on area burned and fire occurrence projections in Portugal under climate change

In this study, we investigated the impact of future climate change on fire activity in 12 districts across Portugal. Using historical relationships and the HIRHAM (High Resolution Hamburg Model) 12 and 25 km climate simulations, we assessed the fire weather and subsequent fire activity under a 2 × CO₂ scenario. We found that the fire activity prediction was not affected by the spatial resolution of the climate model used (12 vs. 25 km). Future area burned is predicted to increase 478% for Portugal as a whole, which equates to an increase from 1.4% to 7.8% of the available burnable area burning annually. Fire occurrence will also see a dramatic increase (279%) for all of Portugal. There is significant spatial variation within these results; the north and central districts of the country generally will see larger increases in fire activity.     

Assessing the influence of climate model uncertainty on EU-wide climate change impact indicators

Despite an increasing understanding of potential climate change impacts in Europe, the associated uncertainties remain a key challenge. In many impact studies, the assessment of uncertainties is underemphasised, or is not performed quantitatively. A key source of uncertainty is the variability of climate change projections across different regional climate models (RCMs) forced by different global circulation models (GCMs). This study builds upon an indicator-based NUTS-2 level assessment that quantified potential changes for three climate-related hazards: heat stress, river flood risk, and forest fire risk, based on five GCM/RCM combinations, and non-climatic factors. First, a sensitivity analysis is performed to determine the fractional contribution of each single input factor to the spatial variance of the hazard indicators, followed by an evaluation of uncertainties in terms of spread in hazard indicator values due to inter-model climate variability, with respect to (changes in) impacts for the period 2041–70. The results show that different GCM/RCM combinations lead to substantially varying impact indicators across all three hazards. Furthermore, a strong influence of inter-model variability on the spatial patterns of uncertainties is revealed. For instance, for river flood risk, uncertainties appear to be particularly high in the Mediterranean, whereas model agreement is higher for central Europe. The findings allow for a hazard-specific identification of areas with low vs. high model agreement (and thus confidence of projected impacts) within Europe, which is of key importance for decision makers when prioritising adaptation options.     

A method to evaluate the usability of interactive climate change impact decision aids

Reducing the impacts from climate change requires people to make decisions that may prompt substantial changes in their lives. One possible way to help them is with personalized decision aids. Here we describe a method for evaluating such aids, in terms of how they affect users’ understanding of their situation, defined in terms of their (a) knowledge, (b) consistency of preferences, and (c) active mastery of the material. Our method provides a simple way to evaluate the usability of climate-change decision aids, and to address concerns that the choice of display could bias users’ attitudes. We demonstrate it with the Surging Seas Risk Finder, a decision aid focused on coastal flooding (http://sealevel.climatecentral.org/).