Northern hemisphere winter atmospheric climate: modes of natural variability and climate change

Under anthropogenic climate change it is possible that the increased radiative forcing and associated changes in mean climate may affect the “dynamical equilibrium” of the climate system; leading to a change in the relative dominance of different modes of natural variability, the characteristics of their patterns or their behavior in the time domain. Here we use multi-century integrations of version three of the Hadley Centre atmosphere model coupled to a mixed layer ocean to examine potential changes in atmosphere-surface ocean modes of variability. After first evaluating the simulated modes of Northern Hemisphere winter surface temperature and geopotential height against observations, we examine their behavior under an idealized equilibrium doubling of atmospheric CO₂. We find no significant changes in the order of dominance, the spatial patterns or the associated time series of the modes. Having established that the dynamic equilibrium is preserved in the model on doubling of CO₂, we go on to examine the temperature pattern of mean climate change in terms of the modes of variability; the motivation being that the pattern of change might be explicable in terms of changes in the amount of time the system resides in a particular mode. In addition, if the two are closely related, we might be able to assess the relative credibility of different spatial patterns of climate change from different models (or model versions) by assessing their representation of variability. Significant shifts do appear to occur in the mean position of residence when examining a truncated set of the leading order modes. However, on examining the complete spectrum of modes, it is found that the mean climate change pattern is close to orthogonal to all of the modes and the large shifts are a manifestation of this orthogonality. The results suggest that care should be exercised in using a truncated set of variability EOFs to evaluate climate change signals.     

Anthropogenic climate change over the Mediterranean region simulated by a global variable resolution model

Two 30-year simulations corresponding to 1960-1989 and 2070-2099 have been performed with a variable resolution atmospheric model. The model has a maximum horizontal resolution of 0.5° over the Mediterranean Sea. Simulations are driven by IPCC-B2 scenario radiative forcing. Sea surface temperatures (SSTs) are prescribed from monthly observations for the present climate simulation, and from a blend of observations and coupled simulations for the scenario. Another pair of forced atmospheric simulations has been run under these forcings with the same uniform low resolution as the coupled model. Comparisons with observations show that the variable resolution model realistically reproduces the main climate characteristics of the Mediterranean region. At a global scale, changes in latitudinal temperature profiles are similar for the forced and coupled models, justifying the time-slice approach. The 2 m temperature and precipitation responses predict a warming and drying of the Mediterranean region. A comparison with the coupled simulation and forced low-resolution simulation shows that this pattern is robust. The decrease in mean precipitation is associated with a significant decrease in soil wetness, and could involve considerable impact on water resources around the Mediterranean basin.     

Attribution of twentieth century temperature change to natural and anthropogenic causes

  We analyse possible causes of twentieth century near-surface temperature change. We use an “optimal detection” methodology to compare seasonal and annual data from the coupled atmosphere-ocean general circulation model HadCM2 with observations averaged over a range of spatial and temporal scales. The results indicate that the increases in temperature observed in the latter half of the century have been caused by warming from anthropogenic increases in greenhouse gases offset by cooling from tropospheric sulfate aerosols rather than natural variability, either internal or externally forced. We also find that greenhouse gases are likely to have contributed significantly to the warming in the first half of the century. In addition, natural effects may have contributed to this warming. Assuming one particular reconstruction of total solar irradiance to be correct implies, when we take the seasonal cycle into account, that solar effects have contributed significantly to the warming observed in the early part of the century, regardless of any relative error in the amplitudes of the anthropogenic forcings prescribed in the model. However, this is not the case with an alternative reconstruction of total solar irradiance, based more on the amplitude than the length of the solar cycle. We also find evidence for volcanic influences on twentieth century near-surface temperatures. The signature of the eruption of Mount Pinatubo is detected using annual-mean data. We also find evidence for a volcanic influence on warming in the first half of the century associated with a reduction in mid-century volcanism. Received: 24 January 2000 / Accepted: 20 April 2000     

A quantitative analysis of the causes of the global climate change research distribution

During the last decades of growing scientific, political and public attention to global climate change, it has become increasingly clear that the present and projected impacts from climate change, and the ability adapt to the these changes, are not evenly distributed across the globe. This paper investigates whether the need for knowledge on climate changes in the most vulnerable regions of the world is met by the supply of knowledge measured by scientific research publications from the last decade. A quantitative analysis of more than 15,000 scientific publications from 197 countries investigates the distribution of climate change research and the potential causes of this distribution. More than 13 explanatory variables representing vulnerability, geographical, demographical, economical and institutional indicators are included in the analysis. The results show that the supply of climate change knowledge is biased toward richer countries, which are more stable and less corrupt, have higher school enrolment and expenditures on research and development, emit more carbon and are less vulnerable to climate change. Similarly, the production of knowledge, analyzed by author affiliations, is skewed away from the poorer, fragile and more vulnerable regions of the world. A quantitative keywords analysis of all publications shows that different knowledge domains and research themes dominate across regions, reflecting the divergent global concerns in relation to climate change. In general, research on climate change in more developed countries tend to focus on mitigation aspects, while in developing countries issues of adaptation and human or social impacts (droughts and diseases) dominate. Based on these findings, this paper discusses the gap between the supply of and need for climate change knowledge, the potential causes and constraints behind the imbalanced distribution of knowledge, and its implications for adaptation and policymaking.     

Learning and climate change

Abstract

Learning—i.e. the acquisition of new information that leads to changes in our assessment of uncertainty—plays a prominent role in the international climate policy debate. For example, the view that we should postpone actions until we know more continues to be influential. The latest work on learning and climate change includes new theoretical models, better informed simulations of how learning affects the optimal timing of emissions reductions, analyses of how new information could affect the prospects for reaching and maintaining political agreements and for adapting to climate change, and explorations of how learning could lead us astray rather than closer to the truth. Despite the diversity of this new work, a clear consensus on a central point is that the prospect of learning does not support the postponement of emissions reductions today.     

Security and climate change

Despite it being the most studied and arguably most profound of global environmental change problems, there is relatively little research that explores climate change as a security issue. This paper systematically explores the range of possible connections between climate change and security, including national security considerations, human security concerns, military roles, and a discussion of the widely held assumption that climate change may trigger violent conflict. The paper explains the ways in which climate change is a security issue. It includes in its discussion issues to do with both mitigation and adaptation of climate change.     

The challenge to detect and attribute effects of climate change on human and natural systems

Future scenarios of the energy system under greenhouse gas emission constraints depict dramatic growth in a range of energy technologies. Technological growth dynamics observed historically provide a useful comparator for these future trajectories. We find that historical time series data reveal a consistent relationship between how much a technology’s cumulative installed capacity grows, and how long this growth takes. This relationship between extent (how much) and duration (for how long) is consistent across both energy supply and end-use technologies, and both established and emerging technologies. We then develop and test an approach for using this historical relationship to assess technological trajectories in future scenarios. Our approach for “learning from the past” contributes to the assessment and verification of integrated assessment and energy-economic models used to generate quantitative scenarios. Using data on power generation technologies from two such models, we also find a consistent extent - duration relationship across both technologies and scenarios. This relationship describes future low carbon technological growth in the power sector which appears to be conservative relative to what has been evidenced historically. Specifically, future extents of capacity growth are comparatively low given the lengthy time duration of that growth. We treat this finding with caution due to the low number of data points. Yet it remains counter-intuitive given the extremely rapid growth rates of certain low carbon technologies under stringent emission constraints. We explore possible reasons for the apparent scenario conservatism, and find parametric or structural conservatism in the underlying models to be one possible explanation.     

Perceptions of climate and climate change by Amazonian communities

The Amazon region has been undergoing profound transformations since the late ‘70s through forest degradation, land use changes and effects of global climate change. The perception of such changes by local communities is important for risk analysis and for subsequent societal decision making. In this study, we compare and contrast observations and perceptions of climate change by selected Amazonian communities particularly vulnerable to alterations in precipitation regimes. Two main points were analysed: (i) the notion of changes in the annual climate cycle and (ii) the notion of changes in rainfall patterns. About 72% of the sampled population reports perceptions of climate changes, and there is a robust signal of increased perception with age. Other possible predictive parameters such as gender, fishing frequency and changes in/planning of economic activities do not appear overall as contributing to perceptions. The communities’ perceptions of the changes in 2013–2014 were then compared to earlier results (2007–2008), providing an unprecedented cohort study of the same sites. Results show that climate change perceptions and measured rainfall variations differ across the basin. It was only in the southern part of the Amazon that both measured and perceived changes in rainfall patterns were consistent with decreased precipitation. However, the perception of a changing climate became more widespread and frequently mentioned, signalling an increase in awareness of climate risk.     

Ethics and intentional climate change

In recent years the idea of geoengineering climate has begun to attract increasing attention. Although there was some discussion of manipulating regional climates throughout the 1970s and 1980s, the discussion was largely dormant. What has reawakened the conversation is the possibility that Earth may be undergoing a greenhouse-induced global warming, and the paucity of serious measures that have been taken to prevent it.In this paper I assess the ethical acceptability of ICC, based on my impressions of the conversation that is now taking place. Rather than offering a dispassionate analysis, I argue for a point of view. I propose a set of conditions that must be satisfied for an ICC project to be morally permissible and conclude that these conditions are not now satisfied. However, research on ICC should go forward so long as certain other conditions are met. I do not intend this to be the last word on the subject, but rather the first word. My hope is that others will be stimulated to think through the ethics of ICC.     

Mass-cargo-affine industries and climate change

The impact of low water periods on inland navigation and companies is well known by ship-operators and companies that rely on this mode of transport but it is rarely a topic of climate impact research. As climate change might affect the frequency and intensity of low water periods, quantifying the impact of climate change on companies and the effects of possible adaptation measures is vital. In this study, we present a model for quantifying the impact of low water events on companies which rely on inland navigation and apply that model to three anonymous iron and steel companies along the River Rhine. The deviation of optimal storage, the storage level that evens out risk vs. fixed capital, is used in the model to measure the vulnerability of companies. The results show that, depending on the climate scenario, the companies might have to deal with either one or five additional days of empty storage in the near future (2021–2050) and up to nine more days by the 2071–2100 period. Seasonal analysis shows that, consistent with the change in the river discharge, the biggest deviations from optimal storage level occur in the late summer/early autumn. Analysis of adaptation options shows that companies would need to increase storage capacity by 2.5 % for the 2021–2050 period, and by 25 % by the 2071–2100 period. A reduction of ship sizes is not an adaptation option for the three companies in this study, because these companies already use relatively small vessels. This is however an efficient adaptation option for companies which employ larger vessels for transport. Another adaptation option would be to reduce the share of transportation via inland waters, but the feasibility of this option depends on the availability and cost of other modes of transport.     

Farm programs and climate change

The view that the agricultural sector could largely offset any negative impacts of climate change by altering production practices assumes the government will not create disincentives for farmers to adapt. U.S. farm programs, however, often discourage such obvious adaptations as switching crops, investing in water conserving technologies, and entry or exit. We outline a simple portfolio model describing producer decision making: we then use this framework to assess how specific U.S. farm programs might affect adaption to climate change. Three future climate scenarios are considered and in each the present structure of U.S. farm programs discourages adaptation.     

Racing climate change: Collaboration and conflict in California's global climate change policy arena

Media accounts routinely refer to California's Assembly Bill 32 (AB 32), the Global Warming Solutions Act of 2006, as “landmark” climate change legislation. On its surface, this label is an accurate reflection of the state's forward-thinking stance across many environmental issues including pesticides, toxic substances, solid waste, and air quality. For all its promise, however, AB 32 can also be considered a low point in the landscape of conflict between state environmental regulators and California's environmental justice movement. While the legislation included several provisions to address the procedural and distributive dimensions of environmental justice, the implementation of AB 32 has been marked by heated conflict. The most intense conflicts over AB 32 revolve around the primacy of market mechanisms such as “cap and trade.” This article examines the drivers and the manifestations of these dynamics of collaboration and conflict between environmental justice advocates and state regulators, and pays particular attention to the scalar and racialized quality of the neoliberal discourse. The contentiousness of climate change politics in California offers scholars and practitioners around the world a cautionary tale of how the best intentions for integrating environmental justice principles into climate change policy do not necessarily translate into implementation and how underlying racialized fractures can upend collaboration between state and social movement actors.     

企业气候变化意识及应对措施调查研究

基于2012—2015年在华北、珠三角和湖南湖北地区对企业管理人员进行的气候变化意识的问卷调查,构建了气候变化意识和企业应对气候变化措施两个一级指数。通过对调查结果交叉列联表分析,得出以下结论：企业管理人员的气候变化意识指数处于一般水平,并且受年龄、产业类型、企业类型的影响显著;企业应对气候变化措施指数也处于一般水平且不同企业水平差距较大,企业管理人员气候变化意识水平、未来预期和自主知识产权拥有量对其影响显著。