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Good intentions by the middle class are not always well guided and do not always lead to measurable or significant results. For example, efforts to limit greenhouse gas emissions may hold broad appeal but can still have negligible impact. Therefore, it is suggested to embark on “Apollo projects”, which bundle the potential and willingness of the middle class. These projects should focus on the development of specific technologies, with economic advantages to support their spread throughout the world. Doing so will harness the middle class in support of greenhouse gas emission reductions in the gigaton-range. Such pan-national projects, for example, could address emission-free ship- or air-propulsion, the electrification of heating or of processes in the chemical industry.

We have designed a method for testing the quality of multidecadal analyses of sea surface temperature (SST) in regional seas by using a set of high-quality local SST observations. In recognizing that local data may reflect local effects, we focus on the dominant empirical orthogonal functions (EOFs) of the local data and of the localized data of the gridded SST analyses. We examine the patterns, variability, and trends of the principal components. This method is applied to examine three different SST analyses, i.e., HadISST1, ERSST, and COBE SST. They have been assessed using a newly constructed high-quality dataset of SST at 26 coastal stations along the Chinese coast in 1960-2015, which underwent careful examination with respect to quality and a number of corrections for inhomogeneities. The three gridded analyses perform generally well from 1960 to 2015, in particular since 1980. However, for the pre-satellite period prior to the 1980s, the analyses differ among each other and show some inconsistencies with the local data, such as artificial break points, periods of bias, and differences in trends. We conclude that gridded SST analyses need improvement in the pre-satellite period (prior to the 1980s) by reexamining in detail archives of local quality-controlled SST data in many data-sparse regions of the world.. © Author(s) 2019.

In view of the need to curb greenhouse gases, the question arises as to the functions of liability in providing effective incentives for emitters in order to change their behavior. Liability for emitting greenhouse gases exists (or can exist) in the area of public law and private law and can be subdivided into international, administrative, and criminal liability (public law liabilities) and tort law liability (private law liability). Actions for holding individual and legal persons (such as states, authorities, and companies) liable can, depending on the specific jurisdiction, be triggered by citizens but also by legal persons, such as authorities, companies, and non-governmental organizations (NGOs), particularly environmental NGOs. The central question in this article is how climate liability is arranged under public law and whether there would be any role for climate liability to play under private law, thereby applying a legal and economic methodology. That so-called law and economics doctrine is a useful approach as it has given a lot of attention, for example, to the different functions of specific legal instruments (more particularly regulation, including taxation and emissions trading and tort law liability) for mitigating greenhouse gases. Meanwhile, in practice, various examples can be identified whereby tort law liability is used as a complement to greenhouse gas regulation. This specific use of tort liability is analyzed in the light of the law and economics literature, thereby pointing at prospects but also at remaining core questions. The success of tort law actions will most likely greatly depend on the (lack of) ambition vested into the emissions regulations at international and national levels. One of the exciting questions for the near future is to what extent judges feel able to step into the regulation of the climate change problem, in an ex ante way. The most difficult cases are obviously those where a regulatory system concerning greenhouse gas mitigation has been put in place and where the court system is strong, but where particular groups consider the regulations to be insufficient.

This paper demonstrates two important aspects of regional dynamical downscaling of multidecadal atmospheric reanalysis. First, that in this way skillful regional descriptions of multidecadal climate variability may be constructed in regions with little or no local data. Second, that the concept of large‐scale constraining allows global downscaling, so that global reanalyses may be completed by additions of consistent detail in all regions of the world. Global reanalyses suffer from inhomogeneities. However, their large‐scale componenst are mostly homogeneous; Therefore, the concept of downscaling may be applied to homogeneously complement the large‐scale state of the reanalyses with regional detail—wherever the condition of homogeneity of the description of large scales is fulfilled. Technically, this can be done by dynamical downscaling using a regional or global climate model, which\'s large scales are constrained by spectral nudging. This approach has been developed and tested for the region of Europe, and a skillful representation of regional weather risks—in particular marine risks—was identified. We have run this system in regions with reduced or absent local data coverage, such as Central Siberia, the Bohai and Yellow Sea, Southwestern Africa, and the South Atlantic. Also, a global simulation was computed, which adds regional features to prescribed global dynamics. Our cases demonstrate that spatially detailed reconstructions of the climate state and its change in the recent three to six decades add useful supplementary information to existing observational data for midlatitude and subtropical regions of the world.

Hans von Storch beschäftigt sich als naturwissenschaftlicher Klimaforscher seit vielen Jahren mit dem Verhältnis von Wissenschaft und Gesellschaft. In zahlreichen Publikationen stellt er sich einem kritischen Dialog mit den Sozialwissenschaften, um folgende Fragen zu klären: Was wissen wir über Eigenlogiken im Wissenschaftssystem und in der Politik, und was sagt das über die Möglichkeiten von wissenschaftlicher Politikberatung aus? Welche Rolle spielen die Massenmedien für die gesellschaftliche Wahrnehmung der Klimaforschung? Und wie können wir die Klimaforschung selbst als einen sozialen Prozess verstehen? Seine wesentlichen Thesen des Vortrages: a) Naturwissenschaftliche Klimaforschung ohne sozialwissenschaftliche Kontextualisierung macht wenig Sinn, sofern es um die Erforschung des menschgemachten Klimawandels und des der damit verbundenen Klimawirkung geht – und darum geht es fast immer. Die Klimaforschung ist fast ausschließlich auf dieses Thema ausgerichtet. Sie wird auch in diese Richtung gepusht, sowohl was Mittel als auch öffentliche Anerkennung angeht. b) Die Naturwissenschaftliche Klimaforschung hat in den letzten 30 Jahren wesentliche Ergebnisse erarbeitet und abgesichert: Das Klima verändert sich stärker als aufgrund natürlicher Vorgänge zu erwarten ist. Eine Erklärung für die Änderungen gelingt nur, wenn die Wirkung der stark erhöhten Konzentrationen atmosphärischen Treibhausgase als dominant verstanden wird. Da der Zuwachs dieser Konzentration durch menschlichen Emissionen zustande kommt, sind die Änderungen grundsätzlich steuerbar durch entsprechende gesellschaftliche Eingriffe c) Naturwissenschaftliche Klimaforschung spricht oft direkt zu Gesellschaft. Sie befindet sich in einer postnormalen Situation, wo bisweilen die politische Nützlichkeit vor der methodischen Qualität steht. d) Klimaforschung, und öfter noch Klimaforscher sind also soziale Akteure. Bisweilen findet man diese Akteure stark involviert in die politische Willensbildung, wobei politische Präferenzen als wissenschaftliche Notwendigkeiten präsentiert werden.

We investigate whether the recently observed temperature and precipitation trends over the Baltic Sea Basin are consistent with state-of-the-art regional climate model projections. To address this question we use several data sources: (1) multidecadal trends derived from various observational data sets, (2) estimates of natural variability provided by a 2000 year paleoclimatic model simulation, and (3) response to greenhouse gas forcing derived from regional climate simulations driven by the A1B and RCP4.5 scenarios (from ENSEMBLES and CORDEX projects). Results indicate that, over the past decades, the climate in the Baltic Sea Basin has undergone a change that is beyond the estimated range of natural variability. We test the hypothesis that this change may be understood as a manifestation of global warming due to increasing concentrations of greenhouse gases (GHGs). We find that changes in near-surface temperature support our hypothesis that the effect of GHG is needed to simulate the observed changes. The pattern correlation and regression results clearly illustrate the concerted emergence of an anthropogenic signal consistent with the GHG signal in summer and autumn in the 21st century. However, none of the 19 regional climate simulations used in this study reproduce the observed warming. The observed trends in precipitation and surface solar radiation are also partially inconsistent with the expected changes due to GHG forcing. We conclude that, besides the regional response to GHG forcing, other human-made drivers have had an imprint. Regional emission of industrial aerosols has been strongly reduced in this region, and we suggest that this reduction may be the missing driver.

This book is an update of the first BACC assessment, published in 2008. It offers new and updated scientific findings in regional climate research for the Baltic Sea basin. These include climate changes since the last glaciation (approx. 12,000 years ago), changes in the recent past (the last 200 years), climate projections up until 2100 using state-of-the-art regional climate models and an assessment of climate-change impacts on terrestrial, freshwater and marine ecosystems. There are dedicated new chapters on sea-level rise, coastal erosion and impacts on urban areas. A new set of chapters deals with possible causes of regional climate change along with the global effects of increased greenhouse gas concentrations, namely atmospheric aerosols and land-cover change. The evidence collected and presented in this book shows that the regional climate has already started to change and this is expected to continue. Projections of potential future climates show that the region will probably become considerably warmer and wetter in some parts, but dryer in others. Terrestrial and aquatic ecosystems have already shown adjustments to increased temperatures and are expected to undergo further changes in the near future. The BACC II Author Team consists of 141 scientists from 12 countries, covering various disciplines related to climate research and related impacts. BACC II is a project of the Baltic Earth research network and contributes to the World Climate Research Programme.

We investigated whether anthropogenic forcing is a plausible explanation for the observed warming in the Baltic Sea catchment area. Therefore, we compared the most recent trends in the surface temperature over land with anthropogenic climate change projections from regional climate model simulations. We analyzed patterns of change with different spatio-temporal resolutions. The observed annual area-mean change in the daily-mean temperature was consistent with the anthropogenic climate change signal. This finding was robust to the removal of the signal of the North Atlantic Oscillation. In contrast to the annual area-mean change, we found little consistency in both annual cycle and spatial variability of the observed and projected changes.

This report presents the findings of two surveys of climate scientists' perceptions of the globalwarming issue. The first survey was conducted in 1996 and the second survey in 2003. Abrief text section demonstrates some of the significant findings. The surveys investigate the meansby which scientific conclusions are reached and the climate scientists interpretations of whatthese conclusions might mean. The complete responses to the surveys are presented in Appendix A:Tables and Appendix B: Figures. Each table and figure is presented in a manner to indicatestatistically significant change in scientists perspectives over the period of the two surveys.

A heat-conduction forward model driven by ground surface temperature from three 1000-year climate simulations with the state-of-the-art ECHO-g model has been used to simulate underground temperature perturbation profiles. An inversion approach has been applied to reconstruct ground surface temperature histories from the simulated profiles and to compare them with the climate model temperatures. Results support the skill of borehole inversion methods to retrieve long-term temperature trends, and the robustness of using the present-day borehole network for reconstructing SAT variations.