The global climate action summit: increasing ambition during turbulent times

In September 2018, leaders in climate action within and outside the U.S. will convene in San Francisco for the Global Climate Action Summit. They plan to demonstrate strong ongoing commitment to exceeding the goals set out in the Paris Agreement, despite U.S. federal opposition under President Trump, and to spur greater ambition among subnational governments and the private sector. Now that the Trump Administration is working to undo the progress made under President Obama, it is more important than ever that states and cities, as well as the private sector, redouble their efforts. Since the 2016 election, many U.S. states have demonstrated leadership by establishing ever-more ambitious clean energy and electric vehicle targets through legislation and executive action; by pushing back on the Trump Administration in public forums and in the courts; and by banding together to realise greater effectiveness through collective action. The commitment of leading states, cities, and businesses alone will not be enough to achieve the rapid reductions needed to keep planetary warming to 1.5 degrees C in the absence of U.S. federal efforts. But coming after a summer of extreme weather events, the Summit represents a critical opportunity to re-energise constituencies, highlight the need for urgent and ambitious action, and bring climate change to the forefront of policy conversations across the U.S. and beyond.

Key policy insights

• The reversal of U.S. ambitious clean energy and transportation policy, including replacing the Clean Power Plan, freezing fuel standards, and withdrawing from the Paris Agreement, have created a gap at the federal level under President Trump that will be difficult – but perhaps not impossible – to fill with subnational action.

• States, local governments, and the private sector have shown a strengthened commitment to combating climate change and to the goals set out in the Paris Agreement through more ambitious legislative and executive targets, and regional initiatives like RGGI and cross-jurisdictional zero emissions vehicle programmes.

• The Global Climate Action Summit in September 2018 is a pivotal moment to energise a broader coalition within and outside the U.S. towards catalysing the level of ambition needed to exceed goals set out in the Paris Agreement.

     

Simulation of intrinsic random fields of order <Emphasis Type="Italic">k</Emphasis> with a continuous spectral algorithm

Intrinsic random fields of order k, defined as random fields whose high-order increments (generalized increments of order k) are second-order stationary, are used in spatial statistics to model regionalized variables exhibiting spatial trends, a feature that is common in earth and environmental sciences applications. A continuous spectral algorithm is proposed to simulate such random fields in a d-dimensional Euclidean space, with given generalized covariance structure and with Gaussian generalized increments of order k. The only condition needed to run the algorithm is to know the spectral measure associated with the generalized covariance function (case of a scalar random field) or with the matrix of generalized direct and cross-covariances (case of a vector random field). The algorithm is applied to synthetic examples to simulate intrinsic random fields with power generalized direct and cross-covariances, as well as an intrinsic random field with power and spline generalized direct covariances and Matérn generalized cross-covariance.     

The great historical 1755 earthquake. Effects and damage in Spain

The access to the complete reports sent in answer of a Royal enquire relative to the 1755 earthquake (Archivo Historico Nacional, 1756) provided us with information more comprehensive than that included in the analysis of such documents prepared by the Spanish Royal Academy of History in 1756 (Real Academia de la Historia, 1756). With such data, we have made a new study of the shock centred mainly in the following points: number of victims, source parameters (including moment magnitude and epicentral location),intensity map and seismogeological effects compared with those expected from the EMS-98. Relevant results from this analysis are: a new intensity attenuation law for earthquakes from the region of the 1755 shocks and first approximation damage probability matrices for buildings of the types common in the XVII to XIX centuries affected by large, distant earthquakes.     

Harpacticoid copepod response to epiphyte load variations in Posidonia oceanica (L.) Delile meadows

We conducted a field experiment to assess the response of phytal harpacticoids to nutrient‐driven increases of epiphyte load in Posidonia oceanica meadows. First, we evaluated differences in species richness, diversity and assemblage structure of phytal harpacticoids in P. oceanica meadows with differing epiphyte loads. Secondly, we conducted a field experiment where epiphyte load was increased through an in situ addition of nutrients to the water column and evaluated the responses of the harpacticoid assemblages. We predicted that there would be changes in the harpacticoid assemblages as a result of nutrient‐driven increases of epiphyte load, and that these changes would be of a larger magnitude in meadows of low epiphyte load. Our results show that the harpacticoid fauna (>500 μm) present in P. oceanica meadows in the Bay of Palma comprised taxa which are considered phytal and other less abundant ones previously described as sediment dwellers or commensal on other invertebrate species. Nutrient addition had an overall significant effect on epiphyte biomass and on harpacticoid abundance, diversity and assemblage structure, possibly as a response to the increased resources and habitat complexity provided by epiphytes. The abundance of dominant species at each location was favoured by nutrient addition and in some cases correlated with epiphytic biomass, although never strongly. This may indicate that structural complexity or diversity of the epiphytic cover might be more important than the actual epiphytic biomass for the harpacticoid species investigated. More species‐specific studies are necessary to ascertain this and clarify the relationships between harpacticoids and epiphytes in seagrass meadows. To our knowledge, this is the first account of harpacticoid species associated with P. oceanica leaves and the epiphytic community they harbour in the Mediterranean Sea.     

On the estimation of hysteretic energy demands for SDOF systems

Based on a statistical study of the dynamic response of single degree of freedom (SDOF) systems subjected to earthquake ground motions, a rule to estimate hysteretic energy demands is proposed. Expressions for elastic–perfectly plastic, stiffness degrading and pinching SDOF systems were obtained. The proposed rule does not explicitly depend on the period of the system; instead, it depends on the elastic pseudo‐acceleration and elastic velocity spectra. It is shown that the proposed rule can be applied to compute hysteretic energy demands for systems located at different soil conditions. In addition, information about scatter and bias of the proposed rule is also presented. Copyright © 2007 John Wiley & Sons, Ltd.