Whatever happened to Gondwana?

The combination of continents into supercontinents, and their subsequent fragmentation and rearrangement is an accepted part of the history of the Earth, but how it happens in detail is not always clear. Did supercontinents split into a few large pieces, or were many small fragments formed in the break-up? Now geophysical measurements have answered this conundrum – which has implications for later continental reconstructions – for the break-up of Gondwana, the supercontinent that existed from about 500–180 million years ago.     

Climate hypersensitivity to solar forcing?

We compare the equilibrium climate responses of a quasi-dynamical energy balance model to radiative forcing by equivalent changes in CO₂, solar total irradiance (S_tot) and solar UV (S_UV). The response is largest in the S_UV case, in which the imposed UV radiative forcing is preferentially absorbed in the layer above 250 mb, in contrast to the weak response from global-columnar radiative loading by increases in CO₂ or S_tot. The hypersensitive response of the climate system to solar UV forcing is caused by strongly coupled feedback involving vertical static stability, tropical thick cirrus ice clouds and stratospheric ozone. This mechanism offers a plausible explanation of the apparent hypersensitivity of climate to solar forcing, as suggested by analyses of recent climatic records. The model hypersensitivity strongly depends on climate parameters, especially cloud radiative properties, but is effective for arguably realistic values of these parameters. The proposed solar forcing mechanism should be further confirmed using other models (e.g., general circulation models) that may better capture radiative and dynamical couplings of the troposphere and stratosphere.     

Dark energy: back to Newton?

Lucy Calder and Ofer Lahav look back at the surprisingly long history of dark energy, the dominant but mysterious component of our universe.     

Have you considered a legacy to the RAS?

Francisco Diego has some ideas and suggestions for outreach from his experience as RAS Lecturer on the Queen Mary 2 and the Queen Victoria .     

Eco-districts in France: What tools to ensure goals achievement?

Globally, to build cities and communities more inclusive, safe, resilient and sustainable is one of the most important sustainable development goals. Eco-districts in cities emerged as an answer to current global environmental concerns and have been developed in France since the 1990s. The objective of this work is to gather operational feedback from sustainable neighborhood projects owners to better understand the key barriers of such projects and how to overcome them. A case study of the eco-district Les Tanneries, Lingolsheim showed that the carbon footprint of each inhabitant annually amounted to 4 tons CO_2 equivalent, more than half of the French average. Rooms for improvements were clearly identified regarding transports and food carbon footprint. Indicators for energy consumption, social diversity and density reached the level of the eco-districts average. A governance review pointed out some superior practices such as the formalization of a specification requirements handbook, a competition between project management teams, and the use of neighborhood sustainability assessment tools to measure and track changes in performance. The validated tools and obtained results can be useful in building sustainable cities and even China's ecological civilization.     

How to model rockburst seismic loads for civil engineering purposes?

Usually rockbursts from underground mining induce minor quakes of MM intensity up to V. Sometimes however the surface tremors reach level of MM epicentral intensity I ₀ = VI to VIII. Since a fast industrial development often takes place in the mining areas then some seismic design rules for new buildings are needed. The main obstacle is then lack of respective design response spectrum and an unclear definition of the level of design acceleration to apply. Particularly the latter one is difficult to overcome because the rockburst ground motion records differ from natural earthquakes when it comes to their spectral properties as well as return periods. This paper presents a method how to rationally define the design acceleration so that a seismic code, e,g, Eurocode 8, can be applied in practical design procedures in the mining areas.