How much information is lost by using global-mean climate metrics? an example using the transport sector

Metrics are often used to compare the climate impacts of emissions from various sources, sectors or nations. These are usually based on global-mean input, and so there is the potential that important information on smaller scales is lost. Assuming a non-linear dependence of the climate impact on local surface temperature change, we explore the loss of information about regional variability that results from using global-mean input in the specific case of heterogeneous changes in ozone, methane and aerosol concentrations resulting from emissions from road traffic, aviation and shipping. Results from equilibrium simulations with two general circulation models are used. An alternative metric for capturing the regional climate impacts is investigated. We find that the application of a metric that is first calculated locally and then averaged globally captures a more complete and informative signal of climate impact than one that uses global-mean input. The loss of information when heterogeneity is ignored is largest in the case of aviation. Further investigation of the spatial distribution of temperature change indicates that although the pattern of temperature response does not closely match the pattern of the forcing, the forcing pattern still influences the response pattern on a hemispheric scale. When the short-lived transport forcing is superimposed on present-day anthropogenic CO2 forcing, the heterogeneity in the temperature response to CO2 dominates. This suggests that the importance of including regional climate impacts in global metrics depends on whether small sectors are considered in isolation or as part of the overall climate change

Ductile to brittle fault zone evolution in Austroalpine units to the southeast of the Tauern Window (Eastern Alps)

© 2015 Swiss Geological Society This study combines structural and thermochronological analysis with published geochronological data to evaluate the tectonic evolution of the ductile Main Mylonite Zone and the adjacent brittle Ragga–Teuchl fault to the southeast of the Tauern Window. The Main Mylonite Zone experienced ductile deformation with top-to-the-NW transport direction. From microstructural analysis and published K/Ar and Ar/Ar data the timing for this ductile deformation is proposed to be Late Cretaceous in age, contemporaneous to a well documented extensional collapse that affected large parts of the Eastern Alps. Subsequent brittle faulting affected the Main Mylonite Zone and neighbouring units. Apatite fission track data suggest that brittle deformation along the Ragga–Teuchl fault and adjacent units occurred in the middle- and late Miocene (~23 and ~11 Ma), contemporaneous with the main phase of lateral extrusion. Our results show that a rather small study area may comprise information about the evolution of the Eastern Alps from Late Cretaceous to late Miocene times. We also demonstrate that low-temperature thermochronology is a viable tool to resolve the timing of brittle faulting and accompanied fluid activity