The Regensburg Model: reference values for the (I)NDCs based on converging per capita emissions†

A core question still remains after the Paris Agreement: who receives how much of the remaining CO₂ budget (resource/burden/effort sharing), so that the increase in the global average temperature is kept to well below 2°C above pre-industrial levels? If converging per capita emissions serve as a possible answer to this question, the discussion focuses primarily on the approach ‘Contraction and Convergence’ (C&C). The Regensburg Model now offers a further option for the mathematical implementation of converging per capita emissions. The authors identify features common to C&C and differences from C&C. They show that, of the convergence models they examined, the Regensburg Model is the most favourable option for industrialized countries.

Policy relevance

In politics, the concept of converging per capita emissions is often accepted at the abstract level. Civil society in particular can then take politicians at their word wherever they take values calculated using the Regensburg Model as points of reference; then prosperous developed countries in particular whose nationally determined contributions do not come up even to these reference values will find it difficult to justify their contributions.     

To tax,or not to tax: preferences for climate policy attributes

Many countries around the world respond to global warming and its consequences with various policy instruments. In the economic literature, policy instruments have typically been analysed with respect to efficiency, but little effort has been expended to understand public preferences for these instruments. In an internet-based choice experiment to address this shortcoming, Swedes were asked to choose between two alternative hypothetical policy instruments, each of which reduces CO₂ emissions by the same amount. The hypothetical policy instruments were characterized by a number of specific attributes. By varying the levels of each of the attributes, respondents indirectly reveal their preferences for these attributes. Half of the respondents are faced with choices labelled ‘tax’ and ‘other’, and the other half are faced with unlabelled choices (hypothetical instruments). The results show that Swedes tend to dislike the term ‘tax’ and show a preference for instruments with a positive effect on environment-friendly technology and climate awareness. A progressive-like cost distribution is preferred to a regressive cost distribution, and the private cost is negatively related to the choice of policy.     

The influence of relative humidity on the SO2 deposition velocity to building stones: a chamber study at very low SO2 concentration

We report on a chamber study to determine the influence of SO₂ concentration and relative humidity (RH) on the deposition velocity of SO₂ to a carbonaceous sandstone (Ihrlerstein sandstone) and to two silicate sandstones (Sand sandstone and Obernkirchen sandstone). Two different chambers were used, one operated at constant inlet SO₂ concentration, the other one at constant outlet concentration. Measurements were carried out at realistically low SO₂ concentrations ranging from 15 ppb to 200 ppb. The relative humidity was varied from 45 to 95 %. The measurements confirm a strong influence of concentration on the deposition velocity for all stones investigated. This concentration dependence can be represented using a very simple model with only one rate constant as the only adjustable parameter. A significant influence of the relative humidity on the deposition velocity to the carbonaceous stone is also observed. In contrast, the deposition velocity to the silicate stones is independent of RH. It is demonstrated that the combined influences of concentration and RH on the deposition velocity can be only correctly determined in chambers with constant outlet concentration.     

Silicon in iron meteorite metal

Abstract– We report Si concentrations in the metal phases of iron meteorites. Analyses were performed by secondary ion mass spectrometry using a CAMECA 1270 ion probe. The Si concentrations are low (0.09–0.46 μg g^?1), with no apparent difference in concentration between magmatic and nonmagmatic iron meteorites. Coexisting kamacite and Ni‐rich metal phases have similar Si contents. Thermodynamic calculations show that Fe,Ni‐metal in equilibrium with silicate melts at temperatures where metal crystallizes should contain approximately 100 times more Si than found in iron meteorites in this work. The missing Si may either occur as tiny silicate inclusions in metal or it may have diffused as Si‐metal into surrounding silicates at low temperatures. In both cases, extensive low‐temperature diffusion of Si in metal is required. It is therefore concluded that low Si in iron meteorites is a result of subsolidus reactions during slow cooling.     

Searching for evidence of hydrothermal activity at Apollinaris Mons,Mars

A multidisciplinary approach involving various remote sensing instruments is used to investigate Apollinaris Mons, a prominent volcano on Mars, as well as the surrounding plains for signs of prolonged hydrologic and volcanic, and possibly hydrothermal activity. The main findings include (1) evidence from laser altimetry indicating the large thickness (1.5–2 km at some locations) of the fan deposits draping the southern flank contrary to previous estimates, coupled with possible layering which point to a significant emplacement phase at Apollinaris Mons, (2) corroboration of Robinson et al. (Robinson, M.S., Mouginis-Mark, P.J., Zimbelman, J.R., Wu, S.S.C., Ablin, K.K., Howington-Kraus, A.E. [1993]. Icarus 104, 301–323) hypothesis regarding the formation of incised valleys on the western flanks by density current erosion which would indicate magma–water interaction or, alternatively, volatile-rich magmas early in the volcano’s history, (3) mounds of diverse geometric shapes, many of which display summit depressions and occur among faults and fractures, possibly marking venting, (4) strong indicators on the flanks of the volcano for lahar events, and possibly, a caldera lake, (5) ubiquitous presence of impact craters displaying fluidized ejecta in both shield-forming (flank and caldera) materials and materials that surround the volcano that are indicative of water-rich target materials at the time of impact, (6) long-term complex association in time among shield-forming materials and Medusae Fossae Formation.The findings point to a site of extensive volcanic and hydrologic activity with possibly a period of magma–water interaction and hydrothermal activity. Finally, we propose that the mound structures around Apollinaris should be prime targets for further in situ exploration and search for possible exobiological signatures.     

A hit-and-run giant impact scenario

The formation of the Moon from the debris of a slow and grazing giant impact of a Mars-sized impactor on the proto-Earth (Cameron and Ward [1976]. Lunar Planet. Sci. Conf.; Canup and Asphaug [2001]. Nature 412, 708) is widely accepted today. We present an alternative scenario with a hit-and-run collision (Asphaug [2010]. Chem. Erde 70, 199) with a fractionally increased impact velocity and a steeper impact angle.     

An experimental analysis of three methods for highlighting colorful pictographic symbols

Highlighting is one of the key functionalities of any interactive visualization environment. Yet, there is little research on highlighting methods. This article focuses on highlighting of colorful pictographic symbols. Three strategies for highlighting were tested by implementing three highlighting methods that were suggested suitable in the literature on attention, perceptual grouping, and motion detection. An experimental design measuring response times and accuracy was used and subjective opinions were collected. The three available strategies for applying the highlighting effect to a subset of visually salient (i.e., colorful) symbols are: (1) to decrease the saliency of the non-highlighted symbols, (2) to increase the saliency of the highlighted symbols, and (3) to add a connecting element for grouping the highlighted symbols. Of these strategies, adding a connecting element was found to be the least efficient based on the response times, whereas both methods for tuning the saliency difference between the highlighted and non-highlighted symbols were found to be equally efficient. However, decreasing the saliency of the non-highlighted symbols was clearly preferred in the subjective evaluation.