Methane Emission Reduction: An Application of FUND

Methane is, after carbon dioxide, the most important anthropogenic greenhouse gas. Governments plan to abate methane emissions. A crude set of estimates of reduction costs is included in FUND, an integratedassessment model of climate change. In a cost-benefit analysis, methane emission reduction is found to be instrumental in controlling the optimal rate of climate change. In a cost-effectiveness analysis, methane emission reduction largely replaces carbon dioxide emission reduction. Methane emission reduction reinforces the case for international cooperation in climate policy, but complicates the efficient allocation of emission reduction efforts. Methane emission reduction at the short run does not help to achieve the ultimate objective of the Framework Convention on Climate Change.     

An Eburnean base metal source for sediment-hosted zinc-lead deposits in Neoproterozoic units of Namibia: Lead isotopic and geochemical evidence

The lead isotopic composition of galena from the Neoproterozoic sediment-hosted Zn-Pb sulphide deposit at Rosh Pinah and the oxidised Zn deposit at Skorpion in the Pan-African Gariep Belt, southwestern Namibia, as well as that of galena from minor occurrences in the wider Rosh Pinah ore province was investigated and is compared with that of other major sediment-hosted base metal ore deposits hosted by Neoproterozoic strata in southwestern Africa and Brazil. The isotope data were supplemented by a geochemical provenance study of the argillitic host rock to the Rosh Pinah deposit and its stratigraphic equivalents. The pre-orogenic Rosh Pinah deposit and the inferred progenitor for the secondary Skorpion deposits have very similar Pb isotopic compositions. In contrast, syn-orogenic deposits (e.g. Tsumeb-type) show a larger proportion of radiogenic Pb from the country rocks that were infiltrated by orogenic ore fluids.In all examples studied, the ore Pb has elevated ²⁰⁷Pb/²⁰⁴Pb ratios compared to Pb that evolved according to average crustal Pb growth models. The isotopic composition of the ore Pb is in agreement with that of the oldest crustal component known from the pre-Gariep basement, i.e. an Eburnean (c. 2.0 Ga) volcanic arc, best preserved in the Richtersveld Terrane, that represents the largest volume of post-Archaean juvenile crust in southern Africa. Erosion of that arc provided the main sediment source for the metasedimentary siliciclastic host to the Rosh Pinah deposit. Derivation of the Pb, and by analogy Zn, from this Eburnean volcanic arc is therefore inferred for the formation of Rosh Pinah-type syn-rift, early diagenetic replacement mineralisation.The calculated ₂- and ₂-values for the Rosh Pinah ore province (around 10.2 and 42, respectively) are higher than predicted by conventional Pb crustal growth models and are similar to those found in the wider region of southern Africa (Otavi Mountain Land) and eastern Brazil. The obtained data highlight not only that calculated Pb model ages may have no geochronological significance but might also point to a common crustal evolution of this part of SW-Gondwana.Editorial handling: M. Chiaradia     

Fire on the horizon: contemporary Aboriginal burning issues in the Tanami Desert,central Australia

As part of a collaborative research project created to promote the coexistence of fire, people and biodiversity in central Australia, a case study was conducted on Aboriginal perceptions of fire and its management in the southern Tanami Desert of Central Australia. The Tanami was chosen due to consecutive wildfire events and reported fire conflicts between Aboriginal and pastoral (cattle station) landholders on fire issues. This paper addresses fire issues from the perspective of Warlpiri Aboriginal people in this region. It shows that many Warlpiri hold strong views concerning the use of fire and its management. Elders, in particular, have retained tradition-based knowledge about fire and its effects on the environment. The complex cultural protocols that structure decisions about who burns, when and where are discussed. It is shown that, although there have been dramatic changes to their subsistence economy, Warlpiri still burn for cultural and economic reasons. At the same time, social change has given rise to new fire-related issues, including lack of access to remote areas in order to undertake burning and a decrease in fire knowledge among younger generations. The paper argues that Warlpiri perceptions of fire management, needs and skills must be incorporated in a regional fire management strategy if the cycle of wildfire that follows above average rainfall periods in the Tanami is to be broken. Proper resourcing of Aboriginal people to fire their land in customary ways will enhance Aboriginal livelihoods as well as benefit other stakeholders in the region.