Development of a tunable diode laser absorption spectrometer for measurement of the 13C/12C ratio in methane

A tunable diode laser absorption spectrometer (TDLAS) for measuring the ratio in methane has been developed. Using a triple path arrangement the spectra of the CH4 sample, a isotope standard and pure 13CH4 are recorded simultaneously and compared to evaluate the ratio of the sample, using a 13CH4---12CH4 absorption line pair near 3007 cm−1. Systematic effects due to variations in temperature, pressure, and optical density were measured for this rotational-vibrational transition pair. Optical interference effects are effectively suppressed by linearly polarizing the laser beam and using Brewster windows for gas cells and detectors. The overall δ13C accuracy vs. the PDB scale is about ± 1 ‰ for a CH4 concentration of 2.5 % (sample size: 5 μmoles = 0.11 STP cm3 CH4) using 36 cm long absorption cells. The future application of a multipass cell should allow measurement concentrations of CH4 down to about 50 ppm. The main advantages of the new method are the short measurement time of 10–15 min for one sample and the direct measurement on the CH4 molecule without the need to chemically convert it to CO2. With the present accuracy the new method should be useful for the measurement of CH4 sources, allowing a greater sample throughput compared to the conventional mass spectrometry technique

A global three-dimensional study of the fate of HCFCs and HFC-134a in the troposphere.

International audienc

Are we willing to give what it takes? Willingness to pay for climate change adaptation in developing countries

Climate change adaptation is gaining traction as a necessary policy alongside mitigation, particularly for developing countries, many of which lack the resources to adapt. However, funding for developing country adaptation remains woefully inadequate. This paper identifies the burden of responsibility that individuals in the UK are willing to incur in support of adaptation projects in developing countries. Results from a nationally representative survey indicate that UK residents are willing to contribute £27 per year (or a median of £6 per year) towards developing country adaptation (US$30 and$7 using the World Bank’s purchasing power conversion factors). This represents less than one third of the back-of-the-envelope $100-140 per capita per year that the authors estimate would be needed to raise the$70-100bn per year recommended by the World Bank to fund developing country adaptation. Regressions indicate that WTP is driven mostly by a combination of beliefs and perceptions about one’s own knowledge levels, rather than actual knowledge of climate change. We conclude that, to engage the many different audiences that make up the ‘public’, communication efforts must move beyond the simple provision of information and instead, connect with people’s existing values and beliefs

The AMMA mulid network for aerosol characterization in West Africa

Three ground based portable low power consumption microlidars (MULID) have been built and deployed at three remote sites in Banizoumbou (Niger), Cinzana (Mali) and M'Bour (Senegal) in the framework of the African Monsoon Multidisciplinary Analyses (AMMA) project for the characterization of aerosols optical properties. A description of the instrument and a discussion of the data inversion method, including a careful analysis of measurement uncertainties (systematic and statistical errors) are presented. Some case studies of typical lidar profiles observed over the Banizoumbou site during 2006 are shown and discussed with respect to the AERONET 7-day back-trajectories and the biomass burning emissions from the Combustion Emission database for the AMMA campaign

Rethinking the Ambiguities of Abstraction in the Anthropocene

The ambiguities of abstraction were at the heart of critical approaches to the problems of modernity. Abstraction, so fundamental to the modernist episteme, was seen to have alienated humanity from itself and from its entangled relations with its environment, constituting a fundamental rift between the subject and the world. This article analyses how the critique of the modernist episteme has increasingly shifted under the auspices of the Anthropocene. Rather than seeking to overcome the ambiguities of abstraction and return the human to the world, approaches that seek to affirm the Anthropocene have emphasised that modernist thought did not take abstraction far enough. Rather than abstraction being problematic for contemporary thought, abstraction is seen to be a facet of the world in its lively, partial and contingent interaction. This article is organised in three sections. The first section introduces the problematic of abstraction in the Anthropocene, highlighting that critical theory approaches tend to see the Anthropocene within a discourse of modernist critique. The second section draws out the importance of understanding the distinct mode of contemporary affirmation, which rather than seeking to return man to the world, emphasises the impossibility of finding meaning in the world. It is this inverting of critical understandings that enables abstraction to be seen positively rather than problematically. The final section expands on this point to consider how contemporary theoretical approaches articulate the transvaluation of abstraction as the guide to contemporary modes of life

The EU societal awareness of landscape indicator: a review of its meaning, utility and performance across different scales

There is increasing recognition that agricultural landscapes meet multiple societal needs and demands beyond provision of economic and environmental goods and services. Accordingly, there have been significant calls for the inclusion of societal, amenity and cultural values in agri-environmental landscape indicators to assist policy makers in monitoring the wider impacts of land-based policies. However, capturing the amenity and cultural values that rural agrarian areas provide, by use of such indicators, presents significant challenges. The EU social awareness of landscape indicator represents a new class of generalized social indicator using a top-down methodology to capture the social dimensions of landscape without reference to the specific structural and cultural characteristics of individual landscapes. This paper reviews this indicator in the context of existing agri-environmental indicators and their differing design concepts. Using a stakeholder consultation approach in five case study regions, the potential and limitations of the indicator are evaluated, with a particular focus on its perceived meaning, utility and performance in the context of different user groups and at different geographical scales. This analysis supplements previous EU-wide assessments, through regional scale assessment of the limitations and potentialities of the indicator and the need for further data collection. The evaluation finds that the perceived meaning of the indicator does not vary with scale, but in common with all mapped indicators, the usefulness of the indicator, to different user groups, does change with scale of presentation. This indicator is viewed as most useful when presented at the scale of governance at which end users operate. The relevance of the different sub-components of the indicator are also found to vary across regions

Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere