Threads and Boundaries: Rethinking the Intellectual History of International Relations

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Towards a comprehensive climate impacts assessment of solar geoengineering

Despite a growing literature on the climate response to solar geoengineering – proposals to cool the planet by increasing the planetary albedo – there has been little published on the impacts of solar geoengineering on natural and human systems such as agriculture, health, water resources, and ecosystems. An understanding of the impacts of different scenarios of solar geoengineering deployment will be crucial for informing decisions on whether and how to deploy it. Here we review the current state of knowledge about impacts of a solar geoengineered climate and identify major research gaps. We suggest that a thorough assessment of the climate impacts of a range of scenarios of solar geoengineering deployment is needed and can build upon existing frameworks. However, solar geoengineering poses a novel challenge for climate impacts research as the manner of deployment could be tailored to pursue different objectives making possible a wide range of climate outcomes. We present a number of ideas for approaches to extend the survey of climate impacts beyond standard scenarios of solar geoengineering deployment to address this challenge. Reducing the impacts of climate change is the fundamental motivator for emissions reductions and for considering whether and how to deploy solar geoengineering. This means that the active engagement of the climate impacts research community will be important for improving the overall understanding of the opportunities, challenges and risks presented by solar geoengineering

Metabolic engineering of novel lignin in biomass crops

Lignin, a phenolic polymer in the secondary wall, is the major cause of lignocellulosic biomass recalcitrance to efficient industrial processing. From an applications perspective, it is desirable that second-generation bioenergy crops have lignin that is readily degraded by chemical pretreatments but still fulfill its biological role in plants. Because plants can tolerate large variations in lignin composition, often without apparent adverse effects, substitution of some fraction of the traditional monolignols by alternative monomers through genetic engineering is a promising strategy to tailor lignin in bioenergy crops. However, successful engineering of lignin incorporating alternative monomers requires knowledge about phenolic metabolism in plants and about the coupling properties of these alternative monomers. Here, we review the current knowledge about lignin biosynthesis and the pathways towards the main phenolic classes. In addition, the minimal requirements are defined for molecules that, upon incorporation into the lignin polymer, make the latter more susceptible to biomass pretreatment. Numerous metabolites made by plants meet these requirements, and several have already been tested as monolignol substitutes in biomimetic systems. Finally, the status of detection and identification of compounds by phenolic profiling is discussed, as phenolic profiling serves in pathway elucidation and for the detection of incorporation of alternative lignin monomers

Bioenergy and climate change mitigation: an assessment

Acknowledgements The authors are indebted to Julia Römer for assisting with editing several hundred references. Helmut Haberl gratefully acknowledges funding by the Austrian Academy of Sciences (Global Change Programme), the Austrian Ministry of Science and Research (BMWF, proVision programme) as well as by the EU-FP7 project VOLANTE. Carmenza Robledo-Abad received financial support from the Swiss State Secretariat for Economic Affairs.Peer reviewedPostprin

Enantiomeric Natural Products: Occurrence and Biogenesis

In nature, chiral natural products are usually produced in optically pure form—however, occasionally both enantiomers are formed. These enantiomeric natural products can arise from a single species or from different genera and/or species. Extensive research has been carried out over the years in an attempt to understand the biogenesis of naturally occurring enantiomers; however, many fascinating puzzles and stereochemical anomalies still remain. Two sides to the story : The formation of enantiomerically opposite natural products by nature is known, although rare (see examples). To date, many puzzles and stereochemical anomalies remain regarding the biogenesis of these unique natural products, despite the substantial body of research that has been carried out over the years in an attempt to understand the biogenesis of enantiomeric metabolites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92098/1/4802_ftp.pd

Enantiomere Naturstoffe: Vorkommen und Biogenese

In der Natur werden chirale Substanzen meist in enantiomerenreiner Form synthetisiert – manchmal entstehen aber auch beide Enantiomere. Solche enantiomeren Naturstoffe können von einer Art oder von verschiedenen Gattungen und/oder Arten gebildet werden. Intensive Forschungen wurden über viele Jahre durchgeführt, um die Biogenese natürlich vorkommender Enantiomere zu verstehen, doch viele faszinierende Rätsel und stereochemische Anomalien sind nach wie vor ungelöst. Bild und Spiegelbild in der Natur: Die Bildung von natürlich vorkommenden Enantiomerenpaaren ist bekannt, wenn auch selten (siehe Beispiel). Bis heute sind noch viele Rätsel und stereochemische Anomalien bei der Biogenese dieser einmaligen Naturstoffe ungelöst, auch wenn im Laufe der Jahre viel Arbeit investiert worden ist, um die Entstehung enantiomerer Metaboliten zu verstehen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91315/1/4886_ftp.pd

Beyond equilibrium climate sensitivity

ISSN:1752-0908ISSN:1752-089