An Approach to Scientific and Legislative Governance of Solar Radiation Modification Research in the United States

The climate crisis requires immediate, rapid, and responsible action across all sectors. Without implementation of aggressive mitigation strategies, the Intergovernmental Panel on Climate Change has warned that we will fail to remain below the catastrophic global warming threshold of 1.5°C. Climate engineering technologies, such as carbon dioxide removal and solar radiation modification (SRM), have been proposed as mitigation strategies, but have not been deployed at scale. In addition to the scaling problems, SRM technologies, particularly stratospheric aerosol injection, have faced criticism over ethical implications of their implementation. The United Nations (UN) efforts to introduce international governance over SRM have been blocked by several countries, including the United States (US). Meanwhile, domestic researchers in the US have independently pursued small-scale experiments. The effects of these experiments remain uncertain, yet, if scaled, extend to non-consenting countries, including those already more susceptible to the climate crisis. We recommend that the US (1) stop blocking the UN from pursuing research into the impacts of SRM to allow for equitable governance options to be explored and (2) establish a national advisory committee on solar geoengineering.

Einfluss einer chemischen Kopplung von strahlenmodifiziertem PTFE mit PA46 auf mechanische Eigenschaften und das Reib- und Verschleißverhalten

In dry-lubricated tribological systems, polytetrafluoroethylene (PTFE) or polyamide (PA) are often used as dry lubricants. PTFE is characterized by a low coefficient of friction and a high wear rate when sliding against steel and a high temperature resistance. In contrast to PTFE, PA has a higher coefficient of friction when sliding against steel. The radiation modification of PTFE in air generates functional groups (-COF and -COOH) and persistent perfluoroalkyl (peroxy) radicals, which, when chemically coupled with suitable polymers, lead to compounds with improved tribological properties. In this paper, the mechanical and tribological properties of PA46-PTFE-cb (chemical bonded) that were kept by reactive extrusion were characterized. For this purpose, Block-on-ring tests were performed using hardened steel discs made of 16MnCr5 as counterparts.

Potential implications of solar radiation modification for achievement of the Sustainable Development Goals

Solar radiation modification, particularly stratospheric aerosol injection, holds the potential to reduce the impacts of climate change on sustainable development, yet could itself generate negative impacts and is subject to intense scholarly debate based on relatively little evidence. Based on expert elicitation involving over 30 individuals with backgrounds across the domains of the United Nations’ Sustainable Development Goals (SDGs), we identify a broad range of potential implications of solar radiation modification for the SDGs. Depending on design and application scenarios, applications could potentially assist in the pursuit of several of the goals by limiting temperature rise and limiting acceleration in atmospheric water cycles as well as extreme weather events. However, by adding to particulates, introducing an additional layer of complexity and potential for conflict in global governance, as well as otherwise altering planetary environments, they might also detract from the pursuit of SDGs and introduce novel risks. The overall impact of solar radiation modification on sustainable development is currently highly uncertain and dependent on climate change mitigation pathways and governance. We identify key areas for further transdisciplinary research the pursuit of which might reduce some uncertainty and help inform emerging governance processes.

E-Beam Effects on Poly(Xylitol Dicarboxylate-co-diol Dicarboxylate) Elastomers Tailored by Adjusting Monomer Chain Length

Poly(xylitol dicarboxylate-co-diol dicarboxylate) elastomers can by synthesized using wide variety of monomers with different chain lengths. Obtained materials are all biodegradable, thermally stable elastomers, but their specific properties like glass transition temperature, degradation susceptibility, and mechanical moduli can be tailored for a specific application. Therefore, we synthesized eight elastomers using a combination of two dicarboxylic acids, namely suberic and sebacic acid, and four different diols, namely ethanediol, 1,3-propanediol, 1,4-buanediol, and 1,5-pentanediol. Materials were further modified by e-beam treatment with a dose of 100 kGy. Materials both before and after radiation modification were tested using tensile tests, gel fraction determination, 1H NMR, and 13C NMR. Thermal properties were tested by Differential Scanning Calorimetry (DSC), Dynamic Thermomechanical Analysis (DMTA) and Thermogravimetric Analysis (TGA). Degradation susceptibility to both enzymatic and hydrolytic degradation was also determined.

Physical Effects of Radiation Modification of Biodegradable Xylitol-Based Materials Synthesized Using a Combination of Different Monomers

There is a possibility of obtaining xylitol-based elastomers sharing common characteristics of biodegradability, thermal stability, and elastomeric behavior by using monomers with different chain-lengths. Therefore, we have synthesized eight elastomers using a combination of four different diols (ethanediol, 1.3-propanediol, 1.4-buanediol, and 1.5-pentanediol) and two different dicarboxylic acids (succinic acid and adipic acid). The obtained materials were further modified by performing e-beam treatment with a dose of 100 kGy. Materials both before and after radiation modification were tested by DSC, DMTA, TGA, tensile tests, gel fraction determination, hydrolytic and enzymatic degradation tests, 1H NMR and 13C NMR and FTIR.

Radiation Modification and Characterization of Polyvinyl alchohol/Starch/Citric Acid/Glycerol Bioblend Film

The blending of polyvinyl alcohol (PVA) with starch with different content of citric acid as crosslinker and glycerol as plasticizer were performed by casting method. The hydroxyl groups of PVA and Starch react with the citric acid (1 %) and glycerol (10 vol %) to form crosslinked network. The FTIR spectral analyses show the successful preparation of the different composition of the prepared PVA/ Starch /Citric acid/Glycerol bioblend films. It is found that the prepared PVA/ Starch /Citric acid/Glycerol with composition (2:1:1/10 vol %) bioblend film characterized by higher water resistance, good mechanical and higher thermal stability than other prepared bioblend films. The using of gamma radiation improved and modified water resistance property were the water uptake at equilibrium reduced remarkably at dose of 10 kGy. Also the thermal stability increased as irradiation dose increased up to dose of 30 kGy The improved mechanical and thermal properties of the selected PVA/ Starch /Citric acid/Glycerol with composition (2:1:1/10 vol %) bioblend film were compared with LDPE and PP packaging films and found to be competitive to the these commercially packaging films which are also nonbiodegradable synthetic polymers than the prepared selected PVA/ Starch /Citric acid/Glycerol with composition (2:1:1/10 vol %) bioblend film. Hence this study can be represent potential development of low cost-effective and modified PVA/ Starch /Citric acid/Glycerol with composition (2:1:1/10 vol %) bioblend film that characterized by several advantages over the commercially available petrochemical films and can be used in different applications such as packaging industry.

Solar Radiation Modification: a multi-century commitment

<p>A growing body of literature investigates the effects of Solar Radiation Modification (SRM) on global and regional climates. Previous studies on SRM have mainly focused on potentials and side effects of deployment without addressing plausible avenues of a subsequent phase-out. This would require large-scale carbon dioxide removal (CDR). Here, we look at SRM deployment lengths to keep global temperature increase to 1.5°C under three emissions scenarios that follow current climate policies until 2100 and are continued with varying assumptions about the magnitude of net-negative CDR (-11.5, -10 and -5 GtCO<sub>2</sub>yr<sup>-1</sup>). Our results show that there would be a lock-in of around 245 - 315 years of continuous SRM engagement. During peak deployment in 2125 around 2.80 Wm<sup>-2</sup> would have to be compensated by SRM, a number at the upper end of currently estimated maximum SRM potential in climate model environments. In total, around 976 - 1344 GtCO<sub>2</sub>would need to be removed from the atmosphere via CDR. We find only minor effects of SRM on carbon fluxes a few decades after cessation. Our study shows that even if SRM is combined with high CDR, SRM would come with very long legacies of deployment, implying centuries of costs, cumulative risks and all negative side effects of SRM and CDR combined. </p>