ALBERT

Description: In the marine realm, microorganisms are responsible for the bulk of primary production, thereby sustaining marine life across all trophic levels. Longhurst provinces have distinct microbial fingerprints; however, little is known about how microbial diversity and primary productivity change at finer spatial scales. Here, we sampled the Atlantic Ocean from south to north (~50°S–50°N), every ~0.5° latitude. We conducted measurements of primary productivity, chlorophyll-a and relative abundance of 16S and 18S rRNA genes, alongside analyses of the physicochemical and hydrographic environment. We analysed the diversity of autotrophs, mixotrophs and heterotrophs, and noted distinct patterns among these guilds across provinces with high and low chlorophyll-a conditions. Eukaryotic autotrophs and prokaryotic heterotrophs showed a shared inter-province diversity pattern, distinct from the diversity pattern shared by mixotrophs, cyanobacteria and eukaryotic heterotrophs. Additionally, we calculated samplewise productivity-specific length scales, the potential horizontal displacement of microbial communities by surface currents to an intrinsic biological rate (here, specific primary productivity). This scale provides key context for our trophically disaggregated diversity analysis that we could relate to underlying oceanographic features. We integrate this element to provide more nuanced insights into the mosaic-like nature of microbial provincialism, linking diversity patterns to oceanographic transport through primary production.

Description: Isotropic three-dimensional (3-D) inversion has become a standard tool in the interpretation of magnetotelluric (MT) data. 3-D anisotropic inversion codes are under development, yet the number of unknowns increases by a factor of 6 rendering the problem extremely ill-posed. The presence of anisotropy is usually inferred from (i) spurious sequences of conductive and resistive bodies or (ii) comparison with two-dimensional anisotropic modelling approaches. Here, we investigate the 3-D structure of the Gawler Craton down to ∼250 km depth using 282 sites of the AusLAMP array located in the southern half of South Australia. Inversions of the MT impedance as phase tensors and real and imaginary parts result in diverging structures at depths 〉 70 km. We demonstrate that a unifying model that explains all data types similarly well is suggestive of an anisotropic resistivity structure at the base of the Gawler Craton lithosphere at depths of 120–210 km. Depth location and orientation of the anisotropy agree well with results from the analysis of seismic receiver functions. We suggest that electric anisotropy in the Gawler Craton is a result of lattice-preferred orientation of olivine crystals and metasomatic processes with macroscopic preferential orientation. Our results illustrate that inversion of phase tensor data is superior for the direct imaging of anisotropic resistivity contrasts in otherwise isotropic resistivity models; inversion models obtained with impedances may miss such structures. “Comparable” overall RMS misfits are often meaningless when comparing inversion results for various data types since sensitivities differ between data types. Reliable inversion results consistent with the entire data set can only be recovered if data fits are assessed systematically for all data representations. We also discuss the influence of error settings for phase tensors on the inversion. Our study also revealed that, if persistent across large areas, (i) parallel orientation of phase tensor major axes, (ii) constantly high phase tensor maximum phases or (iii) diverging directions of phase tensor major axes and induction arrows are suggestive of anisotropic structures and corresponding hypotheses should be evaluated.

Description: The extent of our duties to mitigate climate change is commonly conceptualized in terms of temperature goals like the 1.5°C and the 2°C target and corresponding emissions budgets. While I do acknowledge the political advantages of any framework that is relatively easy to understand, I argue that this particular framework does not capture the true extent of our mitigation duties. Instead I argue for a more differentiated approach that is based on the well-known distinction between subsistence and luxury emissions. At the heart of this approach lies the argument that we have no budget of substantial, net-positive luxury emissions left. In a world in which dangerous climate change has begun, we must expect all further substantial, net-positive luxury emissions to cause harm. Since they lack the kind of justification needed for them to be nevertheless permissible, I conclude that we must stop emitting them with immediate effect. I also briefly discuss the difficult case of subsistence emissions and offer some first thoughts on the morality of a third category of emissions, what I call ‘transition emissions’.

Description: Die Vereinten Nationen haben einen Vertrag zum Schutz der Hohen See verabschiedet. Um sein Potenzial für die globale Meerespolitik zu nutzen, sollten die EU und Deutschland ihr strategisches Engagement in diesem Forum jetzt planen, meinen Miranda Böttcher und Gerrit Hansen.

Description: Since net zero targets have become a keystone of climate policy, more thought is being given to actively removing carbon dioxide from the atmosphere while continuing to drastically reduce emissions. The ocean plays a major role in regulating the global climate by absorbing a large proportion of anthropogenic carbon dioxide emissions. As the challenges of land-based carbon dioxide removal (CDR) approaches are increasingly recognised, the ocean may become the new “blue” frontier for carbon removal and storage strategies in the EU and beyond. However, the ocean is not an “open frontier”; rather, it is a domain of overlapping and sometimes conflicting rights and obligations. There is a tension between the sovereign right of states to use ocean resources within their exclusive economic zones and the international obligation to protect the ocean as a global commons. The EU and its Member States need to clarify the balance between the protection and use paradigms in ocean governance when considering treating the ocean as an enhanced carbon sink or storage site. Facilitating linkages between the ongoing review of the Marine Strategy Framework Directive and the establishment of the Carbon Removal Certification Framework could help pave the way for debate about trade-offs and synergies in marine ecosystem protection and use.

Description: Climate policy in the European Union (EU) and Germany changed significantly with the adoption of net-zero emissions targets. A key new development is the growing importance of carbon management. The umbrella term includes not only the capture and storage of CO2 (carbon capture and storage, CCS), but also CO2 capture and utilisation (carbon capture and utilisation, CCU) as well as the removal of CO2 from the atmosphere (carbon dioxide removal, CDR). It is important to provide clarity when differentiating between these approaches and identifying their relation to so- called residual emissions and hard-to-abate emissions. This is particularly important because it will determine the overall ambition of climate policy as well as shape future policy designs and their distributional impacts. Current policy and legislative processes should ensure that carbon management does not delay the phase-out of fossil fuels. New policy initiatives present an opportunity to actively shape the interface between ambitious climate and industrial policy.

Description: The implementation of the new net emission targets for 2030 and 2050 as part of the European Green Deal is moving the deliberate removal of CO 2 from the atmosphere up the agendas of political decision-makers. In its latest report, the Intergovernmen- tal Panel on Climate Change (IPCC) also recently reiterated that net-zero targets can- not be achieved without the deployment of carbon dioxide removal (CDR) methods. The political debate in the European Union (EU) about CDR has changed rapidly in recent years, with almost all political actors now calling for a new regulatory frame- work for CDR to become an integral building block of EU climate policy. However, fundamental conflicts are brewing over the question as to which removal methods and policy instruments should be implemented and which priorities should be set. There are signs of emerging political alliances on the EU level that will shape the Fit- for-55 legislation in the short term and pre-structure the debate on the design of climate policy between 2030 and 2040.

Description: Sollen wir Climate Engineering (CE) betreiben? Was spricht dafür und was dagegen? Antworten auf diese Fragen müssen empirisch informiert sein. Um mehr zu tun als das Machbare zu benennen, müssen sie sich aber auch mit Fragen der Moral auseinandersetzen, solchen nach Pflichten, Normen und Werten. In diesem Beitrag stellen wir 9 Thesen zur Ethik von CE auf. Wir diskutieren, welche ethischen Aspekte besonders wichtig, welche Chancen und Risiken von CE moralisch besonders bedeutsam sind, und was die Debatte um CE über uns aussagt. Summary Nine theses on the morality of climate engineering: Should we engineer the climate? What speaks in favour of doing it and what against? Answers to these questions must be based in empirical science. But they must also engage with moral questions – those about duties, norms and values – if they want to do more than simply name what is feasible. In this contribution we defend 9 theses on the ethics of climate engineering (CE). We discuss which ethical aspects are of particular importance, what opportunities and risk matter most from a moral point of view, and how the debate on CE reflects upon us. Resumen Nueve tesis sobre la moralidad de la ingeniería climática: ¿Deberíamos aplicar la ingeniería climática (EC)? ¿Qué está a favor y qué en contra? Las respuestas a estas preguntas deben basarse en datos empíricos. Pero para hacer algo más que afirmar lo que es factible, también deben abordar cuestiones de moralidad, de obligaciones, normas y valores. En este documento presentamos 9 tesis sobre la ética de la EC. Debatimos qué aspectos éticos son especialmente importantes, qué oportunidades y riesgos de la EC son moralmente significativos y qué dice de nosotros el debate sobre la EC.

Description: Es werden mögliche Beiträge geologischer und mariner Kohlenstoffspeicher für die Vermeidung von CO2-Emissionen in die Atmosphäre oder für die Entnahme von bereits emittiertem CO2 aus der Atmosphäre vorgestellt. Neben der Einlagerung von CO2 in geologischen Speichern unter Land und unter dem Meeresboden werden eine forcierte CO2-Entnahme aus der Atmosphäre und Abgabe in den Ozean durch Erhöhung der Alkalinität, durch Ozeandüngung und durch das Management vegetationsreicher Küstenökosysteme untersucht. Alle Optionen können sowohl global als auch aus deutscher Perspektive eine Rolle für das Erreichen der Klimaziele spielen. Umweltverträglichkeit, Permanenz der Speicherung sowie infrastrukturelle und rechtliche Voraussetzungen, gesellschaftliche Akzeptanz und wirtschaftliche Realisierbarkeit bedürfen für alle Ansätze weiterer Klärung, bevor hieraus realisierbare Optionen werden können.