Europe’s Climate Target for 2050: An Assessment

Decarbonisation is harder for transport, heating, industry and agriculture. That is, a doubling of the decarbonisation rate requires much more than a doubling of the policy effort. The low-hanging fruit has been picked.

Coping With Turbulence: EU Negotiations on the 2030 and 2050 Climate Targets

This article analyses European Union (EU) negotiations on the European Climate Law and the 2030 Climate Target Plan in the aftermath of the Covid-19 pandemic. Adopting Ansell and Trondal’s (2018) conceptualisation of turbulence, it argues that the pandemic intensified the environmental turbulence within which European policy makers had been operating following Brexit, the rule of law dispute with Poland and Hungary, and the election of Donald Trump as president of the United States. Organisational turbulence within EU institutions also affected the negotiations, particularly due to the reliance of Commission President Ursula von der Leyen on the political support of East-Central European governments that are sceptical of ambitious climate action. Moreover, the Commission, the European Council and the Parliament have taken different positions on the 2030 climate target and on the governance to pursue subsequent targets. Turbulence of scale—reflecting the nature of the EU as a multi-level actor—became relevant too, as the EU found it difficult to agree on its 2030 climate target due to disputes between member states and European institutions. European decision makers responded to turbulence through major policy initiatives, such as the EU Recovery Plan, the Green Deal agenda, and making funds conditional to the respect of the rule of law. They also pursued intra-EU compromises that accommodated different positions—for instance, on the Climate Law. Nonetheless, turbulence continues to pose a formidable challenge to the progress of the EU’s climate agenda.

Legacy effects of climate overshoot scenarios in permafrost-affected regions

<p>Difficulties to quickly reduce carbon emissions to levels compatible with the long-term goal of the Paris Agreement increase the likelihood of scenarios that temporarily overshoot the respective climate targets. We used simulations with JSBACH, the land surface component of the Max-Planck-Institute for Meteorology’s Earth system model MPI-ESM1.2 to investigate the long-term response of the terrestrial Arctic to climate stabilization at such a climate target. In particular, we seek to answer the question whether the state of permafrost-affected soils and the Arctic carbon cycle could converge to different equilibria depending on the climate trajectory that precedes climate stabilization at 1.5°C above pre-industrial levels. To this end, we compare simulations that are forced with the same non-transient atmospheric conditions – corresponding to the 1.5°C-target --, but started from different initial conditions. One simulation was initialized with the conditions before and one simulation with the conditions after a temperature overshoot which follows SSP5-8.5 until the year 2100 subsequent to which the atmospheric conditions are reversed to the 1.5°C-target. Our results reveal that feedbacks between water-, energy- and carbon cycles allow for path-dependent steady-states in permafrost-affected regions. These depend on the soil organic matter content at the point of climate stabilization, which is significantly affected by the soil carbon loss resulting from overshooting the climate target. Here, the simulated steady-states do not only differ with respect to the amount of carbon stored in the frozen fraction of the soil, but also with respect to soil temperatures, the soil water content and even net primary productivity and soil respiration.</p>

The need for clearer climate target definitions - illustrating ambiguities of net zero CO2-eq targets

<p>Article 4 of the Paris Agreement calls for a “balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century”. It is not made explicit if this balance should be achieved for each of the greenhouse gases (GHGs) individually or if some sum of all GHGs is supposed to become net-zero. This confusion translated into several declared climate targets, that range from carbon-neutral, over GHG-neutral to climate-neutral, and sometimes use these terms interchangingly. However, these targets imply different trajectories in terms of single GHG emissions and result in vastly different temperature trajectories.<br>Here, we show the implications of this confusion concerning declared climate target metrics, using the most commonly used metric of CO<sub>2</sub>-equivalent emissions. The same trajectory of net-zero-2050 CO<sub>2</sub>-equivalent emissions, shows vast differences in short term and long-term temperature and carbon cycle responses, depending on the distribution of CO<sub>2</sub>-equivalent emissions across the different GHGs. <br>We emphasize that achieving net zero CO<sub>2</sub> emissions remains a necessary precondition for long-term temperature stabilization. We also show that methane emissions reduction can have large short term benefits, as it would strongly reduce the short term temperature and thereby increase the natural carbon uptake. Going forward we recommend to aim for more transparency in declared climate goals and suggest aiming to achieve net zero anthropogenic emissions for all GHGs individually.</p>

A New Methodology to Design Sustainable Archimedean Screw Turbines as Green Energy Generators

Current energy demand and climate target plans are leading to green energy facilities which are efficient and sustainable. Archimedean screw turbines (ASTs) are used to generate hydroelectricity in low heads. They have been manufactured and installed worldwide. However, there is a lack of knowledge about how to design them efficiently. In this study, the performance of ASTs is analyzed using an analogy between ASTs and bucket elevators. Based on this analogy, a theoretical hypothesis on how to produce efficient ASTs is proposed. The new methodology for the design of ASTs is based on two considerations: the filling level of the AST buckets must be 85% and the increase of leakage losses must be minimized. This hypothesis is numerically and experimentally studied. Two experimental prototypes were developed and installed in the north of Spain. The numerical and experimental results are provided. A discussion comparing the results of this work and other results from the literature is presented. Finally, conclusions are drawn from this work that contribute to the improvement of AST technology as a sustainable facility to generate green energy.