Open Access

The ongoing warming of the Earth's atmosphere is projected to cause a northward shift of species' distributions, as they track their climatic optimum. In the rapidly warming Arctic, this has already led to an increase of shrubs in tundra ecosystems. While this northern expansion of woody biomass has been studied relatively extensively over the last decade, little research has been devoted to shrub growth responses at the southern margins of Northern Hemisphere shrubs. Here, we studied shoot length growth, its responses to climate over the period 2010-2017, and differences in leaf C and N content of the evergreen dwarf shrub Empetrum nigrum, as well as the vegetation composition and soil parameters at four sites located along a gradient of increasing dune age on the island Spiekeroog, northern Germany. The sites are located in the tri-national UNESCO world heritage site, the Wadden Sea. E. nigrum has a predominantly circum-arctic-boreal distribution and its southern distribution margin in European lowlands runs through northern Germany, where it is retreating northwards. We found a negative response to autumn (surface) temperatures and previous summer surface temperatures and/or a positive response to summer precipitation of E. nigrum growth, except at the oldest dune with the strongest E. nigrum dominance. Growth rates and plant species diversity declined with dune age. Our results suggest that E. nigrum growth is drought sensitive at its European southern range margin. We hypothesize that this sensitivity may form the basis for its northward retreat, which is supported by recent observations of E. nigrum dieback in Germany after the extreme drought in 2018 and model projections.

In order to calculate the financial return of energy efficiency measures, a cost-benefit analysis (CBA) is a proven tool for investors. Generally, however, most CBAs for investors have a narrow focus, which is - simply speaking - on investment costs compared with energy cost savings over the life span of the investment. This only provides part of the full picture. Ideally, a comprehensive or extended CBA would take additional benefits as well as additional costs into account. The objective of this paper is to reflect upon integrating into a CBA two important cost components: transaction costs and energy efficiency services - and how they interact. Even though this concept has not been carried out to the knowledge of the authors, we even go a step further to try to apply this idea. In so doing, we carried out a meta-analysis on relevant literature and existing data and interviewed a limited number of energy experts with comprehensive experience in carrying out energy services. Even though data is hardly available, we succeeded in constructing three real-world cases and applied an extended CBA making use of information gathered on transaction costs and energy services costs. We were able to show that, despite these additional cost components, the energy efficiency measures are economically viable. Quantitative data was not available on how energy services reduce transaction costs; more information on this aspect could render our results even more positive. Even though empirical and conceptual research must intensify efforts to design an even more comprehensive CBA, these first-of-its-kind findings can counterargue those that believe energy efficiency is not worth it (in monetary terms) due to transaction costs or energy services costs. In fact, this is good news for energy efficiency and for those that seek to make use of our findings to argue in favor of taking up energy efficiency investments in businesses.

Im vergangenen Jahr waren die Zuwachszahlen im Bereich der Elektromobilität in Deutschland höher als jemals zuvor. Das enorme Wachstum ist vor allem der EU-Verordnung zur Flottenemissionsnorm zu verdanken. Die Elektromobilität hat damit einen wichtigen Schritt gemacht und gezeigt, dass sie das Potenzial hat, den Verbrennungsmotor bald zu verdrängen. Doch allein ein sehr hoher Marktanteil an Elektroautos genügt nicht, um die mittelfristigen deutschen Klimaschutzziele zu erreichen. Dies ist eine der zentralen Aussagen der Autoren des vorliegenden Impulspapiers. Sie empfehlen, dass die Europäische Union Herstellern weiterhin ambitionierte Zielvorgaben für emissionsarme Pkw machen sollte, damit schon im Jahr 2030 annähernd alle neu zugelassenen Pkw elektrisch angetrieben werden. Autos mit Hybridantrieb sind auf diesem Weg maximal eine wichtige Übergangstechnologie. Zentrale Voraussetzung ist zudem, dass die derzeitigen Ladevorgänge erleichtert werden, damit der Umstieg auf Fahrzeuge mit alternativem Antriebskonzept deutlich attraktiver wird.