Anne Holsten

Towards sectoral and standardised vulnerability assessments: the example of heatwave impacts on human health

The relevance of climate change is especially apparent through the impacts it has on natural and societal systems. A standardised methodology to assess these impacts in order to produce comparable results is still lacking. We propose a semi-quantitative approach to calculate vulnerability to climate change, with the ability to capture complex mechanisms in human-environmental systems. The key mechanisms are delineated and translated into a deterministic graph (impact chain). A fuzzy logic algorithm is then applied to address uncertainty regarding the definition of clear threshold values. We exemplify our approach by analysing the direct impacts of climate change on human health in North Rhine-Westphalia, Germany, where the urban heat island potential, the percentage of elderly population as well as the occurrence of heat waves determine impact intensity. Increases in heatwaves and elderly population will aggravate the impacts. While the influence of climatic changes is apparent on larger spatial scales, societal factors determine the small scale distribution of impacts within our regional case study. In addition to identifying climate change impact hot spots, the structured approach of the impact chain and the methodology of aggregation enable to infer from the results back to the main constituents of vulnerability. Thus, it can provide a basis for decision-makers to set priorities for specific adaptation measures within the complex field of climate change impacts.

An integrated and transferable climate change vulnerability assessment for regional application

While sectoral vulnerability assessments have become common usage in the climate change field, integrated and transferable approaches are still rare. However, comprehensive knowledge is demanded to concretize and prioritize adaptation strategies, which are currently being drafted at national and state levels. We present a multisectoral analysis where sensitivity is quantified by the physical, social, environmental and economic dimension by means of tailor-made approaches for specific sectors. These are directly related to relevant exposure variables defined as relative climatic changes until the end of this century. Aggregation of the sector-specific impacts, comprising both sensitivity and exposure, leads to integrated impact measures. These are then combined with the generic adaptive capacity. We exemplify our methodology for municipalities in the German state North Rhine-Westphalia for two regional climate models. Our approach allows for the integrated assessment, while at the same time enabling a sector-specific perspective. However, various limitations remain, especially regarding the aggregation across sectors. We emphasize the need to consider the aim and methodological advantages and disadvantages before applying any vulnerability assessment.

Towards a unified characterization of phenological phases: Fluctuations and correlations with temperature

Phenological timing–i.e. the course of annually recurring development stages in nature–is of particular interest since it can be understood as a proxy for the climate at a specific region; moreover changes in the so-called phenological phases can be a direct consequence of climate change. We analyze records of botanical phenology and study their fluctuations which we find to depend on the seasons. In contrast to previous studies, where typically trends in the phenology of individual species are estimated, we consider the ensemble of all available phases and propose a phenological index that characterizes the influence of climate on a multitude of botanical species.

Climate change mitigation potential of community-based initiatives in Europe

There is a growing recognition that a transition to a sustainable low-carbon society is urgently needed. This transition takes place at multiple and complementary scales, including bottom-up approaches such as community-based initiatives (CBIs). However, empirical research on CBIs has focused until now on anecdotal evidence and little work has been done to quantitatively assess their impact in terms of greenhouse gas (GHG) emissions. In this paper, we analyze 38 European initiatives across the food, energy, transport, and waste sectors to address the following questions: How can the GHG reduction potential of CBIs be quantified and analyzed in a systematic manner across different sectors? What is the GHG mitigation potential of CBIs and how does the reduction potential differ across domains? Through the comparison of the emission intensity arising from the goods and services the CBIs provide in relation to a business-as-usual scenario, we present the potential they have across different activities. This constitutes the foundational step to upscaling and further understanding their potential contribution to achieving climate change mitigation targets. Our findings indicate that energy generation through renewable sources, changes in personal transportation, and dietary change present by far the highest GHG mitigation activities analyzed, since they reduce the carbon footprint of CBI beneficiaries by 24%, 11%, and 7%, respectively. In contrast, the potential for some activities, such as locally grown organic food, is limited. The service provided by these initiatives only reduces the carbon footprint by 0.1%. Overall, although the proliferation of CBIs is very desirable from a climate change mitigation perspective it is necessary to stress that bottom-up initiatives present other important positive dimensions besides GHG mitigation. These initiatives also hold the potential of improving community resilience by strengthening local economies and enhancing social cohesion.