A study on the macroeconomics of climate change

This work aims at exploring the relationship between business cycles, having frequencies rooted in the short run, and climatic phenomena, which span longer time horizons. The ultimate goal is to provide a theoretical framework to address these questions: How could very long run considerations affect short run economic decisions? How short run and transitory decisions could exert a long lasting effect on climate? This is achieved by means of an off-the-shelf real business cycle (RBC) model augmented so as to include a climatic block. The economy is perturbed by a technology shock and an energy-price shock. In general, the model performs relatively well in reproducing the cyclical characteristics of the economic variables; however, it is not as successful in capturing the cyclical behavior of climatic variables. Finally, it proposes a set of policy experiments, all taking the form of an energy tax directly or indirectly linked to the climatic status. As a matter of fact the effect of any tax responsive to the business cycle shows positive aspects: when a technology shock hits the economy, it mitigates global warming with minor costs in terms of potential output losses. It also protects the economy from an increase in energy prices, sustaining a certain level of output despite the fall in fossil energy use.

Relationship between phenotype and environment in marine calcifying organisms: exploring growth and shell properties of different mollusks species in past and modern scenario

Coastal ecosystems represent an inestimable source of biodiversity, being among the most productive areas on the planet. Despite the great ecological and economic value of those environments, many threats endanger the species living in this ecosystem, like the rapid warming and the sea acidification, among many other. Benthic calcifying organisms (e.g. mollusks, corals and echinoderms) in particular, are among the most exposed to those hazards. These organisms use calcium carbonate as a structural and protective material through the biomineralization process, biologically controlled by the organism, but nevertheless, strongly influenced by the environmental surroundings. Evaluating how a changing environment can influence the process of biomineralization is critical to understand how those species of great ecological and economic importance will face the ongoing climate change. This thesis investigates the mechanism of biomineralization in different mollusks’ species of the Adriatic Sea, providing detailed descriptions of shells skeletal, biometric and growth parameters. Applying a multidisciplinary and multi-scale research approach, the influence of external environmental factors on the process of shell formation has been investigated. To achieve this purpose analysis were conducted both on current populations and on fossil remain, which allows to investigate ecological responses to past climate transitions. Mollusks’ shells in fact are one of the best tools to understand climate change in the past, present and future, since they record the environmental conditions prevailed during their life, reflected on the geochemical properties, microstructure and growth of the shell. This approach allowed to overcome the time scale limit imposed by field and laboratory survey, and better understand species long term adaptive response to changing environment, a crucial issue to define proper conservation and management strategies. Furthermore, the investigation of fossil record of mollusks assemblages offered the opportunity to evaluate the long-term biotic response to anthropogenic stressors in the north Adriatic Sea.