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One of the most recognised measures of climate change, global warming, is still subject to significant uncertainty. Even with the best tools available in the form of climate models, wide-ranging estimates are given of the increase in surface temperature for a given emissions scenario. This thesis investigates various mechanisms by which temperature change occurs as driven by energy imbalances introduced into the Earth system. The focus of this work lies on atmospheric stability, a measure of vertical temperature gradients that is well related to convection and thus in turn clouds. Greater stability suppresses convection and encourages low cloud formation which provides a cooling effect on the planet as these low clouds reflect incoming solar radiation. The structure of energy imbalances induced by forcing agents is found to be significant for stability in many ways, from the vertical structure of atmospheric heating, to the horizontal distribution of radiative flux that affects the pattern of sea surface temperature (SST) change, to the time-evolution of the forcing agents themselves. The result of analysing the impact of these structures through stability is that stability is found to explain much in terms of differences between forcing agents, as well as how temperatures evolve in the historical period. This thesis incorporates analysis of publicly available data from Climate Model Intercomparison Project 6 (CMIP6) historical experiments in order to compare and contrast feedbacks from time-evolving aerosol, greenhouse gas (GHG), and natural forcings. Work here shows that historical aerosols cause more amplifying feedbacks (higher effective climate sensitivity) than GHGs. Data from idealised computational experiments run for this project demonstrate that this is due to the extra-tropical skew of aerosol forcing. Furthermore, the time-evolving feedbacks of the historical period are found to be explained by the time-evolving feedbacks for the components of historical forcing. Open Access

In our measurements on samples, characteristic X-rays induced by a radioactive Cd-109 source were deteced in a high resolution Si(Li) detector. In the current experimental arrangement, it is possible to detect X-rays in the interval of energy 2-20 keV. All samples have been analyzed under the same conditions. The elemental composition of two leaden seals from the Republic of Ragusa were measured. Quantitave spectrum analyses showed that in the leaden seals there is gallium and iron in addition to the lead, which is the dominant element. Concentration of bizmuth, gold and selenium were found to be within the detection limit. Metal content, with the exception of silver, have also been measured in two ancient and two medieval silver coins.