LEE- Yer Sistem Bilimi Lisansüstü Programı

Bu topluluk için Kalıcı Uri

http://hdl.handle.net/11527/19499

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Konu "Climate change" ile LEE- Yer Sistem Bilimi Lisansüstü Programı'a göz atma
  • Öge
    Effects of climate change on potential range shifts and composition of Türkiye's terrestrial ecosystems
    (Graduate School, 2024-03-18) Ekberzade, Bikem ; Şen, Ömer Lütfi ; Yetemen, Ömer ; 601192001 ; Earth System Science
    At the current critical juncture with climate change, centennial projections of potential species distributions in biodiversity hotspots, using dynamic vegetation models with integrated ecological notions such as competition, may provide vital insight into conservation efforts. The central aim of this thesis research is to estimate the current and future potential distribution of Türkiye's forests and their composition in the absence of anthropogenic landcover change, to calibrate the bioclimatic thresholds of certain key taxa to reflect their regional distribution in simulations using a process-based dynamic regional-to-global vegetation model (DGVM) to introduce new taxa to the simulations where necessary and in this manner to contribute to past studies on the distribution of European forest taxa by filling an important spatial gap. For this purpose, potential distribution of 25 forest taxa, and a C3-grass type are simulated by means of LPJ-GUESS v. 4.1 for the Anatolian Peninsula, keeping a spatial window large enough to track temporal changes in the vegetation range and composition in its surrounding areas. The model was forced with ERA5-Land reanalysis data for the historical period (1961-2014), and five different global climate model (GCM) contributions to the 6th phase of the Coupled Model Intercomparison Project (CMIP6) for the scenario period (2015-2100). The GCM datasets were interpolated to ERA5-Land's resolution and bias corrected with the climatology of the reference period 1995-2014 from the ERA5-Land dataset. The reference period for bias correction was selected in accordance with the 6th assessment report of Intergovernmental Panel on Climate Change (IPCC 2021), and in part, to reflect the current state of global warming. Shared Socioeconomic Pathways (SSP) 5-8.5, the high emissions scenario, was selected for all simulations. The bioclimatic tolerance levels of all plant functional types were calibrated using the temperature components of 1 km CHELSA dataset, and 9 km ERA5-Land datasets, calculating climatologies where necessary using Climate data operators (CDO) and R computing language; species distribution maps from European forest genetic resources programme (EUFORGEN); and the forest inventory data from General Directorate of Forestry (GDF) of Türkiye. In situ site visits were also undertaken to critical regions within the study area to further finetune the bioclimatic tolerance levels of certain key taxa, and further analysis of both observation data and the simulation results were made using R and ArcGIS. The simulation results from multiple model runs highlighted a consistent increase in woody species biomass for the entire study region, by the end of the century. The increase in biomass, mainly in the grasslands ecosystems was an important outcome of these series of simulations, which highlighted a consistent encroachment of woody taxa into terrain that is otherwise dominated by grasslands in simulations, in part reigniting the discussion over the past anthropogenic influence on the current vegetation composition of the Peninsula. The mountain systems also came out as important potential refugia for many cold-favoring woody taxa. Throughout the centennial simulations, the tree species prioritized an altitudinal move rather than a latitudinal one, consolidating their ranges around high elevation massifs, occasionally giving up their density dominance but gaining biomass. The composition of forest and woodland ecosystems shifted in large part in favor of the temperate taxa, as these species expanded their distribution ranges throughout the study area, without any particular prioritization for altitude or latitude. Temperate taxa with higher tolerance for drought increased their overall biomass and density, while the drought sensitive species gave up their dominance but continued to exist in smaller groups in areas where resource limitation became a determinant for the outcome of competition. All simulated taxa survived the 140-year simulation period at some capacity (there were no potential regional extinctions), finding some form of a footing along this ancient land bridge – some giving up their largely monotypic/homogeneous forest ranges for mixed forest compositions; others either leaving their dominant presence and becoming a "member of the team"; or exerting their dominance over a larger area. Overall, the results from these series of simulations, sans human presence, suggest a high potential for future forest cover throughout the study region by the end of the century under a high emissions scenario, and important changes in vegetation composition including encroachment of grasslands ecosystems by woody taxa. Our findings also corroborate recent paleo studies that highlight the early forest capacity of Asia Minor, and with the right environmental policies in place to ensure a fair human-nature co-existence, the region may continue to play its role as a cradle.
  • Öge
    Endless tug-of-war: impact of social media on science communication of climate change
    (Graduate School, 2023-06-21) Altan, Derin ; Yetemen, Ömer ; 601201006 ; Earth System Science
    The pervasiveness of social media in contemporary society necessitates a comprehensive, particularly by climate scientists, an understanding of social media's undeniable impact on the mass communication and perception of climate change by the "commons". This thesis provides an in-depth exploration into the multifaceted role that social media plays in the dissemination of, and – of course, most importantly – the public understanding of the incredibly complex issue of climate change. The study also further delves into the trajectory of science communication and climate change communication, providing a historical backdrop against which the emerging role of social media is investigated thoroughly. The undeniable capability of modern social media platforms to either augment public comprehension of climate change or contribute to misinformation and misunderstanding is critically evaluated, with a particular emphasis on the phenomenon of online polarization – an agonizing development that can dangerously shackle even the most careful climate communicator. An analysis of various polarized climate change topics on social media uncovers key actors and narratives that significantly shape the public discourse surrounding this critical issue. Parallel to this, the research contrasts the strategies adopted by mainstream media with the logic of effective climate change communication. The examination uncovers inherent contradictions between the two, largely driven by differing business models and journalistic practices that had lead mainstream media platforms for decades, which can ultimately impact public perception and action towards climate change. Moreover, the study sheds light on current trends in climate change communication across different social media platforms. It scrutinizes their potential and the challenges they pose in fostering widespread climate change awareness and inspiring public action. The findings underscore the complexity and multi-dimensionality of climate change communication in the digital age. A nuanced understanding of these dynamics offers scientists, communicators, and policymakers vital insights to develop more effective strategies for engaging the public in climate change discussions and inciting action. In summation, this thesis emphasizes the pressing need to navigate the challenges and seize the opportunities presented by social media. On one hand, the social media platforms provide an incredible opportunity: the ability to reach millions of people with the click of a button. On the other hand, the deep polarization probability of such communication rings the alarm bells, constantly. Regardless, an effective use of the social media platforms by climate change communicators (mostly climate scientists), is expected to enhance the public's general understanding of climate change science, reduce polarization that diminishes public discourse, and stimulate informed action towards developing effective mitigation, adaptation and resilience strategies, all of which are crucial steps in confronting the climate crisis.