Earth and Environmental Science

4:00 pm - 4:25 pm Lindi Coyle: Arctic Methane: A Critical Evaluation of Mechanisms, Measurement, and Modelling in a Permafrost-Influenced Landscape

The Arctic is warming faster than the global average and is becoming a significant source of methane (CH4), which could intensify global warming. This seminar is a critical evaluation of mechanisms of CH4 generation, measurement techniques, and methods for estimating and analyzing factors that control CH4 release. A comparison of slower, gradual-thaw emissions with rapid releases from abrupt-thaw events, such as thermokarst formation, will highlight the temporal variation and the role of methane-cycling microbiomes and geological sources.

This assessment integrates recent literature on wildfire-induced permafrost thaw and cold-season CH4 emissions. Many challenges remain in predicting CH4 impacts, including the limited understanding of Arctic hydrology, the identification of primary sources, and the evaluation of the role of potential methane sinks under drier conditions. Current models often underestimate emissions from localized hotspots and non-summer periods, and discrepancies persist between satellite and ground observations, complicating comprehensive upscaling. Addressing these issues requires improved models and observational strategies to accurately predict permafrost–climate feedback and reconcile the diverse measurement and modelling approaches.

4:30 pm – 4:55 pm Sophie McGuinness: Challenges of Using Large-Scale Presence-Only Observational Data for Biodiversity Studies

This seminar is a critical evaluation of the application of large-scale, presence only observational data in conservation biodiversity studies. This critical review will incorporate a case study to examine the implications and limitations of using presence-only data. Presence-only datasets are commonly used in species distribution and conservation studies but lack true absence data, which can interfere with the estimation of species distributions and biodiversity patterns. Species distribution and conservation datasets are commonly created from a combination of historical records, the latest GPS based data, and citizen science initiatives. They can provide extensive spatial coverage and records of many different species but typically only contain presence-only records. This introduces important methodological challenges, such as sampling and effort biases, taxonomic and spatial biases, and biodiversity metrics all of which can influence ecological interpretations. The use of presence only data can alter the results and accuracy of the study, and its application can impact the effective interpretation of observational data as

well as conservation decision-making. Despite its limitations, presence-only datasets remain valuable when used with appropriate caution and methodological awareness.