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1. A Holocene history of climate, fire, landscape evolution, and human activity in northeastern Iceland

   https://doi.org/10.5194/cp-20-1087-2024  

   Ardenghi, Nicolò; Harning, David J.; Raberg, Jonathan H.; Holman, Brooke R.; Thordarson, Thorvaldur; Geirsdóttir, Áslaug; Miller, Gifford H.; Sepúlveda, Julio (January 2024, Climate of the Past)

   Abstract. Paleoclimate reconstructions across Iceland provide a template for past changes in climate across the northern North Atlantic, a crucial region due to its position relative to the global northward heat transport system and its vulnerability to climate change. The roles of orbitally driven summer cooling, volcanism, and human impact as triggers of local environmental changes in the Holocene of Iceland remain debated. While there are indications that human impact may have reduced environmental resilience during late Holocene summer cooling, it is still difficult to resolve to what extent human and natural factors affected Iceland's late Holocene landscape instability. Here, we present a continuous Holocene fire record of northeastern Iceland from proxies archived in Stóra Viðarvatn sediment. We use pyrogenic polycyclic aromatic hydrocarbons (pyroPAHs) to trace shifts in fire regimes, paired with continuous biomarker and bulk geochemical records of soil erosion, lake productivity, and human presence. The molecular composition of pyroPAHs and a wind pattern reconstruction indicate a naturally driven fire signal that is mostly regional. Generally low fire frequency during most of the Holocene significantly increased at 3 ka and again after 1.5 ka BP before known human settlement in Iceland. We propose that shifts in vegetation type caused by cooling summers over the past 3 kyr, in addition to changes in atmospheric circulation, such as shifts in North Atlantic Oscillation (NAO) regime, led to increased aridity and biomass flammability. Our results show no evidence of faecal biomarkers associated with human activity during or after human colonisation in the 9th century CE. Instead, faecal biomarkers follow the pattern described by erosional proxies, pointing toward a negligible human presence and/or a diluted signal in the lake's catchment. However, low post-colonisation levels of pyroPAHs, in contrast to an increasing flux of erosional bulk proxies, suggest that farming and animal husbandry may have suppressed fire frequency by reducing the spread and flammability of fire-prone vegetation (e.g. heathlands). Overall, our results describe a fire frequency heavily influenced by long-term changes in climate through the Holocene. They also suggest that human colonisation had contrasting effects on the local environment by lowering its resilience to soil erosion while increasing its resilience to fire. 

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2. Reimagining CS Courses for High School Students

   https://doi.org/10.1145/3626253.3635554  

   Smith, Julie M; Twarek, Bryan; McGill, Monica M (March 2024, SIGCSE 2024: Proceedings of the 55th ACM Technical Symposium on Computer Science Education)

   Traditionally, computer science (CS) in the United States has been an elective subject at the high school level. In recent years, however, some school systems have created a CS graduation requirement. Designing a required CS course that meets the needs of anticipated future advancements in the field necessitates exploring the research question, To better understand what these different groups perceive to be the essential content of a foundational high school CS course, we conducted a series of focus groups. These focus groups explored participants' (n = 21) thinking about what content would be most important to prioritize in a required high school CS course. Transcripts of the focus groups were abductively coded and then analyzed to determine what CS content priorities were identified and what disagreements about priorities exist. We found that participants (1) emphasized CS knowledge and skills, with minimal reference to dispositions, (2) prioritized content similar to that found in current CS standards, (3) developed broad, high-level descriptions of content, (4) identified contextually relevant factors, (5) foregrounded AI both a tool and as a subdomain of CS, and (6) emphasized computational thinking. These findings can inform further research on the design and implementation of a required high school CS course designed to meet the needs of the future as well as to support revisions of CS standards for high school students. 

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3. Increasing fire and the decline of fire adapted black spruce in the boreal forest

   https://doi.org/10.1073/pnas.2024872118  

   Baltzer, Jennifer L.; Day, Nicola J.; Walker, Xanthe J.; Greene, David; Mack, Michelle C.; Alexander, Heather D.; Arseneault, Dominique; Barnes, Jennifer; Bergeron, Yves; Boucher, Yan; et al (October 2021, Proceedings of the National Academy of Sciences)

   Intensifying wildfire activity and climate change can drive rapid forest compositional shifts. In boreal North America, black spruce shapes forest flammability and depends on fire for regeneration. This relationship has helped black spruce maintain its dominance through much of the Holocene. However, with climate change and more frequent and severe fires, shifts away from black spruce dominance to broadleaf or pine species are emerging, with implications for ecosystem functions including carbon sequestration, water and energy fluxes, and wildlife habitat. Here, we predict that such reductions in black spruce after fire may already be widespread given current trends in climate and fire. To test this, we synthesize data from 1,538 field sites across boreal North America to evaluate compositional changes in tree species following 58 recent fires (1989 to 2014). While black spruce was resilient following most fires (62%), loss of resilience was common, and spruce regeneration failed completely in 18% of 1,140 black spruce sites. In contrast, postfire regeneration never failed in forests dominated by jack pine, which also possesses an aerial seed bank, or broad-leaved trees. More complete combustion of the soil organic layer, which often occurs in better-drained landscape positions and in dryer duff, promoted compositional changes throughout boreal North America. Forests in western North America, however, were more vulnerable to change due to greater long-term climate moisture deficits. While we find considerable remaining resilience in black spruce forests, predicted increases in climate moisture deficits and fire activity will erode this resilience, pushing the system toward a tipping point that has not been crossed in several thousand years. 

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4. Assessing changes in global fire regimes

   https://doi.org/10.1186/s42408-023-00237-9  

   Sayedi, Sayedeh_Sara; Abbott, Benjamin_W; Vannière, Boris; Leys, Bérangère; Colombaroli, Daniele; Romera, Graciela_Gil; Słowiński, Michał; Aleman, Julie_C; Blarquez, Olivier; Feurdean, Angelica; et al (February 2024, Fire Ecology)

   Abstract BackgroundThe global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300. ResultsRespondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios. ConclusionThe influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities. 

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5. Urban planning and IPCC-like city assessments integration for climate-resilient cities

   https://doi.org/10.1177/23998083251330940  

   Ye, Xinyue; Yigitcanlar, Tan; Xu, Yangyang; Head, Monique; Hang, Yun; Sanchez, Tom; Gong, Wenjing; Niyogi, Dev (March 2025, Environment and Planning B: Urban Analytics and City Science)

   The rapidly intensifying effects of climate change on urban settlements demand that cities move to the forefront of resilience planning. Climate extremes, from heatwaves to flooding, are increasingly testing the adaptability limits of urban systems and the vulnerability of their populations. Recognizing the unique position of cities, the IPCC’s seventh assessment cycle has prioritized urban areas in its upcoming Special Report on Climate Change and Cities. The IPCC report underscores the potential of cities to act as agents of climate adaptation and provides a framework for cities to build climate-resilient systems. Cities are positioned to pioneer practical, integrative solutions that blend climate sciences with urban planning, establishing frameworks that align economic growth, health equity, environmental sustainability, social justice, and effective governance. This opinion piece explores how cities, by positioning themselves as hubs for innovation, policy reform, and community collaboration, can transform climate vulnerabilities into opportunities for community resilience and sustainability, especially by becoming more-than-human cities, setting examples on the global stage. 

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