Multiscalar spatial analysis of urban flood risk and environmental justice in the Charlanta Megaregion, USA Publication date: Available online 19 September 2019 Source: Anthropocene Author(s): Neil Debbage Abstract Previous research exploring the environmental justice implications of urban flood hazards has produced contrasting results due to the different dasymetric mapping techniques used, the various spatial scales of the analyses, and the specific geographical context of the individual study cities, particularly as it relates to the presence of coastal water-based amenities. To better understand if vulnerable populations are disproportionately exposed to urban flood hazards in non-coastal cities, this study assessed the magnitude of socio-economic inequities in flood risk throughout the Charlanta megaregion. Specifically, population characteristics within the 500-year flood zone were estimated using United States Census Bureau data for race, ethnicity, and poverty by applying three dasymetric mapping techniques at four spatial scales. Risk ratios were used to statistically evaluate if vulnerable populations were overrepresented in areas at risk for flooding overall as well as for lake and non-lake regions. Although the results varied according to the scale and socio-economic variable, the most accurate dasymetric mapping approach indicated that environmental injustices were systemic, as vulnerable individuals were between 14% and 42% more likely to reside in areas at risk for flooding when analyzing the entire megaregion. At the metropolitan scale, vulnerable individuals were still significantly more likely to reside in flood zones, and the influence of lake amenities on the disparities was nuanced. A complex spatial landscape of inequities was also observed at the county and census tract levels. Overall, the notable disparities faced particularly by non-Hispanic black and Hispanic populations suggest that urban flood risk inequities in the megaregion are largely due to structural forms of discrimination and residential segregation, which have been pervasive throughout the development of Charlanta.

Deciphering African tropical forest dynamics in the Anthropocene: How social and historical sciences can elucidate forest cover change and inform forest management Publication date: September 2019 Source: Anthropocene, Volume 27 Author(s): G. Walters, J. Angus Fraser, N. Picard, O. Hymas, J. Fairhead Abstract Forests bear the historical legacies of human activities over thousands of years, including agriculture, trade, disease and resource extraction. Many of these activities may represent indices of the proposed geological epoch of the Anthropocene. Modifications to soil, topography and vegetation evidence anthropogenic influences. Yet studies of vegetation change throughout the humid tropics tend to occlude these influences by focussing on forest dynamics, timber, and biodiversity through permanent sample plots or forestry inventory plots. We highlight how history and social science can be combined with ecology to help better understand human signatures in forest dynamics. We (1) critically review ecological methods in the light of the environmental and social history of the Afrotropics; (2) map current plot networks for West and Central Africa in relation to the Human Footprint Index; (3) using two case-studies, demonstrate how history and social science bring new insights and inferences to plot-based studies; all leading to (4) novel forms of interdisciplinary collaboration for sustainable forest conservation, management and restoration.

An evaluation of human interventions in the anthropogenically disturbed Caribbean Coast of Colombia Publication date: September 2019 Source: Anthropocene, Volume 27 Author(s): Cristina I. Pereira, Diego A. Madrid, Iván D. Correa, Enzo Pranzini, Camilo M. Botero Abstract Although human interventions have influenced many coastal areas around the world, research has rarely assessed the environmental impacts of these anthropogenic perturbations. To understand the dominant coastal interventions in countries with tropical areas, this study established a baseline along the continental Caribbean coast of Colombia (approximates 1700 km), based on 29 types of human interventions cataloged via Google Earth images. In total, of the 2742 human interventions identified, the most common were low-density-settlements (n = 971), groins (n = 738), and luxury settlements with piers (n = 188). In addition, the study assessed the environmental impact of each type of intervention based on the extent, intensity, reversibility, and persistence of their effect on coastal processes, as well as their frequency of appearance in the study area. The three most impactful types of human intervention were equivalent to those with the highest frequency: a. Low-density settlements; b. Groins/Jetties; c. Luxury settlements with a pier. In addition, the highest values of environmental impact correspond to material extractions and infrastructure assets such as breakwaters and seawalls. None of these anthropogenic disturbances, however, were within the ten most impactful interventions identified in the study area. The socio-natural patterns of coastal development identified by this study can steer integrated environmental management in coastal tropical countries with rapid economic growth, diversity of human interventions and heterogeneous geographical distribution. Graphical abstract

Anthropogenic energy and carbon flows through Canada’s agri-food system: Reframing climate change solutions Publication date: September 2019 Source: Anthropocene, Volume 27 Author(s): Adekunbi B. Adetona, David B. Layzell Abstract Greenhouse gas accounting for agricultural systems consider methane and nitrous oxide emissions, carbon emissions from liming and urea use, as well as carbon stock changes, but it ignores gross flows of bio-based energy and carbon. This study compiled data for Canada’s agri-food system over the 2010-13 period, from food supply and disposition to crop processing, animal production, and crop/pasture production. The data were converted to units of energy and carbon, tracked through the agri-food system and compared in scale and conversion efficiency with Canadian crude oil recovery to the production of refined petroleum products. Results showed domestic photosynthesis-derived energy and carbon flow equivalent to 75% and 98%, respectively, of the fossil fuel-derived energy and carbon in the crude oil recovered in Canada. This magnitude is substantial since Canada is a nation with high per capita oil demand that exports over 50% of its own production. Only 14% of the agri-food energy and carbon, respectively, emerged in agri-food products, compared to 91% of the energy and carbon in crude oil that resulted in refined petroleum products. The low conversion efficiency of the agri-food system derived, in part, from 40% of bio-based energy and carbon being diverted to crop and animal residues or waste. Per unit of energy in end products, the other energy inputs (e.g. electricity, fuels) needed to support the agri-food system were 5.3-folds higher in the agri-food system than in the crude oil to products system. This study highlights the need to develop strategies to better utilize the energy and carbon flows of the agri-food system, thereby reducing fossil energy use and greenhouse gas emissions associated with human activities. Graphical abstract

Warfare dendrochronology: Trees witness the deployment of the German battleship Tirpitz in Norway Publication date: September 2019 Source: Anthropocene, Volume 27 Author(s): Claudia Hartl, Scott St. George, Oliver Konter, Lorenz Harr, Denis Scholz, Andreas Kirchhefer, Jan Esper Abstract War has an immediate and obvious effect on people and communities, but its impacts on local ecology can be more subtle. This paper shows how one military encounter in the Second World War has left a clear legacy in the northern forests of Norway, trackable more than seventy years later. We used annual growth rings of ∼180 pine and ∼30 birch trees as witnesses of the deployment of the German battleship Tirpitz at the Kåfjord. The Tirpitz was the target of several Allied air attacks, but the Kriegsmarine (German navy from 1935 to 1945) used artificial smoke, consisting of chlorosulfonic acid and zinc/hexachloroethane, to hide the ship. These smoke-screen actions throughout 1944 caused pine forests surrounding the Kåfjord to exhibit a strong and unusual growth decline during the following year. Severe defoliation and limited photosynthetic activity likely triggered this decline. The tree damage extended up to 4 km away from the Tirpitz. In the most extreme case, growth was interrupted for nine years. ‘Warfare dendrochronology’ could help to evaluate potential environmental impacts of the Second World War on forest health and composition elsewhere in the European theatre.

Meteorological catalysts of dust events and particle source dynamics of affected soils during the 1930s Dust Bowl drought, Southern High Plains, USA Publication date: September 2019 Source: Anthropocene, Volume 27 Author(s): Kasey Bolles, Mark Sweeney, Steven Forman Abstract Mineral dust aerosols are a key component of the Earth system and a growing public health concern under climate change, as levels of dustiness increase. The Great Plains in the USA is particularly vulnerable to dust episodes, but land-atmosphere interactions contributing to large-scale dust transport are poorly constrained. This study compiled one of the longest quantitative, spatially-comprehensive records of dust events in the core Dust Bowl region never before available. Combined with experiment station reports from the Soil Conservation Service, reanalysis data products, and contemporary field surveys using a Portable In-Situ Wind Erosion Laboratory (PI-SWERL), the study examined meteorological catalysts for dust events and surficial dynamics of particle emission on the Southern High Plains (SHP). Multivariate statistical analyses of dust event variance yield 6 principal components capturing ˜60% of the variance of all dust event days. Results identified four dominant modes of dust events related to the season of occurrence and principal meteorological controls. A broader assessment of the potential emissivity of SHP soils reveals that disturbed surfaces begin to emit dust at a magnitude-higher rate than undisturbed surfaces as soon as the wind velocity reaches the threshold, increasing linearly with windspeed. Conversely, crusted undisturbed soil surfaces do not begin to reach the same flux rate until much higher windspeeds, at which point crusts are broken and emissivity rates increase exponentially. Significantly, the particle emissivity of undisturbed, loose sandy soils mirrors that of disturbed surfaces in relation to windspeed and potential magnitude of dust emission. This finding suggests that the prevalent sandier, rangeland soils of the SHP could be equal or greater dust sources than cultivated fields during periods of sustained, severe aridity.

Greenhouse gas flux from stormwater ponds in southeastern Virginia (USA) Publication date: Available online 25 August 2019 Source: Anthropocene Author(s): A.L. Gorsky, G.A. Racanelli, A.C. Belvin, R.M. Chambers Abstract Stormwater ponds are ubiquitous features of developed landscapes of the eastern United States. Their design specifically controls the pace of water runoff from impervious cover of surrounding watersheds. Ponds accumulate organic matter that typically decomposes anaerobically in bottom sediments, and thus may be significant sources of greenhouse gases to the atmosphere (e.g., carbon dioxide (CO2), methane (CH4)). We sampled fifteen stormwater retention ponds in southeastern Virginia (USA) during summer 2018 to determine the diffusive emission of greenhouse gases with respect to measured environmental parameters. The equivalent CO2 (CO2e) flux from ponds ranged from 8.3 to 80 mmol m-2 hr-1, with CH4 contributing 94%, CO2 6% and nitrous oxide less than 1% of the CO2e flux, on average. From linear mixed-effects modelling, diffusive flux of CO2 was inversely associated with pH. Maximum depth best explained diffusive flux of CH4, with surface area of secondary importance, i.e. CH4 flux was higher in smaller and more shallow ponds. With 300 stormwater ponds in the county where we conducted this study, we estimate that, during a 100-day warm season, these ponds emit 2.3 x 109 ± 1.5 x 109 SD g C as CO2e. As small, human-constructed ponds are becoming common features of urbanizing landscapes globally, results from this study suggest that, collectively, small ponds can contribute substantially to climate forcing. Better pond designs that reduce sediment methanogenesis, however, can mitigate the hypothesized potential disservice of GHG emissions from unvegetated stormwater retention ponds.

A Survey-Based Assessment of Perceived Flood Risk in Urban Areas of the United States Publication date: Available online 23 August 2019 Source: Anthropocene Author(s): Sharon L. Harlan, Mariana J. Sarango, Elizabeth A. Mack, Timothy A. Stephens Abstract How people perceive the risks of climatic hazards is currently a major research thrust in the field of risk perception. In the wake of recent flood disasters in all regions of the United States and globally, more researchers are investigating social vulnerabilities as well as the role of cognition in explaining risk perceptions. This study analyzed how people in the United States perceive the risk (i.e., likelihood and seriousness) of flooding via a layered analysis that considered several plausible and intertwined lines of inquiry from the risk perception literature. We surveyed 9,250 individuals within nine major urban areas, including the largest city and one smaller city in each region. The National Flood Hazard Layer product provided data for deriving their potential exposure to flood hazards. The analyses tested and confirmed several hypotheses drawn from Social Vulnerability Theory and from Protective Motivation Theory: characteristics associated with social vulnerability (older, female, race/ethnic minorities, low income), previous experiences with and awareness of flood news, and potential exposure to flood hazard (local fraction of flood prone area) significantly increased risk perceptions of floods. Self-confidence in ability to cope with a future flood disaster lowered risk perceptions. This study is the first snapshot of US flood risk perceptions nationwide. It points to needs for more theoretically-driven research about flood risk perceptions and behaviors, flood risk communication within local communities, and more social and economic support for vulnerable populations.

Tree growth patterns associated with extreme longevity: Implications for the ecology and conservation of primeval trees in Mediterranean mountains Publication date: June 2019 Source: Anthropocene, Volume 26 Author(s): Gianluca Piovesan, Franco Biondi, Michele Baliva, Anna Dinella, Luca Di Fiore, Vittoria Marchiano, Emanuele Presutti Saba, Giuseppe De Vivo, Aldo Schettino, Alfredo Di Filippo Abstract This study analyzed with dendrochronology 177 Heldreich’s pines growing on the Pollino Massif in southern Italy for understanding climatic and human impacts on old trees. Most of the large-diameter trees currently living became established in the late Medieval to Renaissance periods under a snowy wet climate and low anthropic influence. Millennium-old (i.e., > 900 years of age) trees in remote sites escaped Medieval human impacts, then a wave of pine stands established in the late 14th and 16th centuries following recurrent human plague epidemics. Stem growth histories showed that both millennium-old and the majority of century-old trees grew along similar trajectories. These old trees have survived long-lasting climatic reversals, clearly a sign of their resilience to extreme events. Cliff habitats played a strategic environmental role for tree conservation during periods of land exploitation; such biodiversity refugia may serve as stepping stones for rewilding mountain landscapes. In recent decades, land abandonment following the collapse of sheep-herding, together with climate warming, have led to a new pulse of tree recruitment. Since 1850, low-frequency variability (50-70-year periods) in tree growth has been in synchrony with the Atlantic Multidecadal Oscillation. Recently observed growth increases counter widespread reports of tree and forest decline in Mediterranean environments, and suggest that extreme longevity does not necessarily reduce stem increment. Discovering, studying, and preserving primeval trees in forest landscapes remains a priority for biodiversity conservation in the Anthropocene. Heldreich’s pine resilience to current global changes bodes well for sustainable development in the Mediterranean mountains they inhabit, and similar studies are needed for threatened habitats and iconic trees of other ecoregions in order to assess their probable survival into the future. Graphical abstract

Glacio-archaeological evidence of permanent settlements within a glacier end moraine complex during 980-1840 AD: The Miyar Basin, Lahaul Himalaya, India Publication date: June 2019 Source: Anthropocene, Volume 26 Author(s): Rakesh Saini, Milap Chand Sharma, Sanjay Deswal, Iestyn David Barr, Pawan Kumar, Parvendra Kumar, Pankaj Kumar, Sundeep Chopra Abstract This study presents glacio-archaeological evidence from the Miyar basin, Lahaul Himalaya, that points towards the former presence of a well settled agricultural society, within a glacier end moraine complex. Three high altitude villages (Tharang, Phundang and Patam, now in ruins) with elaborate irrigation networks thrived within the end moraine complex of Tharang glacier at 3700 m a.s.l. Evidence exists in the form of dilapidated houses which had an organised internal space, chronologically constrained by radiocarbon (14C) dating. These settlements occupied the end moraine complex between 980 and 1840 CE, thereby encompassing the majority of Little Ice Age period (1300–1600 CE), as defined elsewhere. The existence of settlements along with an irrigation system and associate fields at ∼3700-3800 m a.s.l. for almost ∼860 years during the late 10th to early 19th centuries suggests more favourable climatic (warm) conditions that at present. By contrast, present habitation is restricted to areas below ∼3500 m a.s.l. However, the slope controlled irrigation system also suggests moisture stressed conditions during the 980–1840 CE period, similar to present. The available temperature and snowfall proxies for the region support our proposed timing, and suggest favourable climatic conditions for the survival of these settlements.