New results on the ages of star clusters in region B of M82

The post-starburst region B in M82 and its massive star cluster component have been the focus of multiple studies, with reports that there is a large population of coeval clusters of age ～1 Gyr, which were created with a Gaussian initial mass distribution. This is in disagreement with other studies of young star clusters, which invariably find a featureless power-law mass distribution. Here, we present Gemini-North optical spectra of seven star clusters in M82-B and show that their ages are all between 10 and 300 Myr (a factor of 3–100 younger than previous photometric results) and that their extinctions range between near zero and 4 mag (A _V ). Using new HST ACS-HRC U-band observations we age date an additional ～30 clusters whose ages/extinctions agree well with those determined from spectroscopy. Completeness tests show that the reported ‘turn-over’ in the luminosity/mass distributions is most likely an artefact, due to the resolved nature of the clusters. We also show that the radial velocities of the clusters are inconsistent with them belonging to a bound region.     

The effect of spacecraft radiation sources on electron moments from the Cassini CAPS electron spectrometer

Data from the Cassini plasma spectrometer (CAPS) electron spectrometer (ELS) have been found to be contaminated with an energy-independent background count rate which has been associated with radiation sources on Cassini. In this paper we describe this background radiation and quantitatively assess its impact on numerically integrated electron moments. The general properties of such a background and its effects on numerical moments are derived. The properties of the ELS background are described and a model for the background presented. A model to generate synthetic ELS spectra is presented and used to evaluate the density and temperature of pure noise and then extended to include ambient distributions. It is shown that the presence of noise produces a saturation of the electron density and temperature at quasi-constant values when the instrument is at background, but that these noise level moments are dependent on the floating spacecraft potential and the orientation of the ELS instrument with respect to the spacecraft. When the ambient distribution has a poor signal-to-noise ratio (SNR) the noise determines the density and temperature; however, as the SNR increases (increasing primarily with density) the density and temperature tend to those of the ambient distribution. It is also shown that these noise effects produce highly artificial density-temperature inverse correlations. A method to subtract this noise is presented and shown to correct for the presence of the noise. Simulated error estimates for the density and temperature are also presented. The analysis described in this paper not only applies to weak background noise, but also to more significant penetrating backgrounds such as those in radiation belt regions of planetary magnetospheres.     

Generation and expulsion of oils from Permian coals of the Sydney Basin,Australia

Organic geochemical and petrological assessment of coals/coaly shales and fine grained sediments, coupled with organic geochemical analyses of oil samples, all from Permo–Triassic sections of the Southern Sydney Basin (Australia), have enabled identification of the source for the widely distributed oil shows and oil seeps in this region. The Permian coals have higher hydrogen indices, higher liptinite contents, and much higher total organic matter extract yields than the fine grained sediments. A variety of source specific parameters obtained from n-alkanes, regular isoprenoids, terpanes, steranes and diasteranes indicate that the oil shows and seeps were generated and expelled predominantly from higher plant derived organic matter deposited in oxic environments. The source and maturity related biomarkers and aromatic hydrocarbon distributions of the oils are similar to those of the coals. The oil-coal relationship also is demonstrated by similarities in the carbon isotopic composition of the total oils, coal extracts, and their individual n-alkanes. Extracts from the Permo–Triassic fine grained sediments, on the other hand, have organic geochemical signatures indicative of mixed terrestrial and prokaryotic organic matter deposited in suboxic environments, which are significantly different from both the oils and coal extracts. The molecular signatures indicating the presence of prokaryotic organic matter in some of the coal extracts and oils may be due to thin sections of possibly calcareous lithologies interbedded within the coal measures. The genetic relationship between the oils and coals provides new evidence for the generation and expulsion of oils from the Permian coals and raises the possibility for commercial oil accumulations in the Permian and Early Triassic sandstones, potentially in the deeper offshore part of the Sydney Basin.     

Holocene alluvial sequences,cumulic soils and fire signatures in the middle Rio Puerco basin at Guadalupe Ruin,New Mexico

We describe a geoarchaeological survey of a 5‐km reach of the Rio Puerco channel and its tributaries, centered on the Guadalupe Ruin, a pueblo of the late 10th–12th centuries A.D. in north‐central New Mexico, with associated pollen, charcoal, micromorphological, and radiocarbon analyses. Severe erosion has drastically bisected the Puerco valley with four primary arroyos entering the western side of the Guadalupe reach of the valley: Tapia, Salado, Guadalupe and “No Name.” We recorded an 11‐m‐tall alluvial sequence marked by four phases of cumulic soil development, interrupted by six major periods of channel entrenchment that occurred at about 4100–3700 B.C. and 2900–2400 B.C., between 2200 B.C. and ca. A.D. 400, pre‐ and post‐ca. A.D. 900–1300, and in the late A.D. 1800s. Relative floodplain stability and associated cumulic soil development occurred prior to ca. 5700 B.C., between ca. 2600 to 2200 B.C. and A.D. 350 and 550, and ca. A.D. 900–1300. Multiple signatures of fires (oxidized sediment and charcoal) were observed in the Arroyo Tapia tributary sequence, especially in deposits dated ca. 6000 and 2600 B.C. These fires may have helped to enhance food resources for game animals by encouraging grass and shrub growth and/or to increase the growth of wild plants and eventually cultigens such as maize. Palynological evidence of maize in the Arroyo Tapia, dated ca. 2600–2200 B.C. may be the earliest thus far identified in the Southwest. © 2009 Wiley Periodicals, Inc.     

Effects of climate change and extreme events on forest communities in the European North

The European north is increasingly affected by changes in climate and climate variability. These changes and their causes are global in scope but specific impacts vary considerably between different regions. Recent incidents and events show that forest-resource based regions have difficulties in alleviating adverse effects of these changes. Also, the future socio-economic impact is to date unexplored. Norrbotten in Sweden, Lappi in Finland and Arkhangelsk oblast in Russia are regions that differ significantly in terms of their socio-economic characteristics and capacities. A modified employment multiplier model is used to predict future changes. Scenarios of changing forest resources provide quantitative estimations of the sensitivity of regional employment. These estimates are used to assess and discuss the adaptive capacities of the regions. Results show that Arkhangelsk oblast is more vulnerable to climate variability than Norrbotten and Lappi. This is due to the continued dependency on natural resources in combination with different capacities to counteract negative effects or to take advantage of the opportunities offered by climate change in this region.     

Sectoral approaches to improve regional carbon budgets

Humans utilise about 40% of the earth’s net primary production (NPP) but the products of this NPP are often managed by different sectors, with timber and forest products managed by the forestry sector and food and fibre products from croplands and grasslands managed by the agricultural sector. Other significant anthropogenic impacts on the global carbon cycle include human utilization of fossil fuels and impacts on less intensively managed systems such as peatlands, wetlands and permafrost. A great deal of knowledge, expertise and data is available within each sector. We describe the contribution of sectoral carbon budgets to our understanding of the global carbon cycle. Whilst many sectors exhibit similarities for carbon budgeting, some key differences arise due to differences in goods and services provided, ecology, management practices used, land-management personnel responsible, policies affecting land management, data types and availability, and the drivers of change. We review the methods and data sources available for assessing sectoral carbon budgets, and describe some of key data limitations and uncertainties for each sector in different regions of the world. We identify the main gaps in our knowledge/data, show that coverage is better for the developed world for most sectors, and suggest how sectoral carbon budgets could be improved in the future. Research priorities include the development of shared protocols through site networks, a move to full carbon accounting within sectors, and the assessment of full greenhouse gas budgets.     

Predicting high-frequency variation in stream solute concentrations with water quality sensors and machine learning

Stream solute monitoring has produced many insights into ecosystem and Earth system functions. Although new sensors have provided novel information about the fine-scale temporal variation of some stream water solutes, we lack adequate sensor technology to gain the same insights for many other solutes. We used two machine learning algorithms – Support Vector Machine and Random Forest – to predict concentrations at 15-min resolution for 10 solutes, of which eight lack specific sensors. The algorithms were trained with data from intensive stream sensing and manual stream sampling (weekly) for four full years in a hydrologic reference stream within the Hubbard Brook Experimental Forest in New Hampshire, USA. The Random Forest algorithm was slightly better at predicting solute concentrations than the Support Vector Machine algorithm (Nash-Sutcliffe efficiencies ranged from 0.35 to 0.78 for Random Forest compared to 0.29 to 0.79 for Support Vector Machine). Solute predictions were most sensitive to the removal of fluorescent dissolved organic matter, pH and specific conductance as independent variables for both algorithms, and least sensitive to dissolved oxygen and turbidity. The predicted concentrations of calcium and monomeric aluminium were used to estimate catchment solute yield, which changed most dramatically for aluminium because it concentrates with stream discharge. These results show great promise for using a combined approach of stream sensing and intensive stream discrete sampling to build information about the high-frequency variation of solutes for which an appropriate sensor or proxy is not available.     

Teleconnections in a warmer climate: the pliocene perspective

Migrations toward altered sea surface temperature (SST) patterns in the Indo-Pacific region are present in the recent observational record and in future global warming projections. These SSTs are in the form of ??permanent?? El Ni?o-like (herein termed ??El Padre??) and Indian Ocean Dipole (IOD)-like patterns. The Early Pliocene Warm Period, which bears similarity to future warming projections, may have also exhibited these Indo-Pacific SST patterns, as suggested by regional terrestrial paleo-climatic data and general circulation model studies. The ability to corroborate this assessment with paleo-data reconstructions is an advantage of the warm Pliocene period that is not afforded by future warming scenarios. Thus, the Pliocene period provides us with a warm-climate perspective and test bed for understanding potential changes to future atmospheric interactions given these altered SST states. This study specifically assesses how atmospheric teleconnections from El Padre/IOD SST patterns are generated and propagate to create the regional climate signals of the Pliocene period, as these signals may be representative of future regional climatic changes as well. To do this, we construct a holistic diagnostic rubric that allows us to examine atmospheric teleconnections, both energetically and dynamically, as produced by a general circulation model. We incorporate KE??, a diagnostic adapted from the eddy kinetic energy generation field, to assess the available energy transferred to these teleconnections. Using this methodology, we found that relative to our Modern Control experiments, weaker atmospheric teleconnections prevail under warm Pliocene conditions, although pathways of propagation still appear directed toward the southwestern United States from our tropical Pacific sector forcing. Propagation directly emanating from the Indian Ocean forcing sector appears to be largely blocked, although indirect teleconnective pathways appear traversing the Asian continent toward the North Pacific. The changes in the atmospheric circulation of Indian Ocean region in response to the underlying specified SST forcing (and indicated by Pliocene paleo-data) may have a host of implications for energy transfer out of and into the region, including interactions with the Asian jet stream and changes to the seasonal monsoon cycle. These interactions warrant further study in both past and future warm climate scenarios.     

The COVID-19 pandemic and global environmental change: Emerging research needs

The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.     

Disequilibrium response of permafrost in boreal continental western Canada to climate change

In the boreal forest of continental western Canada, permafrost is restricted toSphagnum-dominated peatlands on which air photo interpretation reveals the occurrence of five types of surface physiography. Concentrated in the northern part of the boreal forest, permafrost is present in peat plateaus with and without collapse scars. In the southern part of the boreal forest, continental bogs dominate, representing ombrotrophic peatlands that have never contained permafrost. In the midboreal zone, internal lawns are present in bogs and in fens. These internal lawns do not presently contain permafrost but did in the recent past, representing degradation of permafrost since the Little Ice Age. Evaluation of the distribution of these peat landforms indicates that today 30% of bogs contain permafrost at the –0.4 °C isotherm and 50% of bogs contain permafrost at the –1.2 °C isotherm, whereas in the past, 30% of bogs contained permafrost at the –1.4 °C isotherm and 50% of bogs contained permafrost at the –2.3 °C isotherm. Although spatial degradation has occurred with a shifting of permafrost northwards in response to warming since the Little Ice Age, permafrost cover has increased in any given area where present-day temperatures are between 0.5 and –3.5 °C.