Spatial and Temporal Variability of Extreme Weather in The United States

As the global climate is influenced by increased warming, the frequency of climate extremes will likely become more variable. The United States Historical Climate Network (USHCN) station data from 1900-2011 is used to quantify trends in daily extreme heat events, daily extreme cold events, and extreme daily precipitation within the contiguous United States. Climate data was spatially aggregated into respective Koeppen-Geiger climate zones where the 3 main zones are; arid, warm temperate and snow. Results show a gain or loss of 20 extreme temperature events and a gain or loss of 4 extreme precipitation events. The arid zone exhibited a loss of extreme minimum temperature a gain of extreme maximum temperature and a mixed result for extreme precipitation. The warm temperate zone indicated that the eastern region follows the exact same temperature trends as the arid zone but exhibits an overall loss of extreme precipitation. The western portion of the warm temperate zone exhibits a loss in extreme temperature events, a gain in extreme minimum temperature events and a gain in extreme precipitation. The trends in the snow zone reveal a mixed signal for extreme maximum temperature, a decline in extreme minimum temperature and a gain in extreme precipitation. Paired t-test results indicate statistically significant shifts in the magnitude of extreme weather events in each of the 3 main climate zones (arid, warm temperate and snow). This spatiotemporal analysis highlights how daily trends in extreme heat, extreme cold, and extreme precipitation have changed in the last 100 years in the context of specific climate zones. In order to understand the impact regional climate has on extreme events, trends in teleconnection patterns were examined in conjunction to daily weather. Teleconnection patterns that directly impact US weather are El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). The use of wavelet analysis, including the continuous wavelet transform, the wavelet cross wavelet transform and the wavelet transform coherence provide insight into the timescales of influence from ENSO and PDO on extreme weather events. The power spectra results from each wavelet analysis have been averaged across Koeppen-Geiger zone. Results indicate that extreme precipitation events have significantly different power spectras than normal events across all timescales. Specific patterns at the annual scale and shorter are found the arid zone for extreme maximum temperature, where results for minimum temperature trends vary

Multiscale Interactions between Water and Carbon Fluxes and Environmental Variables in A Central U.S. Grassland

This is the authors accepted manuscript. The published version can be found here: http://dx.doi.org/10.3390/e15041324.The temporal interactions between water and carbon cycling and the controlling environmental variables are investigated using wavelets and information theory. We used 3.5 years of eddy covariance station observations from an abandoned agricultural field in the central U.S. Time-series of the entropy of water and carbon fluxes exhibit pronounced annual cycles, primarily explained by the modulation of the diurnal flux amplitude by other variables, such as the net radiation. Entropies of soil moisture and precipitation show almost no annual cycle, but the data were collected during above average precipitation years, which limits the role of moisture stress on the resultant fluxes. We also investigated the information contribution to resultant fluxes from selected environmental variables as a function of time-scale using relative entropy. The relative entropy of latent heat flux and ecosystem respiration show that the radiation terms contribute the most information to these fluxes at scales up to the diurnal scale. Vapor pressure deficit and air temperature contribute to the most information for the gross primary productivity and net ecosystem exchange at the daily time-scale. The relative entropy between the fluxes and soil moisture illustrates that soil moisture contributes information at approximately weekly time-scales, while the relative entropy with precipitation contributes information predominantly at the monthly time-scale. The use of information theory metrics is a relatively new technique for assessing biosphere-atmosphere interactions, and this study illustrates the utility of the approach for assessing the dominant time-scales of these interactions

Hydrogenation of Organic Matter as a Terminal Electron Sink Sustains High CO2:CH4 Production Ratios During Anaerobic Decomposition

Once inorganic electron acceptors are depleted, organic matter in anoxic environments decomposes by hydrolysis, fermentation, and methanogenesis, requiring syntrophic interactions between microorganisms to achieve energetic favorability. In this classic anaerobic food chain, methanogenesis represents the terminal electron accepting (TEA) process, ultimately producing equimolar CO2 and CH4 for each molecule of organic matter degraded. However, CO2:CH4 production in Sphagnum-derived, mineral-poor, cellulosic peat often substantially exceeds this 1:1 ratio, even in the absence of measureable inorganic TEAs. Since the oxidation state of C in both cellulose-derived organic matter and acetate is 0, and CO2 has an oxidation state of +4, if CH4 (oxidation state -4) is not produced in equal ratio, then some other compound(s) must balance CO2 production by receiving 4 electrons. Here we present evidence for ubiquitous hydrogenation of diverse unsaturated compounds that appear to serve as organic TEAs in peat, thereby providing the necessary electron balance to sustain CO2:CH4 \u3e1. While organic electron acceptors have previously been proposed to drive microbial respiration of organic matter through the reversible reduction of quinone moieties, the hydrogenation mechanism that we propose, by contrast, reduces C-C double bonds in organic matter thereby serving as 1) a terminal electron sink, 2) a mechanism for degrading complex unsaturated organic molecules, 3) a potential mechanism to regenerate electron-accepting quinones, and, in some cases, 4) a means to alleviate the toxicity of unsaturated aromatic acids. This mechanism for CO2 generation without concomitant CH4 production has the potential to regulate the global warming potential of peatlands by elevating CO2:CH4 production ratios

Exposing the myths of household water insecurity in the global north: A critical review

Safe and secure water is a cornerstone of modern life in the global North. This article critically examines a set of prevalent myths about household water in high-income countries, with a focus on Canada and the United States. Taking a relational approach, we argue that household water insecurity is a product of institutionalized structures and power, manifests unevenly through space and time, and is reproduced in places we tend to assume are the most water-secure in the world. We first briefly introduce “modern water” and the modern infrastructural ideal, a highly influential set of ideas that have shaped household water provision and infrastructure development over the past two centuries. Against this backdrop, we consolidate evidence to disrupt a set of narratives about water in high-income countries: the notion that water access is universal, clean, affordable, trustworthy, and uniformly or equitably governed. We identify five thematic areas of future research to delineate an agenda for advancing scholarship and action—including challenges of legal and regulatory regimes, the housing-water nexus, water affordability, and water quality and contamination. Data gaps underpin the experiences of household water insecurity. Taken together, our review of water security for households in high-income countries provides a conceptual map to direct critical research in this area for the coming years. This article is categorized under: Human Water \u3e Human Water

Soil Metabolome Response to Whole-Ecosystem Warming at the Spruce and Peatland Responses Under Changing Environments Experiment

While peatlands have historically stored massive amounts of soil carbon, warming is expected to enhance decomposition, leading to a positive feedback with climate change. In this study, a unique whole-ecosystem warming experiment was conducted in northern Minnesota to warm peat profiles to 2 m deep while keeping water flow intact. After nearly 2 y, warming enhanced the degradation of soil organic matter and increased greenhouse gas production. Changes in organic matter quality with warming were accompanied by a stimulation of methane production relative to carbon dioxide. Our results revealed increased decomposition to be fueled by the availability of reactive carbon substrates produced by surface vegetation. The elevated rates of methanogenesis are likely to persist and exacerbate climate warming

Persistent Helicobacter pylori Specific Th17 Responses in Patients with Past H. pylori Infection Are Associated with Elevated Gastric Mucosal IL-1β

10.1371/journal.pone.0039199PLoS ONE76