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Carbon budget

Nadine Mengis, Antti-Ilari Partanen, Jonathan Jalbert, H Damon Matthews
Estimates of the 1.5 °C carbon budget vary widely among recent studies, emphasizing the need to better understand and quantify key sources of uncertainty. Here we quantify the impact of carbon cycle uncertainty and non-CO2 forcing on the 1.5 °C carbon budget in the context of a prescribed 1.5 °C temperature stabilization scenario. We use Bayes theorem to weight members of a perturbed parameter ensemble with varying land and ocean carbon uptake, to derive an estimate for the fossil fuel (FF) carbon budget of 469 PgC since 1850, with a 95% likelihood range of (411,528) PgC...
April 11, 2018: Scientific Reports
Xiaolong Yao, Yunlin Zhang, Lu Zhang, Yongqiang Zhou
The global application of nitrogen is far greater than phosphorus, and it is widely involved in the eutrophication of lakes and reservoirs. We used a bibliometric method to quantitatively and qualitatively evaluate nitrogen research in eutrophic lakes and reservoirs to reveal research developments, current research hotspots, and emerging trends in this area. A total of 2695 articles in the past 25years from the online database of the Scientific Citation Index Expended (SCI-Expanded) were analyzed. Articles in this area increased exponentially from 1991 to 2015...
April 2018: Journal of Environmental Sciences (China)
Chao Guan, Xinrong Li, Peng Zhang, Yongle Chen
Soil respiration induced by biological soil crusts (BSCs) is an important process in the carbon (C) cycle in arid and semi-arid ecosystems, where vascular plants are restricted by the harsh environment, particularly the limited soil moisture. However, the interaction between temperature and soil respiration remains uncertain because of the number of factors that control soil respiration, including temperature and soil moisture, especially in BSC-dominated areas. In this study, the soil respiration in moss-dominated crusts and lichen-dominated crusts was continuously measured using an automated soil respiration system over a one-year period from November 2015 to October 2016 in the Shapotou region of the Tengger Desert, northern China...
2018: PloS One
Qiqi Sun, Rui Wang, Yaxian Hu, Lunguang Yao, Shengli Guo
The spatial heterogeneity of soil respiration and its temperature sensitivity pose a great challenge to accurately estimate the carbon flux in global carbon cycling, which has primarily been researched in flatlands versus hillslope ecosystems. On an eroded slope (35°) of the semiarid Loess Plateau, soil respiration, soil moisture and soil temperature were measured in situ at upper and lower slope positions in triplicate from 2014 until 2016, and the soil biochemical and microbial properties were determined...
2018: PloS One
B Z Houlton, S L Morford, R A Dahlgren
Nitrogen availability is a pivotal control on terrestrial carbon sequestration and global climate change. Historical and contemporary views assume that nitrogen enters Earth's land-surface ecosystems from the atmosphere. Here we demonstrate that bedrock is a nitrogen source that rivals atmospheric nitrogen inputs across major sectors of the global terrestrial environment. Evidence drawn from the planet's nitrogen balance, geochemical proxies, and our spatial weathering model reveal that ~19 to 31 teragrams of nitrogen are mobilized from near-surface rocks annually...
April 6, 2018: Science
Maximilian Andreas Storz
With Earth Overshoot Day having recently passed, there is no space for complacency regarding taking care of our planet. On August 2, 2017, humanity used nature's resource budget for the entire year. For decades, we have lived far beyond our means by overexploiting natural resources and spewing pollution, such as microplastics and industrial chemicals, into our environment. On the other hand, public awareness of human-induced climate change has also increased since the 1980s. The frequent media coverage about extreme weather conditions and natural disasters, such as Hurricane Irma in 2017, serves as an important reminder that anthropogenic climate change is happening now...
March 12, 2018: Permanente Journal
Jason A Lowe, Daniel Bernie
A number of studies have examined the size of the allowable global cumulative carbon budget compatible with limiting twenty-first century global average temperature rise to below 2°C and below 1.5°C relative to pre-industrial levels. These estimates of cumulative emissions have a number of uncertainties including those associated with the climate sensitivity and the global carbon cycle. Although the IPCC fifth assessment report contained information on a range of Earth system feedbacks, such as carbon released by thawing of permafrost or methane production by wetlands as a result of climate change, the impact of many of these Earth system processes on the allowable carbon budgets remains to be quantified...
May 13, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Elmar Kriegler, Gunnar Luderer, Nico Bauer, Lavinia Baumstark, Shinichiro Fujimori, Alexander Popp, Joeri Rogelj, Jessica Strefler, Detlef P van Vuuren
We explore the feasibility of limiting global warming to 1.5°C without overshoot and without the deployment of carbon dioxide removal (CDR) technologies. For this purpose, we perform a sensitivity analysis of four generic emissions reduction measures to identify a lower bound on future CO2 emissions from fossil fuel combustion and industrial processes. Final energy demand reductions and electrification of energy end uses as well as decarbonization of electricity and non-electric energy supply are all considered...
May 13, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Eduardo Leorri, Andrew R Zimmerman, Siddhartha Mitra, Robert R Christian, Francisco Fatela, David J Mallinson
The age and ability of salt marshes to accumulate and sequester carbon is often assessed using the carbon isotopic signatures (Δ14 C and δ13 C) of sedimentary organic matter. However, transfers of allochthonous refractory carbon (CRF ) from the watershed to marshes would not represent new C sequestration. To better understand how refractory carbon (CRF ) inputs affect assessments of marsh age and C sequestration, Δ14 C and δ13 C of both total organic carbon (TOC), CRF , and non-CRF organic matter fractions were measured in salt marshes from four contrasting systems on the North Atlantic coast...
March 23, 2018: Science of the Total Environment
Fulin Yang, Rafat Qubaja, Fyodor Tatarinov, Eyal Rotenberg, Dan Yakir
Carbonyl sulfide (COS) is a tracer of ecosystem photosynthesis that can advance carbon cycle research from leaf to global scales; however, a range of newly reported caveats related to sink/source strength of various ecosystem components hinder its application. Using comprehensive eddy-covariance and chamber measurements, we systematically measure ecosystem contributions from leaf, stem, soil and litter and were able to close the ecosystem COS budget. The relative contributions of non-photosynthetic components to the overall canopy-scale flux are relatively small (~4% during peak activity season) and can be independently estimated based on their responses to temperature and humidity...
March 25, 2018: Global Change Biology
James K H Fang, Christine H L Schönberg, Matheus A Mello-Athayde, Michelle Achlatis, Ove Hoegh-Guldberg, Sophie Dove
The bioeroding sponge Cliona orientalis is photosymbiotic with dinoflagellates of the genus Symbiodinium and is pervasive on the Great Barrier Reef. We investigated how C. orientalis responded to past and future ocean conditions in a simulated community setting. The experiment lasted over an Austral summer under four carbon dioxide emission scenarios: a pre-industrial scenario (PI), a present-day scenario (PD; control), and two future scenarios of combined ocean acidification and ocean warming, i.e., B1 (intermediate) and A1FI (extreme)...
March 24, 2018: Oecologia
Jeonghyun Kim, Hyung-Mi Cho, Guebuem Kim
Fluorescent dissolved organic matter (FDOM) is important for marine organisms and the global carbon cycle contributing to the optical properties of surface seawater and organic carbon budgets. Rivers are known to be the main source of FDOM in coastal oceans and marginal seas. In this study, however, we show that the contribution of FDOM produced from organic sediments of the northwestern Pacific continental shelf is similar to that from the Changjiang River. FDOM showed relatively higher concentrations at stations off the Changjiang River mouth and in the central Yellow Sea...
March 20, 2018: Scientific Reports
Marco Giovanni Malusà, Maria Luce Frezzotti, Simona Ferrando, Enrico Brandmayr, Fabio Romanelli, Giuliano Francesco Panza
The long-term carbon budget has major implications for Earth's climate and biosphere, but the balance between carbon sequestration during subduction, and outgassing by volcanism is still poorly known. Although carbon-rich fluid inclusions and minerals are described in exhumed mantle rocks and xenoliths, compelling geophysical evidence of large-scale carbon storage in the upper mantle is still lacking. Here, we use a geophysical surface-wave seismic tomography model of the mantle wedge above the subducted European slab to document a prominent shear-wave low-velocity anomaly at depths greater than 180 km...
March 16, 2018: Scientific Reports
Adrien Jacotot, Cyril Marchand, Michel Allenbach
We performed a preliminary study to quantify CO2 and CH4 emissions from the water column within a Rhizophora spp. mangrove forest. Mean CO2 and CH4 emissions during the studied period were 3.35±3.62mmolCm-2 h-1 and 18.30±27.72μmolCm-2 h-1 , respectively. CO2 and CH4 emissions were highly variable and mainly driven by tides (flow/ebb, water column thickness, neap/spring). Indeed, an inverse relationship between the magnitude of the emissions and the thickness of the water column above the mangrove soil was observed...
March 8, 2018: Science of the Total Environment
Franco Tassi, Stefano Fazi, Simona Rossetti, Paolo Pratesi, Marco Ceccotti, Jacopo Cabassi, Francesco Capecchiacci, Stefania Venturi, Orlando Vaselli
Volcanic lakes are characterized by physicochemical favorable conditions for the development of reservoirs of C-bearing greenhouse gases that can be dispersed to air during occasional rollover events. By combining a microbiological and geochemical approach, we showed that the chemistry of the CO2- and CH4-rich gas reservoir hosted within the meromictic Lake Averno (Campi Flegrei, southern Italy) are related to the microbial niche differentiation along the vertical water column. The simultaneous occurrence of diverse functional groups of microbes operating under different conditions suggests that these habitats harbor complex microbial consortia that impact on the production and consumption of greenhouse gases...
2018: PloS One
Sergio Contreras, Josef P Werne, A Araneda, R Urrutia, C A Conejero
Paleolimnological studies in western South America, where meteorological stations are scarce, are critical to obtain more realistic and reliable regional reconstructions of past climate and environmental changes, including vegetation and water budget variability. However, climate and environmental geochemical indicators must be tested before they can be applied with confidence. Here we present a survey of lacustrine surface sediment (core top, 0 to ~1cm) biogeochemical proxies (total organic carbon [TOC], total nitrogen [TN], carbon/nitrogen ratio [C/N ratio] and bulk organic δ13 C and total δ15 N) from a suite of 72 lakes spanning the transition from a Mediterranean climate with a patchwork of cultivated vegetation, pastureland, and conifers in central Chile to a rainy temperate climate dominated by broadleaf deciduous and evergreen forest further south...
February 27, 2018: Science of the Total Environment
Laura Freije-Carrelo, Laura Alonso Sobrado, Mariella Moldovan, Jorge Ruiz Encinar, Jose Ignacio Garcia-Alonso
Dissolved inorganic carbon (DIC) is one of the most important parameters to be measured in seawaters for climate change studies. Its quantitative assessment requires analytical methodologies with overall uncertainties around 0.05% RSD for clear evaluation of temporal trends. Herein, two alternative Isotope Dilution Mass Spectrometry (IDMS) methodologies (on-line and species-specific) using an Isotope Ratio Mass Spectrometer (IRMS) and two calculation procedures for each methodology have been compared. As a result, a new method for the determination of DIC in seawaters, based on species-specific IDMS with Isotope Pattern Deconvolution calculation, was developed and validated...
March 2, 2018: Analytical Chemistry
Tao Bao, Renbin Zhu, Pei Wang, Wenjuan Ye, Dawei Ma, Hua Xu
Stratospheric ozone has begun to recover in Antarctica since the implementation of the Montreal Protocol. However, the effects of ultraviolet (UV) radiation on tundra greenhouse gas fluxes are rarely reported for Polar Regions. In the present study, tundra N2 O and CH4 fluxes were measured under the simulated reduction of UV radiation in maritime Antarctica over the last three-year summers. Significantly enhanced N2 O and CH4 emissions occurred at tundra sites under the simulated reduction of UV radiation. Compared with the ambient normal UV level, a 20% reduction in UV radiation increased tundra emissions by an average of 8 μg N2 O m-2 h-1 and 93 μg CH4 m-2 h-1 , whereas a 50% reduction in UV radiation increased their emissions by an average of 17 μg N2 O m-2 h-1 and 128 μg CH4 m-2 h-1 ...
February 27, 2018: Scientific Reports
Blake L Spady, Philip L Munday, Sue-Ann Watson
There is increasing evidence that projected near-future carbon dioxide (CO2 ) levels can alter predator avoidance behaviour in marine invertebrates, yet little is known about the possible effects on predatory behaviours. Here we tested the effects of elevated CO2 on the predatory behaviours of two ecologically distinct cephalopod species, the pygmy squid, Idiosepius pygmaeus, and the bigfin reef squid, Sepioteuthis lessoniana. Both species exhibited an increased latency to attack and altered body-pattern choice during the attack sequence at elevated CO2 ...
February 20, 2018: Global Change Biology
Lei Wu, Xian Wu, Shan Lin, Yupeng Wu, Shuirong Tang, Minghua Zhou, Muhammad Shaaban, Jinsong Zhao, Ronggui Hu, Yakov Kuzyakov, Jinshui Wu
Rice paddy conversion to vegetable production is a common agricultural practice driven by economic benefits and shifting diets. However, little is known on the initial effects of this land-use conversion on net ecosystem carbon budget (NECB) and greenhouse gas (GHG) balance. Annual NECB and emissions of CH4 and N2O were measured from a native double rice cropping system (Rice) and a vegetable field recently converted from rice paddy (Veg) under no nitrogen (N) fertilization (Rice-N0 and Veg-N0) and conventional N fertilization (Rice-N+ and Veg-N+) during the initial four years upon conversion in subtropical China...
January 27, 2018: Science of the Total Environment
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