An investigation into linearity with cumulative emissions of the climate and carbon cycle response in HadCM3LC

We investigate the extent to which global mean temperature, precipitation, and the carbon cycle are constrained by cumulative carbon emissions throughout four experiments with a fully coupled climate-carbon cycle model. The two paired experiments adopt contrasting, idealised approaches to climate change mitigation at different action points this century, with total emissions exceeding two trillion tonnes of carbon in the later pair. Their initially diverging cumulative emissions trajectories cross after several decades, before diverging again. We find that their global mean temperatures are, to first order, linear with cumulative emissions, though regional differences in temperature of up to 1.5K exist when cumulative emissions of each pair coincide. Interestingly, although the oceanic precipitation response scales with cumulative emissions, the global precipitation response does not, due to a decrease in precipitation over land above cumulative emissions of around one trillion tonnes of carbon (TtC). Most carbon fluxes and stores are less well constrained by cumulative emissions as they reach two trillion tonnes. The opposing mitigation approaches have different consequences for the Amazon rainforest, which affects the linearity with which the carbon cycle responds to cumulative emissions. Averaged over the two fixed-emissions experiments, the transient response to cumulative carbon emissions (TCRE) is 1.95 K TtC-1, at the upper end of the IPCC’s range of 0.8-2.5 K TtC-1

A synergistic and extensible framework for multi-agent system verification

Recently there has been a proliferation of tools and languages for modeling multi-agent systems (MAS). Verification tools, correspondingly, have been developed to check properties of these systems. Most MAS verification tools, however, have their own input language and often specialize in one verification technology, or only support checking a specific type of property. In this work we present an extensible framework that leverages mainstream verification tools to successfully reason about various types of properties. We describe the verification of models specified in the Brahms agent modeling language to demonstrate the feasibility of our approach. We chose Brahms because it is used to model real instances of interactions between pilots, air-traffic controllers, and automated systems at NASA. Our framework takes as input a Brahms model along with a Java implementation of its semantics. We then use Java PathFinder to explore all possible behaviors of the model and, also, produce a generalized intermediate representation that encodes these behaviors. The intermediate representation is automatically transformed to the input language of mainstream model checkers, including PRISM, SPIN, and NuSMV allowing us to check different types of properties. We validate our approach on a model that contains key elements from the Air France Flight 447 acciden

The influence of ocean variations on the climate of Ireland

The influence of the ocean circulation on the climate of Ireland is more subtle than it first appears. Temperatures in Ireland are warmer than similar Pacific maritime climates. It is heat - carried primarily in the Atlantic overturning circulation - released over the Atlantic that provides this additional warmth. We investigate variations in Irish climate using long-term station-based time series. The Atlantic multidecadal oscillation (AMO) explains over 90% of the pronounced decadal temperature and summer precipitation variation. Understanding the impact of these ocean variations when interpreting long climate records, particularly in the context of a changing climate, is crucial

Increased seawater temperature increases the abundance and alters the structure of natural Vibrio populations associated with the coral Pocillopora damicornis.

Rising seawater temperature associated with global climate change is a significant threat to coral health and is linked to increasing coral disease and pathogen-related bleaching events. We performed heat stress experiments with the coral Pocillopora damicornis, where temperature was increased to 31°C, consistent with the 2-3°C predicted increase in summer sea surface maxima. 16S rRNA amplicon sequencing revealed a large shift in the composition of the bacterial community at 31°C, with a notable increase in Vibrio, including known coral pathogens. To investigate the dynamics of the naturally occurring Vibrio community, we performed quantitative PCR targeting (i) the whole Vibrio community and (ii) the coral pathogen Vibrio coralliilyticus. At 31°C, Vibrio abundance increased by 2-3 orders of magnitude and V. coralliilyticus abundance increased by four orders of magnitude. Using a Vibrio-specific amplicon sequencing assay, we further demonstrated that the community composition shifted dramatically as a consequence of heat stress, with significant increases in the relative abundance of known coral pathogens. Our findings provide quantitative evidence that the abundance of potential coral pathogens increases within natural communities of coral-associated microbes as a consequence of rising seawater temperature and highlight the potential negative impacts of anthropogenic climate change on coral reef ecosystems

The carbon cycle in Mexico: past, present and future of C stocks and fluxes

PublishedThe Supplement related to this article is available online at doi:10.5194/bg-13-223-2016-supplement.We modeled the carbon (C) cycle in Mexico with a process-based approach. We used different available products (satellite data, field measurements, models and flux towers) to estimate C stocks and fluxes in the country at three different time frames: present (defined as the period 2000–2005), the past century (1901–2000) and the remainder of this century (2010–2100). Our estimate of the gross primary productivity (GPP) for the country was 2137 ± 1023 TgC yr−1 and a total C stock of 34 506 ± 7483 TgC, with 20 347 ± 4622 TgC in vegetation and 14 159 ± 3861 in the soil. Contrary to other current estimates for recent decades, our results showed that Mexico was a C sink over the period 1990–2009 (+31 TgC yr−1) and that C accumulation over the last century amounted to 1210 ± 1040 TgC. We attributed this sink to the CO2 fertilization effect on GPP, which led to an increase of 3408 ± 1060 TgC, while both climate and land use reduced the country C stocks by −458 ± 1001 and −1740 ± 878 TgC, respectively. Under different future scenarios, the C sink will likely continue over the 21st century, with decreasing C uptake as the climate forcing becomes more extreme. Our work provides valuable insights on relevant driving processes of the C cycle such as the role of drought in drylands (e.g., grasslands and shrublands) and the impact of climate change on the mean residence time of soil C in tropical ecosystems.The lead author (G. Murray-Tortarolo) thanks CONACYT-CECTI, the University of Exeter and Secretaría de Educación Pública (SEP) for their funding of this project. The authors extend their thanks to Carlos Ortiz Solorio and to the Colegio de Posgraduados for the field soil data and to the Alianza Redd+ Mexico for the field biomass data. This project would not have been possible without the valuable data from the CMIP5 models. A. Arneth, G. Murray-Tortarolo, A. Wiltshire and S. Sitch acknowledge the support of the European Commission-funded project LULCC4C (grant no. 603542). A. Wiltshire was partsupported by the Joint UK DECC/Defra Met Office Hadley Centre Climate Programme (GA01101)

Acute Hypernatrem ia Increases Functional Connectivity Between the SFO and OVLT: Time Course of the Response

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A new approach to bulk viscosity in strange quark matter at high densities

A new method is proposed to compute the bulk viscosity in strange quark matter at high densities. Using the method it is straightforward to prove that the bulk viscosity is positive definite, which is not so easy to accomplish in other approaches especially for multi-component fluids like strange quark matter with light up and down quarks and massive strange quarks.Comment: 7pages, talk given in SQM2008. Minor revisions, including clarification and updated reference