Interhemispheric effect of global geography on Earth's climate response to orbital forcing

The climate response of the Earth to orbital forcing shows a distinct hemispheric asymmetry due to the unequal distribution of land in the Northern Hemisphere versus Southern Hemisphere. This asymmetry is examined using a global climate model (GCM) for different climate responses such as mean summer temperatures and positive degree days. A land asymmetry effect (LAE) is quantified for each hemisphere and the results show how changes in obliquity and precession translate into variations in the calculated LAE. We find that the global climate response to specific past orbits is likely unique and modified by complex climate–ocean–cryosphere interactions that remain poorly known. Nonetheless, these results provide a baseline for interpreting contemporaneous proxy climate data spanning a broad range of latitudes, which may be useful in paleoclimate data–model comparisons, and individual time-continuous records exhibiting orbital cyclicity.</p

The role of salinity in circulation of the Cretaceous ocean

The density of seawater is a complex function of temperature, salinity, and pressure. Because of the non-linearity of the equation of state of seawater, the densities of sea waters having the same temperature and the same salinity differences (with respect to the mean salinity of the ocean) will vary with the mean salinity of the ocean. Although this strange property of seawater is evident in a plot of the equation of state, it has never been considered in trying to reconstruct ancient ocean circulation. These differences in the density field may have caused the ocean to respond differently to atmospheric forcing in the past. The different response may hold the key to understanding "ocean anoxic events" and episodes of large-scale burial of organic carbon and production of petroleum source rocks

Pliocene Model Intercomparison Project Experiment 1: implementation strategy and mid-Pliocene global climatology using GENESIS v3.0 GCM

The mid-Pliocene Warm Period (3.29 to 2.97 Ma BP) has been identified as an analogue for the future, with the potential to help understand climate processes in a warmer than modern world. Sets of climate proxies, combined to provide boundary conditions for Global Climate Model (GCM) simulations of the mid-Pliocene, form the basis for the international, data-driven Pliocene Model Intercomparison Project (PlioMIP). Here, we outline the strategy for implementing pre-industrial (modern) and mid-Pliocene forcings and boundary conditions into the GENESIS version 3 GCM, as part of PlioMIP. We describe the prescription of greenhouse gas concentrations and orbital parameters and the implementation of geographic boundary conditions such as land-ice-sea distribution, topography, sea surface temperatures, sea ice extent, vegetation, soils, and ice sheets. We further describe model-specific details including spin-up and integration times. In addition, the global climatology of the mid-Pliocene as simulated by the GENESIS v3 GCM is analyzed and compared to the pre-industrial control simulation. The simulated climate of the mid-Pliocene warm interval is found to differ considerably from pre-industrial. We identify model sensitivity to imposed forcings, and internal feedbacks that collectively affect both local and far-field responses. Our analysis points out the need to assess both the direct impacts of external forcings and the combined effects of indirect, internal feedbacks. This paper provides the basis for assessing model biases within the PlioMIP framework, and will be useful for comparisons with other studies of mid-Pliocene climates

A continuum model (PSUMEL1) of ice mélange and its role during retreat of the Antarctic Ice Sheet

Rapidly retreating thick ice fronts can generate large amounts of mélange (floating ice debris), which may affect episodes of rapid retreat of Antarctic marine ice. In modern Greenland fjords, mélange provides substantial back pressure on calving ice faces, which slows ice front calving rates. On the much larger scales of West Antarctica, it is unknown if mélange could clog seaways and provide enough back pressure to act as a negative feedback slowing retreat. Here we describe a new mélange model, using a continuum-mechanical formulation that is computationally feasible for long-term continental Antarctic applications. It is tested in an idealized rectangular channel and calibrated very basically using observed modern conditions in Jakobshavn fjord, West Greenland. The model is then applied to drastic retreat of Antarctic ice in response to warm mid-Pliocene climate. With mélange parameter values that yield reasonable modern Jakobshavn results, Antarctic marine ice still retreats drastically in the Pliocene simulations, with little slowdown despite the huge amounts of mélange generated. This holds both for the rapid early collapse of West Antarctica and for later retreat into major East Antarctic basins. If parameter values are changed to make the mélange much more resistive to flow, far outside the range for reasonable Jakobshavn results, West Antarctica still collapses and retreat is slowed or prevented only in a few East Antarctic basins.</p

Antarctic bedrock topography uncertainty and ice sheet stability

All Rights Reserved. Antarctic bedrock elevation estimates have uncertainties exceeding 1km in certain regions. Bedrock elevation, particularly where the bedrock is below sea level and bordering the ocean, can have a large impact on ice sheet stability. We investigate how present-day bedrock elevation uncertainty affects ice sheet model simulations for a generic past warm period based on the mid-Pliocene, although these uncertainties are also relevant to present-day and future ice sheet stability. We perform an ensemble of simulations with random topographic noise added with various length scales and with amplitudes tuned to the uncertainty of the Bedmap2 data set. Total Antarctic ice sheet retreat in these simulations varies between 12.6 and 17.9m equivalent sea level rise after 3kyrs of warm climate forcing. This study highlights the sensitivity of ice sheet models to existing uncertainties in bedrock elevation and the ongoing need for new data acquisition. Key Points Quantify how Antarctic bed elevation uncertainty affects ice sheet simulations Simulate retreat of the Antarctic ice sheet for a warm Pliocene climate Identify key areas for future improvements to bed elevation data

Sea-level rise due to polar ice-sheet mass loss during past warm periods

Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sea level during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo–sea level records

EXAME GASTROSCÓPICO APÓS ADMINISTRAÇÃO ORAL DE ANTI-INFLAMATÓRIOS NÃO ESTEROIDAIS EM CÃES

O objetivo deste estudo foi o de avaliar os efeitos gástricos decorrentes da administração oral do carprofeno e vedaprofeno em cães. Para isso, 21 cães foram divididos aleatoriamente em 3 grupos (n=7). O Grupo I, recebeu a dose terapêutica de 2,2 mg/kg de carprofeno oral; o Grupo II recebeu vedaprofeno via oral, na dose terapêutica de 0,5 mg/kg, e ao Grupo III foi administrado placebo via oral, com intervalos entre doses de 12 em 12 horas, durante 30 dias consecutivos. Os cães foram submetidos a endoscopia gástrica antes da administração dos medicamentos, 10 e 30 dias após o início do tratamento. Foram avaliados, diariamente, quanto às alterações de comportamento e exames físicos. Concluise que o carprofeno e o vedaprofeno, podem ser administrados via oral, em dose terapêutica, durante o período de 30 dias consecutivos, causando mínimas alterações gástricas em cães. Gastroscopic examination after oral administration of non steroids antiinflammatory in dogs Abstract An evaluation of the gastric side effects caused by the administration of carpofren and vedaprofen to dogs has been carried out in the present research work. A total of 21 dogs were randomized in 3 groups (n = 7). To Group I carprofen was administered orally at a dose of 2.2mg/kg. To Group II, vedaprofen was administered orally at a dose of 0.5 mg/kg. Group III received a placebo orally. In all three groups, the administration of both the drugs and the placebo took place twice a day, at each 12 hours interval, for a period of 30 days. The animals were then observed for behavioral changes and submitted to physical exams dayly. Following these observations, it was possible to conclude that capofren and vedaprofen could be adminitered orally to dogs, at therapeutic dose rates, for 30 consecutive days, without clinical evidence of side effects in the gastric tract