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CO2 Increase (co2 + increase)
Selected AbstractsResponses of global plant diversity capacity to changes in carbon dioxide concentration and climateECOLOGY LETTERS, Issue 11 2008F. I. Woodward Abstract We model plant species diversity globally by country to show that future plant diversity capacity has a strong dependence on changing climate and carbon dioxide concentration. CO2 increase, through its impact on net primary production and warming is predicted to increase regional diversity capacity, while warming with constant CO2 leads to decreases in diversity capacity. Increased CO2 concentrations are unlikely to counter projected extinctions of endemic species, shown in earlier studies to be more strongly dependent on changing land use patterns than climate per se. Model predictions were tested against (1) contemporary observations of tree species diversity in different biomes, (2) an independent global map of contemporary species diversity and (3) time sequences of plant naturalisation for different locations. Good agreements between model, observations and naturalisation patterns support the suggestion that future diversity capacity increases are likely to be filled from a ,cosmopolitan weed pool' for which migration appears to be an insignificant barrier. [source] Role of land cover changes for atmospheric CO2 increase and climate change during the last 150 yearsGLOBAL CHANGE BIOLOGY, Issue 8 2004Victor Brovkin Abstract We assess the role of changing natural (volcanic, aerosol, insolation) and anthropogenic (CO2 emissions, land cover) forcings on the global climate system over the last 150 years using an earth system model of intermediate complexity, CLIMBER-2. We apply several datasets of historical land-use reconstructions: the cropland dataset by Ramankutty & Foley (1999) (R&F), the HYDE land cover dataset of Klein Goldewijk (2001), and the land-use emissions data from Houghton & Hackler (2002). Comparison between the simulated and observed temporal evolution of atmospheric CO2 and ,13CO2 are used to evaluate these datasets. To check model uncertainty, CLIMBER-2 was coupled to the more complex Lund,Potsdam,Jena (LPJ) dynamic global vegetation model. In simulation with R&F dataset, biogeophysical mechanisms due to land cover changes tend to decrease global air temperature by 0.26°C, while biogeochemical mechanisms act to warm the climate by 0.18°C. The net effect on climate is negligible on a global scale, but pronounced over the land in the temperate and high northern latitudes where a cooling due to an increase in land surface albedo offsets the warming due to land-use CO2 emissions. Land cover changes led to estimated increases in atmospheric CO2 of between 22 and 43 ppmv. Over the entire period 1800,2000, simulated ,13CO2 with HYDE compares most favourably with ice core during 1850,1950 and Cape Grim data, indicating preference of earlier land clearance in HYDE over R&F. In relative terms, land cover forcing corresponds to 25,49% of the observed growth in atmospheric CO2. This contribution declined from 36,60% during 1850,1960 to 4,35% during 1960,2000. CLIMBER-2-LPJ simulates the land cover contribution to atmospheric CO2 growth to decrease from 68% during 1900,1960 to 12% in the 1980s. Overall, our simulations show a decline in the relative role of land cover changes for atmospheric CO2 increase during the last 150 years. [source] Simulated changes in active/break spells during the Indian summer monsoon due to enhanced CO2 concentrations: assessment from selected coupled atmosphere,ocean global climate modelsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2007Sujata K. Mandke Abstract The simulations by ten coupled GCMs under the Intergovernmental Panel on Climate Change Assessment Report-4 are used to study the implication of possible global climate change on active/break spells of the Indian summer monsoon (ISM). The validation of the mean daily cycle of the summer monsoon precipitation over the Indian core region and the spatial pattern of the ISM precipitation climatology with observation suggest that six models simulate fairly well, whereas four models differ from observation. Thus, the identification of active/break spells is confined to six models. The sensitivity to climate change has been assessed from two experiments, namely, 1% per year CO2 increase to doubling and 1% per year CO2 increase to quadrupling. The changes in the daily mean cycle and the standard deviation of precipitation, frequency, and duration of active/break spells in future climate change are uncertain among the models and at times among two experiments. The break composite precipitation anomalies strengthen and spread moderately (significantly) in the doubled (quadrupled) CO2 experiment. Copyright © 2006 Royal Meteorological Society [source] Recalcitrant soil organic materials mineralize more efficiently at higher temperaturesJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2003Roland Bol Abstract As concentrations of atmospheric CO2 increase, it is important to know whether this may result in feedbacks that could modify the rate of increase of CO2 in the atmosphere. Soil organic matter (SOM) represents one of the largest pools of C and mineralization rates are known to be temperature dependent. In this study, we investigated whether different OM fractions present in a forest soil (F/A1 horizon) would respond in a similar manner to elevated temperatures. We examined the trends in isotopic content (12C, 13C, and 14C) of soil respired CO2 at various temperatures (10, 20, and 35 0C) over a two year period in the laboratory. We also examined the total C, total N, and C,:,N ratio in the remaining soil and isolated humic fractions, and the distribution of the individual amino acids in the soil after 5 years of laboratory incubation at the various temperatures. We found that the rate at which C mineralization increases with temperature was occasionally greater than predicted by most models, more C from recalcitrant OM pools being mineralized at the higher temperature. This confirmed that the relationship between soil organic matter decomposition and temperature was complex and that the different pools of organic matter did respond in differing ways to elevated temperatures. Rekalizitrante organische Bodensubstanz mineralisiert bei höheren Temperaturen effizienter Vor dem Hintergrund ansteigender atmosphärischer CO2 -Konzentrationen gewinnt die Erforschung möglicher Rückkopplungs-Mechanismen zunehmend an Bedeutung. Die organische Bodensubstanz stellt eines der größten terrestrischen C-Reservoirs dar. Die Rate der C-Mineralisation aus der organischen Bodensubstanz gilt allgemein als temperaturabhängig. In der hier vorgestellten Untersuchung sollte geprüft werden, ob verschiedene Fraktionen der organischen Bodensubstanz eines Waldstandortes (F/A1-Horizont) ähnlich stark auf erhöhte Temperaturen reagieren. Über einen Zeitraum von zwei Jahren wurde unter Laborbedingungen die Veränderung der Isotopen-Gehalte (12C, 13C und 14C) des bei verschiedenen Temperaturen (10, 20 und 35 °C) inkubierten Bodens untersucht. Ebenfalls erfasst wurden Gesamt-C, Gesamt-N und C,:,N-Verhältnis im Gesamt-Boden und in isolierten Humus-Fraktionen sowie das Verteilungsmuster der Aminosäuren im Boden nach fünfjähriger Inkubationsdauer. Die Ergebnisse zeigen, dass die temperaturbedingte Erhöhung der Mineralisationsrate in einigen Fällen deutlich stärker ausgeprägt ist, als anhand von Modellberechnungen erwartet wurde. Ursache hierfür ist unter erhöhten Temperaturen intensivere C-Mineralisation aus rekalzitranter organischer Bodensubstanz. Dies bestätigt unsere Vermutung, dass es keinen einfachen Zusammenhang zwischen Mineralisationsrate und Temperatur gibt, da verschiedene Humusbestandteile unterschiedlich auf erhöhte Temperaturen reagieren. [source] Control of internal browning and quality improvement of ,Fuji' apples by stepwise increase of CO2 level during controlled atmosphere storageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2005Hun-Sik Chung Abstract To control internal browning injury and to reduce quality loss in ,Fuji' apples during storage, a stepwise controlled atmosphere (CA) method was applied in this study. Both non-bagged and bagged apples during maturation were stored at 0 °C under 1% O2 + 1% CO2, 1% O2 + 3% CO2 or air for 10 months, and 1% O2 + 1% CO2 for 2 months followed by 1% O2 + 3% CO2 for 8 months (stepwise CA). The concentrations of internal ethylene and carbon dioxide in apples kept for 24 h at 20 °C after storage under CA conditions were maintained at low level, but there was no effect of stepwise CO2 increase on internal gas concentrations. The non-bagged and bagged apples stored under stepwise CA were not significantly different from those stored under 1% O2 + 3% CO2 continuously for 10 months in term of flesh firmness, titratable acidity and yellowing index. However, the apples stored under stepwise CA were firmer, more acid and greener than those stored under 1% O2 + 1% CO2 continuously for 10 months. Internal browning injury occurred in apples stored under 1% O2 + 3% CO2 continuously for 10 months, but it was suppressed completely by stepwise CA storage. The stepwise CA, increasing of CO2 level after holding at 1% CO2 for the first 2 months of storage, was effective in maintaining the quality and controlling the internal browning injury in non-bagged and bagged ,Fuji' apples. Copyright © 2005 Society of Chemical Industry [source] An example of the dependence of the transient climate response on the temperature of the modelled climate stateATMOSPHERIC SCIENCE LETTERS, Issue 1 2009Chris M. Brierley Abstract The range in absolute global mean surface temperature projected with a small, perturbed ocean physics ensemble reduces as the levels of CO2 increase. The initial temperature state of an ensemble member is correlated to the amount of global warming seen in that member. The correlation arises, in approximately equal amounts, by variations in the ocean heat uptake within the ensemble and a dependency of the strength of the atmosphere,surface climate feedbacks on the initial climate. This relationship provides a clear warning that some uncertainty in global change projections derives from the simulation of the mean state. Copyright © 2008 Royal Meteorological Society and Crown Copyright [source] A refined technique for determining the respiratory gas exchange responses to anaerobic metabolism during progressive exercise , repeatability in a group of healthy menCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2004Anita G. M. Wisén Summary The respiratory gas exchange and ventilation during an incremental cycle exercise test were analysed in a group of 19 healthy, moderately fit men. Different computer algorithms were used to estimate the V,O2 values where: (i) the rate of V,CO2 increase just exceeds the rate of V,O2 increase (DX, derivative crossing), (ii) V,CO2/V,O2 = 1·00 (PX, point of crossing) and (iii) ventilation (V,E) increases disproportionately in relation to V,CO2 (PQ, point of V,CO2 equivalent rise). The DX and PQ measurements were analysed using a new approach employing polynomial regression and the value of PX was determined following low-pass filtration of raw data. The repeatability of the measurements was evaluated with a 5,6 week interval between the tests. The correlations between tests were 0·75 at DX, 0·85 at PX and 0·62 at PQ. The mean differences between the repeated tests were not statistically significant. The repeatability of V,O2, in absolute values expressed as ±2 SD of the differences between the tests, had values of 5·0, 6·1 and 9·5 ml min,1 kg,1 for DX, PX and PQ, respectively. The mean value of V,O2 for each measurement point expressed as a percentage of V,O2max was 54% at DX, 68% at PX and 70% at PQ. The most common sequence of the measured values was DX < PX < PQ, but the sequence DX < PQ < PX was also observed. It is concluded that the gas exchange responses to developing anaerobic metabolism during progressive exercise can be characterized by a series of thresholds. However, the considerable variation in absolute values in the two testing occasions requires further attention. [source] | |||||||||||||