Increased Carbon Dioxide Levels Research Articles

Will intra‐specific differences in transpiration efficiency in wheat be maintained in a high CO2 world? A FACE study

This study evaluates whether the target breeding trait of superior leaf level transpiration efficiency is still appropriate under increasing carbon dioxide levels of a future climate using a semi-arid cropping system as a model. Specifically, we investigated whether physiological traits governing leaf level transpiration efficiency, such as net assimilation rates (A(net)), stomatal conductance (g(s)) or stomatal sensitivity were affected differently between two Triticum aestivum L. cultivars differing in transpiration efficiency (cv. Drysdale, superior; cv. Hartog, low). Plants were grown under Free Air Carbon dioxide Enrichment (FACE, approximately 550 µmol mol⁻¹ or ambient CO₂ concentrations (approximately 390 µmol mol⁻¹). Mean A(net) (approximately 15% increase) and gs (approximately 25% decrease) were less affected by elevated [CO₂] than previously found in FACE-grown wheat (approximately 25% increase and approximately 32% decrease, respectively), potentially reflecting growth in a dry-land cropping system. In contrast to previous FACE studies, analyses of the Ball et al. model revealed an elevated [CO₂] effect on the slope of the linear regression by 12% indicating a decrease in stomatal sensitivity to the combination of [CO₂], photosynthesis rate and humidity. Differences between cultivars indicated greater transpiration efficiency for Drysdale with growth under elevated [CO₂] potentially increasing the response of this trait. This knowledge adds valuable information for crop germplasm improvement for future climates.

Some species tolerate ocean acidification

Increasing carbon dioxide levels lead to rising ocean acidity, which can harm corals and many other species of ocean life. Acidification causes calcium carbonate, which corals usually need to build skeletons, to dissolve. “Every day, ocean acidification is taking up the weight of 6 million midsize cars' worth of carbon, said Nina Keul, a graduate student at the Alfred Wegener Institute for Polar and Marine Research in Germany during a 7 December press conference at the AGU Fall Meeting. Somewhat surprising, though, is that some species are more tolerant of acidic conditions than scientists had expected. For instance, Keul exposed a species of foraminifera, Ammonia tepida, to seawater with varying acidity and varying carbonate ion concentrations. Previous studies had found that foraminifera growth declined with decreasing carbonate levels, but Keul's foraminifera continued to grow in the acidic conditions. She said that the mechanism that allows this species to tolerate the low carbonate conditions is as yet unknown.

Reduced early life growth and survival in a fish in direct response to increased carbon dioxide

Adult fish seem relatively resilient to increased carbon dioxide levels, but how early-life-stage fish fare remains less clear. In a study, the estuarine fish Menidia beryllina experienced severely reduced survival and growth rates in its early life stages under levels of ocean acidification expected later this century. This suggests that ocean acidification may affect fish populations, because small changes in early-life survival can generate large fluctuations in adult-fish abundance.

Novel Wireless Sensor System for Monitoring Oxygen, Temperature and Respiration Rate of Horticultural Crops Post Harvest

In order to design optimal packages, it is of pivotal importance to determine the rate at which harvested fresh fruits and vegetables consume oxygen. The respiration rate of oxygen (RRO2) is determined by measuring the consumed oxygen per hour per kg plant material, and the rate is highly influenced by temperature and gas composition. Traditionally, RRO2 has been determined at discrete time intervals. In this study, wireless sensor networks (WSNs) were used to determine RRO2 continuously in plant material (fresh cut broccoli florets) at 5 °C, 10 °C and 20 °C and at modified gas compositions (decreasing oxygen and increasing carbon dioxide levels). Furthermore, the WSN enabled concomitant determination of oxygen and temperature in the very close vicinity of the plant material. This information proved a very close relationship between changes in temperature and respiration rate. The applied WSNs were unable to determine oxygen levels lower than 5% and carbon dioxide was not determined. Despite these drawbacks in relation to respiration analysis, the WSNs offer a new possibility to do continuous measurement of RRO2 in post harvest research, thereby investigating the close relation between temperature and RRO2. The conclusions are that WSNs have the potential to be used as a monitor of RRO2 of plant material after harvest, during storage and packaging, thereby leading to optimized consumer products.

CLIMATIC EVALUATION OF SEMI-CLOSED GREENHOUSES

In the Netherlands the development of semi-closed greenhouses is going on for eight years. Increased carbon dioxide levels, reduced pesticide use, and energy saving are the main benefits of semi-closed greenhouses. Companies have developed several concepts with the goal to reduce the ventilation with outside air which mainly have been built at commercial tomato and Phalaenopsis growers. The goal of the project is to monitor the greenhouse climate at these nurseries in a uniform way so the concepts can be compared and to help growers to control the development of the crop in the best way. The climate is analyzed by measuring temperature and relative humidity on three heights: at the top of the canopy, in between the top and the root system, and near the full grown tomatoes. All system parameters regulating the greenhouse climate are registered which includes the air treatment unit used in the semi-closed greenhouse. Additional measurements are done to determine the local climate as a result of the air treatment units. Three concepts include air ducts below the hanging gutters which distribute outside air and/or cooled greenhouse air. Two concepts have air treatment units hanging above the canopy used for cooling. Only one concept is without windows and therefore completely relies on the systems for cooling. The systems with an air duct under the hanging gutters all show in a vertical temperature gradient with cold air near the root system and warm air near the top of the canopy. This gradient is not present in conventional greenhouses. The horizontal temperature distribution is rather homogenous during cooling with air ducts. Heating using the air ducts gives a lower temperature near the sides of the greenhouse than at the center of the greenhouse increasing the risk of botrytis. Coolers hanging above the crop give a homogenous climate during cooling. A disadvantage of these top coolers is the fact that they reduce the light level near the crop.

Surgical Emphysema as a Cause of Severe Hypercapnia during Laparoscopic Surgery

Surgical emphysema is a well-recognised complication of laparoscopic surgery, but its impact on end-tidal carbon dioxide levels and carbon dioxide elimination is seldom reported and may not be fully appreciated by anaesthetists. Four cases are presented where extensive surgical emphysema occurred during laparoscopic surgery. The visual display of the anaesthetic record using the software program Monitor showed substantial rises in end-tidal carbon dioxide levels and allowed calculation of the carbon dioxide elimination, which increased two- to three-fold above normal levels. Having a visual record of carbon dioxide changes facilitated the recognition of surgical emphysema in three out of the four cases. Strategies such as estimating and tracking changes in carbon dioxide elimination from the minute ventilation and end-tidal carbon dioxide levels may assist in early identification, and palpating for surgical emphysema is recommended during laparoscopy if other causes of increased carbon dioxide levels are excluded.

The climate change and agriculture – dimensions and correlations

Global climate changes are taking place and its impacts on economy are already occurring in fields like tourism, agriculture, forestry, infrastructure, insurance industry or capital market. Specialists draw attention that climate change has negative effects and positive effects. For example, in some parts of Europe, especially in north, the agricultural may benefit from temperature rise increasing carbon dioxide levels in the atmosphere. The most important part of these changes is due to greenhouse gas (GHG) emissions from human activity. Between greenhouse gases, carbon dioxide (CO2) is the largest contributor with a weight around of 80% of total GHG emissions. The agriculture is the most affected sector by the climate change, but agricultural activities have many negative implications on environment through emissions of methane and nitrous oxide that result from changes in land use. Besides the negative impact, the agriculture may play a positive role to environment protection through the production of bio fuels. Because of the huge implications of climate change on human activities, the public authorities have made important steps in order to control this phenomenon, to reduce and prevent the negative impact.

Down with the Clowns

Ecology![Figure][1] CREDIT: SIMON FOALE One consequence of rising levels of atmospheric carbon dioxide is an increase in the absorption of CO2 by the ocean. This leads to a gradual decrease in oceanic pH, a change that has been predicted to have adverse effects on marine organisms such as corals because more acidic conditions may inhibit the accretion of calcium carbonate skeletons. Munday et al. show that the recruitment of reef fish populations may also be under threat, due to the effects of higher carbon dioxide levels on the olfactory systems of larval fish. Benthic fish larvae use chemical cues both to locate suitable habitats and to detect and avoid predators. Experiments with larval clownfish and damselfish showed that increasing carbon dioxide levels interfered with their normal aversion to chemical cues derived from predator fish, resulting in riskier behavior that led to increased larval mortality. Proc. Natl. Acad. Sci. U.S.A. 107 , 12930 (2010). [1]: pending:yes

ROLE OF ANTHROPOGENIC EMISSIONS IN CLIMATE CHANGE

Climate change is any long-term significant change in the expected patterns ofaverage weather of a specific region (or more relevantly to contemporary sociopoliticalconcerns, of the Earth as a whole) over an appropriately significant periodof time. Climate change reflects abnormal variations to the expected climate withinthe Earth’s atmosphere and subsequent effects on other parts of the Earth, such asin the ice caps over durations ranging from decades to millions of years. Increasedcarbon dioxide levels are thought to exacerbate the heating effects of the GreenhouseEffect by reducing the re-radiation of heat from the sun and, therefore, increasingthe temperature contained in the atmosphere. The climate of the Earth is alwayschanging. In the past it has altered as a result of natural causes. The changes wehave seen over recent years and those which are predicted over the next 80 yearsare thought to be mainly as a result of human behaviour rather than due to naturalchanges in the atmosphere. The present paper focuses on different type ofanthropogenic emissions and how it contributes and its major role in changingour climate

Flowering and changes in respiration in Asiatic hybrid lilies as influenced by bulb vernalization

Asiatic hybrid lilies, Lilium × elegans Thunb., ‘Red Carpet’ and ‘Sunray’ were used to investigate the effect of bulb vernalization at 2.5 °C on plant growth, flowering, and CO 2 production (respiration), and to use the CO 2 production pattern to monitor the time of flower bud initiation and development. Lily shoot emergence and flowering were accelerated when bulbs received 2.5 °C bulb vernalization; however, flowering was delayed when bulbs were stored at 20 °C before treatment at 2.5 °C; this indicated that bulbs were de-vernalized. The maximum CO 2 level, and the minimum level, reached in 78 h in non-vernalized bulbs and in 110 h in 6 weeks of 2.5 °C (6 weeks/2.5 °C) treated bulbs, was increased as the 2.5 °C duration was increased; this indicated that CO 2 level can be an useful parameter to measure the cold stimulus (i) accumulated in bulbs following bulb vernalization. The respiration rate higher than the predicted values of the best-fit curves derived from the quadratic equations was designated as Blip A and this was correlated to the time of flower bud initiation and development. Shoot elongation may follow the rise in carbon dioxide levels after reaching the minimum level. It is proposed that increased carbon dioxide levels higher than the predicted levels (Blip A), was correlated to the time of flower bud initiation and development. Measurement of carbon dioxide production upon receipt of bulbs may be a useful technique to provide important information for optimum vernalization treatments for bulbs that have accumulated different levels of low temperature stimulus after bulb vernalization.

Seed longevity of dominant plant species from degraded savanna in semi-arid Tanzania

Artificially buried seeds were followed by periodic exhumation and germination during 21 months in Kondoa Irangi Hills, central Tanzania. Viable seeds from thirteen selected species were buried in polythene envelopes at a depth of 15 cm below woodland vegetation. Lethal germination, fungal decay and insect infestation were singled out as the most important contributors to loss of viability among seeds. Hierarchical clustering based on a seed’s mean viability, seed shape and presence or absence of dispersal appendages, produced three distinct groups: (1) non-dormant seeds (2) seeds with enforced dormancy and (3) seeds with seed coat imposed dormancy. The low decay constant of some species is an indication of their abilities to form persistent seed banks. The intermittent and extended germination of seeds of the same species from the same batch shown by some species may be regarded as an ecological adaptation to prevent synchronous germination in unpredictable harsh environments, whereas prompt germination of some Acacia seeds may be viewed as a strategy to avoid seed predation in the soil. Seed dormancy, which predicts seed longevity, is strongly dependent on seed moisture content and partly on other environmental factors, notably low temperatures, light and increased carbon dioxide levels.

Should South Africa worry about carbon dioxide?

There is huge international uproar surrounding the impact of increasing carbon dioxide levels on our planet. Why is this the case? An increase in carbon dioxide levels (carbon dioxide is the second most abundant greenhouse gas) is said to be one of the main causes of the phenomenon 'global warming' (defined by Mastrandrea & Schneider (2007), page 1, as 'measurable increases in the average temperature of earth's atmosphere, oceans, and landmasses'.)

Stomatal conductance changes due to increasing carbon dioxide levels: Projected impact on surface ozone levels

Stomatal conductance changes due to increasing carbon dioxide levels: Projected impact on surface ozone levels

Multidecadal to millennial‐scale shifts in drought conditions on the Canadian prairies over the past six millennia: implications for future drought assessment

AbstractThree high‐resolution climatic reconstructions, based on diatom analyses from lake sediment cores from the Canadian prairies, show that shifts in drought conditions have prevailed on centennial to millennial time scales for at least the past six millennia. These shifts in mean aridity exhibit broad regional synchrony, with particularly pronounced shifts at all sites between ∼1700–2000 cal. yr bp and ∼3600–3900 cal. yr bp, as well as at ∼5400–5500 cal. yr bp for the two sites which extend back to at least 6000 cal. yr bp. The two Saskatchewan lakes exhibited significant coherence in both the timing and direction of these shifts, whereas inferred changes at the westernmost site in Alberta were significantly correlated to the Saskatchewan sites, but opposite in sign, and exhibited more high‐frequency variation on the scale of centuries. The mechanisms behind these abrupt shifts in aridity are poorly understood, but may be linked to changes in oceanic–atmospheric interactions that influence the mean position of the jetstream and the associated storm tracks. Natural shifts in mean climatic conditions may accelerate with increasing carbon dioxide levels intensifying the likelihood of extreme droughts in North American prairies.

Effects of fasting and carbohydrate consumption on voluntary resting apnea duration

Breath holding is normally terminated due to the urge to breathe, mainly caused by the increasing carbon dioxide level. It was recently shown that a combination of 18 h of carbohydrate-free diet and prolonged exercise prior to breath holding lowered the respiratory exchange ratio (RER) and end-expiratory PO(2 )at maximal breath-hold break-point (MBP). Current hypothesis: fasting will result in longer breath-hold duration than will fasting followed by carbohydrate intake. It was also hypothesized that breath-holds during carbohydrate supplementation would be ended at a higher alveolar PO(2). Ten male non-divers performed multiple breath-holds either to the first diaphragmatic contraction (PBP), or to MBP. The breath-holds were performed during normal diet (control; C), twice during fasting (F14 h, F18 h), followed by post fasting carbohydrate consumption (PFCC) and a repetition of the breath-hold testing 1-2 h after ingestion of carbohydrates. Duration, RER, end-tidal PO(2) and PCO(2), SaO(2) and blood glucose were determined. RER and blood glucose increased after PFCC compared with fasting and control conditions (P < 0.001). PBP breath-hold duration increased from 129 +/- 34 s at C to 148 +/- 33 s at F18 h, and was reduced during PFCC to 122 +/- 30 s (P < 0.001). End-tidal PO(2) was higher at PFCC compared to F18 h (10.4 +/- 1.2 vs. 9.5 +/- 1.2 kPa at PBP, P < 0.05). Similar trends in breath-hold duration and physiology were seen in breath-holds that were terminated at MBP. Dietary restriction can affect breath-hold duration. The lower O(2) level at breakpoint during fasting suggests that breath holding may be less safe during fasting; the increased risk may be mitigated by ingestion of carbohydrates before breath holding.

Effects of carbon dioxide exposure on feed intake and gonad growth in green sea urchin, Strongylocentrotus droebachiensis

The effects of carbon dioxide (CO 2(aq)) on gonad growth and feed intake in green sea urchin, Strongylocentrotus droebachiensis, were examined. Adult sea urchins with a mean (S.D.) live weight of 50.0 (11.2) g were exposed to two levels of carbon dioxide (CO 2(aq)), (1.1 (control) and 18.1 mg l − 1 ), for 56 days at 6.0 °C and 33‰. Gonad growth was significantly reduced in the high CO 2 concentration group compared to the control group. In the high carbon dioxide treatment, gonad growth was 67% less than the control treatment. Weekly feed intake and total feed consumption were significantly reduced in the high concentration group. The reduction in gonad growth was attributed to a decrease in feed intake and impaired feed conversion efficiency. The present study demonstrates that adult green sea urchins show low tolerance to increased carbon dioxide levels, and are unable to maintain high gonad growth facing such conditions.

Tropical rainforest canopies and climate change

Abstract There is less certainty about the impact of climate change on tropical rainforests than on temperate forests because of the comparative lack of background data and because few large scale experiments have been, and are being, carried out in tropical rainforests. Many of the factors critical to the future of tropical rainforests concern canopies, the key processes that take place there, and the roles and interactions of canopy biodiversity. In particular there are almost no data on how forest canopies and processes are changing with increased carbon dioxide levels. The implications of elevated carbon dioxide, climatic stress and related changes in water‐use efficiency, nutrient availability and other such changes are discussed particularly with references to Australia's tropical rainforests.

Stomatal conductance changes due to increasing carbon dioxide levels: Projected impact on surface ozone levels

The impact of increasing levels of carbon dioxide on stomatal conductance and surface ozone levels was investigated using a global three-dimensional general circulation model (GCM) coupled to an interactive land surface scheme and a chemistry model. Pre-industrial, present day and doubled present day levels of carbon dioxide were used. This approach was used to examine the sensitivity of modelled surface ozone levels to changes in stomatal conductance via dry deposition. A doubled level of carbon dioxide was found to increase surface ozone levels by between 2 and 8 ppb in all four seasons owing to reduced dry deposition fluxes, although the location and extent of the changes were very different between each season. No change in levels of nitrogen oxides (NO and NO2) was modelled. A similar experiment to examine the same effect on modelled pre-industrial ozone levels showed that the ozone levels over Europe were only slightly smaller (by 1–1.5 ppb) when the CO2 level was decreased from 369 ppm to 280 ppm.

The use of canola oil coatings to extend the storage life of Nashi pears

Nashi cv. Nijisseiki was coated with canola oil before storage at 0°C over 3 consecutive seasons. This resulted in greater retention of green colour, even after only 8 weeks of storage. This effect continued throughout the 40-week storage period and after 1 week at 20°C. Physiological disorders were generally low. The internal atmosphere was measured during storage at 0°C. The mean carbon dioxide levels for control and treated fruit were approximately 0.5 and 1.9%, and oxygen levels were 20 and 13%, respectively. The mean ethylene levels were approximately 5 and 30 μL/L, respectively. Thus, in oiled fruit, increased carbon dioxide levels may have overcome the effects of increased levels of ethylene. When fruit was transferred to 20°C, carbon dioxide and ethylene levels rose and oxygen levels fell but no damage was evident at the lower oil concentrations. Non-oiled fruit was then stored in polyethylene bags with or without a carbon dioxide absorbent (Calcium hydroxide) and an ethylene absorbent (Purafil). Fruit stored with the former became as yellow as the control fruit in air, whilst fruit with Purafil remained greener than fruit held in bags alone. When the absorbents were used together, much of the fruits’ green colour was lost. Carbon dioxide levels therefore appear to be most important for the retention of green colour, and generally improve storage life. Ethylene removal further improves the retention of green colour in the Nijisseiki cultivar. A storage life of at least 40 weeks at 0°C was achieved with fruit from several sources in 3 seasons. Preliminary recommendations for small-scale hand applications are 1 or 2 drops per 240 g fruit. Commercial trials could involve dipping or spraying with 1–2% oil emulsified with Tween 80.

Adult Identified with Congenital Central Hypoventilation Syndrome–Mutation in PHOX2b Gene and Late-Onset CHS

In light of our recent review of the genetic basis for congenital central hypoventilation syndrome (CCHS) (1), we bring to your attention a 35-year-old adult recently identified as having had late-onset CHS and the CCHS-mutation in PHOX2b. One year ago this patient presented with a history of snoring “for his whole life,” nocturnal gasping, and “stopping breathing and turning blue.” During polysomnography he had 46 obstructive events (38 hypopneas, 8 apneas), 16 central apneas, and an apnea–hypopnea index of 77 events/hour, with an SaO2 nadir of 65% in room air and 80% with supplemental oxygen. He temporarily responded to Bi-Pap with supplemental oxygen during sleep, but within 6 months was referred for uvulopalatopharyngoplasty. He was readmitted 48 hours after discharge with intermittent confusion, difficulty staying awake, and respiratory failure (awake arterial Pco2 of 73 mm Hg). His admission hematocrit was 73%, body temperature was 35.5 C, chest X-ray revealed cardiomegaly, and ECG revealed right axis deviation, enlargement, and hypertrophy. He required intubation and mechanical ventilation, then a tracheostomy; however, mechanical ventilation was discontinued. We were contacted by the family when an arterial blood gas assay upon awakening revealed a Pco2 of 129 mm Hg (pH 7.03). Because of his daughter’s diagnosis of late-onset CHS 3 years before, and documentation that she is heterozygous for the CCHS-related PHOX2b polyalanine expansion mutation, we conducted the same assay with the father’s DNA. Figure 1 demonstrates the identical mutation in the 4-year-old daughter and the father, as well as in the 2-yearold daughter, who also has alveolar hypoventilation (all three have a genotype of 20/25). In retrospect, we learned that the father uses Dexadrine to “stay on task,” has symptoms compatible with autonomic nervous system dysregulation (low body temperature, postural hypotension, pinpoint pupils minimally reactive to light, no shortness of breath despite markedly increased carbon dioxide levels), and has awakened with headaches and periods of disorientation for several years. On the basis of this remarkably late presentation of the alveolar hypoventilation component of CHS, we suggest that adult pulmonologists and intensivists consider the possibility of lateonset CHS, confirmable by PHOX2b assay, when caring for adults with hypercarbia of unknown etiology. From a scientific perspective, this case raises the possibility of a regulatory gene that modifies the expression or activity of PHOX2b, determining the severity of the autonomic dysregulation in late-onset CHS.