Effect of elevated carbon dioxide on biology and morphometric parameters of yellow stem borer, Scirpophaga incertulas infesting rice (Oryza sativa)

An experiment was conducted at Research Farm, National Rice Research Institute, Cuttack, Odisha, India to quantify the effect of elevated carbon dioxide (CO2) concentrations on the biology and morphometric parameters of yellow stem borer (Scirpophaga incertulas, Pyralidae, Lepidoptera). Yellow stem borer is one of the major pest of rice in the whole rice growing regions of South East Asia. The effect of three carbon dioxide concentrations i.e. 410 ppm (ambient), 550 ppm and 700 ppm on the duration of the developmental period as well as morphometric parameters of each stage of the lifecycle of the pest was analysed. It was found that, there was an increase in the duration of the developmental period of each stage of life cycle as the concentration of CO2 increases. However, the life span of the adult moth was significantly lower under the elevated CO2 concentrations when compared with ambient CO2 concentration. Morphometric parameters viz., mean length, width and weight of each larval instar, pupa and adult were found to be significantly higher in elevated concentrations of CO2 as compared to ambient concentration.

Carbon dioxide, COVID-19 and the importance of restaurant ventilation: a case study from Spain approaching Christmas 2021

Restaurants present an especial challenge in the prevention of the spread of COVID-19 via exhalatory bioaerosols because customers are unprotected by facemasks while eating, so that ventilation protocols in such establishments become especial important. However, despite the fact that this pandemic airborne disease has been with us for two full years, many restaurants are still not successfully prioritising air renovation as a key tool for reducing infection risk. We demonstrate this in the run-up to the 2021 Christmas celebrations by reporting on CO2 concentration data obtained from a hotel breakfast room and restaurants during the 5-day Spanish holiday period of 4th-8th December. In the case of the breakfast room, poor ventilation resulted in average CO2 levels ranging from 868 to 1237 on five consecutive days, with the highest levels coinciding with highest occupancy numbers. Inside the five restaurants, three of these were well ventilated, maintaining stable average CO2 concentrations below 700ppm. In contrast, two restaurants failed to keep average CO2 levels below 1000ppm, despite sporadic, but ineffective, attempts by one of them to ventilate the establishment. More effort needs to be made to foster in both restaurant managers and the general public an improved awareness of the value of CO2 concentrations as an infection risk proxy and the relevance of ventilation issues to the propagation of respiratory diseases.

Glacial-interglacial productivity in the Polar Frontal Zone, southwest Pacific Ocean

<p>The Southern Ocean has a central role in regulating global climate change. Research has shown evidence of changes in biological productivity are coincident with increased iron deposition and rising atmospheric CO2 concentrations. The current data suggests these processes occur homogenously throughout the Southern Ocean, where research largely focuses on changes in biogenic silica as a proxy for upwelling and enhanced opal production. The role of calcium carbonate productivity, however, is rarely discussed, or is referred to in terms of preservation changes associated with shoaling and deepening of the lysocline. This assumption ignores potentially important effects of carbonate productivity and inter-basin complexities on ocean-atmosphere CO2 exchange. Two gravity cores (TAN1302-96 and TAN1302-97) collected from the southwest Pacific Polar Frontal Zone (PFZ) provide more insight into productivity changes and inter-basin differences across glacial-interglacial timescales. Detailed geochemical analysis, together with δ18O stratigraphy and 14C chronology, were used to reconstruct glacial-interglacial changes in terrigenous input and paleoproductivity in the PFZ. Sedimentological and biological analyses provide additional information to support the geochemical observations. This study highlights two distinct productivity modes (i.e. biogenic silica and calcium carbonate) that vary over glacial-interglacial timescales and with respect to the position of the Polar Front (PF). Key findings include; 1) a systematic series of key biological changes are repeated during glacial Terminations I (TI) and II (TII), the order of which depends on the position relative to the PF; 2) calcium carbonate productivity dominates the early part of the Termination north of the PF, whereas the production of biogenic silica dominates the early Termination south of the PF; 3) following TI and TII, calcium carbonate leads productivity in the early interglacials (i.e. MIS 5e and the Holocene), followed by the production of biogenic silica during the late interglacials, concurrent with declining atmospheric CO2 concentrations.</p>

Glacial-interglacial productivity in the Polar Frontal Zone, southwest Pacific Ocean

<p>The Southern Ocean has a central role in regulating global climate change. Research has shown evidence of changes in biological productivity are coincident with increased iron deposition and rising atmospheric CO2 concentrations. The current data suggests these processes occur homogenously throughout the Southern Ocean, where research largely focuses on changes in biogenic silica as a proxy for upwelling and enhanced opal production. The role of calcium carbonate productivity, however, is rarely discussed, or is referred to in terms of preservation changes associated with shoaling and deepening of the lysocline. This assumption ignores potentially important effects of carbonate productivity and inter-basin complexities on ocean-atmosphere CO2 exchange. Two gravity cores (TAN1302-96 and TAN1302-97) collected from the southwest Pacific Polar Frontal Zone (PFZ) provide more insight into productivity changes and inter-basin differences across glacial-interglacial timescales. Detailed geochemical analysis, together with δ18O stratigraphy and 14C chronology, were used to reconstruct glacial-interglacial changes in terrigenous input and paleoproductivity in the PFZ. Sedimentological and biological analyses provide additional information to support the geochemical observations. This study highlights two distinct productivity modes (i.e. biogenic silica and calcium carbonate) that vary over glacial-interglacial timescales and with respect to the position of the Polar Front (PF). Key findings include; 1) a systematic series of key biological changes are repeated during glacial Terminations I (TI) and II (TII), the order of which depends on the position relative to the PF; 2) calcium carbonate productivity dominates the early part of the Termination north of the PF, whereas the production of biogenic silica dominates the early Termination south of the PF; 3) following TI and TII, calcium carbonate leads productivity in the early interglacials (i.e. MIS 5e and the Holocene), followed by the production of biogenic silica during the late interglacials, concurrent with declining atmospheric CO2 concentrations.</p>

A missing link in the carbon cycle: phytoplankton light absorption

Marine biota and biogeophysical mechanisms, such as phytoplankton light absorption, have attracted increasing attention in recent climate studies. Under global warming, the impact of phytoplankton on the climate system is expected to change. Previous studies analyzed the impact of phytoplankton light absorption under prescribed future atmospheric CO2 concentrations. However, the role of this biogeophysical mechanism under freely-evolving atmospheric CO2 concentration and future CO2 emissions remain unknown. To shed light on this research gap, we perform simulations with the EcoGEnIE Earth system model and prescribe CO2 emissions following the four Representative Concentration Pathways (RCP) scenarios. Under all the RCP scenario, our results indicate that phytopankton light absorption increases the surface chlorophyll biomass, the sea surface temperature, the atmospheric CO2 concentrations and the atmospheric temperature. Under the RCP2.6, RCP4.5 and RCP6.0 scenarios, the magnitude of changes due to phytoplankton light absorption are similar. However, under the RCP8.5 scenario, the changes in the climate system are less pronounced due to the temperature limitation of phytoplankton growth, highlighting the reduced effect of phytoplankton light absorption under strong warming. Additionally, this work evidences the major role of phytoplankton light absorption on the climate system, suggesting a highly uncertain feedbacks on the carbon cycle with uncertainties that are in the range of those known from the land biota.

Low Level Carbon Dioxide Indoors—A Pollution Indicator or a Pollutant? A Health-Based Perspective

With modern populations in developed countries spending approximately 90% of their time indoors, and with carbon dioxide (CO2) concentrations inside being able to accumulate to much greater concentrations than outdoors, it is important to identify the health effects associated with the exposure to low-level CO2 concentrations (<5000 ppm) typically seen in indoor environments in buildings (non-industrial environments). Although other reviews have summarised the effects of CO2 exposure on health, none have considered the individual study designs of investigations and factored that into the level of confidence with which CO2 and health effects can be associated, nor commented on how the reported health effects of exposure correspond to existing guideline concentrations. This investigation aimed to (a) evaluate the reported health effects and physiological responses associated with exposure to less than 5000 parts per million (ppm) of CO2 and (b) to assess the CO2 guideline and limit concentrations in the context of (a). Of the 51 human investigations assessed, many did not account for confounding factors, the prior health of participants or cross-over effects. Although there is some evidence linking CO2 exposures with health outcomes, such as reductions in cognitive performance or sick building syndrome (SBS) symptoms, much of the evidence is conflicting. Therefore, given the shortcomings in study designs and conflicting results, it is difficult to say with confidence whether low-level CO2 exposures indoors can be linked to health outcomes. To improve the epidemiological value of future investigations linking CO2 with health, studies should aim to control or measure confounding variables, collect comprehensive accounts of participants’ prior health and avoid cross-over effects. Although it is difficult to link CO2 itself with health effects at exposures less than 5000 ppm, the existing guideline concentrations (usually reported for 8 h, for schools and offices), which suggest that CO2 levels <1000 ppm represent good indoor air quality and <1500 ppm are acceptable for the general population, appear consistent with the current research.