High Atmospheric Carbon Dioxide Research Articles

Moderate greenhouse climate and rapid carbonate formation after Marinoan snowball Earth

When the Marinoan snowball Earth deglaciated in response to high atmospheric carbon dioxide (CO2) concentrations, the planet warmed rapidly. It is commonly hypothesized that the ensuing supergreenhouse climate then declined slowly over hundreds of thousands of years through continental weathering. However, how the ocean affected atmospheric CO2 in the snowball Earth aftermath has never been quantified. Here we show that the ocean’s carbon cycle drives the supergreenhouse climate evolution via a set of different mechanisms, triggering scenarios ranging from a rapid decline to an intensification of the supergreenhouse climate. We further identify the rapid formation of carbonate sediments from pre-existing ocean alkalinity as a possible explanation for the enigmatic origin of Marinoan cap dolostones. This work demonstrates that a moderate and relatively short-lived supergreenhouse climate following the Marinoan snowball Earth is a plausible scenario that is in accordance with geological data, challenging the previous hypothesis.

Effects of global warming and Tibetan Plateau uplift on East Asian climate during the mid-Cretaceous

Sedimentary records indicate that subtropical and mid-latitude East Asia exhibited considerable drying and wetting, respectively, during the mid-Cretaceous, which is considered to be relevant to much higher atmospheric carbon dioxide (pCO2) concentrations and/or proto-Tibetan Plateau (proto-TP) uplift. In order to explore and compare their roles on the East Asian climate evolution, we conducted simulations of the mid-Cretaceous climate system with different atmospheric pCO2 levels and varying topographies. The results show that both factors had significant influences on the East Asian climate. As the increase in atmospheric pCO2 levels from ∼560–1120 ppmv to ∼1120–2240 ppmv, the precipitation increases considerably over mid-latitude East Asia, but only small changes in the subtropical portion of East Asia occur. Simultaneously, the effects of the proto-TP uplift are opposite to those of global warming trend during that period. Generally, it leads to a precipitation decrease over subtropical East Asia, but rather minor changes over mid-latitude East Asia. These changes are qualitatively consistent with the deduction based on the geological records, but the magnitudes of the modeled precipitation changes are relatively smaller. Therefore, we can conclude that the subtropical East Asian drying during the mid-Cretaceous can be partly explained by the proto-TP uplift, while the mid-latitude East Asian wetting was partly due to global warming. However, additional factor(s) also played a significant role in the East Asian climate evolution during the mid-Cretaceous.

A Review on Protected Cultivation of Vegetables: Opportunities and Challenges

Protected farming techniques are set of agricultural practices that are designed to produce a plant in a controlled environmental condition by using soil cover and / or crop covers to control pests and effect of climate. While a protected farming method can increase the productivity of vegetable crops as well as growth and yield. It is evident that protected farming has been found beneficial for farmers. In addition to its great importance, it challenges many biotic and abiotic factors such as photo-stress, water stress, heat stress, weed growth, soil nutrient deficiencies, high wind velocities and atmospheric carbon dioxide, pest and diseases. The various benefits of a protected vegetable crop are quality, profitability, and a good level of marketing for farmers. Protected cultivation is an imminent technique for raising vegetables, flowers and other high rated as well as consumable crops. In advance agriculture, protected structures held an excessive potential for more production with greater productivity. The chapter contains the status, challenges and opportunities of protected cultivation and related government schemes for horticultural plants in India especially Uttar Pradesh. It has been found that the cumulative area has been acquired under NHM-protected cultivation in India. Financial support or funding is also provided by the government agency to spread this methodology throughout the country. Recourses are used wisely in these structures because modern methods/techniques were applied.

East Asian summer monsoon variations across the Miocene−Pliocene boundary recorded by sediments from the Guide Basin, northeastern Tibetan Plateau

Records of atmospheric carbon dioxide concentration, sea-surface temperature, and global vegetation show that Earth’s climate and environment changed significantly during the late Miocene−early Pliocene. Understanding the environmental response to insolation forcing during this transitional period may provide insights into future environmental variations resulting from the perturbation of the global carbon cycle caused by fossil fuel combustion. However, terrestrial paleoclimate records capable of resolving orbital time-scale environmental variations are mostly from Europe, especially from the region around the Mediterranean Sea. Here, we present high-resolution records of grain size, black carbon, and geochemistry from a sedimentary sequence from the northeastern margin of the Tibetan Plateau, where precipitation is mainly via the East Asian summer monsoon. We observed increases in sediment accumulation rate and black carbon mass accumulation rate at ca. 5.3 Ma, which we interpret as the result of intensified seasonal precipitation associated with the strengthening of the East Asian summer monsoon; concurrently, precessional and obliquity cycles became more prominent during the early Pliocene. Our results suggest that, in response to current and future high atmospheric carbon dioxide concentrations, changes in the East Asian summer monsoon are likely to result in increased precipitation and seasonality within its region of influence.

Impact of high atmospheric carbon dioxide on the biotic stress response of the model cereal species Brachypodium distachyon.

Losses due to disease and climate change are among the most important issues currently facing crop production. It is therefore important to establish the impact of climate change, and particularly of high carbon dioxide (hCO2), on plant immunity in cereals, which provide 60% of human calories. The aim of this study was to determine if hCO2 impacts Brachypodium distachyon immunity, a model plant for temperate cereals. Plants were grown in air (430 ppm CO2) and at two high CO2 conditions, one that is relevant to projections within the coming century (1000 ppm) and a concentration sufficient to saturate photosynthesis (3000 ppm). The following measurements were performed: phenotyping and growth, salicylic acid contents, pathogen resistance tests, and RNAseq analysis of the transcriptome. Improved shoot development was observed at both 1000 and 3000 ppm. A transcriptomic analysis pointed to an increase in primary metabolism capacity under hCO2. Alongside this effect, up-regulation of genes associated with secondary metabolism was also observed. This effect was especially evident for the terpenoid and phenylpropanoid pathways, and was accompanied by enhanced expression of immunity-related genes and accumulation of salicylic acid. Pathogen tests using the fungus Magnaporthe oryzae revealed that hCO2 had a complex effect, with enhanced susceptibility to infection but no increase in fungal development. The study reveals that immunity in B. distachyon is modulated by growth at hCO2 and allows identification of pathways that might play a role in this effect.

Effect of Temperature on Growth, Quality, Yield Attributing Characters and Yield of Rice – A Review

Rice (Oryza sativa L.) is the second most important food in the world after wheat. Most rice is now grown in areas where the temperature is higher than the optimum growing temperature (28/22°C); therefore, a further increase in average temperature or high temperature occurring in the sensitive phase of the crop can affect growth and yield. Clutter. For every 1°C increase in daytime maximum/night minimum temperature from 28°C/21°C to 34°C/27°C, rice yield decreases by 7% to 8%. Additionally, the benefits that crops derive from high atmospheric carbon dioxide concentrations must be lost due to warming. The thermal stability of cell membranes is thought to correlate well with yield performance. Temperature is important in photosynthesis, but too hot can cause reduced photosynthesis of leaves and reduced distribution of dry matter to shoots and roots. The disadvantage of temperature is not limited to the above-ground rice. The underground area is affected, if not more, by the flood, and the temperature of the soil changes due to the heat. Future increases in global temperatures threaten people worldwide who depend on crops for their health and food security. In the past, the stress of the crisis on rice production focused on the rice crop. This review highlights the importance of rice in the world, the effect of high temperature on the growth, quality, yield and properties of rice, and the need for future research.

Seasonal climate conditions impact the effectiveness of improving photosynthesis to increase soybean yield.

Photosynthetic stimulations have shown promising outcomes in improving crop photosynthesis, including soybean. However, it is still unclear to what extent these changes can impact photosynthetic assimilation and yield under long-term field climate conditions. In this paper, we present a systematic evaluation of the response of canopy photosynthesis and yield to two critical parameters in leaf photosynthesis: the maximum carboxylation rate of ribulose-1,5-bisphosphate carboxylase/oxygenase (Vcmax) and the maximum electron transport of the ribulose-1,5-bisphosphate regeneration rate (Jmax). Using the field-scale crop model Soybean-BioCro and ten years of observed climate data in Urbana, Illinois, U.S., we conducted sensitivity experiments to estimate the changes in canopy photosynthesis, leaf area index, and biomass due to the changes in Vcmax and Jmax. The results show that 1) Both the canopy photosynthetic assimilation (An) and pod biomass yields were more sensitive to the changes in Jmax, particularly at high atmospheric carbon-dioxide concentrations ([CO2]); 2) Higher [CO2] undermined the effectiveness of increasing the two parameters to improve An and yield; 3) Under the same [CO2], canopy light interception and canopy respiration were key factors that undermined improvements in An and yield; 4) A canopy with smaller leaf area index tended to have a higher yield improvement, and 5) Increases in assimilations and yields were highly dependent on growing-season climatic conditions. The solar radiation, temperature, and relative humidity were the main climate drivers that impacted the yield improvement, and they had opposite correlations with improved yield during the vegetative phase compared to the reproductive phase. In a world with elevated [CO2], genetic engineering crop photosynthesis should focus more on improving Jmax. Further, long-term climate conditions and seasonal variations must be considered to determine the improvements in soybean canopy photosynthesis and yield at the field scale. Quantifying the effectiveness of changing Vcmax and Jmax helps understand their individual and combined contributions to potential improvements in assimilation and yield. This work provides a framework for evaluating how altering the photosynthetic rate parameters impacts soybean yield and assimilation under different seasonal climate scenarios at the field scale.

Naked Mole-Rats Demonstrate Profound Tolerance to Low Oxygen, High Carbon Dioxide, and Chemical Pain.

Naked mole-rats (Heterocephalus glaber) are very unusual among subterranean mammals in that they live in large colonies and are extremely social, spending large amounts of time gathered together in underground nests more than a meter below the surface. Many respiring individuals resting in deep, poorly ventilated nests deplete the oxygen supply and increase the concentration of carbon dioxide. Consistent with living in that atmosphere, naked mole-rats tolerate levels of low oxygen and high carbon dioxide that are deadly to most surface-dwelling mammals. Naked mole-rats appear to have evolved a number of remarkable adaptations to be able to thrive in this harsh atmosphere. In order to successfully survive low oxygen atmospheres, they conserve energy utilization by reducing the physiological activity of all organs, manifest by reduced heart rate and brain activity. Amazingly, they resort to the anaerobic metabolism of fructose rather than glucose as a fuel to generate energy when challenged by anoxia. Similarly, high carbon dioxide atmospheres normally cause tissue acidosis, while naked mole-rats have a genetic mutation preventing both acid-induced pain and pulmonary edema. Together, these putative adaptations and the tolerances they provide make the naked mole-rat an important model for studying a host of biomedical challenges.

Diverse Carbonates in Exoplanet Oceans Promote the Carbon Cycle

Carbonate precipitation in oceans is essential for the carbonate-silicate cycle (inorganic carbon cycle) to maintain temperate climates. By considering the thermodynamics of carbonate chemistry, we demonstrate that the ocean pH decreases by approximately 0.5 for a factor of 10 increase in the atmospheric carbon dioxide content. The upper and lower limits of ocean pH are within 1–4 of each other, where the upper limit is buffered by carbonate precipitation and defines the ocean pH when the carbon cycle operates. If the carbonate compensation depth (CCD) resides above the ocean floor, then carbonate precipitation and the carbon cycle cease to operate. The CCD is deep (>40 km) for high ocean temperature and high atmospheric carbon dioxide content. Key divalent carbonates of magnesium, calcium and iron produce an increasingly wider parameter space of deep CCDs, suggesting that chemical diversity promotes the carbon cycle. The search for life from exoplanets will benefit by including chemically more diverse targets than Earth twins.

Elevation-dependent temperature response in early Eocene using paleoclimate model experiment

Mountains become warmer with elevation in response to greenhouse gas warming, an effect known as elevation-dependent warming. The Eocene is considered a replica of the future climate in an epoch with high atmospheric carbon dioxide concentration (CO2). Therefore, the topographic features of the Eocene strata are of interest. However, obtaining proxy data for mountain regions during the Eocene hothouse is challenging. Paleoclimate model simulation is an effective tool for exploring past climate change. Therefore, we conducted sensitivity experiment simulations employing the Community Earth System Model version 1.2 forced by proxy-estimated CO2 levels. This is the first Eocene study demonstrating the elevation-dependent temperature changes and illustrated using the surface energy budget decomposition. Here five major mountain ranges have been chosen based on their paleogeographic continental location. We found a nonlinear response of elevation-dependent temperature change to CO2 concentrations regulated by seasonal variations. The radiative and non-radiative feedback compensation is responsible for the elevation-dependency temperature changes. Our results suggest temperature perturbations regulate elevation-dependent changes in skin temperature through a combination of feedback under greenhouse warming in the early Eocene. These findings also show future paradox response exhibiting elevation-dependent cooling overall mountain regions due to lower elevation warming.

Effects of Different Oxygen Levels with High-Carbon Dioxide Atmosphere on Postharvest Quality of Fresh Fig under Palliflex Storage Systems

Regulation of storage atmosphere composition with high carbon dioxide (CO2) is a highly effective and alternative approach to control quantity and quality losses in many horticultural crops. The aim of the study was to determine the effects of different O2 with constant high-level CO2 on the postharvest quality of fig cv. Bursa Siyahi in a new practical approach. For this purpose, 6% O2 + 15% CO2 (PL1), 9% O2 + 15% CO2 (PL2) and 21% O2 + 0.03% CO2 (Control) compositions were tested under a palliflex storage system during the cold storage and shelf-life. PL1 and PL2 were found to be more effective than the control for investigated parameters in general. After 28 days of cold storage and +3 days shelf-life, PL1 was also effective in controlling weight loss, ethylene production, antioxidant activity, decay incidence, decay severity, and total microorganisms. However, there were no significant differences between PL1 and PL2 for total soluble solids, titratable acidity, taste, visual appearance, firmness, respiration rate, and anthocyanin content. PL1 could be an effective composition for controlling decay and maintaining the postharvest quality of fresh figs during cold storage and shelf-life without any side effects on visual appearance and taste.

Why is Mars the “Red Planet”? A New, Novel Hypothesis on the Features of Mars and the Origin of the Asteroid Belt

Mars has always been known as the “Red Planet because it is the only planet in our solar system with a red surface. The reasons for this uniqueness have never been proposed, other than the fact that its soil and surface rocks have a high content of iron oxide. In order to attempt to resolve this issue, a novel hypothesis is proposed herewith. Formulation of this hypothesis involved considering the unique features of Mars and putting them into a rational correlating explanation. The scenario involves the collision of a formerly much larger Mars with another planet early in the solar system’s history. The crust and mantle were blown off, forming the asteroid belt, leaving the iron core intact. Upon cooling and solidification, the iron core combined with oxygen in the remaining atmosphere to form rust-colored iron oxide (rust). Methane in the early atmosphere underwent combustion, forming its current high carbon dioxide atmosphere.  The combustion of methane also produced massive amounts of liquid water, explaining the dried-up erosional features of the planet’s surface, such as river valleys. The point of impact formed a long, deep canyon, Valles Marineris, and the nearby giant volcano, Olympus Mons, even in the absence of Mars’ tectonic activity. The cooled, solidified core may explain why Mars has no magnetic field. If accurate, these ideas may help space programs prepare astronauts for manned exploration of the Red Planet, as well as facilitating an understanding of its unusual features.

Does a Large Ear Type Wheat Variety Benefit More From Elevated CO2 Than That From Small Multiple Ear-Type in the Quantum Efficiency of PSII Photochemistry?

Recently, several reports have suggested that the growth and grain yield of wheat are significantly influenced by high atmospheric carbon dioxide concentration (CO2) because of it photosynthesis enhancing effects. Moreover, it has been proposed that plants with large carbon sink size will benefit more from CO2 enrichment than those with small carbon sink size. However, this hypothesis is yet to be test in winter wheat plant. Therefore, the aim of this study was to examine the effect of elevated CO2 (eCO2) conditions on the quantum efficiency of photosystem II (PSII) photochemistry in large ear-type (cv. Shanhan 8675; greater ear C sink strength) and small multiple ear-type (cv. Early premium; greater vegetative C source strength) winter wheat varieties. The experiment was conducted in a free air CO2 enrichment (FACE) facility, and three de-excitation pathways of the primary reaction of PSII of flag leaf at the anthesis stage were evaluated under two CO2 concentrations (ambient [CO2], ∼415 μmol⋅mol–1, elevated [CO2], ∼550 μmol⋅mol–1) using a non-destructive technique of modulated chlorophyll fluorescence. Additionally, the grain yield of the two varieties was determined at maturity. Although elevated CO2 increased the quantum efficiency of PSII photochemistry (ΦPSII) of Shanhan 8675 (SH8675) flag leaves at the anthesis stage, the grain number per ear and 1,000-kernel weight were not significantly affected. In contrast, the ΦPSII of early premium (ZYM) flag leaves was significantly lower than that of SH8675 flag leaves at the anthesis stage, which was caused by an increase in the regulatory non-photochemical energy dissipation quantum (ΦNPQ) of PSII, suggesting that light energy absorbed by PSII in ZYM flag leaf was largely dissipated as thermal energy. The findings of our study showed that although SH8675 flag leaves exhibited higher C sink strength and quantum efficiency of PSII photochemistry at the anthesis stage, these factors alone do not ensure improved grain yield under eCO2 conditions.

Global Health Implications of Nutrient Changes in Rice Under High Atmospheric Carbon Dioxide.

A growing literature has documented that rising concentrations of carbon dioxide in the atmosphere threaten to reduce the iron, zinc, and protein content of staple food crops including rice, wheat, barley, legumes, maize, and potatoes, potentially creating or worsening global nutritional deficiencies for over a billion people worldwide. A recent study extended these previous nutrient analyses to include B vitamins and showed that, in rice alone, the average loss of major B vitamins (thiamin, riboflavin, and folate) was shown to be 17–30% when grown under higher CO2. Here, we employ the EAR cut‐point method, using estimates of national‐level nutrient supplies and requirements, to estimate how B vitamin dietary adequacy may be affected by the CO2‐induced loss of nutrients from rice only. Furthermore, we use the global burden of disease comparative risk assessment framework to quantify one small portion of the health burden related to rising deficiency: a higher likelihood of neural tube defects for folate‐deficient mothers. We find that, as a result of this effect alone, risk of folate deficiency could rise by 1.5 percentage points (95% confidence interval: 0.6–2.6), corresponding to 132 million (57–239 million) people. Risk of thiamin deficiency could rise by 0.7 points (0.3–1.1) or 67 million people (30–110 million), and riboflavin deficiency by 0.4 points (0.2–0.6) or 40 million people (22–59 million). Because elevated CO2 concentrations are likely to reduce B vitamins in other crops beyond rice, our findings likely represent an underestimate of the impact of anthropogenic CO2 emissions on sufficiency of B vitamin intake.

Effect of micro-climate variations on carbonation rate of concrete in the inland environment

In an inland environment, carbonation is the primary cause of initiation for potential corrosion of steel in reinforced concrete. This problem has been exacerbated over recent years by increased urbanisation and vehicular traffic, resulting in higher atmospheric carbon dioxide contents – a problem typical of economically active cities throughout the world. It is important that designers of reinforced concrete structures respond to these variations through appropriate specifications to ensure that structures perform satisfactorily over their intended service lives. This paper is part of a study undertaken to assess the carbonation of concretes exposed to a range of micro-climate variations in inland environments, particularly with variations in carbon dioxide content, temperature and relative humidity conditions with the intent of developing a prediction model for the rate of carbonation. Concretes samples were prepared using three binder types representing variations of blends with FA, GGBS and four w/b ratios ranging from 0.4 to 0.75 and subjected to different degrees of initial water curing (3, 7, 28 days). These samples were placed in three exposure conditions: indoors in laboratory air, outdoors sheltered from rain and sun and outdoors fully exposed to the elements. The depths of carbonation of these samples were monitored over a period of 24 months in order to determine the rates of carbonation. Concrete samples in the outdoor sheltered sites presented the highest rate of carbonation. Although samples in this exposure site carbonated faster, the risk of reinforcement corrosion is likely to be low because the samples are protected from direct moisture effect. Keywords: Carbonation, Corrosion, Reinforced concrete, Micro climate, Inland environments

Changes due to high oxygen and high carbon dioxide atmospheres on the general quality and the polyphenolic profile of strawberries

The aim of this work was to study and model the effects of refrigerated storage with high O2 and high CO2 atmospheres (70 kPa O2 + 20 kPa CO2 and 90 kPa O2 + 10 kPa CO2) on microbial growth, general quality attributes, and the polyphenolic compound profile of fresh strawberries. The storage of samples in 70 kPa O2 + 20 kPa CO2 controlled microbiological decay and slightly affected soluble solids and pH values for 20 d at 5 °C. Moreover, vitamin C and proanthocyanidin contents of these samples were kept almost constant throughout the storage period. Samples in 90 kPa O2 + 10 kPa CO2 controlled microbiological decay for 12 d at 5 °C, soluble solids and pH values were slightly affected, and vitamin C and proanthocyanidin contents experienced up to 15% decrease during this period. However, anthocyanins underwent a substantial increase during the first 3–5 d of storage in these samples. The highest anthocyanin accumulations occurred for pelargonidin-3-O-glucoside, pelargonidin-3-O-rutinoside, and pelargonidin-3-O-acetylglucoside, which increased by 68%, 132%, and 167%, respectively over their initial values at 5 d. Thereafter, anthocyanins content decreased gradually or remained even higher than their initial values at 12 d. This behavior was associated with a physiological response to stress and was not seen for strawberries stored at 70 kPa O2 + 20 CO2, probably due to its higher CO2 concentration which was deleterious for anthocyanin stability. Flavonols, phenolic acids, and ellagitannins also experienced increases up to 130% at 5–12 d of storage in samples exposed to both atmospheres. The changes in general quality attributes were fitted with zero or first-order kinetics, and changes in individual phenolic compounds were adequately fitted with a consecutive reaction mechanism kinetic model.

Dynamics of morpho-physiological characteristics of Cassia tora L. (Fabaceae) in oil field pollution stress environment

Flaring of natural gas is an environmental degrading phenomena and effect on texture of the atmosphere. Higher atmospheric carbon dioxide (CO2) changes plant morphological as well as biochemical composition, leading to nitrogen limitation for the plant. Cassia tora, a common weed, was selected to measure the impact of gas flaring in two group gathering stations (GGSs) of Sivasagar district of Assam, India. Epidermal peels as well as scanning electron microscopy observation revealed possible changes in leaf epidermal traits of the plant. CO2 was recorded as the dominant atmospheric gases in nearby areas of gas flaring sites. Apart from this, significant reduction in nitrogen (%), specific leaf area (SLA) (mm2 mg−1), chlorophyll (mg−g) and stomatal pore length (µm) as well as increases in leaf dry matter content (LDMC), leaf thickness (mm) and carbon percentage of C. tora were recorded under CO2 stress environment at both the GGSs. Simulation studies conducted under open-top chamber (OTC) also revealed similar trend.

Communication: Photoinduced carbon dioxide binding with surface-functionalized silicon quantum dots.

Nowadays, the search for efficient methods able to reduce the high atmospheric carbon dioxide concentration has turned into a very dynamic research area. Several environmental problems have been closely associated with the high atmospheric level of this greenhouse gas. Here, a novel system based on the use of surface-functionalized silicon quantum dots (sf-SiQDs) is theoretically proposed as a versatile device to bind carbon dioxide. Within this approach, carbon dioxide trapping is modulated by a photoinduced charge redistribution between the capping molecule and the silicon quantum dots (SiQDs). The chemical and electronic properties of the proposed SiQDs have been studied with a Density Functional Theory and Density Functional Tight-Binding (DFTB) approach along with a time-dependent model based on the DFTB framework. To the best of our knowledge, this is the first report that proposes and explores the potential application of a versatile and friendly device based on the use of sf-SiQDs for photochemically activated carbon dioxide fixation.

Constraints to Vegetable Production Resulting from Pest and Diseases Induced by Climate Change and Globalization: A Review

Vegetable production worldwide is constrained by pests and diseases which effects are exacerbated by climate change and variability. Greenhouse gas emissions are also increasing due to poor agricultural practices and other human activities. This will continue to have a negative impact on the prevalence of insect pests and diseases. This review focuses on the climatic factors that impact on insect pests and diseases of vegetable crops. High atmospheric temperatures and elevated carbon dioxide increases pest development, survival of pests and distribution of pest to new areas. The distribution of insect pests and diseases are not due to climate changes only but are also a result of globalisation and poor biosecurity measures at country borders. There is limited information on the distribution of pests and diseases due to globalisation in African countries. New exotic pests will continue to be introduced to countries if biosecurity measures are not improved. Future research must focus on how to manage emerging pests and diseases influenced by high temperatures and carbon dioxide and other climatic conditions which influence pest severity under smallholder farmers in the southern African regions.

Building facade failures in the urban environment

In the urban environment, building facades can be exposed to conditions that are not present in other environments. These include acid rain, higher atmospheric carbon dioxide and other agents that can deteriorate or attack the facades of city buildings or other urban structures. Sulfurous, sulfuric and nitric acids present in polluted air dissolve calcite minerals in marble and limestone facades or in concrete and mortar aggregates. Harsh cleaning chemicals or methods used to wash away city soil and soot can damage facades. Sealants can degrade and discolour from airborne deposits and contaminants. Facades may suffer impact and abuse from adjacent building construction activities. While failure of building facades or their connections can result from countless causes, the extent and consequences of such failures are often exacerbated by pollutants and chemicals that are commonly present in the urban environment. This paper addresses special considerations, conditions and risks that are associated with building facade failures in cities. The majority of urban facade failure descriptions and cases presented in this paper are based on the author’s experience in the USA.