52,611 research outputs found
The Consequences of Increasing Ocean Acidification on Local and Global Fishing Industries
As human activities continue to generate accelerating levels of carbon dioxide emissions, the worldâs oceanic resources are threatened by variability in seawater chemistry, known as ocean acidification. Recent increases in atmospheric carbon dioxide have resulted in decreased carbonate ion concentrations and ocean pH levels, leading to increasingly acidic waters. The exact consequences of these chemical changes on ecosystems and individual species are difficult to predict; however, research has shown that economically valuable calcifying species will experience reduced reproductive fitness and population declines. Ocean acidification, therefore, poses an immediate risk to both fish stocks and fishery industries. From a local perspective, individual regions will need to implement dynamic management strategies to prepare for anticipated economic consequences. In a global context, international cooperation is required for further research and collaborative efforts must be made to reduce future acidification
Geoengineering and Non-Ideal Theory
The strongest arguments for the permissibility of geoengineering (also known as climate engineering) rely implicitly on non-ideal theoryâroughly, the theory of justice as applied to situations of partial compliance with principles of ideal justice. In an ideally just world, such arguments acknowledge, humanity should not deploy geoengineering; but in our imperfect world, society may need to complement mitigation and adaptation with geoengineering to reduce injustices associated with anthropogenic climate change. We interpret research proponentsâ arguments as an application of a particular branch of non-ideal theory known as âclinical theory.â Clinical theory aims to identify politically feasible institutions or policies that would address existing (or impending) injustice without violating certain kinds of moral permissibility constraints. We argue for three implications of clinical theory: First, conditional on falling costs and feasibility, clinical theory provides strong support for some geoengineering techniques that aim to remove carbon dioxide from the atmosphere. Second, if some kinds of carbon dioxide removal technologies are supported by clinical theory, then clinical theory further supports using those technologies to enable âovershootâ scenarios in which developing countries exceed the cumulative emissions caps that would apply in ideal circumstances. Third, because of tensions between political feasibility and moral permissibility, clinical theory provides only weak support for geoengineering techniques that aim to manage incoming solar radiation
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Atmospheric effects of the emerging mainland Chinese transportation system at and beyond the regional scale
Local surface travel needs in the People's Republic of China (mainland China) have traditionally been met largely by nonpolluting bicycles. A major automobile manufacturing/importing effort has begun in the country over the last decade, and planning documents indicate that the Chinese may strive to acquire more than 100 million vehicles early in the next century. By analogy with large automotive fleets already existing in the western world, both regional and global scale pollution effects are to be expected from the increase. The present work adopts the latest projections of Chinese automobile manufacture and performs some quantitative assessments of the extent of pollution generation. Focus for the investigation is placed upon the oxidant ozone. Emissions of the precursor species nitrogen oxides and volatile organics are constructed based on data for the current automotive sector in the eastern portion of the United States. Ozone production is first estimated from measured values for continental/oceanic scale yields relative to precursor oxidation. The estimates are then corroborated through idealized two dimensional modeling of the photochemistry taking place in springtime air flow off the Asian land mass and toward the Pacific Ocean. The projected fleet sizes could increase coastal and remote oceanic ozone concentrations by tens of parts per billion (ppb) in the lower troposphere. Influences on the tropospheric aerosol system and on the major greenhouse gas carbon dioxide are treated peripherally. Nitrogen oxides created during the vehicular internal combustion process will contribute to nitrate pollution levels measured in the open Pacific. The potential for soot and fugitive dust increases should be considered as the automotive infrastructure develops. Since the emerging Chinese automotive transportation system will represent a substantial addition to the global fleet and all the carbon in gasoline is eventually oxidized completely, a significant rise in global carbon dioxide inputs will ensue as well. Some policy issues are treated preliminary. The assumption is made that alterations to regional oxidant/aerosol systems and to terrestrial climate are conceivable. The likelihood that the Chinese can achieve the latest vehicle fleet goals is discussed, from the points of view of new production, positive pollution feedbacks from a growing automobile industry, and known petroleum reserves. Vehicular fuel and maintenance options lying before the Chinese are outlines and compared. To provide some perspective on the magnitude of the environmental changes associated with an Asian automotive buildup, recent estimates of the effects of future air traffic over the Pacific Rim are described
No way out? The double-bind in seeking global prosperity alongside mitigated climate change
In a prior study, I introduced a simple economic growth model designed to be
consistent with general thermodynamic laws. Unlike traditional economic models,
civilization is viewed only as a well-mixed global whole with no distinction
made between individual nations, economic sectors, labor, or capital
investments. At the model core is an observationally supported hypothesis that
the global economy's current rate of primary energy consumption is tied through
a constant to a very general representation of its historically accumulated
wealth. Here, this growth model is coupled to a linear formulation for the
evolution of globally well-mixed atmospheric CO2 concentrations. While very
simple, the coupled model provides faithful multi-decadal hindcasts of
trajectories in gross world product (GWP) and CO2. Extending the model to the
future, the model suggests that the well-known IPCC SRES scenarios
substantially underestimate how much CO2 levels will rise for a given level of
future economic prosperity. For one, global CO2 emission rates cannot be
decoupled from wealth through efficiency gains. For another, like a long-term
natural disaster, future greenhouse warming can be expected to act as an
inflationary drag on the real growth of global wealth. For atmospheric CO2
concentrations to remain below a "dangerous" level of 450 ppmv, model forecasts
suggest that there will have to be some combination of an unrealistically rapid
rate of energy decarbonization and nearly immediate reductions in global
civilization wealth. Effectively, it appears that civilization may be in a
double-bind. If civilization does not collapse quickly this century, then CO2
levels will likely end up exceeding 1000 ppmv; but, if CO2 levels rise by this
much, then the risk is that civilization will gradually tend towards collapse
Box Models of Volatile Cycles over the Entire Phanerozoic
Three stand-alone geochemical box models have been developed to simulate globally coupled biogeochemical cycles. These models reflect the evolution of the participating biotic and abiotic constituents in marine and terrestrial environments, including the lower atmosphere. The single models focus on the calculation of: 1) the chemical evolution of seawater, 2) the atmospheric methane concentration, and 3) the concentration of oxygen in surface and deep ocean water over the entire Phanerozoic (570 Ma). The models are driven by geological and evolutionary forcings and are controlled by proxy data. Internal feedback is provided by model outputs serving as input to other model components. The Phanerozoic biogeochemical evolution of seawater (dissolved inorganic carbon, alkalinity, nutrients, and oxygen), its isotope sulfur and carbon composition, as well as the atmospheric partial pressures of oxygen (pO2), carbon dioxide (pCO2), and methane (pCH4) are calculated by standard runs of the individual models
Atmospheric Evolution
Earth's atmosphere has evolved as volatile species cycle between the
atmosphere, ocean, biomass and the solid Earth. The geochemical, biological and
astrophysical processes that control atmospheric evolution are reviewed from an
"Earth Systems" perspective, with a view not only to understanding the history
of Earth, but also to generalizing to other solar system planets and
exoplanets.Comment: 34 pages, 3 figures, 2 tables. Accepted as a chapter in
"Encyclopaedia of Geochemistry", Editor Bill White, Springer-Nature, 201
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Airborne observations of the tropospheric CO2 distribution and its controlling factors over the South Pacific Basin
Highly precise measurements of CO2 mixing ratios were recorded aboard both the NASA DC-8 and P3-B aircraft during the Pacific Exploratory Mission-Tropics conducted in August-October 1996. Data were obtained at altitudes ranging from 0.1 to 12 km over a large portion of the South Pacific Basin representing the most geographically extensive CO2 data set recorded in this region. These data along with CO2 surface measurements from the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) and the National Institute of Water and Atmospheric Research (NIWA) were examined to establish vertical and meridional gradients. The CO2 spatial distribution in the southern hemisphere appeared to be largely determined by interhemispheric transport as air masses with depleted CO2 levels characteristic of northern hemispheric air were frequently observed south of the Intertropical Convergence Zone. However, regional processes also played a role in modulating background concentrations. Comparisons of CO2 with other trace gases indicated that CO2 values were influenced by continental sources. Large scale plumes from biomass burning activities produced enhanced CO2 mixing ratios within the lower to midtroposphere over portions of the remote Pacific. An apparent CO2 source was observed in the NOAA/ CMDL surface data between 15° N and 15° S and in the lower altitude flight data between 8° N and 8.5° S with a zone of intensity from 6.5° N to 1° S. Inferred from these data is the presence of a Southern Ocean sink from south of 15° S having two distinct zones seasonally out of phase with one another. Copyright 1999 by the American Geophysical Union
Assessing a New Clue to How Much Carbon Plants Take Up
Current climate models disagree on how much carbon dioxide land ecosystems take up for photosynthesis. Tracking the stronger carbonyl sulfide signal could help
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