Advances in Earth Science outlines the latest developments and new research directions currently being made world-wide in the earth sciences. It contains invited and refereed articles by leading younger researchers on their cutting-edge research, but aimed at a general scientific audience.
This exciting volume explains how powerful methodologies such as satellite remote sensing and supercomputing simulations are now profoundly changing research in the earth sciences; how the earth system is increasingly being viewed in a holistic way, linking the atmosphere, ocean and solid earth; and how the societal impact of the research in the earth sciences has never been more important.
Published by Imperial College Press in collaboration with the Royal Society of London, the book features many articles originating from invited papers published in the Philosophical Transactions of the Royal Society. Eleven of the distinguished contributors hold prestigious Royal Society Research Fellowships.
Sample Chapter(s)
Chapter 1: Introduction (102 KB)
https://doi.org/10.1142/9781860948718_fmatter
The following sections are included:
https://doi.org/10.1142/9781860948718_0001
Economics and climate change science have a lot in common. Both rely on sound predictions of what the future will bring, these being largely based on what has gone before. Just, though, as you can only make an educated guess at what the housing market will do next year, you cannot be wholly sure how emissions of greenhouse gas will increase in years to come, and exactly how the planet's climate will then react. Bring all these unknowns together, by attempting on the one hand to calculate the economic impacts of climate change and on the other the costs of climate change mitigation, and the range of possible outcomes is almost limitless. Given such uncertainty, both the environmental lobby and the oil lobby can use economic arguments to justify their differing stance on climate change mitigation.
Existing cost-benefit analyses of greenhouse gas reduction policies are examined, with a view to establishing whether any such global reductions are currently worthwhile. The potential for, and costs of, cutting our own individual greenhouse gas emissions is also assessed. I find that a host of abatement strategies are able to deliver significant emission reductions at little or no net cost when the full economic impacts of climate change are considered. Additionally, I find that there is great potential for individuals to simultaneously reduce their climate impact and save money. I conclude that the use of economics to excuse political inaction on greenhouse gas emissions is not justified.
https://doi.org/10.1142/9781860948718_0002
The release of carbon dioxide from fossil fuel combustion and land use change has caused a significant perturbation on the natural cycling of carbon between land, atmosphere and oceans. The perturbation of the carbon cycle, and other aspects of global biogeochemical cycle, is so large and fundamental that it has been suggested the Earth has entered a new geological epoch, the Anthropocene, characterised by overwhelming human perturbation of global biogeochemistry. Understanding and managing the effects of this perturbation are likely to be amongst the most pressing issues of the twenty first century. However, the present-day carbon cycle is still poorly understood. One remarkable feature is that an increasing amount of atmospheric carbon dioxide appears to be being absorbed by terrestrial vegetation.
In this paper I review the recent evidence for the magnitude and spatial distribution of this "terrestrial carbon sink", drawing on (i) current research on the global atmospheric distribution and transport of carbon dioxide, oxygen and their isotopes (ii) direct measurement of CO2 fluxes above various biomes, and (iii) inventories of forest biomass and composition. I review the likely causes of these carbon sinks and sources, and their implications for the ecology and stability of these biomes.
Finally, I examine prospects and key issues over coming decades. Controlling deforestation and managing forests has the potential to play a significant but limited part in reaching the goal of stabilising atmospheric CO2 concentrations. However, there are likely limits to the amount of carbon storage possible in natural vegetation and in the long term terrestrial carbon storage may unstable to significant global warming, with the potential to accelerate rather than brake global warming.
https://doi.org/10.1142/9781860948718_0003
Understanding the response of the Earth's climate system to anthropogenic perturbation is a pressing priority for society. To be successful in this enterprise we need to analyse climate change within an all-encompassing "Earth system" framework; the suite of interacting physical, chemical, biological, and human processes that, in transporting and transforming materials and energy jointly determine the conditions for life on the whole planet. To illustrate the integrative thinking that is required we review the diverse roles played by atmospheric transport of mineral 'dust', particularly in its capacity as a key pathway for the delivery of nutrients essential to plant growth, not only on land, but more importantly, in the ocean. Here, the global importance of dust arises because of the control it exerts on marine plant productivity and thus the uptake of CO2 from the atmosphere. The complex way in which dust biogeochemically links land, air, and sea presents us with new challenges in understanding climate change and forces us to ask questions that transcend the traditional scientific disciplines.
https://doi.org/10.1142/9781860948718_0004
The extinction event at the close of the Permian period was the largest of the Phanerozoic. Understanding this event is crucial to understanding the history of life on Earth, and the past decade has witnessed a dramatic increase in the number of publications relating to this event. Four main areas of research and debate are considered to be the reason for the recent surge in scientific interest. These are (1) issues of dating and stratigraphy, (2) potential causes (specifically the debate of extra-terrestrial impact versus volcanically triggered global warming), (3) the patterns and rate of extinction, and (4) the nature of the post-extinction recovery. These key research areas are outlined below.
https://doi.org/10.1142/9781860948718_0005
In 1986 Austen et al. proposed that a technique from medical imaging, tomography, could be used to image the Earth's ionosphere. Tomography was already very successful in creating images of the inside organs of human bodies by the mathematical manipulation of a series of X-ray measurements taken from multiple viewing angles around the body. The new idea was to use multiple satellite-to-ground radio signals to produce snapshots of the Earth's ionised environment. Tomography has now progressed into a technique for imaging the ionised plasma around the entire Earth. It is now feasible to create real-time movies of the ionised plasma, allowing us to watch the results of our planet's bombardment by the solar wind during events known as storms. The vision of the pioneering scientist Sir Edward V. Appleton for 'Ionospheric Weather' forecasting [1947], now a topical issue under the 'space weather' umbrella, is on the verge of being realised through new imaging-modelling approaches known as assimilation. It is becoming clear that ionospheric forecasting cannot be improved without storm warnings and consequently new research projects to link together models of the entire solar-terrestrial system, including the Sun, solar wind, magnetosphere, ionosphere and thermosphere, are now being proposed. The prospect is on the horizon of assimilating data from not just the ionosphere but the whole solar-terrestrial system to produce a real-time computer model and 'space weather' forecast. The application of tomographic imaging far beyond the ionosphere to include the whole near-Earth space plasma realm and possibly that of other planets is a likely possibility for the future.
https://doi.org/10.1142/9781860948718_0006
We are now able to simulate a dynamic rupture process of real earthquakes, once the fault geometry, stress field applied to the fault, and friction law on the fault surface have been provided. The next question will be what kind of information is now available and what are still required to reproduce more realistic rupture process of earthquakes. This procedure will provide us with physical insights of earthquake dynamics as well as clues to predicting the fault rupture of future earthquakes. In this paper, I review how to simulate earthquake dynamic rupture based on available information.
https://doi.org/10.1142/9781860948718_0007
Time scales and rates of change are fundamental to an understanding of natural processes in the Earth sciences. Short-lived U-series isotope studies are revolutionising this field by providing time information in the range 102–104 years. Here I review how their application has been used to constrain the time scales of magma formation, ascent and storage beneath island arc volcanoes. Different elements are distilled-off the subducting plate at different times and in different places. Contributions from subducted sediments to island arc lava sources appear to occur some 350 kyr to 4 Myr prior to eruption. Fluid release from the subducting oceanic crust into the mantle wedge may be multi-stage and occurs over a period ranging from a few 100 kyr, to < 1 kyr, prior to eruption. This implies that dehydration commences prior to the initiation of partial melting within the mantle wedge consistent with recent evidence that the onset of melting is controlled by an isotherm and thus the thermal structure within the wedge. Furthermore, time scales of only a few kyr require a rapid fluid transfer mechanism, such as hydrofracture. U-Pa disequilibria reflect the partial melting process, rather than fluid addition, and indicate that the matrix is moving through the melt region. The preservation of large 226Ra disequilibria permit only a few kyr between fluid addition and eruption. This requires rapid melt segregation, magma ascent by channelled flow at 100–1000's m/yr and minimal residence time within the lithosphere. The evolution from basalt to basaltic-andesite probably occurs rapidly during ascent. Some magmas subsequently stall in more shallow crustal level magma chambers where they evolve to more differentiated compositions on time scales of a few 1000 yrs or less. Degassing typically occurs for a few decades prior to eruption but may not drive major compositional evolution of the magmas.
https://doi.org/10.1142/9781860948718_0008
Rifted continental margins are the product of stretching, thinning and, ultimately, breakup of a continental plate into smaller fragments. The rocks lying beneath them store a record of this rifting process. Earth scientists can read this record by direct sampling and with remote geophysical techniques. These experimental studies have been complemented by theoretical analyses of continental extension and associated melting of the mantle. Some rifted margins show evidence for extensive volcanic activity and uplift during rifting; at these margins, the record of the final stages of rifting is obscured by erosion and by the thick volcanic cover. Other margins have been underwater throughout their formation and have had rather little volcanic activity; here the ongoing deposition of sediment provides a clearer record. During the last decade, vast areas of exhumed mantle rocks have been discovered at such margins between continental and oceanic crust. This observation conflicts with well-established ideas that the mantle melts to produce new crust when brought close to the Earth's surface. In contrast to the steeply dipping faults commonly seen in zones of extension within continental interiors, faults with very shallow dips play a key role in the deformation immediately preceding continental breakup. Future progress in the study of continental breakup will depend on studies of pairs of margins that were once joined, and on the development of computer models which can handle rigorously the complex transition from distributed continental deformation to seafloor spreading focussed at a mid-ocean ridge.
https://doi.org/10.1142/9781860948718_0009
We review recent advances in the study of the Earth's iron core, focussing on three areas: The properties of the core-forming materials, the manner in which core motions generate the Earth's magnetic field (the dynamo), and the evolution of both the core and the dynamo. Ab initio computer simulations of the behaviour of iron alloys under core conditions suggest that the inner (solid) and outer (liquid) core contain 8% sulphur/silicon, and 8–10% sulphur/silicon plus 8–13% oxygen, respectively. The inner core boundary for these materials is at ~5500 K. Although computer simulations of the dynamo lack sufficient resolution to match likely terrestrial parameter values, such models can now reproduce the spatial and temporal behaviour of the observed magnetic field. The present-day dynamo occurs because the mantle is extracting heat from the core (at a rate of 9 ± 3 TW); the resulting inner core growth drives core convection and implies a young inner core age (< 1.5Gyr). A long-lived dynamo requires rapid core cooling, which tends to result in an inner core larger than that observed. A possible solution to this paradox is that radioactive potassium may reside in the core. We also briefly review the current state of knowledge for cores and dynamos in other planetary bodies.
https://doi.org/10.1142/9781860948718_0010
When whole mountainsides collapse, they feed giant landslides that travel kilometres within minutes. Their size and speed prevent effective hazard mitigation after collapse. Risk reduction therefore depends on advance warning of collapse, as well as assessment of how far such a landslide might travel. Early studies invoked special mechanisms to explain catastrophic collapse and runout. It is now apparent, however, that their core behaviour can be explained in terms of common physical processes, from accelerating crack growth before failure to pressurised granular flow during transport. Nevertheless, as mountainous districts become more populated, new data are required to enhance current methods of evaluating the threat from giant catastrophic collapse.
https://doi.org/10.1142/9781860948718_0011
The earthquake cycle is poorly understood. Earthquakes continue to occur on previously unrecognised faults. Earthquake prediction seems impossible. These remain the facts despite nearly a hundred years of intensive study since the earthquake cycle was first conceptualised. Using data acquired from satellites in orbit 800 km above the Earth, a new technique, radar interferometry (InSAR) has the potential to solve these problems. For the first time, detailed maps of the warping of the earth's surface during the earthquake cycle can be obtained with a spatial resolution of a few tens of metres and a precision of a few millimetres. InSAR does not need equipment on the ground or expensive field campaigns, so it can gather crucial data on earthquakes and the seismic cycle from some of the remotest areas of the planet. In this article, I review some of the remarkable observations of the earthquake cycle already made using radar interferometry, and speculate on breakthroughs that are tantalisingly close.
https://doi.org/10.1142/9781860948718_0012
The global biogeochemical cycles of several trace metals are presently dominated by human activities, a result of the nature and magnitude of historical resource consumption. Lead has been mined since ancient times, often as a by-product of silver extraction, and has one of the longest associations with man of all heavy metals [Nriagu (1983)]. As of 1983, human activities accounted for an estimated 97% of the global mass balance of lead [Nriagu and Pacyna (1988)]. At that time as well as today, most of the lead was derived from leaded gasoline [Nriagu (1990)], where it was used as an anti-knock agent.
New estimates of anthropogenic sources of lead suggest that the overall burden of anthropogenic lead emissions has decreased but new pollution sources (e.g. China, Mexico) have become important [Pacyna and Pacyna (2001); Pacyna et al. (1995)] leaving anthropogenic Pb emission to remain a global problem and leaded gasoline as the main source. In addition, as metals are not biodegradable, the Pb in the environment has accumulated over the decades and its fate and pathways within the ecosystem need to be investigated.
In a manner similar to chlorofluorocarbons and radionuclides derived from atomic testing, the release of lead into the environment represents an inadvertent geochemical tracer experiment, providing new insights into its fate and transport within marine and terrestrial systems. There have been several review papers and books discussing lead, its historical place in society and its impact on human and environmental health [Boutron (1995); Needleman (1997); Nriagu (1983); Nriagu (1989b); Nriagu (1990); Reuer and Weiss (2002); Shotyk and Le Roux (2005); Weiss et al. (1999)] and the reader is encouraged to refer to these works as well.
https://doi.org/10.1142/9781860948718_0013
The introduction of legislation in the western world over the last 20 years or so requires that poisonous exhaust emissions from cars are reduced. Catalytic converters fitted to exhaust systems make these poisonous gases safer. Now nearly half the world's annual production of platinum (Pt) and palladium (Pd) is being used in the manufacture of catalytic converters. As cars travel around our cities these converters lose Pt and Pd which are ejected onto roads. This creates artificial concentrations of Pt and Pd in the urban environment that is a new addition to the global distribution. We know very little about such concentrations but we know much more about Pt and Pd concentrations in geological settings. Pt and Pd occur naturally at the Earth's surface only in a very few rare locations in rocks formed by an unusual combination of geological processes. The major Pt and Pd deposits were formed by crystallisation of magma which concentrated the metals into specific minor rock units within large igneous intrusions. As these precious metals are very rare on the Earth's surface they are economic at concentrations of only a few parts per million. Recent studies, including those described here, show that values of Pt and Pd accumulating in our cities are approaching values found in natural deposits. Certainly Pt and Pd can be located in road dust at road junctions in the cities in the wealthy western world at levels well above natural background values.
https://doi.org/10.1142/9781860948718_0014
This chapter describes a vision for a future objectively optimised earth observation system with integrated scientific analysis. The system envisioned will dynamically adapt the what, where, and when of the observations made in an online fashion to maximise information content, minimise uncertainty in characterising the systems state vector, and minimise both the required storage and data processing time for a given observation capability. Higher level goals could also be specified such as the remote identification of sites of likely malaria outbreaks. By facilitating the early identification of potential breeding sites of major vector species before a disease outbreak occurs and identifying the locations for larvicide and insecticide applications. This would reduce costs, lessen the chance of developing pesticide resistance, and minimise the damage to the environment. Here we describe a prototype system applied to atmospheric chemistry with two relatively mature symbiotic components that seeks to achieve this goal. One component is the science goal monitor (SGM), the other is an Automatic code generation system for chemical modeling and assimilation (AutoChem) described online at www.AutoChem.info/. The Science Goal Monitor (SGM) is a prototype software tool to determine the best strategies for implementing science goal driven automation in missions. The tools being developed in SGM improve the ability to monitor and react to the changing status of scientific events. The SGM system enables scientists to specify what to look for and how to react in descriptive rather than technical terms. The system monitors streams of science data to identify occurrences of key events previously specified by the scientist. When an event occurs, the system autonomously coordinates the execution of the scientist's desired goals. The data assimilation system can feed multivariate objective measures to the SGM such as information content and system uncertainty so that SGM can schedule suitable observations given the observing system constraints. The observing system may of course be a sensor web suite of assets including orbital and suborbital platforms. Once the observations are made an integrated scientific analysis is performed which automatically produces a cross-linked web site for easy dissemination and to facilitate investigation of the scientific issues. A prototype is available at www.CDACentral.info/.
https://doi.org/10.1142/9781860948718_bmatter
The following sections are included:
Sample Chapter(s)
Chapter 1: Introduction (102k)