Pontus Lurcock and Fabio Florindo
Antarctic climate changes have been reconstructed from ice and sediment cores and numerical models (which also predict future changes). Major ice sheets first appeared 34 million years ago (Ma) and fluctuated throughout the Oligocene, with an overall cooling trend. Ice volume more than doubled at the Oligocene-Miocene boundary. Fluctuating Miocene temperatures peaked at 17–14 Ma, followed by dramatic cooling. Cooling continued through the Pliocene and Pleistocene, with another major glacial expansion at 3–2 Ma. Several interacting drivers control Antarctic climate. On timescales of 10,000–100,000 years, insolation varies with orbital cycles, causing periodic climate variations. Opening of Southern Ocean gateways produced a circumpolar current that thermally isolated Antarctica. Declining atmospheric CO2 triggered Cenozoic glaciation. Antarctic glaciations affect global climate by lowering sea level, intensifying atmospheric circulation, and increasing planetary albedo. Ice sheets interact with ocean water, forming water masses that play a key role in global ocean circulation.
Joan Martí Molist
Volcanoes represent complex geological systems capable of generating many dangerous phenomena. To evaluate and manage volcanic risk, we need first to assess volcanic hazard (i.e., identify past volcanic system behavior to infer future behavior. This requires acquisition of all relevant geological and geophysical information, such as stratigraphic studies, geological mapping, sedimentological studies, petrologic studies, and structural studies. All this information is then used to elaborate eruption scenarios and hazard maps. Stratigraphic studies represent the main tool for the reconstruction of past activity of volcanoes over time periods exceeding their historical record. This review presents a systematic approach to volcanic hazard assessment, paying special attention to reconstruction of past eruptive history. It reviews concepts and methods most commonly used in long- and short-term hazard assessment and analyzes how they help address the various serious consequences derived from the occurrence (and nonoccurrence in some crisis alerts) of volcanic eruptions and related phenomena.
Eduardo Marone, Ricardo de Camargo, and Julio Salcedo Castro
This article describes the threat costal hazards pose to existing life in light of climate change and natural disaster. It includes an overview of flooding, extreme waves, and other water-related stressors. The article discusses how human-induced risks in the coastal zone, resulting from mismanaged urbanization, persistent pollution, and overexploitation of resources, exacerbate matters and pose extra pressure on the environment, science, and society. Ways of measurement and reaction to these events, as well as best practices for preparedness, are discussed. Businesses, individuals, and ecosystems are under threat of destruction from these circumstances. The article also emphasizes the need to make scientific work in this field accessible and understandable to society and decisión makers.
This article discusses the importance of assessing and estimating the risk of earthquakes. It begins with an overview of earthquake prediction and relevant terms, namely: earthquake hazard, maximum credible earthquake magnitude, exposure time, earthquake risk, and return time. It then considers data sources for estimating seismic hazard, including catalogs of historic earthquakes, measurements of crustal deformation, and world population data. It also examines ways of estimating seismic risk, such as the use of probabilistic estimates, deterministic estimates, and the concepts of characteristic earthquake, seismic gap, and maximum rupture length. A loss scenario for a possible future earthquake is presented, and the notion of imminent seismic risk is explained. Finally, the chapter addresses errors in seismic risk estimates and how to reduce seismic risk, ethical and moral aspects of seismic risk assessment, and the outlook concerning seismic risk assessment.
Physical Mechanisms Responsible for Track Changes and Rainfall Distributions Associated with Tropical Cyclone Landfall
Johnny C.L. Chan
As a tropical cyclone approaches land, its interaction with the characteristics of the land (surface roughness, topography, moisture availability, etc.) will lead to changes in its track as well as the rainfall and wind distributions near its landfall location. Accurate predictions of such changes are important in issuing warnings and disaster preparedness. In this chapter, the basic physical mechanisms that cause changes in the track and rainfall distributions when a tropical cyclone is about to make landfall are presented. These mechanisms are derived based on studies from both observations and idealized simulations. While the latter are relatively simple, they can isolate the fundamental and underlying physical processes that are inherent when an interaction between the land and the tropical cyclone circulation takes place. These processes are important in assessing the performance of the forecast models, and hence could help improve the model predictions and subsequently disaster preparedness.
Howard B. Bluestein
In the past four decades much has been discovered about tornado formation and structure from observations, laboratory models, and numerical-simulation experiments. Observations include nearby movies and photographs of tornadoes, fixed-site, airborne, and ground-based mobile Doppler radar remote measurements, and in situ measurements using instrumented probes. Laboratory models are vortex chambers and numerical-simulations are based on the governing fluid dynamical equations. However, questions remain: How and why do tornadoes form? and How does the wind field associated with them vary in space and time? Recent studies of tornadoes based on observations, particularly by radar, are detailed. The major aspects of numerically simulating a tornado and its formation are reviewed, and the dynamics of tornado formation and structure based on both observations and laboratory and numerical-simulation experiments are described. Finally, future avenues of research and suggested instrument development for furthering our knowledge are discussed.
This work reports on the main physical processes that arise in the environment of the megacity from the “urban metabolism”—the complex interactions of the climate with the activities performed in the city and its built structure and texture—as well as on associated large-scale processes that generate hazards for the megacity’s inhabitants. It is estimated that in a few decades most of the world’s population will live in urban centers. Both the growth of megacities and climate change will increase the vulnerability of huge sectors of the population to climatic consequences of the urban metabolism. These include urban heat islands, pollution, and extreme weather events such as heat waves and floods. Developing policies to mitigate these threats will require integrating scientific knowledge with management skills, communication among cities about effective approaches, and taking into account residents’ needs for health and the capacity to live safely.