Climatic Variations And Forcing Mechanisms Of The Last 2000 Years

A profound knowledge of the past climate is vital for our understanding of global warming. The past 2000 years are both the period which is of most relevance to the next century and that for which there is the most evidence. High-resolution proxy records for this period are available from a variety of sources. Five sections consider dendroclimatology, ice cores, corals, historical records, lake varves, and other indicators. The final two sections cover the histories of various forcing factors and attempt to bring together records from a variety of sources and provide explanations.

In response to a request from Congress, Surface Temperature Reconstructions for the Last 2,000 Years assesses the state of scientific efforts to reconstruct surface temperature records for Earth during approximately the last 2,000 years and the implications of these efforts for our understanding of global climate change. Because widespread, reliable temperature records are available only for the last 150 years, scientists estimate temperatures in the more distant past by analyzing "proxy evidence," which includes tree rings, corals, ocean and lake sediments, cave deposits, ice cores, boreholes, and glaciers. Starting in the late 1990s, scientists began using sophisticated methods to combine proxy evidence from many different locations in an effort to estimate surface temperature changes during the last few hundred to few thousand years. This book is an important resource in helping to understand the intricacies of global climate change.

A multidecadal cooling is known to have occurred in Europe in the final decades of the sixteenth-century. It is still open to debate as to what might have caused the underlying shifts in atmospheric circulation and how these changes affected societies. This book is the fruit of interdisciplinary cooperation among 37 scientists including climatologists, hydrologists, glaciologists, dendroclimatologists, and economic and cultural historians. The known documentary climatic evidence from six European countries is compared to results of tree-ring studies. Seasonal temperature and precipitation are estimated from this data and monthly mean surface pressure patterns in the European area are reconstructed for outstanding anomalies. Results are compared to fluctuations of Alpine glaciers and to changes in the frequency of severe floods and coastal storms. Moreover, the impact of climate change on grain prices and wine production is assessed. Finally, it is convincingly argued that witches at that time were burnt as scapegoats for climatic change.

Changes in climate are driven by natural and human-induced perturbations of the Earth's energy balance. These climate drivers or "forcings" include variations in greenhouse gases, aerosols, land use, and the amount of energy Earth receives from the Sun. Although climate throughout Earth's history has varied from "snowball" conditions with global ice cover to "hothouse" conditions when glaciers all but disappeared, the climate over the past 10,000 years has been remarkably stable and favorable to human civilization. Increasing evidence points to a large human impact on global climate over the past century. The report reviews current knowledge of climate forcings and recommends critical research needed to improve understanding. Whereas emphasis to date has been on how these climate forcings affect global mean temperature, the report finds that regional variation and climate impacts other than temperature deserve increased attention.

Many factors contribute to variability in Earth's climate on a range of timescales, from seasons to decades. Natural climate variability arises from two different sources: (1) internal variability from interactions among components of the climate system, for example, between the ocean and the atmosphere, and (2) natural external forcings, such as variations in the amount of radiation from the Sun. External forcings on the climate system also arise from some human activities, such as the emission of greenhouse gases (GHGs) and aerosols. The climate that we experience is a combination of all of these factors. Understanding climate variability on the decadal timescale is important to decision-making. Planners and policy makers want information about decadal variability in order to make decisions in a range of sectors, including for infrastructure, water resources, agriculture, and energy. In September 2015, the National Academies of Sciences, Engineering, and Medicine convened a workshop to examine variability in Earth's climate on decadal timescales, defined as 10 to 30 years. During the workshop, ocean and climate scientists reviewed the state of the science of decadal climate variability and its relationship to rates of human-caused global warming, and they explored opportunities for improvement in modeling and observations and assessing knowledge gaps. Frontiers in Decadal Climate Variability summarizes the presentations and discussions from the workshop.

The climate record for the past 100,000 years clearly indicates that the climate system has undergone periodic-and often extreme-shifts, sometimes in as little as a decade or less. The causes of abrupt climate changes have not been clearly established, but the triggering of events is likely to be the result of multiple natural processes. Abrupt climate changes of the magnitude seen in the past would have far-reaching implications for human society and ecosystems, including major impacts on energy consumption and water supply demands. Could such a change happen again? Are human activities exacerbating the likelihood of abrupt climate change? What are the potential societal consequences of such a change? Abrupt Climate Change: Inevitable Surprises looks at the current scientific evidence and theoretical understanding to describe what is currently known about abrupt climate change, including patterns and magnitudes, mechanisms, and probability of occurrence. It identifies critical knowledge gaps concerning the potential for future abrupt changes, including those aspects of change most important to society and economies, and outlines a research strategy to close those gaps. Based on the best and most current research available, this book surveys the history of climate change and makes a series of specific recommendations for the future.

This multi-authored book provides an updated description of climate variability in the Mediterranean basin, focusing on decadal and centennial time scales and on the results available on the impact of future emission scenarios at regional scale. The authors describs both local physical processes responsible for these variability - such as changes in the surface properties and land use- and globalprocesses - such as changes in the large scale atmospheric circulation associated to global warming, NAO, tropical monsoon and ENSO. Regional climate change issues are also addressed. Mediterranean Climate Variability aims to review the research on this region and to provide at the same time both an introduction and a reference for researchers. It covers topics typical of Climatology, Climate history, Meteorology, Oceanography, Environmental Science but the information here provided would also be useful for research in agriculture, social and economic studies. It is addressed to scientists and students interested in the Mediterranean climate and environment. Some topics have interesting connections to nearby regions: Northern Atlantic, West Africa, central and Eastern Europe. Each chapter will contain a summary meant to provide information to policy makers, researchers from other fields, and in general to a wide audience without a technical expertise on climate. * Provides an updated analysis of the Mediterranean climate features and guidelines for future research * Considers both oceanographic and atmospheric aspects * Analyzes the Mediterranean climate in a global perspective

Describes the effect of human action on the world's environment.