نتایج جستجو برای: climate elements

تعداد نتایج: 443615  

2014
Catherine Vaughan Suraje Dessai

Climate services involve the generation, provision, and contextualization of information and knowledge derived from climate research for decision making at all levels of society. These services are mainly targeted at informing adaptation to climate variability and change, widely recognized as an important challenge for sustainable development. This paper reviews the development of climate servi...

2011
Edward W. Sawyer Bernardo Cesare Michael Brown

The continental crust is 41.4 km thick on average and covers 39% of the Earth’s surface. Information from the isotopic and trace element composition of >4-billion-yearold (Ga) zircon grains and the evolution of mantle isotopic reservoirs indicates that 75%, and possibly more, of the continental crust was created before 2.5 Ga (Harrison 2009; Belousova et al. 2010). Thus, the continental crust i...

2002
David S. WHITLEY Ronald I. DORN

A central problem in archaeological research has been the chronometric dating of petroglyphs (rock engravings). Recent improvements in the understanding of the chemistry of rock varnish (or patina) that develops on rock surfaces in arid regions has resulted in the development of a calibrated dating technique, cation-ratio (CR) dating. This is based on calibrating chemical changes in minor and m...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2008
Timothy M Lenton Hermann Held Elmar Kriegler Jim W Hall Wolfgang Lucht Stefan Rahmstorf Hans Joachim Schellnhuber

The term "tipping point" commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term "tipping element" to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic fo...

Journal: :Proceedings of the National Academy of Sciences 2008

Climatic variables are among the factors influencing the performance of various crop and livestock products. Considering the advanced climate change, the impact of climate indicators on livestock production can present an important challenge for producers. The prediction of crop yields is one of the most important issues in the food security debate to increase the economic efficiency of livesto...

2010
Josefa González Talia L. Karasov Philipp W. Messer Dmitri A. Petrov

Investigating spatial patterns of loci under selection can give insight into how populations evolved in response to selective pressures and can provide monitoring tools for detecting the impact of environmental changes on populations. Drosophila is a particularly good model to study adaptation to environmental heterogeneity since it is a tropical species that originated in sub-Saharan Africa an...

2011
P. Blaser

This article deals with the principles of soil formation and shows the problems to recognize and visualize the many effects of man made stress in soils. Soils are transformation products of minerals and organic matter with a defined organization, morphology and structure. They are closely related to site factors and for this, the soil properties vary considerably in time and space. Due to many ...

2005
J. H. Ellis B. F. Hobbs F. Joutz

Objective of Research: : This research program has four major modeling elements: climate change and variability, electrical energy demand and production, regional air pollution, and human health effects associated with air pollution exposure. Our overall objective is to develop a scientifically credible modeling facility that will help policy makers and analysts understand the effects of human ...

2008
E. Somanathan Robert N. Stavins Albert Pratt

The goal of the Harvard Project on International Climate Agreements is to help identify key design elements of a scientifically sound, economically rational, and politically pragmatic post-2012 international policy architecture for global climate change. It draws upon leading thinkers from academia, private industry, government, and non-governmental organizations from around the world to constr...

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