Climate and atmospheric composition

One approach to elucidating the contribution of natural variability to recent temperature trends is to examine markers for temperature over much longer time scales, prior to the industrial revolution. A major source of such data is ice cores (see also Section B.2a). These ice cores provide a record of climate and atmospheric composition for at least 110,000 years, for which there is agreement among various studies. Data are available for 250,000 years before the present (bp), but there is some uncertainty in the dating of the layers corresponding to these older ice core depths (Chappel-laz et al., 1997). 

Despite the richness of the records, ice-core data alone can give only clues and not definitive answers concerning the mechanisms of the observed changes. This is because climate and atmospheric composition are multidimensional phenomena that cannot be adequately indexed by measurements from one or two regions. Changes in climate have distinctive spatial sig-... 

FIGURE 2 Climate and atmospheric composition over the past 420,000 years from the Vostok core (Petit et tiL, 1999). 

In the preceding chapters, we have discussed the ocean s pivotal role in the crustal-ocean-atmosphere fectory. For example, the ocean serves as a receptacle for chemical flows originating from land. We have seen that the ocean s ability to either store these chemicals or bury them in the sediments is a crucial component of the global biogeo-chemical cycles that influence climate and, hence, the hydrological cycle and ocean circulation. These and other linkages support feedbacks that act on biological diversity and abundance, terrestrial erosion, and atmospheric composition. 

The chemical composition of a wine is influenced by the climatic and atmospheric conditions, soil type, vine cultivation and the treatment to which it is subjected. Due to this reason amount of phenolics vary from one brand and type of wine to another. Process difference causes red wines to contain almost ten times higher amount of phenolics. 

The condensed phases also are important to the physical processes of the atmosphere however, their role in climate poses an almost entirely open set of scientific questions. The highest sensitivity of physical processes to atmospheric composition lies within the process of cloud nucleation. In turn, the albedo (or reflectivity for solar light) of clouds is sensitive to the number population and properties of CCN (Twomey, 1977). At this time, it appears impossible to predict how much the temperature of the Earth might be expected to increase (or decrease in some places) due to known changes in the concentrations of gases because aerosol and cloud effects cannot yet be predicted. In addition, since secular trends in the appropriate aerosol properties are not monitored very extensively there is no way to know... 

Atmospheric aerosols have a direct impact on earth s radiation balance, fog formation and cloud physics, and visibility degradation as well as human health effect[l]. Both natural and anthropogenic sources contribute to the formation of ambient aerosol, which are composed mostly of sulfates, nitrates and ammoniums in either pure or mixed forms[2]. These inorganic salt aerosols are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence in humid air. That is, relative humidity(RH) history and chemical composition determine whether atmospheric aerosols are liquid or solid. Aerosol physical state affects climate and environmental phenomena such as radiative transfer, visibility, and heterogeneous chemistry. Here we present a mathematical model that considers the relative humidity history and chemical composition dependence of deliquescence and efflorescence for describing the dynamic and transport behavior of ambient aerosols[3]. 

Such a thought-provoking model was naturally subject to criticism Catling (Department of Earth Science, University of Bristol) considered the calculations to be unrealistic, since (for example) the authors had underestimated the temperatures of the upper layers of the atmosphere. The prompt answer of the authors to these criticisms was quite clear Hence, the ancient atmosphere was hydrogen rich (Catling, 2006 Tian et al., 2006). J. F. Kasting and M. Tazewell (2006) have given a detailed account of the climate of the primeval Earth and the composition of its atmosphere. 

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