Volcanic eruptions temperature changes

Volcanic eruptions provide one test of the relationship between light scattering by sulfate particles and the resulting change in temperature, since they generate large concentrations of sulfate aerosol in the lower stratosphere and upper troposphere. These aerosol... 

FIGURE 14-56 Temperature anomalies in the Northern Hemisphere compared to the 1881-1960 mean, calculated based on measured changes in tree ring densities. The 95% confidence limit is i0.3°C. The line shows bidecadal smoothed levels. Arrows on the lower axis mark some of the major volcanic eruptions (adapted from Briffa et al., 1998). 

Extreme climatic phenomena such as droughts, large shifts of seasonal temperatures, change of solar radiation due to the large-scale input of aerosols to the atmosphere (e.g., by volcanic eruptions or by the large-scale fires that took place in Iraq in connection with recent military operations). 

Newell RJE., Stratospheric temperature change from the Mt. Agung volcanic eruption of 1963. J. Atmos. Sci., 27, 977-978 (1970). 

The observed trends in the NAM towards higher indices may have resulted from human-induced changes in the temperature structure of the lower stratosphere in response to greenhouse gas emissions and ozone depletion (Shindell et al., 2001). The radiative effects of solar activity and of volcanic eruptions may also have produced NAM- like signatures detectable at the Earth s surface. The response of the Earth system to climate forcing may therefore involve changes in particular dynamical modes, and hence the human influence on climate at the Earth surface may occur in part by way of the stratosphere. 

This includes also catastrophic events such as volcanic eruptions and the impaet of celestial bodies. It is beyond the focus of this book to describe the physics of sueh alterations. However, with an understanding of the chemical evolution of the eli-mate system (Chapter 2), it is evident that different chronological processes are superposed and that the different causes are interlinked in the sense of climatic feedbacks which make it very difficult to quantify climate changes and variations. Temperature and precipitation, as the most important climatic factors, are interrelated, but they are also interrelated with atmospheric composition and surface characteristics which again are interrelated. 

In regions of recent active volcanism, hydrothermal processes which bring about substantial removal and redeposition of many elements, and in particular of iron, from volcanic rocks are extensively developed. Study of the physicochemical conditions of migration and deposition of elements from such waters is complicated by the continual change in properties of the waters themselves (temperature, pH, Eh) as they leave the eruptive centers. In this case, naturally, there is practically no equilibrium in the system studied, except the state of equilibrium established between the congealing products of deposition and the pore solutions. 

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