Global Warming: Causes and Chemistry of Climate Change

Extract

[...] 252) N2O + hν N2 + ∙O N2O + ∙O 2 NO Absorption of light or heat and subsequent radiation are important processes of the GHG molecules in their contribution to global warming. Apart from the vast number of photochemical reactions, the rotation and vibration of molecules are the underlying phenomena of such processes. The heat of the earth is to some extent radiated as infrared light into space. GHG molecules, especially carbon dioxide, water, chlorofluorocarbons (CFCs) and methane absorb the infrared light leading to additional vibration and rotation in an excited state of the molecule. A permanent or temporary dipole moment is the prerequisite for this process. [...]

[...] Global Warming: Causes and Chemistry of Climate Change Introduction The term "global warming" is synonymous with "climate change" which is adapted to describe the phenomena by the relevant international organizations as outlined below. The most influential and authoritative organization are the United Nations Framework Convention on Climate Change (UNFCCC) (UNFCCC, 2014a) and the Intergovernmental Panel on Climate Change (IPCC) (IPCC, 2014). Registered parties of the UNFCCC amount to 195 members. While one of the tasks of the UNFCCC deals with the launch of national strategies to adapt to the impacts of climate change, the Convention of Parties (COP) hosted in turn by different countries adopts decisions and resolution based on published reports and aims at the implementation of those. [...]

[...] The so-called "adjusted lifetime" takes this into consideration. In addition, the adjusted lifetime also differs regionally and is different in the tropics compared to over the poles. (Seinfeld & Pandis p. 1099) Most atmospheric reactions are radical reactions. A common radical present in the atmosphere of importance to this topic is the hydroxyl radical, OH, which can be formed in a photochemical reaction from ozone and water vapor. It reacts with methane to carbon monoxide, CO, and other species. CO depletes OH radicals via secondary reactions and this decrease in radical concentration in turn prolongs the lifetime of methane in the atmosphere. [...]

[...] Myhre, Shindell, Bréon,F-M; Collins, Fuglestvedt, Huang, Koch, Lamarque, Lee, Mendoza, Nakajima, Robock, Stephens, Takemura, T & Zhang, H (2013): Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T Qin, Plattner, Tignor, Allen, S Boschung, Nauels, Xia, Bex; V and Midgley, P M (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Seinfeld, J. H. & Pandis, S. N Atmospheric Chemistry and Physics - From Air Pollution to Climate Change. [...]

[...] The global warming potential (GWP) of more than 200 chemicals has been assessed and listed by the IPCC Working Group (Myhre et al. - IPCC Working Group pp. 731-738). Of the list of gases (see Table carbon dioxide is the most common greenhouse gas with a GWP of 1 by definition. GWP is related to a time period which is given as an index, e.g., GWP100 refers to the global warming potential over a time span of 100 years. The GWP100 value of a compound is the total radiative forcing by this compound per ppb over 100 years divided by the total radiative forcing of carbon dioxide per ppb over 100 years. [...]