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Unformatted text preview: Global Atmospheric Change 1 Updated IPCC report (2007) Optional reading ! highlighted in 3rd edition of Masters http://www.ipcc.ch/ipccreports/ar4- wg1.htm ! The Scientific Basis ! If youre interested, you can read the other reports too (mitigation, economic impacts, etc.) 2 Global Change Recent Proclamations Earth Atmospheric Structure Oxygen Isotopes ! 16 O and 18 O vs. Temperature Record Global Temperature and Solar Effects Greenhouse Effect ! Solar vs. Terrestrial Radiation ! Greenhouse Gases 3 Global Energy Balance Greenhouse Enhancement ! Radiative Forcing ! Climate Sensitivity ! Greenhouse Gases vs. Temperature Record ! Global Warming Potential 4 Background Quotes The balance of evidence suggests a discernable human influence on global climate. Consensus of 2500 scientists involved in the Intergovernmental Panel on Climate Change, 1995 There is new and stronger evidence that most of the observed warming over the last 50 years is attributable to human activities. Intergovernmental Panel on Climate Change, 2000, consensus of ~2500 scientists. 5 Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations Intergovernmental Panel on Climate Change, 2007, consensus of ~2500 scientists Be worried, be very worried Time, April 3, 2006 6 78% 21% 1% Nitrogen Oxygen Argon Overview of Earths Atmosphere Mostly made up of nitrogen (78%) and oxygen (21%), followed by Argon (1%). Other gases present in small concentrations: carbon dioxide (CO 2 ), nitrous oxide (N 2 O), methane (CH 4 ), ozone (O 3 ), water vapor, CFCs (chlorofluorocarbons), NO x , SO x , VOCs. 7 Human activities are much more likely to affect trace gas concentrations than [O 2 ] and [N 2 ] Layers of the atmosphere according to changes in temperature: ! troposphere, stratosphere, mesosphere, thermosphere Atmosphere is well-mixed up to about 85 90 km altitude, then composition varies with altitude 8 Troposphere contains 90% of the mass of the atmosphere, and it is generally well mixed, with mixing time scales from a few minutes (vertical mixing in a thunder cloud) to a year (interhemisphercal mixing). The stratosphere is a stable layer, containing not quite 10% of the atmospheric mass. Defn. Climate: Average temperature, precipitation, extreme weather events, winds, glaciation, etc., over a period of decades. 9 In order to have a hope of predicting the future, we study the Earths temperature in the past. Climatologists study tree rings, ice volume (i.e. markers of glaciation), fossil pollen, and oxygen isotopes to try and figure out the past temperature record....
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This note was uploaded on 09/24/2009 for the course AO 104 taught by Professor Jeffery during the Spring '09 term at UCLA.
- Spring '09