GEOL150_week1_3_Composition_1 - The Climate System& the...

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Unformatted text preview: The Climate System & the Atmosphere Julien Emile-Geay University of Southern California, Los Angeles Geosystems From Understanding Earth, 5th Ed The Climate System Many components, all interacting The Climate System: forcings and responses (Ultimately powered by the Sun) “A gaseous mixture surrounding a planet” The Atmosphere in shell Global Dynamic Earthrise from Apollo 8. Source : NASA “ the combined mass of liquid water found on, under, and over the surface of the planet” The Hydrosphere Rivers Lakes + “Hidden” water : aquifers, soil moisture Oceans hat the observed recent acceleration (Rignot and Kanagaratnam 006) of Jakobshavn Isbrae may be attributed to thinning from he arrival of warm waters in the region. estabilization of floating ice shelves has been widespread long the Antarctic Peninsula with seven collapsing in the last 0 years. Warming along the Peninsula has been dramatic, and n the western side has been substantially above the global verage. Most recently, in March 2009, more than 400 square ilometers collapsed off the Wilkins Ice Shelf on the western ide of the Antarctic Peninsula. A number of mechanisms re thought to play important roles in destabilizing floating ntarctic ice shelves. These include: surface warming leading to he creation of melt ponds and subsequent fracturing of existing revasses (van den Broeke 2005); subsurface ice shelf melting om warming ocean waters (Rignot et al. 2008b); and internal e shelf stresses (Bruan and Humbert 2009). While the collapse f a floating ice shelf does not itself raise sea level, its collapse followed by rapid acceleration of glacier outflow – which does The Cryosphere raise sea level – due to the removal of the ice shelf buttressing effect (e.g. Rignot et al. 2004; Scambos et al. 2004). There is evidence for the melting of ice shelves in the Amundsen Sea, with impacts on the flow speed of glaciers draining this part of West Antarctica. A recent modeling study has suggested that the West Antarctic Ice Sheet would begin to collapse when ocean temperatures in the vicinity of any one of the ice shelves that surround it warm by about 5°C (Pollard and DeConto 2009). There is also evidence that these changes are not limited to West Antarctica and may also affect the coastline of East Antarctica, for example in Wilkes Land (Pritchard et al. 2009; Shepherd and Wingham 2007). The widespread thinning and acceleration of glaciers along the Antarctic coast may indicate a significant impact of oceanic changes on glacier dynamics, a factor that has received little attention in past IPCC reports due to the lack of observational data on ice-ocean interactions and how climate change might influence coastal ocean waters. Sea Ice Glaciers (Land Ice) Ice Shelves (margin) Julien Emile-Geay Biosphere From Understanding Earth, 5th Ed “Biosphere = global sum of all ecosystems = the zone of life on Earth” Water is a common currency exchanged between atmosphere, hydrosphere, cryosphere and biosphere. Another is heat. e two are deeply related. The Climate System: unity The climate is made of various components separated by their physical, chemical or biological properties These components all exchange matter and energy But on different time scales. For example, the atmosphere tends to be fast (hours, days) and the cryosphere very slow (years, millennia) These interactions are complex and give rise to weather and climate phenomena storms, droughts, El Niño, Ice Ages, ... Atmospheric Composition: Permanent Gases Nitrogen Argon Oxygen Other Most of what you breathe is nitrogen... Gases Atmospheric Composition: Variable gases Water vapor the most variable (0.001 to 4%) Usually tiny amounts, but highly active ! Aerosols Solid or liquid particles in suspension: Dust, sea spray, ashes, sulfates (volcanoes) Aerosols Soot Dust Volcanoes Sprays Usually tiny amounts, but highly active ! Structure of the Atmosphere Stratified + Ozone layer Well Mixed The Troposphere Where we live 90% of the mass of the atmosphere (in the lower 16km) Temperature decreases with height Where almost all the water vapor stays 70% of the course... ...
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