Lecture 18 Climate Change Impacts
Lecture 18 Climate Change Impacts GC 170A
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This 4 page Class Notes was uploaded by Gigi on Friday November 6, 2015. The Class Notes belongs to GC 170A at University of Arizona taught by E. Bigio in Fall 2015. Since its upload, it has received 32 views. For similar materials see INTRO TO GLOBAL CHANGE in Global Studies at University of Arizona.
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Date Created: 11/06/15
Lecture 18 Climate Change Impacts Thursday, November 5, 2015 1:21 PM Global Climate Models Reproduce the increasing temperature trend of the 20th century climate and show the natural climate without the influence of humans Blue line= model output Black line=observations of temperature Observedtemperature trend is uman & naturalforces Human: increased CO2 Natural: Sunspots & Volcanoes *There is no increasing trend in the natural temperature without the influence of humans Climate Change Impacts Artic Sea ices, ice sheets, & Glaciers Sources of Ice 1. Arctic Sea Ice 2. Ice Sheets (Greenland/Antarctica) 3. Mountain Glaciers Changes in theses sources leads to sea- level rise & changes in weather patterns 2. Ice Sheets (Greenland/Antarctica) 3. Mountain Glaciers Changes in theses sources leads to sea- level rise & changes in weather patterns Arctic Sea Ice Frozen sea water on the ocean surface -Fluctuates seasonally: peaks in February, lowest in August/September -High variability year to year -Influenced by artic storms & warming Changes in past 35 years: 1. Decreasing in area 2. Decreasing in thickness Consequences of Arctic 1. Reduced Albedo (more incoming Sea Ice Loss radiation absorbed at surface) 2. Change in storms & weatherpatterns in the arctic -Does not contribute to global sea -level rise -Economically advantageous since new shipping routes will open in the arctic Consequences of More long wave emitted back to earth: Artic Melting Ice becomes warmer Jet Stream With warming temperatures, jet stream becomes wavier & slower -Weather patterns become more persistent, lasting for weeks to months = North East: more snow California: drought Ice Sheets Greenland & Antarctica -Snow accumulates over thousands of years -Compresses into ice -Very thick (1 -2 miles) -Thickest in the center & thinner towards edges -Ice flows outwards from the center -Compresses into ice -Very thick (1 -2 miles) -Thickest in the center & thinner towards edges -Ice flows outwards from the center Greenland/Antarctic Ice Study: Sheets 1. Snow accumulation measured on the surface 2. Surface melting is monitored daily by satellites • Surface melts & refreezes every season • Increase in extent of surface melting observed in the summer season over past 30 years • Sheets decrease in size Glaciers on E & W sides of Antarctica are rapidly melting and retreating Warm water circulating underneath ice shelf accelerates melting Consequences of Ice Destabilizes the glacier, leads to further • Sheet Melting melting • Potential for sea-level rise in the future = 4 + meters • Not yet a major cause of sea-level rise Mountain Glaciers Mass of ice on a mountain or in an alpine valley -Formed by constant accumulation of snow -Requires permanent, year-round snow to form ice The whole glacier flows like plastic & moves slowly down slope • Greatest amount of melting in response to Global Warming • Sensitive to small changes in temperature *Contribute greatest portion of recent sea - level rise to Global Warming • Sensitive to small changes in temperature *Contribute greatest portion of recent sea - level rise Repeat Photography Taking photos at the same locations at different point in time -Qualitative method, though effective for observing environmental change -Important method for observing melting glaciers Current Sea-level rise 1. Melting of mountain glaciers & ice sheets 2. A large portion is also related to thermal expansion of ocean water related to global warming