● read Collapse● Must do Ch. in Simutext on Climate Change● Natural Capital○ climate■ ex: Greenland, Anasazi, Maya & Tikopia■ have had big local changes in climate○ water■ ex: water in California● How have temperatures changed with time?● graph: Temp of Planet Earth has become stable in recent thousands of years (Holocene era)○ a few degrees make a BIG difference● scientists have gotten information by drilling deep for ‘Ice cores’, and analyzing air in compressed snow - to measure amount of CO2 in air● Temperature Anomaly = difference from average temperaturesHW: read link to article on climate● Q: what happens to solar energy reaching the earth?● absorbed by ozone, 34% reflected by atmosphere, infrared.○ visible light > heat > infrared > absorbed by CO2 > keeps earth warm > N2O2 outer space● Oceans store greenhouse gases and heat (CO2 & H2O)● Coral reefs made of calcium & carbonate > calcium bicarbonate**The Carbon Cycle - very important to know!! review the graph!● Fossil Fuel = “new carbon” bc the carbon never got respired● The Keeling Curve - Mauna Loa Record○ plot of high elevation CO2 in Hawaii 1960 till present○ zigzag, annually = winter net respiration, more CO2○ bc northern hemisphere has more landmass = summer net respiration less CO2**Numbers you must know for exam!● Climate Change and Human Activity○ 20th century: hottest century in past 1000 years○ since 1900, average temp has increased 0.6C● CO2 levels are high bc burning of fossil fuels● methane levels are high bc of agriculture● Consequences & Feedbacks● sea ice doesn’t affect sea level but land ice does.○ b/c ice does not displace more than its own area.● Melting snow & ice○ In Glacier National Park, 27/150 glaciers still remain○ Melting of Greenland ice sheet = scary bc there’s so much○ as ice melts, darker less reflective surfaces are exposed and absorb more sunlight, causing more melting● Negative feedback loop○ ex: human body, brain is control center○ too hot > take off clothes > less hot● Positive feedback loop in nature = rare○ ex: human’s deforestation for agriculture causes erosion/unstable land. then cleares more forest○ instead of stabilizing system, drives it toward one extreme or another● Albedo = reflectance○ 0 - totally black, absorbs○ 1 - mirror, reflects○ ex: Methane - frozen in ice & permafrost■ when permafrost melts, releases more methane, which warms the
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