II.   HISTORICAL CHANGES

A.   Most Recent Ice Age

1. peaked 22,000 yrs BP (world coverage)
2. sea level change ; "Bering Land Bridge"
3. Younger-Dryas
4. warmer 5000-6000 yrs BP ?? 2000 yrs BP? 1000 yrs BP?

1. 1816 = "year with no summer"
2. current warming starts in late 1800s
   • What should one expect after the Little Ice Age?

II.   MECHANISMS, PROCESSES, THEORIES

A.   Feedback Mechanisms

1. positive
2. negative

1. eccentricity
   • orbital shape change
   • 100,000 yr cycle
2. precession of the axis
   • wobble in Earth's rotation
     ** tilt to the "right" or "left"?
   • change in aphelion/perihelion
   • 23,000 yr cycle
3. obliquity
   • tilt angle change
     ** due to wobble
   • 41,000 yr cycle
4. the connections
   • ice sheets peaked every 100,000 yrs
   • smaller advances at 41,000 & 23,000 yrs

1. Tambora, Indonesia - 1815
2. El Chichon, Mexico - 1982
3. Pinatubo, Philippines - 1991
   • ** 20 million tons of SO₂!!
4. Yellowstone eruptions??
5. Western U.S. volcanoes!
6. Impact of volcanic eruptions on atmosphere?

1. 11 yr cycle
2. past 10,000 years
3. Maunder Minimum
   • 1645-1715
   • coldest part of Little Ice Age
4. correlation of solar activity to temperature ... Arctic temps?

1. 1998 = the warmest year ever!
   • Actually, it wasn't ... unless you adjust temps
   • Also happened to be a big El Nino year
2. winter 2007-08? coldest winter in....?
   • snow in Baghdad!
   • Global Warming in Cancun? Oops!
3. 2010?
   • trend?
   • sign of impending ice age?
4. major data issues
   • loss of 1000s of stations
     
   • station distribution (temp reporting stations) = skews global numbers!
   • station location = skews temps!

1. poor understanding of science?
   • Modern CO₂ levels not unusual?
     • CO₂ levels still concerning?
   • more hurricanes? No, more damage
   • Snow and ice all melting?
     • Arctic ice all back... and it wasn't global warming?
     • Arctic melted before? ... Arctic temps graph ... PDO graph
     • Ah, but the Antarctic is melting... right?!
     • 2013: Greenland melt alarming! (Oops! Computer glitch)
     • Alaska glacier is nearly melted away! (read paragraph 1)
   • ... or maybe it's volcanoes melting the Antarctic ice
   • Is Mars warming? And other planets, too??
   • Are the polar bears going to die? (from Apr 2012)
   • global warming ate my homework
2. What about consensus? answer
   • Oh, and the consensus survey wording...
3. distortion of science??
4. On what evidence do we base our conclusions?
   • evidence of global warmings effect on polar bears
   • ... or maybe this?
   • ... or this?
5. Predictions nearly exclusively based on computer models! (accuracy??)

"... The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by an endless series of hobgoblins, most of them imaginary."

      H.L. Mencken, In Defense of Women, II.13.

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