Global Warming Spring 2013

Lecture 18 1

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Keeling, a researcher at Scripps Institute for Oceanography, started measuring atmospheric CO2 from Mauna Loa in Hawaii in 1958. Besides the annual photosynthetic cycle, a profound trend is seen.

400 ppm = 400 parts-per-million = 0.04% by volume

Q

2.0 ppm/yr

1.85 ppm/yr reference

just passed 400 ppm for first time in millions of years

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Global Warming Spring 2013

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O2

H2O H2O

H2O, CO2 H2O, CO2

Atmospheric absorption

above the atmosphere

at ground level but the thermal emission is farther out in infrared (IR)

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Global Warming Spring 2013

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Spring 2013 11 Often called the “hockey stick” curve

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4 2 0

-2 -4 -6 -8

-10

300

275

250

225

200

175

Note: Greenland’s ice sheet is 110,000 years old: melted in last interglacial period.

Today’s CO2 level!!

Global Warming Spring 2013

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Spring 2013 13 from http://www.pewclimate.org/global-warming-basics/slr.cfm

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Note: this is a good example of real data: lots of measurements from different scientists around the world all pointing to similar (and sensible) results. Note also error bars.

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Global Warming Spring 2013

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Global Warming Spring 2013

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Spring 2013 22 plots from 2001 IPCC assessment

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Spring 2013 24 current rate is 3 mm/year → about a foot per century

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A note of significance: none of these have yet stabilized as of 2100. Even the green curve (eliminating CO2 emissions by 2100) is still steadily climbing. This effect won’t play out until 2300 at least.

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