Greenhouse Gases and climate change

2

Equilibrium: Energy/time in = Energy/time out Earth gains energy from the sun, by radiation Earth loses energy to outer space, by radiation Radiated power proportional to T4 (T in Kelvins) With no atmosphere, Earth’s average temp would be

-18 C

3

The greenhouse effect: absorption and re-radiation of em waves

Light radiated outward from the earth’s surface is absorbed by molecules in the atmosphere

Molecules re-radiate that energy in a random direction– some continues outward; some is redirected back towards the earth’s surface

4http://en.wikipedia.org/wiki/Image:Atmospheric_Transmission.png

5

Greenhouse effect: some of the energy radiated outward by the earth is absorbed by greenhouse gases, and reradiated

Thus the earth’s surface is +14 C on average, much warmer than the -18 C we would be have the atmosphere.

In equilibrium (power in = power out), the temperature remains very stable (averaged over the globe).

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Greenhouse Gases and Global Warming

http://yosemite.epa.gov/oar/globalwarming.nsf/content/climate.html

7

8

9

Deforestation by logging is not a “feedback” mechanism

http://www.youtube.com/watch?v=YegdEOSQotE&feature=related

10

11http://www.ipcc.ch/present/graphics.htm

Current Climate Forcings

12http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf, p 10

13

Temperature Changes in the Last Millennium

http://yosemite.epa.gov/oar/globalwarming.nsf/content/climate.html

14

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf, p. 2

15

16

CO2 Increase Observed at Mauna Loa Since 1974

http://gaw.kishou.go.jp/wdcgg/PlotData.php?file=co2/monthly/mlo519n0.dat

Average slope =1.54 ppm CO2/year

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CO2 Increase Observed at South Pole Since 1974

Increase is occurring over the entire earthIncrease is occurring over the entire earthThis increase is observed everywhere, even at the South Pole.

http://gaw.kishou.go.jp/wdcgg/PlotData.php?file=co2/monthly/spo789s0.dat

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CO2 Increase Observed At Siple in Recent Past

                                 

                                                         

Siple Station, Antarctica75°55' S, 83°55' W

http://cdiac.esd.ornl.gov/trends/co2/siple.htm

The increase in CO2 is accelerating.

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CO2 Fluctuations Obtained from Vostok Ice Core Samples over the Last 400,000 yrs

                                 

                                                         

                           

                                                        

Vostok, Antarctica 78°28' S, 106°48'E3488 m above MSL

http://cdiac.esd.ornl.gov/trends/co2/graphics/vostok.co2.gif

1 kyr = 1 kilo year = 1000 years

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Temperature Fluctuations Obtained from Vostok Ice Core Samples over the Last 400,000 yrs

                                 

                                                         

“Because isotopic fractions of the heavier 18-O and D in snowfall are temperature-dependent and a strong spatial correlation exists between the annual mean temperature and the mean isotopic ratio (18O or D) of precipitation, it is possible to derive ice-core climate records… [This was] completed in January 1998, reaching a depth of 3623 m, the deepest ice core ever recovered (Petit et al. 1997, 1999). The resulting core allows the ice core record of climate properties at Vostok to be extended to ~420 kyr BP.”

Source: http://cdiac.esd.ornl.gov/trends/temp/vostok/graphics/tempplot5.gif

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22

Correlation Between CO2 and ΔT†

Slope = 0.883±0.063 ˚C / 10 ppm CO2

†J.-M. Barnola, D. Raynaud, C. Lorius Laboratoire de Glaciologie et de Géophysique de l'Environnement, CNRS, BP96, 38402 Saint Martin d'Heres Cedex, France N.I. Barkov Arctic and Antarctic Research Institute, Beringa Street 38, 199397, St. Petersburg, Russia, and J.R. Petit, D. Raynaud, and C. Lorius, Laboratoire de Glaciogie et Géophysique de l'Environnement, CNRS, Saint Martin d'Hères Cedex, France, J. Jouzel and G. Delaygue, Laboratoire des Sciences du Climat et de l'Environnement (LSCE), CEA/CNRS, L'Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France

http://cdiac.ornl.gov/trends/trends.htm

Regression line shown with

95 % confidence intervals

Regression extrapolated to current CO2 level of 380 ppm. The red bar indicates 95% confidence limits on predicted temperature change.

Cur

rent

CO

2

Data analysis by JD

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Temperature Increases Are Observed In Northern and Southern Hemispheres

http://cdiac.esd.ornl.gov/trends/temp/lugina/graphics/allann.jpg

Carbon Dioxide Information Analysis Center

24

Temperature Increases Are Observed On Both Land And Ocean Surfaces

http://www.ncdc.noaa.gov/img/climate/research/anomalies/triad_pg.gif

25

Temperature Increases Are Greater in the Polar Regions

http://cdiac.esd.ornl.gov/trends/temp/lugina/annual.html

26

http://ww

w.ipcc.ch/pdf/assessm

ent-report/ar4/w

g2/ar4-wg2-spm

.pdf, p. 8

27

http://ww

w.ipcc.ch/pdf/assessm

ent-report/ar4/w

g1/ar4-wg1-spm

.pdf, p 11

28

http://ww

w.ipcc.ch/pdf/assessm

ent-report/ar4/w

g1/ar4-wg1-spm

.pdf, p. 6

29

Global per capita CO2 Emission

Estimates Have Remained Constant

http://cdiac.esd.ornl.gov/trends/emis/glo.htm

30

31

http://www.ipcc.ch/present/graphics.htmhttp://www.ipcc.ch/present/graphics.htm

http://www.ipcc.ch/present/graphics.htm

Two CO2 Scenarios

About 50% of a CO2 increase will be removed from the atmosphere within 30 years, and a further 30% will be removed within a few centuries. The remaining 20% may stay in the atmosphere for many thousands of years.

32http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-spm.pdf, p. 8

33http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-spm.pdf, p. 8

http://www.youtube.com/watch?v=w9SGw75pVas&feature=player_embedded

http://www.ipcc.ch/ http://www.epa.gov/climatechange/

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