Climate Change Green House Gasses and Atmospheric Chemistry

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Climate Change Green House Gasses and
Atmospheric Chemistry

• Ole John Nielsen
• Department of Chemistry, University of Copenhagen
• ojn_at_kiku.dk and www.cogci.dk

Peking University 2009
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Ole John Nielsen
1954 Born 1973 Began at UoC (chemistry and
physics) 1974 Important Atmospheric Year 1978
M.Sc. and on to do a PhD at Risø Nat.
Lab. 1978-95 Risø National Laboratory 1995-96
Ford Research Center Aachen, Germany 1996-99
Risø National Laboratory 1999-? Professor at
UoC 2007 Nobel Peace Prize together with Al Gore
and 2500 scientists IPCC Intergovernmental
Panel of Climate Change Gas phase kinetics and
reaction mechanisms - relevant to the atmosphere
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Outline

• Climate Change is a broad issue where are we?
• How do we do our experiments?
• Results
• Conclusions
• Questions

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The green house effect

• I do not believe in the green house effect
• Then I do not believe in gravity

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How can the radiative balance be changed?
Lots of Feedbacks
Melting ice - reflection Water Growing plants/the
biosphere Warming oceans Fast and slow
feedbacks Positive (amplify) Negative (deminish)
Changing incoming radiation (sun and orbit)
Changing the albedo (particles, clouds, ice)
Changing longwave back-radiation to space (GHG
and particles)
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Greenhouse Gas, Aerosol Net Climate Forcing
Satellite missions will provide aerosol data
1 Watt
2 Watts
Greenhouse gas forcing is accurately known (3
W/m2), but aerosol forcing is very uncertain.
Source IPCC (2007)
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Temperature, CO2, CH4 and N2O back in time
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Update of Fig. 2A of Hansen and Sato (PNAS 101,
16109, 2004). IPCC Scenarios from Houghton et al.
(2001).
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Mean airborne fraction, 56, shows no evidence of
increase. 44 of fossil fuel emissions
disappears, despite deforestation
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Methane sources and sinks?
Nobody knows why? There are only three ways of
changing the concentration of a gas in the
atmosphere!
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Isotope studies
www.methanetomarkets.org
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N2O sources and sinks?
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Update of Fig. 2C of Hansen and Sato (PNAS 101,
16109, 2004). IPCC Scenarios from Houghton et al.
(2001).
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Update of Fig. 1A of Hansen and Sato (PNAS 101,
16109, 2004), with one additional measured gas
(CH3Br).
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CFCs and halons had a Unique Combination of
Properties...
Performance wide liquid range compatibility solven
cy stability
Safety nonflammable low toxicity
CFCs and halons are also depleting stratospheric
ozone? Montreal Protocol
... useful for many industrial applications
Cleaning Drying Lubricant Deposition Refrigeration
Heat Transfer
Aerosol Formulations Fire Extinguishing Foam
Blowing Dielectrics
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1st generation alternatives

• Decrease atmospheric lifetime
• Decrease lifetime insert hydrogen atoms
• HCFCs (HydroChloroFluoroCarbons)
• Remove the chlorine and bromine
• HFCs (HydroFluoroCarbons)
• HFC134a CF3CFH2 (replacement for CF2Cl2)
• GWP100(CF3CFH2) 1/8 GWP100(CF2Cl2)

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• The Montreal Protocol has slowed and reversed the
  accumulation of ozone depleting substances (ODSs)
  in the stratosphere.
• (Effective stratospheric chlorine is the weighted
  sum of chlorine and bromine gases in the
  stratosphere.)

SO WHY?
UNEP/WMO Ozone Assessment, 2006
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We need 2nd generation alternatives with smaller
GWPs
2005 emissions
Change 1990-2005 FCs 19
HFCs gone up by a factor 1.5
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What must be done before using a new chemical in
large quantities?

• The complete atmospheric degradation mechanism
  (quantification)
• Atmospheric lifetime
• Degradation products

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How do we do it?Cl2h??2ClCH3ONOh?? CH3O
NO CH3O O2 ? HCHO HO2 HO2 NO ? OH
NO2O3 from an ozonizer
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EU law will be Global Warming Potential lt
150How to make GWP lower?
References papers published by CCAR and Dr.
Wallingtons group at Ford Motor Company
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Effect of Ether Oxygen on Atmospheric Lifetime
Relative Reactivity of
Ether with OH CH3OCH3 vs CH3CH3
9X C2H5OC2H5 vs C4H10
6X C3H7OC3H7 vs C6H14
3X
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Effect of Ether Oxygen on Atmospheric Lifetime
Atm. GWPCompound
Lifetime (yrs) (100 Yr ITH)
CH3CF3 (HFC-143a) 52
4,470 alkaneCH3OCF3 (HFE-143a) 4.3
756 ether CF3CFHCF3 (HFC-227ea)
34.2 3,220CF3CFHOCF3 (HFE-227ea)
11 1,500 CF3CH2CF3 (HFC-236fa) 240
9,810CF3CH2OCF3 (HFE-236fa) 3.7
470 CF3CH2CHF2 (HFC-245fa) 7.6
1,030CF3CH2OCHF2 (HFE-245fa2) 4.9
659
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Atmospheric Lifetimes of Segregated HFEs

• Rf - O - Rh k(OH) ?
  (cm3molecules-1s-1) (years)
• n-C4F9-O-CH3 1.20 x 10-14 4.7
• i-C4F9-O-CH3 1.54 x 10-14 3.7
• n-C4F9-O-C2H5 6.4 x 10-14 0.9
• i-C4F9-O-C2H5 7.7 x 10-14 0.7
• C4F9-O-(CH2)3-O-C4F9 1.44 x 10-13 0.4
• 5.93 x 10-14 1.0

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New hydrofluoroethers and fluoropropenes will
cause less radiation forcing
Precision Cleaning and Coating Electronics
Cleaning/Defluxing Deposition Solvents Heat
Transfer Fluids Refrigeration
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End with the bad news and the good news
The Montreal Protocol have reduced net
GWP-weighted emissions from ODSs in 2010 by 5-6
times the reduction target of the first
commitment period (2008-2012) of the Kyoto
Protocol.
The Montreal Protocol will have reduced net
GWP-weighted emissions from ODSs in 2010 by about
11 Gt CO2-eq yr-1.
Greenhouse gases CO2, CH4, N2O, HFCs, PFCs, SF6
G. Velders et al., PNAS, 2007
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The bad news
2004-2007 30 increase in global CO2-weighted
HCFC emissions. 2007 HCFC emissions were 2.6
of fossil-fuel and cement related CO2 emissions
(30 Gt/yr)
Montzka et al. GRL 2008
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Conclusions on 2nd Generation CFC Replacements

• FCs lifetimes and GWPs cover very wide range
• Possible to create fluorochemicals with much
  lower GWPs
• In many industrial applications, significant
  radiation forcing reductions can be obtained
  using lower GWP materials
• The Montreal Protocol has reduced net
  GWP-weighted emissions from ODSs in 2010 by 5-6
  times the reduction target of the first
  commitment period (2008-2012) of the Kyoto
  Protocol
• The Montreal Protocol process could serve as a
  guide for the COP15 meeting in Copenhagen in
  December 2009

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Conclusions on Climate Change There are
different reasons for doing something about it
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Conclusions on Climate Change There are
different reasons for doing something about it
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How Can Climate be Stabilized?

• Must Restore Planets Energy Balance
• Modeled Imbalance 0.75 0.25 W/m2
• Ocean Data Suggest 0.5 0.25 W/m2
• Requirement Might be Met Via
• Reducing CO2 to ?
• and
• Reducing non-CO2 forcing 0.25 W/m2
• Geo-Engineering? (Sulphur in the Strat ?)

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Thank you for your attention
Special Acknowledgements James Hansen (NASA),
Timothy J. Wallington (FORD), John Owens (3M)
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Extra Slides
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Global Warming Potential (GWP)

• Calculated using IPCC method
• Basis of 1 kg of compound released
• Calculated over a specified integration time
  horizon (ITH)
• Result is equivalent number of kg of CO2 released

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Radiative Forcing in the Atmosphere
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IR Absorbance of Fluorochemicals Radiative
Forcing of hydrofluorocarbons (HFCs) and
perfluorocarbons (PFCs)
Radiative Forcing values as reported in WMO
Global Ozone Research and Monitoring Report No.
44 Scientific Assessment of Ozone Depletion -
1998
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Lifetime and GWP of Fluoroalkanes
Atm. GWPCompound
Lifetime (yrs) (100 Yr ITH) IPCC
2007 CF4 (PFC-14) 50000 7,390CHF3
(HFC-23) 270 14,800
nonflammableCH2F2 (HFC-32) 4.9
675 flammableCH3F (HFC-41)
3.7 140 CF3CF3 (PFC-116)
10000 12,200CF3CHF2 (HFC-125) 29
3,500CF3CH2F (HFC-134a) 14
1,430CF3CH3 (HFC-143a) 52
4,470CHF2CH3 (HFC-152a) 1.4
124CH2FCH3 (HFC-161) 0.25
10 CF3CHFCF3 (HFC-227ea) 34.2
3,220CH2FCF2CHF2 (HFC-245ca) 6.6
720 CF3CH2CF2CH3 (HFC-365mfc) 8.6
794 CF3CHFCHFC2F5 (HFC-43-10mee) 15.9 1,640
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Effect of Ether Oxygen on Atmospheric Lifetime

• Insertion of -O- affects reactivity with OH
• Lifetime reduces with increasing number of H
  atoms
• HFEs with lone C-H bond can be longer lived than
  analogous alkanes
• HFEs with more than one H per C exhibit greater
  effect -CH2F, -CH2-, CH3
• F substitution on same C or ? to the C-H bond can
  reduce effect
• Some of the largest effects occur with segregation

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Segregated Hydrofluoroethers (HFEs)

• CnF2n1-O-CmH2m1
• Rf-O-Rh

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Segregated Hydrofluoroethers (HFEs)

• Rf-O-Rh-O-Rf
• C4F9-O-(CH2)3-O-C4H9

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Atmospheric Lifetimes of Segregated HFEs

• Rf - O - Rh k(OH) ? (cm3molecules-1s-1
  ) (years)
• n-C3F7 - OCH3 1.18 x 10-14 4.8
• C6F13- OCH3 1.51 x 10-14 3.8
• C7F15- OC2H5 2.24 x 10-14 2.2
• Rf1- O - CH3 2.1 x 10-14 2.7
• Rf3- O - C2H5 5.9 x 10-14 1.0
• Rf4- O - CH3 1.13 x 10-14 5.0
• Rf5 - O - CH3 1.34 x 10-14 4.2

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Atmospheric Lifetimes of Segregated HFEs

• Rf groups include
• linear
• branched
• cyclic
• primary ethers
• secondary ethers
• di-ethers
• All structures result in lifetimes ? 5 years

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Comparison of Global Warming Potentials
PFCs
All HFCs
Nonflammable
HFCs
HFC
-
23
HFC
-
236ea
All HFEs
HFE
-
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Segregated HFEs
Naturally
Occurring
Compounds
0
5000
10000
15000
20000
Global Warming Potential (100 yr ITH)
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Novec Fluids - Hydrofluoroethers
C3F7-O-CH3 C4F9-O-CH3 C4F9-O-C2H5
Novec 7000 Novec 7100 Novec 7200
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Potential Reductions in Greenhouse Gas Emissions

• Segregated HFEs typically replace high GWP
  compounds
• For many applications substitutions are made on
  an equal mass basis
• Reductions can range from 80 to 99 on C or CO2
  basis when to replace a PFC or HFC

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Potential Reductions in Greenhouse Gas
Emissions(on a CO2 basis)
HFC-43-10mee (GWP1640)
PFC-5-1-14 (GWP9300)
C4F9OCH3 HFE-449sc1 (GWP297)
C4F9OC2H5 HFE-569sfc2 (GWP59)
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Reducing HFC Emissions
GWP mass (kg)
equivalent to Compound (100 Yr ITH)
emissions of from typical
automobile over 1 yr HFC-23 14800
0.2 HFC-236fa 9810 0.6 HFC-125
3500 0.8 HFC-227ea 3220
0.9 HFC-43-10mee 1640 3.8 HFC-134a
1430 4.3
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Update of Fig. 1A of Hansen and Sato (PNAS 101,
16109, 2004), with one additional measured gas
(CH3Br).
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2005 Global Greenhouse Gas Emissions
Contribution on CO2 Basis
Change 1990-2005 FCs 19
HFCs gone up by a factor 1.5
We need 2nd generation alternatives with less GWPs
UNFCCC
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Atmospheric Lifetime of Fluoroalkanes
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Atmospheric Lifetime of Fluorocarbons

• Do not undergo photolysis in lower atmosphere
  (lmax typically 200 nm)
• Not expected to be removed by wet or dry
  deposition (non-polar with water solubility in
  ppmw)
• Principal removal mechanism for
  hydrofluorocarbons is the reaction with OH

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Solar variability
11 year sunspot cycle, Current understanding is
that solar intensification can at most explain
about 1/3 of the warming of the last 25 years.
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Greenhouse Gas, Aerosol Net Climate Forcing
Greenhouse gas forcing is accurately known (3
W/m2), but aerosol forcing is very uncertain.
Source IPCC (2007)
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Climate forcings with primary indirect effects
grouped with the sources of the direct
forcing. Source Hansen et al., JGR, 110, D18104,
2005.
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Observed temperature change (a), simulations for
different forcings. Soot O3 CH4 yields same
warming as CO2.
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• Inference
• 1. Non-CO2 Forcings Substantial
• Comparable to CO2 forcing today
• 2. Strategic Mitigation Role
• If coal phased out, non-CO2 important
• 3. Aerosols Complicate the Story
• If all pollution is reduced, how much will
  aerosol cooling effect be altered?

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• Nasty Aerosol Problem
• 1. Aerosol Forcing Not Measured
• Based in good part on presumptions
• 2. Aerosol Data Include Feedbacks
• Aerosols decrease in warming climate
• 3. Aerosol Cloud Effects Complex
• Aerosol forcing practically unknown

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Greenhouse Gas, Aerosol Net Climate Forcing
Greenhouse gas forcing is accurately known (3
W/m2), but aerosol forcing is very uncertain.
Source IPCC (2007)
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Sophie explains 2 Watts of forcing to brother
Connor
Sophie Explains GH Warming Its 2 W/m2 Forcing.
Connor only counts 1 Watt
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Sophie and Connor 4 years later (2008) What is
the forcing? Response We dont know.
Scientific Reticence?
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• Assessment of Target CO2
• Phenomenon Target CO2 (ppm)
• 1. Arctic Sea Ice 300-325
• 2. Ice Sheets/Sea Level 300-350
• 3. Shifting Climatic Zones 300-350
• 4. Alpine Water Supplies 300-350
• 5. Avoid Ocean Acidification 300-350
• ? Initial Target CO2 350 ppm
• assumes CH4, O3, Black Soot decrease
• Reference Hansen et al. Target Atmospheric CO2,
  Open Atmos. Sci., 2008

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Update of Fig. 2B of Hansen and Sato (PNAS 101,
16109, 2004). IPCC Scenarios from Houghton et al.
(2001).
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Green and orange measurements. Total includes
scenarios for unmeasured gases. Note IPCC
scenarios close to measured data)
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From Global Warming East-West Connections,
Hansen and Sato, in preparation, 2009.
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Update of Fig. 4 of Hansen and Sato (PNAS 101,
16109, 2004). IPCC Scenarios from Houghton et al.
(2001).
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Coal phase-out by 2030 ? peak CO2 400-425 ppm,
depending on oil/gas Faster return below 350 ppm
requires additional actions
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(a) Fossil fuel CO2 emissions with coal phase-out
by 2030 based on IPCC and EIA estimated fossil
fuel reserves. (b) Resulting atmospheric CO2
based on use of a dynamic-sink pulse response
function representation of the Bern carbon cycle
model.
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Are Needed Actions Feasible?

• Coal must be phased out Unconventional Fossil
  Fuels avoided
• Requires Carbon Tax Dividend
• Cap Trade a Proven Failure
• Do not lump non-CO2 forcings w CO2
• Methane Ozone most important (reduction
  feasible as fossil fuel use declines)
• Emphasize BC reductions among aerosols
• My opinions

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How good are the models ?
IPCC 2007
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Do the most cost efficient first ????
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