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Climate Change – Green House Gasses and Atmospheric Chemistry. Ole John Nielsen Department of Chemistry, University of Copenhagen ojn@kiku.dk and www.cogci.dk. Peking University 2009. Ole John Nielsen. 1954 Born 1973 Began at UoC (chemistry and physics)

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climate change green house gasses and atmospheric chemistry

Climate Change – Green House Gasses and Atmospheric Chemistry

Ole John Nielsen

Department of Chemistry, University of Copenhagen

ojn@kiku.dk and www.cogci.dk

Peking University 2009

ole john nielsen

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

outline
Outline
  • Climate Change is a broad issue – where are we?
  • How do we do our experiments?
  • Results
  • Conclusions
  • Questions
the green house effect
The green house effect
  • “I do not believe in the green house effect”
  • Then I do not believe in gravity”
slide5

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)

slide7

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)

slide11

Update of Fig. 2A of Hansen and Sato (PNAS 101, 16109, 2004).

IPCC Scenarios from Houghton et al. (2001).

slide12

Mean airborne fraction, 56%, shows no evidence of increase.

44% of fossil fuel emissions ‘disappears’, despite deforestation

methane sources and sinks
Methane sources and sinks?

Nobody knows why?

There are only three ways of changing

the concentration of a gas in the atmosphere!

slide14

Isotope studies

www.methanetomarkets.org

slide16

Update of Fig. 2C of Hansen and Sato (PNAS 101, 16109, 2004).

IPCC Scenarios from Houghton et al. (2001).

slide17

Update of Fig. 1A of Hansen and Sato (PNAS 101, 16109, 2004), with one additional measured gas (CH3Br).

cfcs and halons had a unique combination of properties
CFCs and halons had a Unique Combination of Properties...

Performance

wide liquid range

compatibility

solvency

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

1 st generation alternatives
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)
slide20

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

slide21

We need 2nd generation alternatives with smaller GWPs

2005 emissions

Change 1990-2005

FCs +19%

HFCs gone up by

a factor 1.5

what must be done before using a new chemical in large quantities
What must be done before using a new chemical in large quantities?
  • The complete atmospheric degradation mechanism (quantification)
  • Atmospheric lifetime
  • Degradation products
slide23
How do we do it?Cl2+hν→2ClCH3ONO+hν CH3O + NO CH3O + O2 HCHO + HO2 HO2 + NO  OH + NO2O3 from an ozonizer
eu law will be global warming potential 150 how to make gwp lower

Compound Atm. Lifetime GWP100y

  • CF3CH2CF3 (HFC-236fa) 240 y 9810
  • CF3CH2OCF3 (HFE-236fa) 3.7 y 470
  • CF3CF=CF2 18 d 6
  • CF3CF=CH2 11 d 4
  • 1 y 55
EU law will be: Global Warming Potential< 150How to make GWP lower?

References: papers published by CCAR and Dr. Wallingtons group at Ford Motor Company

effect of ether oxygen on atmospheric lifetime
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

effect of ether oxygen on atmospheric lifetime28
Effect of Ether Oxygen on Atmospheric Lifetime

Atm. GWPCompoundLifetime (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

slide29

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
slide30

New hydrofluoroethers and fluoropropenes will cause less radiation forcing

Precision Cleaning and Coating

Electronics Cleaning/Defluxing

Deposition Solvents

Heat Transfer Fluids

Refrigeration

end with the bad news and the good news
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

the bad news
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

conclusions on 2 nd generation cfc replacements
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
slide34

Conclusions on Climate Change

There are different reasons for doing something about it:

slide35

Conclusions on Climate Change

There are different reasons for doing something about it:

how can climate be stabilized
How Can Climate be Stabilized?
  • Must Restore Planet’s 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 ?)
thank you for your attention
Thank you for your attention

Special Acknowledgements:

James Hansen (NASA), Timothy J. Wallington (FORD), John Owens (3M)

slide39

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
slide40

5

Black Body Radiation @ 294K

4

Attenuated Terrestrial Radiation

IR Absorption of Fluorochemicals

3

Flux (Wm-2)

2

1

0

0

500

1000

1500

2000

2500

Wavenumber (cm-1)

Radiative Forcing in the Atmosphere

slide41

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

lifetime and gwp of fluoroalkanes
Lifetime and GWP of Fluoroalkanes

Atm. GWP*CompoundLifetime (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

slide43

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
segregated hydrofluoroethers hfes

Segregated Hydrofluoroethers (HFEs)

CnF2n+1-O-CmH2m+1

Rf-O-Rh

segregated hydrofluoroethers hfes45

Segregated Hydrofluoroethers (HFEs)

Rf-O-Rh-O-Rf

C4F9-O-(CH2)3-O-C4H9

slide46

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
atmospheric lifetimes of segregated hfes

Atmospheric Lifetimes of Segregated HFEs

Rf groups include:

linear

branched

cyclic

primary ethers

secondary ethers

di-ethers

All structures result in lifetimes  5 years

slide48

Comparison of Global Warming Potentials

PFCs

All HFCs

Nonflammable

HFCs

HFC

-

23

HFC

-

236ea

All HFEs

HFE

-

125

Segregated HFEs

Naturally

Occurring

Compounds

0

5000

10000

15000

20000

Global Warming Potential (100 yr ITH)

slide49

O-C2H5

O-CH3

C3F7CFCF(CF3)2

C2F5CFCF(CF3)2

Novec 7500

Novec 7300

Novec 7800

Novec Fluids - Hydrofluoroethers

C3F7-O-CH3 C4F9-O-CH3 C4F9-O-C2H5

Novec 7000 Novec 7100 Novec 7200

potential reductions in greenhouse gas emissions
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
slide51

97% reduction

82% reduction

96% reduction

99% reduction

Potential Reductions in Greenhouse Gas Emissions(on a CO2 basis)

HFC-43-10mee (GWP=1640)

PFC-5-1-14 (GWP=9300)

C4F9OCH3

HFE-449sc1 (GWP=297)

C4F9OC2H5

HFE-569sfc2 (GWP=59)

reducing hfc emissions
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

slide53

Update of Fig. 1A of Hansen and Sato (PNAS 101, 16109, 2004), with one additional measured gas (CH3Br).

2005 global greenhouse gas emissions contribution on co 2 basis
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

atmospheric lifetime of fluorocarbons

CF3H + •OH CF3• + H2O

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
solar variability
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.

slide60

Greenhouse Gas, Aerosol & Net Climate Forcing

Greenhouse gas forcing is accurately known (~3 W/m2), but aerosol forcing is very uncertain. Source: IPCC (2007)

slide61

Climate forcing agents in the industrial era. “Effective” forcing accounts for “efficacy” of forcing mechanisms.

Source: Hansen et al., JGR, 110, D18104, 2005.

slide62

Climate forcings with primary indirect effects grouped with the sources of the direct forcing.

Source: Hansen et al., JGR, 110, D18104, 2005.

slide64

Observed temperature change (a), simulations for different forcings.

Soot + O3 +CH4 yields ~ same warming as CO2.

slide65
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?
slide66
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
slide67

Greenhouse Gas, Aerosol & Net Climate Forcing

Greenhouse gas forcing is accurately known (~3 W/m2), but aerosol forcing is very uncertain. Source: IPCC (2007)

slide68

Weren’t you coaching Sophie?

Sophie explains 2 Watts of forcing to brother Connor

Sophie Explains GH Warming:

“It’s 2 W/m2 Forcing.”

Connor only counts 1 Watt

slide69

Sophie and Connor 4 years later (2008): What is the forcing? Response: “We don’t know.” [Scientific Reticence?]

slide70
Assessment of Target CO2
  • PhenomenonTarget 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
slide71

Update of Fig. 2B of Hansen and Sato (PNAS 101, 16109, 2004).

IPCC Scenarios from Houghton et al. (2001).

slide72

Green and orange = measurements. Total includes scenarios for unmeasured gases. Note: IPCC scenarios close to measured data)

slide74

Update of Fig. 4 of Hansen and Sato (PNAS 101, 16109, 2004).

IPCC Scenarios from Houghton et al. (2001).

slide75

Coal phase-out by 2030  peak CO2 ~400-425 ppm, depending on oil/gas

Faster return below 350 ppm requires additional actions

slide76

(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.

are needed actions feasible
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