Facts, Lies, Myths and Opinions about the Greenhouse Effect: [subtitle] are we doomed, or what are we going to do?

(West Midlands Chemistry Teachers Centre, Birmingham, 20.1.15)

Professor Richard Tuckett (Chemistry, University of Birmingham) 

What is the greenhouse effect? Does it cause global warming? Is global warming the same as climate change? · What is the relationship between ozone depletion and the greenhouse effect? Should politics be involved?

· What are the physical properties of a greenhouse gas that determines its effectiveness as a compound that causes climate change and global warming? · Why are we obsessed with CO2 as if it is the only greenhouse gas? Is this backed up by the scientific evidence?

What are facts, myths, opinions or even lies in this most ‘political’ of scientific subject ? And what are we going to do ………..

Four myths about atmospheric science· ‘The Greenhouse Effect is all bad news ; detrimental to life on earth’· ‘Its all about carbon dioxide’· ‘No difference between the Greenhouse effect and Ozone depletion’· ‘Weather and Climate are the same phenomenon’

Two very strong statements from scientists· ‘Global warming is the most serious phenomenon affecting the world’s security and prosperity, more so than terrorism’ (David King, UK Government Chief Science Adviser, 200007)

· ‘Don’t undermine the science just because you don’t like the economics. That’s a dangerous slope because you are not just undermining [the issue], you’re also undermining the basis of rational decision-making in society’ (Brian Cox, Guardian, Sept 2014)

Statements from an influential non-scientist· ‘Global warming is not occurring. Even if it is, it is unrelated to man’s activities on earth’ 'I have opinions of my own, strong opinions, but I don't always agree with them’ (George Bush, 2000-2008, 2015?)

90% of earth’s atmosphere in troposphere, 10% in stratosphere99% of earth’s atmosphere is N2 or O2

Regions of the earth’s atmosphere

Vacuum-UV( l < 200 nm)

UV(200 < l < 390 nm)

¬ Visible(390 < l < 700 nm)

4

Simple Photochemistry

Vacuum-UV 100 – 200 nmUV 200 – 400 nm visible 400 – 750 nm IR 750 - 20000 nm

E = hn = hc / l (E as l )

E, energy of photonh, Planck’s Constantn, frequency of photonc, velocity of lightl, wavelength of photon

200 nm : 50000 cm-1, 598 kJ mol-1; 3000 nm or 3 mm : 3333 cm-1, 40 kJ mol-1

For a bond to break hn > bond energy. IR absorption only causes thermal effects

Education in Chemistry (RSC) (2008) 45, 17-21.

Chapter 1 : R P Tuckett

The role of atmospheric gases in global warming

August 2009

DOI : 10.1016/B978-0-444-53301-2.00001-4

ISBN : 978-0-444-53301-2

2nd edition (August 2015) :

The causes of enhanced concentrations of greenhouse gases in the atmosphere : possible solutions?

CO2 concentrations are rising : 280 ppmv to 394 ppmv in period 1750-2014.I ppmv (at 1 bar and 298 K) is a number density of 2.5 x 1013 molecules cm-3

Year / AD

CO2 and Temperature change over ‘recent’ years : guilty ?

Is the correlation between CO2 concentration and global T ‘proven’ ? No ……. (i) Middle ice age [1460 AD], (ii) first years after Ind Rev [1750-1920 AD]

The infamous ‘hockey stick’ graph.UBC Canada Environ Agency. Accuracy of data, especially in 1000-1750 AD?

Development of Antarctic Ozone Hole, 1979-1997

O3

ClO

Clear anti-correlation of ClO· and O3 concentrations in Spring in AntarcticJ G Anderson, J. Geophys. Res., (1989) 94, 11465

RESOLUTION in the data

Black-Body curves of Sun (5780 K) and Earth (290 K)

5780K

peak at~0 .5 m

peak at~10 m

w avelength / m

Sun Earth290K

0.1 0.5 1 5 10 50 100

Em

itted

en

ergy

Emitted energy a T4

lmax a T-1

Energy balance : UV + Visiblein (sun) = IRout (earth)

Tearth should be 256 K (-17 oC)

Absorption of IR radiation emitted by the earth by gases in the troposphere.

Radiation (ca. 38%) is trapped, like a greenhouse. Some reflected back to earth.

Leads to an increase intemperature of ca. 34 K : 30 K is due to H2O, 3 K due to CO2, 1 K to CH4, N2O, O3. These are the ‘primary’ GH gases, all good news. H2O the most important.

Earth’s atmosphere is 78% N2, 21% O2 ; neither absorb IR radiation.

4/1

4

)1(

s

AFsTearth =

Fs solar flux, s Stefan’s Constant, A Earth’s albedo

Satellite data confirming trapping of IR radiation (Nimbus 4)RP Wayne, Chemistry of atmospheres (1991)

- - - - - spectrum expected for a black body at temperature T. ‘Primary’ GH gases : n2 mode of CO2 (12-16 mm), O3 (9.6 mm), H2O (< 6.3 mm)· ‘Secondary’ GH gases : (i) pollutants that absorb IR strongly in range 6-25 mm where CO2 and H2O do not absorb (e.g. CH4, N2O, CFCs, HFCs, PFCs).

(ii) increasing concentrations of CO2 and O3 since Industrial Revolution.

CO2 O3 H2O (+ N2O, CH4)

Molecule Mole Fraction ppmv (2014) ppmv (1748) % increase________________________________________________________________________________________ N2 0.78 or 78 % 780 900 780 900 0 O2 0.21 or 21 % 209 400 209 400 0

H2O 0.03 (100% humidity, 298 K) 31 000 31 000 0 H2O 0.01 (50% humidity, 298 K) 16 000 16 000 0

Ar 0.01 or 1 % 9 300 9 300

0

CO2 3.8 x 10-4 or 0.038 % 393 279 41

Ne 1.8 x 10-5 or 0.002 % 18 18 0

CH4 1.77 x 10-6 or 0.0002 % 1.80 0.72 150

N2O 3.2 x 10-7 or 0.00003 % 0.32 0.27 18

O3 (troposphere) 3.4 x 10-8 or 0.000003 % 0.036 0.025 44

All CFCs 8.7 x 10-10 or 8.7 x 10-8 % 0.0009 0

All HCFCs 1.9 x 10-10 or 1.9 x 10-8 % 0.0002 0

All PFCs 8.3 x 10-11 or 8.3 x 10-9 % 0.00008 0

All HFCs 6.1 x 10-11 or 6.1 x 10-9 % 0.00006 0 [Data from : IPCC 2013 5th Assessment Report]

The increase in GH concentrations since ca. 1750 causes the secondary GH effect …….

· Vibration must change the dipole moment of the molecule, dm / dq ≠ 0. N2 and O2 (99% of atmosphere) play no role. Atmosphere is very ‘fragile’.

Molecule must absorb in the range 5-25 mm. Coincidentally, CO2 absorbs at 15 mm ; the spectroscopic properties of CO2 are being unkind to nature.

Long lifetime in the earth’s atmosphere ; no reaction with OH and O*(1D), or photodissociation in troposphere (300-700 nm) or stratosphere (200-300 nm).

IR spectroscopy, absolute absorption coefficientsReaction kinetics of greenhouse gas with OH and O*(1D)

Photodissociation of greenhouse gas with UV / visible radiation (200-500 nm)

Global Warming Potential (GWP)

A molecule with a large GWP is one with strong IR absorption, long

lifetimes, and concentrations rising rapidly due to man’s activity

CO2 = 1, CH4 = 28, CF2Cl2 = 10200, SF6 = 23500 CF3SF5 = 17400

Properties of greenhouse gases (absorption of infra-red radiation into vibrational modes of the gas)

n2 mode of CO2

2.0 x 1013 vibrations per second (or 50 fs per vibn)667 cm-1 or 15.0 mm

Infra-red active : causes all the problems

O C O

Greenhouse Gas (IPCC 2013 data)

CO2 O3 CH4 N2O CF2Cl2

[all CFCs]SF6 SF5CF3

Concentration (2014) / ppmv

393 0.036 1.80 0.32 0.0005[0.0009]

7.3 x 10-6 1.2 x 10-7

DConcentration (1748 - 2014) / ppmv

114 0.011 1.08 0.05 0.0005[0.0009]

7,3 x 10-6 1.2 x 10-7

Radiative efficiency, ao / W m-2 ppbv-1

1.4 × 10-5 3.3 × 10-2 4.6 × 10-4 3.4 × 10-3 0.32[0.18 - 0.32]

0.57 0.59(world record)

Total radiative forcing / W m-2

1.82 ca. 0.35 0.48 0.17 0.17[0.27]

4.1 × 10-3 9.4 × 10-5

Contribution from long-lived GH gases to overall secondary greenhouse effect / %

64 11 17 6 6 [9]

0.14 0.003

Lifetime, t / years ca. 50-200 ca. days- weeks

12 121 100[45 - 1020]

3200 800

Global Warming Potential (100-year projection)

1 - 28 265 10200[4660 -13900]

23500 17400

Ravishankara and Lovejoy, JCS Faraday Trans., (1994) 90, 2159[written six years before the CF3SF5 story began]

‘When CFCs were invented and released into the atmosphere, their deleterious effects were not known. Fortunately, CFCs are relatively short-lived (ca. 100 years) compared to perfluorocarbons, CxFy (ca. 1000 years) ; it will take only about a century for CFCs to be removed from the atmosphere once their emissions are curtailed.

The release of any very long-lived species into the atmosphere should be viewed with great concern. PFC (and CF3SF5) lifetimes, though long on historical timescales, are short compared to evolutionary timescales. Life on Earth may not be able to adopt to the changes these emissions may cause.’

‘Thus, it seems prudent to ask if a long-lived molecule should be considered ‘guilty’, unless proven otherwise.’

or Don’t put a long-lived pollutant up into the atmosphere in the first place. Attack problem at source. (Carbon trading is nonsense.)

‘Ravi’

Targets for carbon reduction

UK : Reduce GH gas emissions to less than 20% of 1990 levels by the year 2050. Reduce CO2 emissions to less than 74% of 1990 levels by the year 2020.

EU : Reduce CO2 emissions to less than 60% of 1990 levels by the year 2030. Produce at least 27% of energy from renewable sources by 2030.

Enshrined in law (UK) and EU protocols, but what happens if ..

US : Less strict reduction targets, Obama is committed, but will they survive a change in President in 2016?

China : Vague commitment that GH emissions will slow down after 2030.

India : NothingAfrica : Nothing

Kyoto Protocol (1997) : so out of date that it is worthless

What do these numbers mean to you and me?

David MacKay : Sustainable Energy – without the hot air (2009) UIT Cambridge(free from the internet)

Units are metric tons of CO2 emitted per person per year. Estimate of how little CO2 we should be emitting if T is to be limited to 2 oC by the year 2100.

Population / billion (2014) (2100)-----------------------------------------------------------------------------------------------Planet Earth 7.27 5.8 1.5 China 1.40 6.2 1.5India 1.27 1.3 1.5 UK average 0.06 13.7 1.5EU average 0.51 15.0 1.5US average 0.32 23.0 1.5

MacKay again. Now different units of kWh energy usage per person per day

Currently, the average person in the UK uses 125 of these unitsHe suggests :

Approx savingWhat we as individuals can doTurn down thermostats and wear more clothes 20Stop flying 35Modify our means of short-distance transport 20Become vegetarian 10Change all lights to LED 4Keep old gadgets such as computers 4

What we as individuals have less control overAvoid packaging and buying clutter 20

But do not do ‘guilt’ : it is negative and not constructive

Policies cannot apply to the young, old, disabled or infirm

What are we going to do? It is everyone’s problem

Concentrate first on us in the UK. Break problem down …….

(1) What would be easy to implement? If I were Prime Minister ........

· Reduce the minimum working temperature from 16 oC to 15 oC

Reform Sunday trading laws

Price domestic air travel in the UK out of the market

with Huge expansion of train travel within the UK

with Huge expansion of safe cycling routes in the UK

Reform 1988 Education Act so that everyone attends their local school

Provide free double glazing and roof insulation to all domestic houses

Reform Health & Safety legislation : is packaging on everything needed?

(2) What would be moderately difficult to implement? ... But still possible if we are serious

Carbon tax via credit cards : ‘the polluter pays’

Complete re-think on our food policy : what we eat and where it comes from.

Vegetarian, Vegan ; Localism

Abolish all forms of Carbon trading within the EU and the world.

(3) What would be incredibly difficult to implement? ........ would any Government stay in power a month if even suggested?

Population policy : limit access to the Welfare State for n > a certain value. Twins?

But what about world population?

3.3 billion in 1964, 7.3 billion in 2014, possibly 11.0 billion in 2100. HELP!!!

Hugely enhanced role for the United Nations The Catholic Church must be brought on board : when will Popes ever learn?