Valuing Our Life Support SystemsSavoy Place, 29 April 2009

IMPACTS ON THE ENVIRONMENT:

CLIMATE CHANGE

Robert M May

Zoology Department

Oxford OX1 3PS, UK

Humanity’s ImpactsOver the past century and a half:

• the human population has increased x 7

• the global average energy use per person has increased x 7

• That is, overall energy use has

increased roughly fifty-fold

Fig. 2: ECOLOGICAL FOOTPRINT AND BIOCAPACITY BY REGION, 2003 (After Ref. 5)

STATEMENT BY SCIENCE ACADEMIES OF THE G8, plus CHINA, INDIA, BRAZIL

Calls on G8 countries to “identify cost-effective steps that can be taken now to contribute to substantial and long-term reduction in net global greenhouse gas emission [and] recognise that delayed action will increase the risk of adverse environmental effects and will likely incur a greater cost”

Building a Low-Carbon Economy –The UK's Contribution to Tackling

Climate Change

www.theccc.org.uk

1. The 2050 target

(i) Required global emissions reduction

(ii) Appropriate UK contribution

(iii) Technologies for meeting required reductions

(i) Required global emissions reduction

Required global emissions reduction of 50%

• 20-24 GtCO2e emissions in 2050

• 8-10 GtCO2e in 2100

Required global emissions reduction of 50%

• 20-24 GtCO2e emissions in 2050

• 8-10 GtCO2e in 2100

What’s changed?• Advances in science• Actual emissions higher

than forecast

What’s changed?• Advances in science• Actual emissions higher

than forecast

Assessment of damageDecision rule• keep temperature

change close to 2°C• and probability of 4°C

increase at very low level (less than 1%)

Assessment of damageDecision rule• keep temperature

change close to 2°C• and probability of 4°C

increase at very low level (less than 1%)

Global trajectories considered

• Early or later peak (2015 vs. 2030)

• 3%/4% annual emissions reduction

Global trajectories considered

• Early or later peak (2015 vs. 2030)

• 3%/4% annual emissions reduction

(ii) Appropriate UK contribution

50% global reduction 50% global reduction

Burden share• Alternative methodologies (contract and

converge, intensity convergence, triptych etc.)

• Equal per capita emissions:

D 20-24 GtCO2e total at global level in 2050

D Implies 2.1-2.6 tCO2e per capita

Burden share• Alternative methodologies (contract and

converge, intensity convergence, triptych etc.)

• Equal per capita emissions:

D 20-24 GtCO2e total at global level in 2050

D Implies 2.1-2.6 tCO2e per capita

All GHGsAll GHGsAviation and shipping included Aviation and shipping included

2.1-2.6 CO2e per capita gives a UK reduction of at least 80% in 2050

Conclusion

• 80% cut in GHG emission by 2050 relative to 1990: all

GHGs, aviation and shipping included

• Unilateral 34% cut in GHGs by 2020 relative to 1990

(21% relative to 2005)

• 42% cut in GHGs by 2020 relative to 1990 (31%

relative to 2005) after global deal is achieved

• 34% cut predominantly through domestic emissions

reduction

• 42% through domestic emissions reduction and credit

purchase

• 2020 cost less than 1% of GDP

• 80% cut in GHG emission by 2050 relative to 1990: all

GHGs, aviation and shipping included

• Unilateral 34% cut in GHGs by 2020 relative to 1990

(21% relative to 2005)

• 42% cut in GHGs by 2020 relative to 1990 (31%

relative to 2005) after global deal is achieved

• 34% cut predominantly through domestic emissions

reduction

• 42% through domestic emissions reduction and credit

purchase

• 2020 cost less than 1% of GDP

Climate Change - a Multiplier for Instability

Recent Conflicts

DemographyDemography Crop decline Hunger Coastal riskWater scarcity