7. Climate change: Science and policy

What is global warming?

Certain gases in the earth’s atmoshphere have the effect of blocking emmissions of heat from the earths surface

Heat from the sun allowed to pass through these gases to reach the earth but when it rebounds from the earths surface it is prevented from escaping back into space

In effect these gases form a glass screen above the earth → green house effect → GDG gases

What is the science behind GHG?

GHG all occur naturally, they regulate earths temperature

• without them the average tenoerature of earths surface would be -19^oC rather than +15^oC

• There is a natural greenhouse effect

• there is increasing evidence that there is an enhanced greenhouse effect caused by increasing emissions of these gases as a result of human activity (anthropogenic GHG emissions)

Scientific consensus is that human activity is influencing the climate

What are the 5 main green house gases?

• carbon dioxide (CO₂) : burning fossil fuels, solid waste, trees and other biological materials

• Methane (CH₄): agriculture, foaail fuels, and decomposition of landfill waste

• Chlorofluorocarbons (CFC-11 and CFC-12) : refrigerators, air conditioners, different types of sprays, fire extinguishers and paints

• Nitrous oxide (N₂O): agriculture, particularly fertilised soila nd animal waste

What is Global Warming Potential (GWP)

the relative strength of one unit of each gas in contributing to global warming

What is the lifespan of GHG?

some have a very long atmoshpheric life

• even if emissions start to fall, atmoshpheric concentrations will continue to increase for many years

Which GHGs are especially higher than pre-industrial concentrations?

CFCs which are a man made gas

How are the gases released?

Gases are all released by industrial and agricultural activity

Carbon dioxide is released when fossil fuels are burnt. others come from a variety of sources

What are the 2 main discussions for GHG emissions?

1. Who emits the most?

   Asia is by far the largest emitter → 53% of global emissions

   However, Asia is home to 60% of the worlds population

2. Who has contribute dthe most to global CO₂ Emissions?

   The US has emmitted more CO₂ than any other country to date

   Since 1751, US is responsible for 25% of historical CO₂ emissions

Who emits the most vs who is impacted the most

What are the states for Global CO₂ emiisions and cumulative global CO₂ emissions?

What is production based emissions?

Considers emissions that take place within national territroy and offshore areas over which the country has jurisdiction → aka territorial based emmisions

What are consumption based emissions?

emissions from domestic final consumption and those caused by the production of imports → take into account the effects of trade

Who emits the most?

Is there uncertainty with climate change?

great deal of uncertainty surrounding the exact effect that these gases have on global climate patterns

scenarious below e.g. based on changes in human life, governmental policy response, atmoshpheric changes etc.

What are the different sources of uncertainty?

• change in technology

• change in weather conditions and feedbacks in the atmosphere once warming starts

• change in scientific thresholds

• change in our adaption policie

What are the impacts of climate change?

IPCC 5th Assessment Report 2014:

• anthropogenic GHG emissions are extremely likely to have been the dominant cause of the observed warming since the mid 20th C

• “Surface temperature is projected to risk over the 21st century under all assessed emission scenarious. it is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions. the ocean will continue to warm and acidify, and global mean sea level to rise

What are the consequences of climate change?

Likely to be complex and far reaching

• sea level increase will cause major problems for low lying areas and will necessitate the construction of large scale sea defences

• rising temperatures will have serious implications for ecology and agriculture

• occurence of storms and hurricanes will uncrease and new areas will start to experience tropical storm

What are the several points to bear in mind when it comes to formulating policy responses:

1. There is a long time lag btw our current actions and the effect of them on the climate. Climate change is an intergenerational issue: do we act now or save money for the future

2. For the main GHG there is no end of pipe technology, i.e. we cannot use new technology to reduce emissions , in the same way that we can for other air pollutants

3. since the effect of emissions is felt globally, it is not good if one or two countries reduce emissions, if other do not → any action has to be implemented globally

What are potential policy responses?

Mitigation: actions to limit the magnitude or rate of long-term climate change, i.e. actions that reduce the amount of GHG released into the atmosphere

Adaptation: Actions to reduce the vulnerability of social and biological systems to climate change, i.e. actions that lower the risks caused by climate change

How would a policy of mitigation work?

• policies that concentrate on the reduction of energy use and encouraging the switch to cleaner fuels since this provides the greatest scope for emissions reduction

• CO2 mitigation policies

  • use energy more efficiently and switch to less carbon intensive fuel (gas and renewables ), i.e. to prevent emissions

  • Increase the amount of carbon that is absorbed by trees by increasing forested areas and preventing deforestation

How would the policy of adaptation work?

Policies that concentrate on teh reduction of local or regional vulnerabilities

What is deforestation?

the purposeful clearing of forested land, especially for the purpose of making space for agriculture and animal grazing, and to obatin wood for fuel, manufacturing and construction

What are the challenges for the design of climate policies

• policy makers will select policies that yield the greatest net benefits (benefits minus costs)

• Costs of climate policies (e.g. building a flood defence

  • uncertainty of cost → low

  • time scale of benefit → short term

• Benefits of climate policies:

  • Mitigation: reduction of future CC damages due to the decrease in GHG

  • Adaptation: reduction of future CC damages due to the implementation of policies to reduce the vulnerability of social and biological systems

• Benefits depend on future climate

  • uncertainty of cost → high

  • time scale of benefit → short term

• Uncertainty may lead to regret in design of climate policies

What are the time-scale challenges for the design of climate policies?

different time scale costs and benefits of climate policies means that projects to tackle climate change are not likely to be favoured

• Costs of climate policy: time scale → sjort term

• Benefits of climate policy: time scale → long term

Cost benefit analysis

• Cost-benefit rule: politicians will focus on Net Present Value (NPV)

• NPV calculate the difference btw PV benefits and PV costs of the project

In summary, what are the 3 main challenges for the design of climate policies?

1. Global phenomenon (local actions are not enough)

2. Long term phenomenon (intergenerational nature)

3. Uncertainty (benefits are long-term, mostly)