1.Introduction Flashcards
What is the science behind global warming?
I-Physical Greenhouse gas effect:
- CO2
- CH4
- N2O
- PFC
- HFC
- SF6
- water vapouz
- Incoming solar radiation passing the atmosphere: 343 W/m²
- from the sun we have net incoming radiation: 240 W/m²
- Outgoing solar radiation reflected by the atmosphere and earth’surface 103 W/m²
- The energy is absorbed by the earth’s surface and warms it 168 W/m² and converted into heat causing the emission of longwave infrared radiation back to the atmosphere.
- Some of the infrared radiation is absorbed and re-emitted by the greenhouse gas molecules–> warming the earth’s surface and the troposphere
5- Surface gains more heat and infrared radiation is emitted again–> Infrared radiation (heat energy) trapped in the atmosphere by pollutants
Greenhouse Effect history:
Long establishment in history e.g.Tyndall 1800s
II-Anthropogenic causes:
Today we have increasing levels of ghg in the atmosphere from 280 ppm in the pre-industrial period to 407 ppm this august.
Causes:
- Energy sector, burning fossile fuels
- Deforestation (land use)
- Transport
- Industry
- Agriculture
CH4: methane and N2O: nitrous di-oxide are increasing the most
if concentrations remain constant: 1-3 C above preindustrial levels
Increasing GHG concentration and feedback effects
The increase in ghg concentrations has positive and negative feedback effects, Change in regional weather patterns/cycles will affect regions unevenly: leading to an acceleration of warming (positive feedback) or deceleration (negative feedback)
Negative:
1) increasing cloud cover will reduce the amount of radiation entering the earth’s atmosphere
2) higher rates of carbon dioxide will lead to higher rates of plant growth and thus trapping carbon dioxide
Positive:
1) higher temperatures may generate widespread forest fires & forest dieback
2) emission of methane & CO2 currently trapped in frozen bogs & peat fields at high latitudes
3) Release of methane from wetlands, permafrost –> Land carbon sinks -> Absorption (varies) –Release = Net Emission
4) reduced the capacity of ocean organisms to fix carbon dioxide in their shells –> Ocean sinks reduce (absorbing limitations of algae)
–> Positive feedback effects could increase temperature (1 -2 C) by 2100
Name some global consequences of increases in temperature:
- •Water supply (irrigation and food provision)
- •Episodes of extreme events
- •More heat waves/droughts
- •Reduction in crop yields
- •Spread of vector-borne diseases -malaria
- •Rising sea levels/reduction of ice sheets (feedback effects)
- •Extinction of flora and diverse species–>
Irreversible effect -destruction of ecosystems in long run!
Give consequences of increasing temperature in
Europe:
- Weakening of the Atlantic thermohaline Circulation: cooling effect
- Increased sea levels
- Increased occurrences of rainfall and flooding
- Increasesin temperature
- 20% fall in crop yield and water supply in southern Europe with a 2oC temperature increase
Potential benefits:
- Possible higher agricultural productivity
- Less winter mortality
- Increased tourism in some areas e.g. Scandinavia
What possible climate impacts are related to each degree of temperature rise from 1 to 5 degrees rise?
Water, Food, Health, Land, Environment, and abrupt and large scale impacts
What levels of concentrations should be agreed upon?
- According to Stern (2006):
- 2 C degree change: Stabilisingat or below 550 ppm CO2e (around 440 –500 ppm CO2 only) would require global emissions to peak in the next 10 -20 years, and then fall at a rate of at least 1 -3% per year.
- By 2050, global emissions would need to be around 25% below current levels. These cuts will have to be made in the context of a world economy in 2050 that maybe 3 to 4 times larger than today -so emissions/GDP would need to be just 1/4 of current levels by 2050.
What are the expected costs for achieving emissions reductions and stabilization around 500 ppm CO2e in the in Stern Review?
What are the issues with the projected costs?
Will likely be around 1% of GDP by 2050 -range of +/-3% which reflects uncertainties in the:
- The scale of mitigation required
- The pace of technological innovation and the degree of policy flexibility
Issues with projected Cost
- The timing of abatement, (later abatement will cost more)
- Assumptions used in the models about technological progress/change
- The extent to which global pollution is “flexible” (including international cooperation)
- The extent of the target: large change in costs from 550 ppm to 450 ppm
- CO2 is stock pollution around for 40-50 years –>stabilization is not a reduction in the stock of CO2
What are the arguments of CC skeptics?
- No link between human activity and global warming
- ->Evidence shows this clearly
- Neither the rate nor magnitude of recent warming is exceptional.
- There was no significant warming from 2002-2008
- ->Evidence shows this clearly: Intergovernmental Panel on Climate change’ (IPCC) ‘s global tem increase by at least 0.2 degrees per decade
PS:
- The IPCC models may have overestimated the climate sensitivity for greenhouse gases, underestimated natural variability, or both.
- Therefore systematic upward bias in the impacts estimates based on these models just from this factor alone.
Agreement and disagreements :Stern vs. Nordhaus:
Stern Review on the Economics of Climate Change:William Nordhaus:
https://www.youtube.com/watch?v=ne5XtJkt4sI
minute 4 to 5
What is Climate Change Economics about?
Answering these 3 questions:
- What are the incentives for citizens, firms and governments in mitigating GHGs?
- How can we mitigate GHG to a specific level efficiently? –> How much pollution is too much? –> i.e. how can we minimize the cost of GHG abatement?
- What mechanisms are optimal/desirable for Climate change mitigation, and under what conditions are some mechanisms preferred to other types?
