Lec 33: Mitigation to Climate Change

Question 1

What is the main driver in global climate change

Answer 1

Excessive addition of GHG to the atmosphere through anthropocentric activities

Adding more GHG to the atmospheric reservoir than can be naturally removed

Question 2

What is Mitigation

Answer 2

Addressing the cause of climate change

Question 3

What is adaptation

Answer 3

responding to the effects of climate change

Question 4

What is a “wedge” (stabilization wedges)

Answer 4

A “wedge” is a strategy to reduce carbon emissions that grows in 50 years from 0 to 1 GtC/yr

Cumulatively, a wedge redirects the flow of 25GtC in its first 50 years

Question 5

What are the 4 wedge categories (15 wedge strategies)

Answer 5

(4) efficiency and conservation
(1) nuclear energy
(4) fossil-fuel-based Strategies
(6) Renewables and Biostorage

Question 6

What are the 4 wedge strategies of Efficiency and Conservation

Answer 6

1. Transport efficiency
2. Transport Conservation
3. Building Efficiency
4. efficiency of electricity production

Question 7

What are the 4 wedge strategies of Fossil-Fuel-based

Answer 7

1. Fuel switching (coal to gas)
2. Fossil-based electricity with carbon capture and storage (CCS)
3. Coal synfuels with CCS
4. Fossil-based hydrogen fuel with CCS

Question 8

What are the 6 wedge strategies of Renewables and biostorage

Answer 8

1. wind-generated electricity
2. solar electricity
3. wind-generated hydrogen fuel
4. biofuels
5. forest storage
6. soil storage

Question 9

Transport efficiency

Answer 9

1 wedge = fuel efficiency of all cars was doubled from 30 mpg to 60 mpg

efficiency improvements: Hybrid and diesel engines, making vehicles out of stronger, lighter material

There is a total energy loss of 75-82% in gasoline vehicles (which is huge!)

Question 10

Transport conservation

Answer 10

1 wedge= number of miles travelled by the world’s cars were cut in half

Urban planning leading to more use of mass transit and if electronic communication becomes a good substitute for face-to-face meetings

Question 11

Building efficiency

Answer 11

1 wedge = if emissions in all new and existing residential and commercial buildings were cut by 25%

Largest potential savings are : heating and cooling, water heating , lighting and appliances

Carbon savings from end-use efficiency strategies (wall and roof insulation), renewable energy strategies (solar water heating passive solar design)

Question 12

Fuel-Switching for electricity

Answer 12

1 wedge = if 1400 large (1 billion watts) natural gas plants displaced similar coal-electric plants

Because of lower carbon content of natural gas and higher efficiencies of natural gas plants -> 50% emissions of from coal

Question 13

wind electricity

Answer 13

1 wedge= if current wind capacity scaled up by a factor of 10

currently produces 2% of total global electricity

requires 1 million large windmills (area of Germany)

growing rate of 30% per year

Question 14

Solar electricity

Answer 14

1 wedge = if installed solar arrays with an area of two million hectares (20 000 Km2)

convert sunlight to electricity, CO2 free and renewable

lower land demand than other renewables

currently provides less than 4% of total energy

Question 15

Nuclear electricity

Answer 15

1 wedge = if the world’s current nuclear capacity by nuclear electric plants was tripled

currently provides 10 % of the world’s electricity, no CO2, world’s second largest source of low-carbon power

1960s global installed nuclear capacity of about 2000 billion watts was projected by 2000 - now only 1/6 (if done = 2 wedges)

Question 16

what are the safest and cleanest sources of energy ?

Answer 16

Wind, Nuclear and solar

Question 17

Forest storage

Answer 17

1 wedge = if global deforestation was stopped

current global deforestation adds 1-2 billion tons of carbon to atmosphere

“natural sinks”

Requires reduction in deforestation + planting new trees

Question 18

geoengineering frame works:

Answer 18

carbon dioxide removal

increasing global or local albedo

Question 19

give some examples of bioengineering proposals

Answer 19

• Increased reflectivity from low clouds (by spraying sea salt into them)
• thinning high clouds (clouds act as a blanket, retaining heat)
• ocean fertilisation (increasing population of carbon-absorbing plankton)
• Increased reflectivity from the oceans (microbubbles increase reflectivity)
• Biochar (carbon-rich charcoal from burnt crops added to soil)
• Direct capture and storage of CO2
• Afforestation
  …

Question 20

Stratospheric aerosol injection

Answer 20

Intentional injection of molecules which interact with, and reflect shortwave solar radiation in the atmosphere

Question 21

an exemple of stratospheric aerosol injection ( that has happened)

Answer 21

The year with no summer due to the mass release of SO2 from volcanoes

Question 22

Does SO2 interact directly with shortwave radiation?

Answer 22

No it interacts with Hydroxyl, water and oxygen molecules, forming sulfuric acid droplets wich do interact and reflect shortwave radiation

Question 23

T or F: Aerosol suspension in the atmosphere is temporary

Answer 23

TRUE

Question 24

what is aerosol masking

Answer 24

The reflection of incoming solar radiation by aerosols (man-made and natural)

(like a layer of dirty insulation)

Question 25

what is marine cloud brigthening:

Answer 25

Generate more, longer lasting, high-altitude clouds over marine environmnets through the injection of sea salt particles into the air

(Based on observations that aerosols in ehaust of modern marine shipping leaves trails (ship tracks) which induce the formation of clouds)

Question 26

Refreezing arctic sea ice

Answer 26

water from the arctic ocean is pumped onto thin arctic ice, allowing the water to freeze and thicken the ice layer

Question 27

Ocean fertilization (and its process)

Answer 27

Utilizing the biological pump of the ocean to sequester carbon in the sediment layer

Process:
Add one or more nutrients to stimulate growth in the trophic level which uptakes dissolved carbon from the water ( phytoplankton and algea)

Increase in algea / phytoplankton = increase in carbon which enters the biological pump

and ultimately enters the sediment layer in the ocean

Question 28

what are the potential issues with ocean fertilization

Answer 28

overfertilization causing shifts in food webs or eutrophication

Question 29

Carbon capture

Answer 29

Direct capture and storage of carbon

atmospheric carbon is removed from the atmospheric reservoir, and incorporated into long term storage in commercial products or the rock layer

Question 30

what are the considerations to have regarding geoengineering?

Answer 30

who gets to decide how things are implemented?

some countries will likely experience weather disruptions, how will the be compensated?

what is we make things worse?

The main barrier is how to scale