L20 - geoengineering

Question 1

what is Geoenginnering (definition)

Answer 1

Deliberate manipulation of Earth’s climate to counteract the effects of greenhouse gases

Question 2

There are two methods of geoenginnering related to positive and negative forcing, what are these?

Answer 2

Reducing the positive forcing – affecting albedo

Increasing the negative forcing – affecting co2

Question 3

what is the main difference between carbon dioxide removal and solar radiation management

Answer 3

Carbon dioxide removal techniques address the root
cause of climate change by removing greenhouse gases
from the atmosphere.
Solar radiation management techniques attempt to
offset effects of increased greenhouse gas concentrations by causing the Earth to absorb less solar radiation.

Question 4

how much solar radiation do we get?

Answer 4

342 Wm^-2

Question 5

how much solar radiation is reflected?

Answer 5

107 Wm^-2

Question 6

What is SRM

Answer 6

solar radiation management

Question 7

give some examples of SRM approaches

Answer 7

• Cloud albedo enhancment
• desert albedo enhancment
• human settlement albedo
• more reflective crops
• stratospheric aresols
• space - based reflectors
• conventional mitigation

Question 8

what is marine cloud albedo enhancement or cloud brightening

Answer 8

Create a fleet of vessels that would spray sea spray into the sky
Increases the number of cloud drops
Increases the reflectivity

Question 9

what are the advantages and disadvantages of marine cloud brightening

Answer 9

Technologically quite straight forward

Problems
Spray it but the plume doesnt always get into the cloud

Question 10

what other impacts inadvertent impacts can sea spray have

Answer 10

affect weather patterns

Question 11

what is the prediction of temperature response to stratospheric aerosol geoengineering

Answer 11

Temperature response to 2 x CO2 without (top) and with (bottom) 1.84% reduction in mean global insolation.

Question 12

general arguments for geoengineering

Answer 12

“An opportunity to ‘buy time’ while technologies are improved to enable effective emissions reductions and development of non-fossil fuel energy sources”

“Not an alternative to mitigation”

Question 13

general arguments against geoengineering

Answer 13

“At best, a last resort to preserve habitability when all else fails; at worst, dangerous interference with the Earth system with catastrophic consequences”

“Insurance policies can encourage risky behaviour”

Question 14

3. By roughly how much would we need to adjust the albedo of the Earth’s surface to cancel our 4 W m-2 of radiative forcing due to increases in greenhouse gases? 0.1%, 1%, 3% or 10%?

Answer 14

3. It would require about a 3% increase in surface albedo.

Question 15

4. Name three methods that have been proposed for solar radiation management and which are capable (potentially) of cancelling out several W m-2 of greenhouse gas warming.

Answer 15

4. The methods of solar radiation management are: changing the albedo of clouds, injecting sulphate aerosols into the stratosphere, modifying the albedo of crops, space-based reflectors, increasing the albedo of the unused Earth surface by placing reflectors.

Question 16

5. Aside from the practical aspects of implementing solar radiation management, what major negative consequence has been identified?

Answer 16

5. Significant shifts in global precipitation patterns.

Question 17

6. What major climate change problem is not solved by solar radiation management?

Answer 17

6. The effect of rising arbon dioxide on ocean acidification.

Question 18

7. Name two methods of carbon dioxide removal that could remove a significant fraction of industrial emissions over the next century.

Answer 18

7. Carbon dioxide concentrations could rise by well over 100 ppm, so the only viable methods are enhanced weathering, chemical CO2 capture, and possibly biomass burning and carbon sequestration (pumping the CO2 into old oil wells).