L5 - Feedbacks

Question 1

What does an initial change in radiative forcing induce changes in? (clear sky feedback)

Answer 1

• Water vapour in atmosphere
• Vertical distribution of water vapour
• Tropospheric lapse rate (in cloud free regions)

Question 2

Emissivity

Answer 2

the ratio of radiation of an object to that of a blackbody at the same temperature

Question 3

negative lapse rate feedback?

Answer 3

larger temp change in the upper troposphere

Question 4

positive lapse rate feedback?

Answer 4

larger temperature change at the surface

Question 5

Where is global warming strongest?

Answer 5

Warming is amplified at the poles (2-6 times stronger) due to snow albedo feedback and increase in lapse rate (positive LR feedback)

Question 6

What is the impact of doubling co2 on lapse rate at the equator?

Answer 6

This will result in a negative lapse rate feedback with a larger temp change in upper troposphere. This is because there is more water vapour in the atmosphere and higher up, increasing temps here. However at the equator there is some evaporative cooling due to more rainfall

Question 7

What is the impact of doubling co2 on lapse rate at the poles?

Answer 7

A positive lapse rate feedback will result with a larger temperature change at the surface than in the upper troposphere. This is because increasing co2 increases ice melting thus lowers albedo and more absorption takes place at the surface, however there is little change higher up.

Question 8

Temperature gradient (Teq - Tp):

Answer 8

Lower troposphere -> negative trend (reduced storms)
Upper troposphere -> positive trend (increased storms)

Question 9

Positive ice albedo

Answer 9

cooling amplified by LW radiation reflected

Question 10

Negative-growth-thickness feedback

Answer 10

increased heat loss from ocean when ice melts, more ice production, original thinning will be less (i.e. ice loss is suppressed by ocean cooling)

Question 11

Cirrus clouds

Answer 11

high thin clouds with a LOW albedo. Tend to warm. Long wave term dominant

Question 12

Cumulus clouds

Answer 12

low thick clouds with HIGH albedo. Tend to cool. Short wave albedo term dominant

Question 13

Rubisco

Answer 13

primary carboxylase of the photosynthetic process.
- Binding to O2 = respiration
- Binding to CO2 = photosynthesis

Question 14

Chloroplasts

Answer 14

specialized cell organelles which are located in mesophyll and palisade cells in leaves

Question 15

Law of diminishing returns

Answer 15

when you increase the limiting factor (co2), the short term plant response will likely saturate. Eventually co2 is no longer the limiting factor

Question 16

Permafrost/cryotic soil

Answer 16

soil which is at or below 0 degrees for 2 or more years
- Little decomposition
- When they thaw large amounts of methane are released

Question 17

how does forest cover impact albedo

Answer 17

decreases albedo by absorbing LW radiation

Question 18

components of radiative forcing?

Answer 18

blackbody feedback (0), lapse rate feedback (L), water vapour feedback (W), cloud feedback (C), albedo feedback (a)

Question 19

How do clouds heat?

Answer 19

By trapping LW radiation with high cirrus clouds. These have low albedo and let most SW radiation through

Question 20

How do clouds cool?

Answer 20

By reflecting SW radiation with low cumulus clouds. These have high albedo

Question 21

What are the carbon and biogeochemical feedbacks?

Answer 21

1. Concentration carbon
2. Climate carbon
3. Permafrost
   4.Interactions climate and terrestrial biosphere

Question 22

What is the effect of increased co2 on stomata size over time?

Answer 22

Decreases stomata size, thus less water loss. Extended growing season in water limited environments and reduction in soil drying.

Question 23

What limits plant production?

Answer 23

Temperature, radiation and water supply