Unit 2 - Climate Science

Question 0

What are the 4 layers of the athmosphere and there temperature caracteristics?

Answer 0

1. Troposphere, upto 12km, declining temp (to -60) upto the tropopause
2. Stratosphere, upto 45km, increasing temp after the tropopause due to the ozon layer - which absorbs incoming ultraviolet radiation from the sun and warms that layer of the athmosphere.
3. Mesosphere, upto 80km, declining temp (to -100)
4. Thermosphere, above 80km, increasing temp due to ionic interactions that produce heat.

Question 1

what is the athmosphere?

Answer 1

a thin layer of mixed gases extending to a height of 80km above the surface. The main constituent gases of the dry atmosphere are nitrogen (78%), oxygen (21%), argon (1%) and CO2 (0.035%) + many other substances.

it is constantly changing, in overall composition but also in terms of the complex set of interactions of its constituent substances.

Question 2

What is albedo?

Answer 2

High albedo = high reflectivity of the earth/atmosphere surface (like snow, ice, terrestrial surfaces)

Low albedo = low reflectivity (darker areas, oceans)

Question 3

what happens with solar radiation?

Answer 3

• some is absorbed by the athmosphere, especially the ultraviolet part in the stratosphere
• some is reflected back by bright clouds and aerosol particles
• some is reflected back at earth by albedo surfaces
• some is absorbed by the earth - and can be re-emitted in the form of heat (a longer wavelength) as an outgoing terrestrial radiation.

Question 4

The heat budget of the earth

Answer 4

the balance between the energy arriving at, and leaving the earth which is achieved by adjustments in the earth’s temperature.

Question 5

What is global circulation?

Answer 5

The movement of air masses (together with heat and ocean currents) that accurs in response to the uneven heating of the earths surface by solar radiation.

Question 6

What is the “Green House Effect”

Answer 6

the warming of the earth’s atmosphere that occurs as a consequence of the existence of GHG (which absorb long-wave radiation) in the atmosphere.

The heat is retained close to the earth’s sueface by a “blanket” of atmospheric gases.

This is a natural phenomenon.

Question 7

What is the enhanced GreenHouse effect?

Answer 7

The added (heating/blanket) effect caused by the gases present in the atmosphere due to human activities such as deforestation and the burning of fossil fuels.

Question 8

What are GHG’s?

Answer 8

The gases that are involved in absorbing some of the energy radiated by the earth’s surface.

Question 9

how would you define the term “climate”?

Answer 9

Climate = the condition of the atmosphere over many years: the mean behaviour of the weather over some appropriate averaging time (which is conventionally taken as 30 years).

Mean behaviour includes the amount of variability - for example the number of extreme events.

the average and variability of temperature, precipitation and wind over a period of time, ranging from months to millions of years (IPPC, 2007)(30 yrs = common period)

Question 10

Which are GHG’s?

Answer 10

Focus is on 6 main GHGs:

1. CO2
2. CH4
3. N2O - nitrous oxide
4. HFC - Hydrofluorocarbon
5. PFC - Perfluorocarbons
6. SF6 - Sulphur Hexafluoride

but also: water vapour (H2O) + ozon (o3)

Question 11

The importance of GHG in promoting GW depends upon?

Answer 11

1. the concentration in the athmosphere
2. the GH effect of each molecule as a result of their absorption of radiation, a consequence of their chemical structure
3. the length of time that the gases stay in the atmosphere

Question 12

what is the GWP (Global Warming Potential)?

Answer 12

the GWP of different gases compared with the same quantity of CO2.

1. the GH effect of each molecule as a result of their absorption of radiation
2. the length the gases stay in the athmosphere.

Question 13

Why is water vapour not concidered on the list of anthropogenic GHGs?

Answer 13

Even though it does trap heat in the atmosphere and is therefore a GHG it also is an important component of other environmental systems and processes.
Its concentration is the atmosphere is largely determined by temperature and other features of the climate system.

Question 14

Why is ozon not concidered on the list of anthropogenic GHGs?

Answer 14

The effect of human’s on the concentration of ozone in the atmosphere are limited by EMISSIONS but are more influenced by the effects of chlorofluorocarbons (CFC’s) in the atmosphere as these break down ozone. (a link to the depletion of the polar stratispheric ozone layer)

Ozon has a positive (GHG) effect in the troposphere but a negative effect in the stratosphere - so the overall effect is less strong.

Question 15

How are human activities promoting accumulation of GHG?

Answer 15

1. Direct GHG emissions / release

2. loss of “sinks” (that also may result in releasing stored GHGs)

Question 16

What are the 3 anthropogenic causes of climate change?

Answer 16

1. contribution to accumulation of GHG’s
2. emissions and formation of aerosols
3. changes in albedo of the earth’s surface

Question 17

UNFCC definition of climate change.

Answer 17

A change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods

CC vs CLimate variability

Question 18

What is climate sensitivity?

Answer 18

a measure of how much the climate is expected to change in response to a given perturbation.

Question 19

what is equilibrium climate sensitivity?

Answer 19

the equilibrium global average surface warming following a doubling of the atmospheric CO2 concentration.

Question 20

Climate Change according to the IPCC

Answer 20

a change in the state of the climate that can be identified (eg using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer.

Question 21

What is the global climate system?

Answer 21

• the athmosphere
• the oceans
• the cryosphere (ice)
• the lithosphere (geology) (land)
• the biosphere (biota) (living things on earth)

Question 22

The 4 major roles the oceans play in the climate system?

Answer 22

1. a major but slow absorber of heat energy
2. tranferring heat from the tropical to the polar regions (Thermohaline circulation also called the conveyor belt)
3. as a heat source for the atmosphere, through evaporation and the rising of warm water vapour from the oceans go into the atmosphere (also important to form clouds and rain)
4. the storage of GHG -capture of CO2
   - CO2 dissolves in water
   - marine organisms contain large amounts of C that was obtained by the plants in the sea.

Question 23

The importance of ice/cryosphere for the climate system?

Answer 23

1. the albedo effect
2. if melted the salinity of the oceans would be influenced which would effect the thermohaline circulation.
3. snow/ice affect seasonal temperature patterns and winds
4. permafrost affects soils containing large amounts of organic matter (peat) and methane, and is therefore important to store GHG.

Question 24

What is climate forcing?

Answer 24

the regularity in glacial events have lead scientist to search for forcing factors or driving mechanisms of CC

1. external forcings = processes originating outside of the atmosphere
2. Internal forcings = processes originating within the atmosphere.

Question 25

What are external forcings?

Answer 25

Driving mechanisms of climate change that originate outside of the atmosphere.

1. Solar variability
2. atronomical variations
3. tectonic processes
4. vulcanic eruptions

Question 26

What are internal forcings?

Answer 26

Driving mechanisms of climate change that originate within the athmosphere (might be stimulated by external forcings)

changes in atmospheric composition and cloud cover & the cryophere affecting the extent of snow and ice

Natural reasons for changes in atmospheric composition:
1. growth in biosphere (increasing sequestration)
2. changes in earth’s thermohaline circulations and threfore vegetation paterns
3. cloud cover as a result of continental drift
4, cryosphere
5. GHG concentrations

Question 27

Feedback mechanisms

Answer 27

Processes that have the effect of modfying the original perturbation (verstoring)

\+ = amplifying the original perturbation
- = damping the original perturbation

Question 28

4 kinds of aerosols

Answer 28

1. black carbonaceous particles (soot) - absorb - warming effect
2. water-soluble inorganic aerosols - backscatter radiation - cooling effect.
3. condensed organic aerosols - backscatter - cooling
4. mineral dust - absorbs - warming effect

Question 29

Some effects of vegetation change (example only)

Answer 29

EXAMPLE ONLY:
replacement of tropical forest by ag crops will reduce the tropical cloud coverage (reduced cycling of water). Also there will be an albedo increase of around 10% locally or more due to the reduced clouds and water cycling

Question 30

IPCC stands for…

Answer 30

Intergovernmental Panel on Climate Change

Started in 1988 jointly by:

• World Meteorological Organisation (WMO)
• UNEP

Question 31

3 working groups of the IPCC assessments:

Answer 31

1. physical science basis of CC
2. CC impacts, adaptation and vulnerability
3. Mitigation of CC

Question 32

CC leads to changes in…

Answer 32

frequency, intensity, spatial extent, duration, and timing of weather events including extreme weather, and can result in unprecedented extreme weather and climate events (IPCC, 2012).

Question 33

Available Carbon Space =

Answer 33

(Tanner/Horn-Phathanothai, 2014)

the total amount of CO2 emmissions that can be allowed if stabilization target were taken seriously.

also called the “carbon budget”