Climate - Atmospheric system (1. Causes of global climate change)

Question 1

What is sunspot activity?

Answer 1

Sunspots are magnetic storms that, paradoxically, increase overall solar output.Sunspot activity follows an ~11-year cycle, alternating between solar maximum and solar minimum.

Question 2

Is sunspot activity linked to a rise in global temepratures?

Answer 2

Periods of high sunspot activity correlate with higher global temperatures, but the IPCC revised solar forcing’s contribution to only ~20% of recent warming (from a previously estimated 40%).

Question 3

How do volcanic eruptions affect global temperatures?

Answer 3

Aerosols and sulphur dioxide are ejected into the stratosphere.

Sunlight is reflected and short-term global cooling is caused

Question 4

What is global dimming?

Answer 4

A phenomenon where where atmospheric pollution (like soot and sulphates) reduces the amount of sunlight reaching Earth — estimated to decrease by 2% per decade.

Question 5

What is the positive feedback loop present in relation to terrestrial albedo?

Answer 5

Melting ice reduces albedo, exposing darker surfaces that absorb more energy → leads to further warming and more melting — a positive feedback loop.

Question 6

How much lower is the area of arctic sea ice in 2024 comapred to the 1981-2010 average?

Answer 6

30% - area comparable to the size of Texas

Question 7

How much more potent is methane compared to CO2?

Answer 7

28x

Question 8

What are the two main sources of methane?

Answer 8

1. Thawing permafrost in the Arctic - releases trapped methane
2. Agriculture - cattle & rice paddies

Question 9

Example of a feedback loop with methane

Answer 9

Rising temperatures → permafrost thaws → methane is released → more warming → more permafrost thaws.

Question 10

What are the four main GHG released by human activity?

Answer 10

CO₂ (carbon dioxide) from fossil fuel combustion (transport, electricity, industry).

CH₄ (methane) from agriculture and landfill.

N₂O (nitrous oxide) from fertilizer use and industrial processes.

CFCs (chlorofluorocarbons) from refrigeration and aerosols (now largely banned).

Question 11

Insolation

Answer 11

Incoming shortwave radiation from the Sun (mostly UV and visible light)

Question 12

Shortwave vs Longwave Radiation

Answer 12

Sun emits shortwave; Earth re-emits absorbed energy as longwave (infrared) radiation

Question 13

Back Radiation

Answer 13

Longwave radiation re-radiated downward by greenhouse gases

Question 14

Sensible Heat

Answer 14

Heat that changes temperature but not state

Question 15

Latent Heat

Answer 15

Heat absorbed/released during phase change

Question 16

Sunspot Activity

Answer 16

Magnetic disturbances on the sun, create more energy output

Question 17

What type of equillibrium did the Earth used to be in?

Answer 17

The atmosphere was once in radiative equilibrium, but human activities have disrupted this by increasing greenhouse gases.

Question 18

What is an example of a negative feedback loop?

Answer 18

negative feedback - counteracts (reverses) the initial forcing process / reverses

example: increased heat → increased plant growth → absorbs CO₂

Question 19

How are carbon sinks disrupted?

Answer 19

melting permafrost, forest loss → more emissions

Question 20

What would the temperature of the Earth be without the natual greenhouse effect?

Answer 20

-18°C

Question 21

What GHG is the most abundant in the atmosphere?

Answer 21

Water vapor: Most abundant, but not anthropogenic