Organizing Ideas and Concepts Related to Global Warming
February 14 th
Solutions
1) Explain carefully in words how greenhouse gases warm the Earth. Draw a diagram if it helps.
We know that the greenhouse effect occurs.
An explanation from class of how the greenhouse effect occurs:
The Earth heats up as it absorbs radiant energy from the Sun. The warmed Earth re-emits energy as infrared radiation.
Greenhouse gases are gases that absorb in the frequencies of IR that the Earth emits and re-emits some of it back to the surface of the earth. They also block the
Earth from releasing some of its input energy. Thus the Earth reaches a higher
T than before and its released energy matches the solar input and the T stabilizes.
• We know we are adding greenhouse gases (GHGs) to the atmosphere.
2) Give the chemical formula for the following important atmospheric gases, and rank them from the most to least abundance in the atmosphere: carbon dioxide, methane, nitrogen, oxygen, ozone. Which of these are greenhouse gas?
Nitrogen, N
2
,
Oxygen, O
2
Carbon Dioxide, CO
2
, Greenhouse Gas
Most Abundant
Methane CH
4
, Greenhouse Gas
Ozone, O
3
, Greenhouse Gas Least Abundant
3) Define “albedo.” Describe 3 primary contributions to Earth’s albedo. Which one is the largest contributor?
What happens to the Sun’s energy when it hits the earth?

30% is reflected back to space. This is known as the Albedo of the Earth. o Albedo – is how much of the incoming sunlight is reflected away. o This reflection is due to ice, snow and especially clouds.

o Visible light is bounced back

70% is absorbed by the planet
4) List the two factors that contribute to sea level rise in a warming climate, and describe how they do so.
Note: It takes about 2000 year fro sea-level to stabilize! That means any thing we are doing that may change sea level will still be changing sea level 2000 years from now!
If we warm the Earth a little bit
- Ice melts, within a couple of 100 years all the ice that could melt is done melting so sea level will start to stabilize (the red line in the above diagram)
- As the ocean gets warmer, the water expands
- Thermal expansion (the green line in the above diagram) causes sea level rise too.
- At the beginning Sea Ice is responsible for the big jump in sea level rise. As time passes the sea ice part becomes less important and the thermal expansion effect takes over.
- Even if there was no melting whatsoever you’d still get rising due to thermal expansion.
- It takes 2000 years for the entire ocean to experience the warming that is going on at the ocean surface.
- What ever warming we are doing now will still be causing thermal expansion of the ocean for the next 2000 years?
5) The Keeling curve plots the observed concentration of some gas over the past 5 decades.
Which gas is plotted? What are the main features of the Keeling curve? Explain why it has the appearance that it does.
Keeling Curve: Measurements of CO2 through time


Measurements taken at Mauna Loa, Hawaii from Mid 1950s to the present.

CO
2
wiggles on a seasonal basis o More three during growing season take up CO
2
so atmospheric concentration goes down o In winter trees don’t need as much so atmospheric concentration goes up.

General trend up due to the burning of fossil fuels
The Keeling Curve shows how CO
2 has increased over the past 40 years. The yearly oscillation is due to the net growth of plants while the larger increasing trend is due to our activities and the increase of CO
2
through the burning of fossil fuels.