Quiz 1c Flashcards
Relative importance of climate change
Most serious environmental problem facing humanity is global climate change.
Probable causes of climate change
Anthropogenic enhancement of the greenhouse effect, which has increased levels of carbon dioxide and other greenhouse gases.
Is anyone currently sure of the extent or timing of future temperature increases associated with global warming?
No, no one currently is sure of the extent or timing of future temperature increases.
Do current atmospheric models predict significant warming in current decades?
Yes.
Albedo
The fraction of sunlight reflected back into space by an object.
Global Warming Trend: 1910 - 1940, first increase
Slight difference in sun emission and less volcano activity.
Global Warming Trend: 1940 - 1970, decrease
Scattering from aerosols and more volcanic activity.
Global Warming Trend: 1970 - present, increase
Anthropogenic releases of greenhouse gases.
What must be true of the sources and sinks or Earth’s energy if the average temperature of the Earth is to remain constant over time?
The sources and sinks must be equal.
Earth is called the blue planet, is the blue light reflected or emitted?
Reflected: the energy emitted from Earth is not visible.
Greenhouse Effect (GHE)
Atmospheric constituents intercepting outgoing Earth IR, dissipation of that into heart which warms up the atmosphere. Has been going on forever. H20 and CO2.
Enhance Greenhouse Effect (EGHE)
Artificial global warming, increase trace gases in atmosphere increasing the GHE.
Different ways of sending energy from sun back into space: Reflection
Changes direction, not energy. Large impact on Earth temperature because any light reflected isn’t absorbed. This is why the ocean is blue.
Different ways of sending energy from sun back into space: Scattering
Photon/wave in contact with particles of similar size. After interaction with a particle, scattering is in a random direction.
Different ways of sending energy from sun back into space: Absorption
Increases energy of the molecule.
Is it heat or work: A photon of light leaves the sun due to the high temperature of Sun’s surface.
Work.
Is it heat or work: A photon of light travels through space from the sun to the Earth.
No energy loss, neither.
Is it heat or work: A photon of light i absorbed by a molecule on a rock, causing the molecule to vibrate, which in turn increases both the kinetic energy and the temperature.
Work.
Is it heat or work: Rock molecule collides with air molecule, increasing the air molecules kinetic energy and temperature.
Heat.
Fixed Carbon
CO2 that is captured as polymeric CH2O by photosynthesis, no longer free to function as a gas.
Seasonal Nature of Fixed Carbon
Spring/summer: increase in photosynthesis = a decrease in CO2, fall/winter: increase in decay = an increase in CO2.
What are permanent sinks for CO2? (2)
Dissolution in deep sea waters and precipitation in deep sea waters as CaCO3.
What are temporary sinks for CO2? (2)
Dissolve in surface of sea water or are absorbed by a growing plant.
CO2 Fertilization
Increase in growth rate of certain types of trees due to the increase concentrations of CO2 in air.
What is the most important GHG?
Water Vapour
Positive Feedback
The operation of a phenomenon produces a result that itself further amplifies the result.
Why are night time temperatures colder when air is dry and free of cloud cover?
There is little to no water vapour in these conditions. Water vapour contributes significantly to the GHE, increasing Earth’s surface temperature.
Why is the atmospheric window important in determining the degree to which various trace gases will increase contributions to the GHE?
Allow IR from 8 to 13 um pass through to space without intermediate absorption and re-emission (this IR doesn’t heat atmosphere then). If a trace gas (like CH4, O3, CFCs, or NOx) absorbs IR in that window, it will greatly increase the GHE.
What is the lifetime of methane in the atmosphere?
What are three sinks of atmospheric methane?
Reaction with hydroxyl molecules, reaction with soil and loss to stratosphere.
1 kg of methane is how many times more effective than CO2 at raising air temperature?
23 times.
To date, how much CH4 vs. CO2 has contributed to global warming?
1/3 as much as CO2.
What % of CH4 emissions are anthropogenic?
70%
Six most important sources of atmospheric CH4, in decreasing order.
Natural wetlands (25%) > Energy production and distribution / ruminant livestock > rice production > biomass burning > landfills
Identify three potential positive feedback patterns for CH4.
Increasing rate of decay, melting permafrost, and releasing methane hydrate from ocean floor.
Decay: increase CH4 emissions = increase GHE = increase warming = increase rate of decay = increase methane
Runaway Greenhouse Effect
The super positive feedback loop caused by the simultaneous increase of all positive feedback patterns. Combined will trigger unstoppable warming of Earth.
Clatherate
A compound in which molecules of one compound are physically trapped within the crystal structure of another.
Example of a Clatherate
Methane Hydrate (CH4 . 6H2O) is methane trapped in water at bottom of ocean due to the increased pressure and decrease temperature conditions of the ocean floor.
Compare short term effects of NOx vs CO2
206 times as effective as CO2 in causing an immediate increase in global warming.
Atmospheric lifetime of N2O
About 120 years.
Net effect of NOx vs. CH4 on global warming.
1/3 as much.
Sources of atmospheric N2O (4)
Anthropogenic: nylon industry, fertilizer use, natural: oceans, soils.
Sinks of atmospheric N2O (1)
None, usually N2O rises to stratosphere and decompose after interacting with UV.
Why is it important to know that CFCs absorb in the atmospheric window?
Even a small amount of CFCs significantly contributes to GHE.
CFC vs. CO2 effect on global warming
1 molecule CFC = tens of thousands of molecules of CO2.
SF6 vs. CO2 global warming potential
SF6 is 23, 900 times greater than CO2
Atmospheric lifetime for SF6
About 3200 years
What are sources for tropospheric ozone? (4)
Pollution from: power plants, vehicles, fires and natural processes.
What % tropospheric GHE from ozone?
10%
Aerosol
A colloidal suspension of particles dispersed in air or gas.
What is effect of aerosols on global warming?
They offset, and thereby mask, a significant fraction of the atmospheric temperature increases that would have otherwise occurred due to anthropogenic GHG emissions.
Use the Pinatubo Eruption to explain the ways that aerosols can effect the energy flow from the sun, to the Earth, and then back to space. (Initially and Long-term)
Initially: lower stratosphere warmed due to large volcanic ash particles absorbing some incoming sunlight and outgoing IR, this large ash falls quickly.
Long-term: Stratospheric aerosol (sulfate) created from oxidation of 30 million tonnes SO2 efficiently reflects sunlight back to space for many years. In the area of this eruption there is significantly decreased ground temperatures.
What is main sink for atmospheric aerosol?
Rain
What is atmospheric lifetime of an aerosol particle?
Several years.
Three main geographical hotspots for aerosols?
SE USA/NE Mexico, North Africa, and East Asia
Decreasing order in magnitude of warming contribution of different GHGs.
Water vapour > CO2 > CH4 > O3 > CFCs > N2O
Which areas of Earth experiencing greatest increases in temperature due to global warming?
Over land areas, especially in the arctic.
What type of feedback does Arctic ice melting cause?
Positive Feedback
Most important problems to modelling future global warming?
Don’t fully understand all sources and sinks of GHGs or the net effect of aerosols.
What is the effect of low and high lying cloud on global warming?
Low lying: warm clouds that re-emit some of outgoing Earth IR towards Earth, but the net effect is cooling from reflection of incoming sun.
High lying: cold clouds that absorb outgoing Earth IR and converts that IR to heat. Net effect is warming.
List six shifts that indicate that climate change is indeed occurring.
- Precipitation has decreased in most areas, but decreased in others.
- Extreme weather is becoming more common.
- Winters about 11 days shorter.
- Earth’s ice cover is shrinking fast.
- Warming water is killing coral in reefs and threatening sea life.
- Mosquito bourne diseases reaching high altitudes.
