Download 13-2 ch19-1 pt 2 lec

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Warm-up: (3-14-17)
1. List 3 sources of methane that you have learned about this year.
2. What trend does the Keeling curve show? What accounts for the seasonal fluctuation in CO2?
3. Over the last million years, glacial periods lasting about ___ years have alternated with interglacial periods
lasting about ___ years.
4. What was the concentration of CO2 (in ppm) in the troposphere around 1900? 2000? now?
5. T/F. Sulfur dioxide and NO2 are greenhouse gases.
6. Explain how heat is transferred from the equator to the poles.
Chapter 19-1 pt.2
Global Climate Change
Goals for today:
 List sources of methane and nitrous oxide (N2O)
 Describe how slowing down the Great Ocean Conveyer Belt can influence climate
 Explain how the oceans and the albedo effect can change climate
 Describe what is causing sea levels to rise
 Major Greenhouse Gases
The major greenhouse gases are:
water vapor
carbon dioxide
Methane
nitrous oxide (N2O)
 These gases have always been present.
Major Greenhouse Gases
Increases in average concentrations between 1860 and 2004, mostly due to:
Fossil fuel burning
Deforestation
Agriculture
Burning methane releases…
Clearing land for agriculture releases…
Cows release…
Bacteria that live in wetlands release _____
_____ has a global warming potential of 20-25 times more potent compared to CO2
Using more inorganic fertilizers release _____
Trees and the ocean are carbon _____ because they absorb CO2 out of the atmosphere.
Nitrous oxide is produced naturally in soils by microbes doing denitrification and nitrification.
Emissions of N2O can be increased by:
use of synthetic and organic fertilizers
Sewage- break down of urea, ammonia, proteins
during fossil fuel combustion
production of nitrogen-fixing crops
livestock manure on croplands
Planting _____ fields- N2O and methane
Oceans
Why haven’t we seen more of an increase in CO2 in the atmosphere in the last century?
Oceans can absorb _____ and _____
About ½ the CO2 emitted by humans is absorbed by oceans.
If they absorb too much CO2, what happens to the pH?
What happens next?
If the oceans warm up, what are some consequences?
Rising Sea Levels
During the last century, the world’s sea level rose by 10-20 cm, mostly due to:
runoff from melting land-based ice
expansion of ocean water as temperatures rise
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Computer climate models
Understanding past climate and predicting future climate change rely on computer climate models
Global temperature computer model
Which seems to be warming more? Arctic or Antarctic
EFFECTS OF GLOBAL WARMING
Between 1979 and 2005, average Arctic sea ice dropped 20% (as shown in blue hues above).
How is a polar bear like a canary?
Ice is thinning. Good news for boats that want to go through the Northwest passage, but bad news for polar
bears.
Antarctic sea ice is not changing very much
Grows in winter, shrinks in summer
But in 2002, the Larsen B ice shelf in the Antarctic, collapsed over a few months
Size of Rhode Island
Pools of water collecting on the surface started to seep under the ice
Made wedges that later collapsed
Now, the land ice is no longer held back from the ocean
Albedo
Average overall albedo of Earth: 0.30 to 0.35
0 is energy completely absorbed (not reflected)
Example would be dark colored surfaces
1 is energy completely reflected (not absorbed)
If Earth’s albedo increased, what would happen to the surface temperature?
Snow albedo can be as high as 0.9
Clouds also reflect light
Which is more dense?
cold water or warm water
Salty or fresh water
Currents
Rising Sea Levels
During this century rising seas levels are projected to flood low-lying urban areas, coastal estuaries, wetlands,
coral reefs, and barrier islands and beaches.
Rising Sea Levels
Ex. Bangladesh- climate refugees
50% of the population of Bangladesh lives less than 5 meters above sea level.
Scientists predict Bangladesh will lose 17% of its land by 2050 due to flooding caused by climate change.
The loss of land could lead to as many as 20 million climate refugees from Bangladesh.
Rising Sea Levels
If seas levels rise by 9-88cm during this century, islands and their coral reefs will be flooded.
Inc. erosion of coasts
Contaminate aquifers with salt
Flooding
More flooding and stagnant water could mean more…
Spread of Malaria and Mosquitoes
 Warmer temperatures in Alaska, Russia, and the Arctic are melting permafrost releasing more CO2 and
CH4 into the troposphere.
 Rising temperatures melt permafrost releasing more methane and carbon dioxide. This is a (positive,
negative) feedback loop.
Methane may be released from oceanic mud as ocean waters warm.
Gas seep sites are covered by methane hydrates (frozen)
solid crystals of methane encapsulated in ice due to low temperatures and high pressures
55 million years ago, Paleocene-Eocene Thermal Maximum (PETM)
Foram data shows a brief period of extreme warming due to massive greenhouse gas increase
Deep ocean warmed 6-7 degrees C
 Methane released turned into carbon dioxide that left the ocean, went into the atmosphere, then went back
into the ocean again.
 No shells in some layers.
 Phenology
 Phenology: study of the timing of seasonal activities such as flowering or breeding
 We can see how these are influenced by variations in climate
 Ex. Spring coming too early or late
 Migrating butterflies + blooming flowers
 Birds having babies + abundance of caterpillars
 Final Thoughts…
 Climate change reduces Arctic/Antarctic sea ice. This can lead to more land based ice entering the ocean. This
will cause …
 Alpine glaciers are melting. This will result in…
 Rising sea levels could result in…
 As the location of certain types of vegetation shifts, …
 Warmer oceans could cause…
 Melting permafrost could lead to…
 Fewer glaciers means the albedo of Earth will _____, and this will lead to a _____ in temps.
 Check for Understanding:
 1. Increased greenhouse gases originate from _____
 2. Explain how oceans affect climate.
 3. Rising sea levels can lead to…
 4. List 3 ways biodiversity will be reduced by climate change.