aim: how do we contribute to global warming and what is...
TRANSCRIPT
AIM: How do we contribute to Global Warming and what is the greenhouse effect?
Do Now: Why is climate change bad?
Notepack 42
CLIMATE CHANGE
• Any change in global temperatures and precipitation over time due to natural variability or to human activity.
• Some think a greenhouse effect could cause a disruption to the climate system
Climate vs. Weather
• The difference between Climate-Weather is really a measure of time.
Weather is what happens over a short time
Climate is the behavior of the atmosphere over a longer period.
How does the Greenhouse Effect work?
• Solar Radiation passes through the atmosphere.
• This radiation contains different wavelengths.
• Only a few types of wavelengths affect the Earth’s climate.
How does the Greenhouse Effect work?
• Some solar energy passes through the atmosphere and is absorbed by the ground.
• As this energy enter the ground, it warms the Earth’s surface
• Some energy is re-emitted into the atmosphere as Infrared Radiation ( heat or long waves)
• Under normal conditions, much of the heat leaves the atmosphere and goes into space.
How does the Greenhouse Effect work? (cont)
• Some Infrared radiation is absorbed by Greenhouse Gases which radiates this heat back towards the Earth’s surface—warming the Earth
• However, as more greenhouse gases are released into the atmosphere, more heat is trap causing the atmosphere’s temperature to rise.
Copy Diagram into your notebook
Greenhouse Effect Sun
What are 3 the Greenhouse Gases?
Carbon Dioxide (CO2) = deforestation and burning of fossil fuels
for cars and factories. (number 1 greenhouse gas)
Methane (CH4) = animal waste, burning fossil fuels, landfills,
sewage
Water Vapor (H20) = evaporation (oceans), plant transpiration
• Greenhouse Gases are very important for survival on Earth.
• When these gases are balanced, they keep the planet at a comfortable temperature.
• Without them Earth would be frozen, an average temp being about 0 degrees F or -18C
Are Greenhouse Gases Important?
Global Temperature Rise
• The global temperature seems to be on a rise.
• Since around 1880 (when records were first being kept) the average temperature has been rising.
• The 10 warmest years of global temperature all occur within the past 15 years
• This rapid rise in temperature is unmatched in the last million years
• The “Last” global warming at the end of an ice age was a gradual process taking about 5000 years
What have we seen because of temp rise?
• Based on scientific observations of increases in global temperature, also there have been: – decreases in the length of river and lake ice seasons. – worldwide reduction in glacial mass and extent in the
20th century. – melting of the Greenland Ice Sheet – Snow cover decrease in many Northern Hemisphere
regions – Decrease in sea ice thickness in the Arctic – Ocean temperatures increasing – Sea level rise due to the melting of land ice
Carbon Dioxide
Worldwide Carbon Emissions C
arb
on
(10
9 m
etr
ic t
on
s)
0
1
2
3
4
5
6
7
8
1750 1800 1850 1900 1950 2000 Year
Liquid fuel Total
Gas fuel Solid fuel
Annual Carbon Emissions
Annual carbon emissions Atmospheric CO2
Atmospheric CO2 average
1955 1965 1975 1985 1995 2005 0
4
6
8
2
Year
Carb
on
(10
9 m
etr
ic t
on
s)
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1880 1900 1920 1940 1960 1980 2000
Year
D M
ea
n T
em
pera
ture
(°
C)
Recorded Worldwide Temperatures
Flat Decreasing
Future Carbon Dioxide Levels
• There is speculation that there will be an increase of CO2 emissions, especially in China and developing countries
• Likely to double within 150 years because of:
– Increased coal usage
– Increased natural gas usage
– Decreased petroleum usage (increased cost and decreasing supply)
Past Temperatures
Temperature History of the Earth • Climate change is a natural process of the Earth
• Cool/warm cycles occur ~1,500 years – Little ice age (1400-1840) – 1°C cooler
– Medieval warm period (800-1300) – 1°C warmer than today
• Affect mostly Northeastern U.S. and North Atlantic
• Mostly due to changes in the ocean currents which bring warm water to cold regions.
• When these current are redirected or stopped, these northern regions become cold; allowing ice sheets to form (Ice Ages).
Main Ocean Currents
Adapted from IPCC SYR Figure 4-2
Temperature History of the Earth (cont)
• For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods
• These climate periods are largely the result of cycles in the earth’s orbit – precession, obliquity, and eccentricity
• Last ice age began to thaw 15,000 years ago, but was interrupted by the “Younger Dryas” event 12,900 years ago
Consequences of Global Warming
2007 Temperature Changes Compared to 1951-1980
-3 -2.5 -1.5 -1 -.5 -.1 .1 .5 1 1.5 2.5 3.4
Ice Sheets Melting?
• GRACE (gravity measured by satellite) found melting of Antarctica equivalent to sea level rise of 0.4 mm/year (2 in/century)
• Zwally, 2005 (satellite radar altimetry)
– confirmed Antarctica melting
– Greenland ice melting on exterior, accumulating inland (higher precipitation)
1000
800
600
400
200
0
-200
-400
-600 2003 2004 2005
Ice M
as
s (
km
3)
Year
Changes in Antarctica Ice Mass
Rise in Sea Levels?
• Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century)
• Accelerating at a rate of 0.013 ± 0.006 mm/yr2
• If acceleration continues, could result in 12 in/century sea level rise
How Much Temperature Increase?
• Some models propose up to 9°C (48o F) increase by the year 2100.
• Imagine on a average summer day of 80o F in the future it will be 128o F.
• There would be no more snow – ANYEVER!
• Mountain snow is very important for bring drinking water to people.
• A rise in air temperature means that the air can hold more water, therefore less rainfall.
Wildlife Effects
• Polar Bears – Require pack ice to live
– Might eventually go extinct in the wild
• Sea turtles – Breed on the same islands as
their birth
– Could go extinct on some islands as beaches are flooded
• Other species may go extinct as rainfall patterns change throughout the world
Effect on Humans
• Fewer deaths from cold, more from heat
• Warm / cold ocean currents circulation
– Cooler temperatures in North Atlantic
• CO2 fertilization effect
• Precipitation changes • Droughts and famine (some areas)
• Expanded arable land in Canada, Soviet Union
Potential Worldwide Precipitation Changes
-50 -20 -10 -5 5 10 20 50
Drought in Africa
Lake Faguibine Lake Chad
Possible Solutions to Global Warming
Mitigation of Global Warming
• Conservation – Reduce energy needs
– Recycling
• Alternate energy sources – Nuclear
– Wind
– Geothermal
– Hydroelectric
– Solar
– Fusion?
1. Do you think that the graphs
provide evidence of a
correlation between human
use of fossil fuels and the
temperature and CO2 levels
in the atmosphere?
a)If so, which graphs show
evidence of a correlation?
1. Should we be concerned
about the changes that are
occurring in the environment
due to technology?
a)Why or why not?
Notebook Problem Set
1. What is a cyclone – which direction does air flow?
2. Where do most hurricanes that hit NY originate?
3. What are the trade winds?
4. What is the difference between weather and climate?
5. What is a monsoon?
6. How do mountain ranges effect climate?
7. How does deforestation affect climate?
8. Name three green house gases.