Global Warming

Key Questions- ?????
Is the earth’s atmosphere warming?
Is this warming causing climate change?
Are humans impacting on this warming?
If so, what can I do about it?

Is the Earth’s Atmosphere Warming?
Review global temps for last 150 years
Variations in last 150
19th century – constant; Rise in early 20th; Level off in mid 20th; Rapid rise 1990-2009 - Why?
What causes this pattern?
Early – volcanoes, sun; Later – Burning fossil fuels
Variations on global average temps
Land warmer than ocean; More increase towards poles
Average temps have risen about 1.5 degrees since start of 20th century. Is this significant?

Indicators - Butterflies,
Glaciers, and Hurricanes
Surface temps are not only indicators of warming
Earths’ inner temps; Upper levels of oceans; Lower levels of atmosphere warming - upper levels cooling
Earth’s cryosphere (snow & ice cover) is decreasing
Glaciers, Arctic ice, Ice caps, Ice sheets - Reflections
Weather patterns over decades show changes
More extreme hot and cold; Precipitation changes, Night temps; Increase in hurricanes
Plants and animal species are moving
NH moving northward and upward – 6 miles – 6 feet; Springtime events earlier : 2-3 days (per decade)

What Determines a Planet’s Temperature?
Energy balance – between incoming sunlight and radiated heat loss
Sun sends in ultraviolet rays; Planet sends out infrared rays – Earth balances out at zero (0) degrees
Earth’s atmosphere causes “greenhouse effect”
Atmosphere is 80% nitrogen, 20% oxygen – transparent to sun’s incoming rays and Earth’s outgoing rays
Water vapor and CO2 is transparent to sun’s incoming ultraviolet rays BUT opaque to Earth’s outgoing infrared rays – Result – increase in Earth’s temp to 60 degrees

A Tale of Three Planets
Neighboring planets (Mars, Venus) can provide us with a “greenhouse experiment”
Comparison of Temps – No Atmosphere
Mars: -90 F; Earth: o F; Venus: 110 F
Comparison of Temps – With Atmosphere
Mars: -120 F; Earth: 60 F; Venus: 500 F (melt lead)
Comparison of Atmospheres
Mars: 1% (.01) of Earth’s density; Cooler – reflects heat
Earth: 1.0 density – provides normal greenhouse effect
Venus: 100 times Earth’s density – 96% is CO2; All water is evaporated – powers greenhouse effect; CO2 - permanent

The Human Factor
Three factors affect temps – two are natural, one is us
1. Volcanoes
Throws dust into air; forms clouds; decreases temps
2. Sun
Burn rate varies; distance from Earth; tilt of Earth axis
3. Anthropogenic – caused by humans
Burn fossil fuels – increases CO2 in atmosphere
Other factors
Methane (minor); Aerosals – particles in air
Why blame us?
Strong correlation – CO2 , higher temps; Natural causes - varying effects; Dominant correlation in recent decades has been anthropogenic

Projected Impact of Climate Change - 2100
There will be a steady rise in global temps
Most likely 3-8 degrees; Drop of 11 degrees would bring new Ice Age; Increase of 9 degrees – tropics in NH
Extreme weather events will increase – greater fluctuation in weather
Heat waves; Intense precipitation; Droughts; Intense tropical storms
Sea levels will rise
Average will be 6”- 18” (maybe 20); Caused by warmer water, not melting ice; Salt water will encroach on fresh
Polar advances of species will accelerate

What to Do? – Replace Fossil Fuels
Two questions: 1. Do we have it? 2. Can we get it?
Three main sources of energy:
1. Sun
Solar, Wind – Expensive; Limited; Variable availability – cloud cover, no air moving
2. Fossil Fuels
Natural gas – burns cleaner; Oil – running out (decades left); Coal – dirtiest, but most abundant (300 years left); Nuclear – cleanest, but most dangerous
3. Tidal waves
Rivers, dams, ocean waves – limited, most being used already

Why is Global Warming So Controversial?
Some people insist this is just an unproven theory
Scientists have trouble communicating this to the general public
Climate change can be confusing and upsetting to people
Solutions will have serious economic and lifestyle impacts
Political differences among government leaders impacts progress towards solutions

What to Teach
Students?
1. There is a difference between weather and climate
2. Global warming is accelerating and is caused mainly by humans burning fossil fuels
3. Global warming is causing climate change and will have a significant impact on people and nature
4. Earth’s temperatures will most likely rise 3-8 degrees by the year 2100.
5. Sea levels have already risen and are projected to rise much more
6. There is scientific consensus that global warming is causing climate change and presents us with some serious challenges

What to Teach Students? (2)
7. Governmental leaders from many countries are working on international agreements to deal with climate change
8. New technologies must be developed to stabilize and reduce greenhouse gases
9. Saving energy and developing alternative energy sources will help
10. Every individual person can take actions daily to help with this situation

What can Students and their Families Do?
Turn off electrical devices when not in use
Take shorter showers
Close blinds/drapes on hot, sunny days
Turn off lights when you leave a room
Switch to fluorescent light bulbs
Plant trees
Combine and reduce trips in cars
Recycle whenever possible
Purchase recycled products
Spread the word – encourage wise energy consumption