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In examining global warming, we will be looking at questions such as Is the world getting warmer? If so, are the actions of mankind to blame for earth’s temperature increases? What can or should be done about global warming? Are the potential resolutions to global warming worth the cost to implement them?
This is a big picture examination of the earth’s climate The Earth was formed around 4.6 billion years ago And was originally very hot However, the Sun’s energy output was only 70% of what it is presently Liquid water was present on the surface around 4.3 billion years ago
The first life forms appeared ~3.8 billion years ago Photosynthesis began 3.5-2.5 billion years ago, which produced oxygen and removed carbon dioxide and methane, which are greenhouse gases, from the atmosphere As a result, the Earth went through periods of cooling, commonly referred to as “Snowball Earth” and subsequent warming Earth began its current cycles of glacial and interglacial periods around 3 million years ago
The temperature of the earth is directly related to the energy input from the Sun. Some of the Sun’s energy is reflected by clouds. Other is reflected by ice. The remainder is absorbed by the earth.
If amount of solar energy absorbed by the earth is equal to the amount radiated back into space, the earth remains at a constant temperature.
However, if the amount of solar energy is greater than the amount radiated, then the earth heats up.
If the amount of solar energy is less than the amount radiated, then the earth cools down.
Global warming is the rise in the average temperature of Earth&apos;s atmosphere and oceans since the late 19th century and its projected continuation. Since the early 20th century, Earth&apos;s mean surface temperature has increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980
To a certain degree, the earth acts like a greenhouse. Energy from the Sun penetrates the glass of a greenhouse and warms the air and objects within the greenhouse. The same glass slows the heat from escaping, resulting in much higher temperatures within the greenhouse than outside it.
Likewise, the earth’s atmospheric gases affect the ability of the earth to radiate the Sun’s energy back into space. Nitrogen and Oxygen make up 99% of the earth’s atmospheric gases and are non-greenhouse gases. Water, Carbon Dioxide, and Methane make up 1% of the earth’s atmosphere, but are greenhouse gases, since they cause the earth to retain heat.
Carbon dioxide stays in the atmosphere for approximately 100 years, methane lasts about 12 years. Other greenhouse gases last even longer. As these gases continue to raise surface temperatures, they trigger the release of even greater quantities of carbon dioxide and methane that are currently trapped in frozen Arctic permafrost and tundra soils, further increasing temperatures.
This spike is due to the exponential increase in the use of fossil fuels over the last 150 years. Shown here are emissions of carbon from gas, solid, liquid fuels, and the total carbon emissions.
Malaria and cholera increase, due to temperature increase Shifting flora and fauna to different areas. Extinction of some species. More extreme climates in inland locations. More frequent and devastating hurricanes. Reduced snow cover in some areas. Glaciers melt in Antarctica. Reduction of areas suitable for human habitation, for example. lowland Bangladesh.
Future Carbon Emissions will probably increase, especially in China and developing countries This will result in a likely doubling of carbon dioxide levels within 150 years, due to Increased coal usage And increased natural gas usage, although petroleum usage is likely to decrease due to increased cost and decreasing supply
“The Greatest Threat”
Is the world getting warmer?
If so, are the actions of mankind to blame for
earth’s temperature increases?
What can/should be done about these issues?
History of Earth’s Climate
Earth formed ~4.6 billion years ago
Originally very hot
Sun’s energy output only 70% of present
Liquid water present ~4.3 billion years
History of Earth’s Climate
Life appeared ~3.8 billion years ago
Photosynthesis began 3.5-2.5 billion years
Produced oxygen and removed carbon
dioxide and methane (greenhouse gases)
Earth went through periods of cooling
(“Snowball Earth”) and warming
Earth began cycles of glacial and interglacial
periods ~3 million years ago
What is Global Warming?
•An increase in the earth's average atmospheric
temperature that causes corresponding changes in
climate and that may result from the greenhouse effect
•Since the last century, Earth's mean surface temperature
increased by 0.8 °C.
Households are Big Contributors to Climate Change
Of all greenhouse gas
emissions come from
• Home Heating
Our reliance on cars that burn fossil fuels is
one of the major causes of increased levels
of carbon dioxide in the atmosphere and it is
the primary cause of urban smog.
Facts about Global Warming
The world emits about 25.6 billion metric tons of
greenhouse gases annually.
These greenhouse gases last a long time.
The amount of oxygen dissolved in the oceans
Warming begets more warming.
Global Warming’s Impact on
Future Carbon Dioxide Levels
Increasing CO2 emissions, especially in China and
Likely to double within 150 years:
Increased coal usage
Increased natural gas usage
Decreased petroleum usage (increased cost and
So how can each of us
slow global warming now?
Reduce our consumption of fossil fuels
•Because greenhouse gas emissions are tied very closely to
our energy consumption, using less fossil fuel based energy
puts fewer greenhouse gases into the atmosphere.
This will help slow global warming.
•50% of electricity in the United States is produced
We can make some simple substitutions
•Replacing just 1 incandescent light bulb with 1
compact florescent bulb saves about 150 pounds of
carbon dioxide per year!
•If every household replaced
just 5 high-use incandescent
bulbs with compact florescent
lights we'd collectively save
more than $8 billion each year
in energy costs and we would
prevent the greenhouse gases
equivalent to the emissions
from nearly 10 million cars.
Small changes really add up
Drive JUST 10 fewer miles
520 pounds CO2
Replace your old
refrigerator with a new
700 pounds CO2
Wash clothes in cold water
500 pounds CO2
Reduce your garbage by 10%
through greater recycling or
1200 pounds CO2
Caulk and weather-strip around
doors and windows
650 pounds CO2
These are mid-range estimates from
published sources; your savings may vary.
Turning off lights saves
energy and money.
The more energy used,
the more rivers are
dammed or more fossil
fuel is burned, causing air
pollution and increased
levels of carbon dioxide in
Making paper and plastic bags
uses energy and resources.
The bags add to our litter and
waste problems, and plastic is not
Recycling is not the best answer
because collecting and recycling
materials requires energy.
Instead, carry a reusable cloth bag
or a knapsack with you.
Our take-home message…
Each of us must take steps to protect our