CLIMATE CHANGE: What We Know and What We Don't Know

1
CLIMATE CHANGE What We Know and What We Don't
Know

• Baased on a Presentation by Daniel L. Albritton,
• Director of NOAA Aeronomy Laboratory, during
  early 2001.

2
There is a natural Greenhouse Effect. It keeps
the earth warmer than it would be otherwise.
3
Our planets atmosphere is composed of

• 78 Nitrogen
• 20 Oxygen
• 2 Water Vapor (greenhouse gas)
• 0.03 Carbon Dioxide (greenhouse gas)

Dry Air Composition without water vapor
4
If an object is bathed in sunlight...

• It warms up
• and...
• It emits infrared light (heat)

5
Water Vapor and Carbon Dioxide have been part of
our atmosphere for millions of years.

• They cause an average surface temperature of
  about 60oF.
• Without them, the average would be about 5oF.

6
Greenhouse gases are increasing in the atmosphere
because of human activities, and they are
increasingly trapping more heat.

• -Carbon Dioxide has increased by 31 between 1800
  and 2000, as measured by ice cores and air
  samples
• -Other gases have increased, too
• Methane
• Sulfur

What is the main cause of this increase?
7
There is a collective picture of a warming world,
and human activities have likely contributed.

• -Global temperatures are up 0.7 - 1.4 oF over the
  past 100 years
• -Which seems to be causing
• Glacial retreat
• Snow-cover decrease
• Freeze-free periods     lengthened
• Sea-level increased 4-8 inches

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What could this mean for the Earths future?
9
Carbon Dioxide abundancewill likely double
before 2100

• Predicted climate responses   
• Global temperature rise of 2.5 - 10 oF by 2100
• If so, this would exceed the natural changes over
  the past 10,000 years
• Sea level rise of 4 - 35 inches by 2100

10
We live on a complex planet and we have
imperfect knowledge so, we cant predict the
future very well.

• We cant predict a small areas changes, but
  possibly a continents changes
• Temperatures may increase
•     as much as 40 above average
• Mid-continent soil may experience
•     increased drying
• A warmer world may mean heavier rains,
•     with large differences between regions
• Its much tougher to call if hurricanes
•     will be more or less frequent

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BOTTOM LINE - THE VAST MAJORITY OF SCIENTISTS
AGREE

• The issue is a real one
• The first signs of human-caused climate change
  have likely occurred
• Some degree of further change appears inevitable
• Exactly where (regions), when (rate of change),
  how much (magnitude) is hard to predict

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The End
What can you do?

• Remember your three Rs! Reduce, Reuse, Recycle!