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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. There is a natural Greenhouse Effect. It keeps the earth warmer than it would be otherwise. Our planet’s atmosphere is composed of:.

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climate change what we know and what we don t know

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.

our planet s atmosphere is composed of
Our planet’s 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

slide4

If an object is bathed in sunlight...

It warms up

and...

It emits infrared light (heat)

water vapor and carbon dioxide have been part of our atmosphere for millions of years
Water VaporandCarbon Dioxidehave 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.

slide6
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?

there is a collective picture of a warming world and human activities have likely contributed
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

carbon dioxide abundance will likely double before 2100
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
slide10
We live on a complex planet and we have imperfect knowledge; so, we can’t predict the future very well.
  • We can’t predict a small area’s changes, but possibly a continent’s 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

    • It’s much tougher to call if hurricanes

    will be more or less frequent

bottom line the vast majority of scientists agree
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
the end
The End

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

What can you do?