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Climate Change:

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How it happens and how it affects us.

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Outline

  • What is climate?
  • What makes the climate change?
  • How has climate changed in the past?
  • Human caused climate change: the greenhouse effect.
  • Have we changed the climate?
  • What will the future climate look like?
  • How will climate change affect people?

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What is climate?

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Climate is an average of weather (Temperature, Rainfall...) over a “long” time (more than 2-3 weeks).

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weather

climate (average min/max)

Weather and Climate in Seattle:

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What makes climate change?

  • Changes in the sun
  • Changes in the earth's orbit
  • Changes in the clouds
  • Changes in ice sheets
    • Volcanic eruptions
  • Changes in the gases in the atmosphere (Greenhouse effect)
  • Internal Wiggles (for example El Nino)

Some cause bigger changes, some cause small changes

Some cause slower changes, some cause fast changes

Some cause changes that last, some cause changes that go away fast

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How has climate changed in the past?

  • Ice Ages
    • Big swings in climate over 100,000 yrs
    • Occurred over last million years
    • Advance and retreat of ice sheets
    • We are in between ice ages right now

Now

21 thousand years ago

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  • Eocene Warm Period
    • 50 million years ago
    • Palm trees in Puget Sound
    • Crocodiles in the Arctic

How has climate changed in the past?

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Human-Forced Climate Change

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  • Climate changes can be natural or human caused.
  • Humans can affect

the climate by

changing the gases

in the atmosphere.

(greenhouse

effect).

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The Greenhouse Effect

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  • Carbon Dioxide (CO2) is a major greenhouse gas
  • Human burning of fossil fuels, and plants releases CO2

Human influence on climate: the greenhouse effect

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Have we changed the climate?

Changes in global temperature over the last 125 years

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Have we changed the climate?

Changes in global temperature over the last 1,000 years

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Have we changed the climate?

Everywhere (almost) is warming!

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1928

2000

The South Cascade glacier retreated dramatically in the 20th century

Courtesy of the USGS glacier group

Have we changed the climate?

Glaciers are retreating all over the world

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Have we changed the climate?

Global Climate Models

  • Use a computer to make a “model” of the earth
    • Tell the computer how to force the climate
    • Use science to come up with equations at points on the earth that tell what the Temperature, Winds,.. are and how they change
    • Change things around and see what happens!!!

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Natural Climate Influence

All Climate Influences

Have we changed the climate?

Climate models capture the last 100 year's warming only if we include the human effects

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What will the future climate look like?

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  • Global warming due to greenhouse gases will continue for many years even if we stop releasing CO2
  • How much warming occurs depends on what societies and businesses decide about how much fuel they burn
  • We use climate models to predict what might happen in different cases

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IPCC (www.ipcc.ch)

What will the future climate look like?

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What will the future climate look like?

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  • Changes are greater in far north / south
  • Changes in rain and snow are likely, but not as well understood
  • In WA snow will melt earlier

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How will climate change affect people?

Understanding: Good

Everywhere:

  • Sea-level rise
  • Ecosystem change
    • effect on species
    • effect on farming
  • Melting of polar ice
    • effect on shipping
    • effect on wildlife
  • Coral death

WA:

  • Less mountain snow
  • Less water to go around in the summer
  • Coastal flooding (Olympia)
  • Harder for Salmon to survive in freshwater

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US Geological Survey

How will climate change affect people?

Understanding: Medium

Everywhere:

  • Increase in intensity of hurricanes
  • Increase in droughts in some places
  • Increase in intense rain in some places

WA:

  • Changes in how well forests grow
  • Increased habitat for pests
  • Farming: some crops will grow better, some will grow worse

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How will climate change affect people?

Understanding: Low

Everywhere:

  • How will humans react
  • Surprise changes

WA

  • Increased winter flooding
  • Increased landslides
  • Overall forest health
  • Coastal erosion

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