Climate Change:

How it happens and how it affects us.

Objectives

Given information about climate change, you will be able to:

● Define climate● Explain causes of climate change● Describe how climate has changed in the past● Diagram the greenhouse effect● Postulate what future climate will look like● Discuss effects on humans now and into the future● Decide on what you can do about it

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?● What can we do about it?

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

weather

climate (average min/max)

Weather and Climate in Seattle:

1. What is climate?

2. 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 changesSome cause slower changes, some cause fast changes Some cause changes that last, some cause changes that go away fast

3. 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

Now21 thousand years ago

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

3. How has climate changed in the past?

4. Human-forced climate change

● Climate changes can be natural or human caused.

● Humans can affect the climate by changing the gases in the atmosphere. (greenhouse effect).

The Greenhouse Effect

4. Human-forced climate change

● Carbon Dioxide (CO2) is a major greenhouse gas

● Human burning of fossil fuels, and plants releases CO2

4. Human-forced climate change

5. Have we changed the climate?Changes in global temperature over the last 125 years

Changes in global temperature over the last 1,000 years

5. Have we changed the climate?

Everywhere (almost) is warming!

5. Have we changed the climate?

1928

2000

The South Cascade glacier retreated dramatically in the 20th century

Courtesy of the USGS glacier group

Glaciers are retreating all over the world

5. 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• Use “hindcasting” techniques to validate/verify modelling for accuracy• Change things around and see what happens – iteration process

5. Have we changed the climate?

Natural Climate Influence(No Human Effects Included)

All Climate Influences (Including Human Effects)

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

5. Have we changed the climate?

6. What will the future climate look like?● 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

IPCC (www.ipcc.ch)

6. What will the future climate look like?

● Changes are greater in far north / south

● Changes in rain and snow are

likely, but not as well

understood

● In CA snowpack will melt

earlier

6. What will the future climate look like?

7. How will climate change affect people? 1. 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 (temp, acid)

CA:● Less mountain snow● Less water to go around in the summer● Coastal flooding (Delta)● Harder for Salmon to survive in freshwater● Longer fire season

US Geological Survey

2. Understanding: Medium

Everywhere:● Increase in intensity of hurricanes● Increase in droughts in some places● Increase in intense rain in some places

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

7. How will climate change affect people?

7. How will climate change affect people?

3. Understanding: Low

Everywhere:● How will humans react● Surprise changes

CA● Increased winter flooding● Increased landslides● Overall forest health● Coastal erosion

7. How will climate change affect people?

8. What can we do about it?

Top Ten Things You Can Do To Reduce Global Warming:

1. Reduce, Reuse, Recycle

2. Use Less Heat and Air Conditioning

3. Change a Light Bulb

4. Drive Less and Drive Smart

5. Buy Energy-Efficient Products

6. Use Less Hot Water

7. Use the "Off" Switch

8. Plant a Tree

9. Get a Report Card From Your Utility Company (PG&E)

10. Encourage Others to Conserve

Summary● Climate is an average of weather● Climate changes due to: sun, earth’s orbit, clouds,

ice sheets, volcanoes, atmospheric gases, and internal “wiggles”

● Climate has been both warmer and colder in past● Humans are changing the Climate● In the Future: sea level rise, ecosystem changes,

ice cap melting, coral death, other effects less understood at this point

● What we can do: Reduce, Reuse, Recycle, Educate Others