1. Chapter 1 Earth System and Climate System
What are the components of the Earth system, especially Earth’s climate system?
How does climate change differ from day to day weather?
Climate variability and climate change?
What factors drive changes in Earth climate？
How does the climate system work?

2. The Habitable Earth
The earth is the only habitable planet in our solar system.
Oceans: 70% of the surface
Land: 30%
Earth’s climate is favorable to life.
In the era of population explosion, climate change is critical to human life.

3. Earth History Earth’s age: 4.55 billion years (Byr)
This course focuses on only recent 10% of its age.

4. Schematic diagram of the Earth system, showing interactions among its four components.

5. Weather versus Climate
The condition of atmosphere at a given time and place
Short-term (and large) fluctuations that arise from internal instabilities
of the atmosphere
Occurs as a wide variety of phenomena that we often experience
Effects are immediately felt
Social and economic impacts are great but are usually localized
Governed by non-linear chaotic dynamics; not predictable
deterministically beyond a week or two

6. Low Pressure High Pressure
Anti-Cyclonic
Turning:
divergence
leads to downward
vertical motions.
Cyclonic Turning:
Convergence
leads to upward
vertical motions.
Cold Air
Warm Air

7. Impacts of Weather
Figure 1.15

8. Impacts of Weather

9. Hurricane: Gustav in New Orleans. 2 Million people evacuated (Sep

10. Climate versus Weather
Defined as the average state of the atmosphere over a finite time
period and over a geographic region (space).
Can be thought of as the “prevailing” weather, which includes the
mean but also the range of variations
The wide range of natural variability associated with daily weather
means small climate changes are difficult to detect
Intimate link between weather and climate provides a basis for
understanding how weather events might change under a
changing climate
Involves atmospheric interactions with other parts of the climate
system and external forcing
Climate prediction is complicated by considering the complex
interactions between, as well as changes within, all components.

12. Climate is what you expect and weather is what you get.
Climate tells what clothes to buy, but weather tells you what clothes to wear.

13. Review Questions
Which of the following statements relate more to weather (A) and which relate more to climate (B)?
1. The summers in Prince George are cool and dry.
2. It is 30°C right now, partly sunny, and south winds 10 to 20 miles per hour.
3. September 2001 was the 2nd coolest September of record for Prince George International Airport.
4. The pressure now is inches and steady, and humidity is 84%.

14. The limits of Weather Forecast and Climate prediction
Weather forecast model tries to predict the future state of the
atmosphere using the laws of physics given the current state (i.e., the
weather now)

16. Lorenz Model

18. The limits of Weather Forecast and Climate prediction
Climate can be viewed as concerning the status of the entire Earth system,
including the atmosphere, land, oceans, snow, ice and living things
that serve as the global background conditions that determine weather patterns.
Long-term variations brought about by changes in the composition of the atmosphere are much more predictable than individual weather events.
(the time when a woman die vs the average age of death of women in Canada)

19. Temperature anomaly forecast
for Sep. Oct. and Nov., 2014
The confidence level of the forecast

21. Climate Variability vs Climate Change
ENSC 425/625
4/20/2017
Climate Variability vs Climate Change

22. Climate Variability vs Climate Change
Which of the following statements relate more to weather (A) and which relate more to climate (B)?
1. The summers in Prince George are cool and dry. (B)
2. It is 30°C right now, partly sunny, and south winds 10 to 20 miles per hour. (A)
3. September 2001 was the 2nd coolest September of record for Prince George International Airport. (B)
4. The pressure now is inches and steady, and humidity is 84% (A).

23. How scientists study climate changes
(1) spend much time to gather and analyze
data from the kind of climatic archives. To
publish results in peer-reviewed journals.
(2) need to explain and interpret results –
Hypothesis, theory.
(3) Models

24. Components of the Climate System
Five major components: air (atmosphere), water (hydrosphere), ice (cryosphere), vegetation (biosphere), and land (lithosphere).
Major processes: energy cycle, water cycle, carbon cycle, …

25. Climate System Components
Atmosphere
Fastest changing and most responsive component
Previously considered the only “changing” component
Ocean
The other fluid component covering ~70% of the surface
Plays a central role through its motions and heat capacity
Interacts with the atmosphere on days to thousands of years
Cryosphere
Includes land snow, sea ice, ice sheets, and mountain glaciers
Largest reservoir of fresh water
High reflectivity and low thermal conductivity
Land and its biomass
Slowly changing extent and position of continents
Faster changing characteristics of lakes, streams, soil moisture
and vegetation
Human interaction
agriculture, urbanization, industry, pollution, etc.

26. The climate system evolves in time under the influence of its own internal dynamics and due to changes in external factors that affect climate (called ‘forcings’).
External forcings include natural phenomena such as volcanic eruptions and solar variations, as well as human-induced changes in atmospheric composition.

27. Climate Forcing: can be defined as an imposed perturbation of Earth’s energy balance.
(1) natural forcing: luminosity of the sun;
volcanic eruption; earth’s orbit
(2) Anthropogenic forcing (fossil fuel burning) –
greenhouse gases
forcing (unit: )  changes in global
temperature.
Climate Sensitivity

28. Forcing and Response: A Bunsen Burner Experiment
Flame is far enough away

29. Climate: An Engineer’s View Anthropogenic forcing
Machine
Output
Input

30. Time Scales of Climate Change
Earth’s climate changes all the time, e.g., last 300 Myr, last 3 Myr, last 50,000 yr, and last 1000 yr.

31. Main drivers of climate change (~ hundreds of years)