Download Earth system and Climate Change

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?
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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.
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Earth History
Earth’s age:
4.55 billion years
(Byr)
= 4,550,000,000
years
= 4.55 × 109 years
This course
focuses on only
recent 10% of its
age.
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Schematic diagram
of the Earth system,
showing
interactions among
its four
components.
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Weather versus Climate
Weather
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
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Low Pressure
Cyclonic Turning:
Convergence
leads to upward
vertical motions.
High Pressure
Anti-Cyclonic
Turning:
divergence
leads to downward
vertical motions.
Cold Air
Warm Air
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Impacts of Weather
Figure 1.15
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Impacts of Weather
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Hurricane: Gustav in New Orleans. 2
Million people evacuated (Sep. 1, 2008)
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Climate versus Weather
Climate
 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.
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 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.
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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 29.75 inches and steady, and
humidity is 84%.
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The limits of Weather Forecast and Climate prediction
Weather Forecast
 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)
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Lorenz Model
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The limits of Weather Forecast and Climate prediction
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)
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Temperature anomaly forecast
for Sep. Oct. and Nov., 2014
The confidence level of the
forecast
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Climate Variability vs Climate Change
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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 29.75 inches and steady, and
humidity is 84% (A).
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• 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
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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, …
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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.
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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.
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•
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:
2 )  changes in global
w/ m
temperature.
Climate Sensitivity
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Forcing and Response: A Bunsen Burner Experiment
Flame is far enough away
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Climate: An Engineer’s View
Anthropogenic
forcing
Machine
Output
Input
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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.
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Main drivers of climate change (~ hundreds of years)
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