1 Chapter 1 Earth System and Climate Chapter 1 Earth System and Climate System System What are the components of the Earth system, What are the components of the Earth system, especially Earth’s climate system? especially Earth’s climate system? How does climate change differ from day to day How does climate change differ from day to day weather? weather? Climate variability and climate change? Climate variability and climate change? What factors drive changes in What factors drive changes in Earth climate Earth climate ？ ？ How does the climate system work? How does the climate system work?
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Chapter 1 Earth System and Climate SystemChapter 1 Earth System and Climate System
What are the components of the Earth system, especially Earth’s What are the components of the Earth system, especially Earth’s climate system?climate system?
How does climate change differ from day to day weather?How does climate change differ from day to day weather?
Climate variability and climate change?Climate variability and climate change?
What factors drive changes in What factors drive changes in Earth climateEarth climate ？？
How does the climate system work? How does the climate system work?
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The Habitable EarthThe Habitable EarthThe earth is the only habitable planet in our solar system.The earth is the only habitable planet in our solar system.
Oceans: 70% of the surfaceOceans: 70% of the surfaceLand: 30%Land: 30%
Earth’s climate is favorable to life.Earth’s climate is favorable to life.
In the era of population explosion, climate change is In the era of population explosion, climate change is critical to human life. critical to human life.
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Earth HistoryEarth History
Earth’s age:Earth’s age:
4.55 billion years 4.55 billion years (Byr) (Byr)
= 4,550,000,000 = 4,550,000,000 yearsyears
= 4.55 × 10= 4.55 × 1099 years years
This course This course focuses on only focuses on only recent 10% of its recent 10% of its age.age.
Schematic diagram of the Earth system, showing interactions among its four
components.
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Weather versus Climate
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
The condition of atmosphere at a given time and placeWeather
Low Pressure High Pressure
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Cyclonic Turning:
Convergence
leads to upward
vertical motions.
Anti-Cyclonic
Turning:
divergence
leads to downward
vertical motions.
Cold Air
Warm Air
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Impacts of WeatherImpacts of Weather
Figure 1.15Figure 1.15
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Impacts of WeatherImpacts of Weather
Hurricane: Gustav in New Orleans. 2 Million people evacuated (Sep. 1, 2008)
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ClimateClimate versus Weather
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.
Defined as the average state of the atmosphere over a finite time period and over a geographic region (space).
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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.
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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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)
The limits of Weather Forecast and Climate prediction Weather Forecast
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Lorenz Model
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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)
The limits of Weather Forecast and Climate prediction
Climate Prediction
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Temperature anomaly forecastfor Sep. Oct. and Nov., 2014
The confidence level of the forecast
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Climate Variability vs Climate Change
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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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Climate Variability vs Climate Change
• 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 SystemComponents of the Climate System
Five major components: air (atmosphere), water (hydrosphere), ice Five major components: air (atmosphere), water (hydrosphere), ice (cryosphere), vegetation (biosphere), and land (lithosphere).(cryosphere), vegetation (biosphere), and land (lithosphere).Major processes: energy cycle, water cycle, carbon cycle, …Major processes: energy cycle, water cycle, carbon cycle, …
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Climate System ComponentsAtmosphere• 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.
• 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 (Anthropogenic forcing (fossil fuel burning) – greenhouse gases forcing (unit: ) changes in global temperature.
Climate Sensitivity
2mw /
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Forcing and Response: A Bunsen Burner ExperimentForcing and Response: A Bunsen Burner Experiment
Flame is far enough awayFlame is far enough away
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Climate: An Engineer’s ViewClimate: An Engineer’s View
InputInput
MachineMachineOutputOutput
Anthropogenic Anthropogenic forcingforcing
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Time Scales of Climate ChangeTime Scales of Climate Change
Earth’s climate changes all the time, e.g., last 300 Earth’s climate changes all the time, e.g., last 300 Myr, last 3 Myr, last 50,000 yr, and Myr, last 3 Myr, last 50,000 yr, and last 1000 yr..
