Chapter 6:Chapter 6:

Weather & ClimateWeather & Climate

Chapter 6:Chapter 6:

Weather & ClimateWeather & Climate

Midterm ExamMidterm Exam

9:33

8: 22335778

7 : 5788

6:2335778

Average Score = 77

9:33

8: 22335778

7 : 5788

6:2335778

Average Score = 77

2 Topics before Chapter 6 Material2 Topics before Chapter 6 Material

1. Keeling Curve

2. How scientists approach Climate Change

1. Keeling Curve

2. How scientists approach Climate Change

Keeling CurveKeeling Curve

+400 ppm

Keeling CurveKeeling Curve

Keeling CurveKeeling Curve

Shows atm. CO2 rising at unprecedented rates Driven by burning of fossil fuels past 200 yrs. Pioneered in 1958 by scientist Charles Keeling. Longest-running tally of carbon dioxide levels in atm. Maintained by Scripps Institution of Oceanography. Up 22 points from a decade ago.

Many scientists have warned that carbon dioxide readings must be brought down to 350 ppm to avoid severe climate impacts and stall "feedback loops" that will exacerbate the rise.

Shows atm. CO2 rising at unprecedented rates Driven by burning of fossil fuels past 200 yrs. Pioneered in 1958 by scientist Charles Keeling. Longest-running tally of carbon dioxide levels in atm. Maintained by Scripps Institution of Oceanography. Up 22 points from a decade ago.

Many scientists have warned that carbon dioxide readings must be brought down to 350 ppm to avoid severe climate impacts and stall "feedback loops" that will exacerbate the rise.

Keeling CurveKeeling Curve

Previous 800,000 years, CO2 levels never exceeded 300 ppm

There is no known geologic period in which rates of increase

have been so sharp.

Was about 280 ppm at the advent of Industrial Revolution

“I wish it weren't true, but it looks like the world is going to

blow through the 400-ppm level without losing a beat," said

Scripps geochemist Ralph Keeling, who has taken over the

Keeling curve measurements from his late father. "At this

pace we'll hit 450 ppm within a few decades."

Previous 800,000 years, CO2 levels never exceeded 300 ppm

There is no known geologic period in which rates of increase

have been so sharp.

Was about 280 ppm at the advent of Industrial Revolution

“I wish it weren't true, but it looks like the world is going to

blow through the 400-ppm level without losing a beat," said

Scripps geochemist Ralph Keeling, who has taken over the

Keeling curve measurements from his late father. "At this

pace we'll hit 450 ppm within a few decades."

Large body of evidence supports conclusion that human activity is primary

driver of recent warming.

Large body of evidence supports conclusion that human activity is primary

driver of recent warming.

1. Our understanding of how gh gases trap heat,

how climate system responds to increases, and

how other human and natural factors influence

climate.

2. Many indirect estimates of climate changes over

the last 1,000 to 2,000 years. Ice cores, tree rings

and corals - show recent T rise is unusual

1. Our understanding of how gh gases trap heat,

how climate system responds to increases, and

how other human and natural factors influence

climate.

2. Many indirect estimates of climate changes over

the last 1,000 to 2,000 years. Ice cores, tree rings

and corals - show recent T rise is unusual

Large body of evidence…Large body of evidence…

3. Comparisons of actual climate with computer

models. When models are run with historical inc. in

gh gases show gradual warming of Earth, increases

in ocean heat content, rise in sea level, retreat of

sea ice and snow cover. In agreement with

observations.

3. Comparisons of actual climate with computer

models. When models are run with historical inc. in

gh gases show gradual warming of Earth, increases

in ocean heat content, rise in sea level, retreat of

sea ice and snow cover. In agreement with

observations.

Climate Model Indications & the Observed ClimateClimate Model Indications & the Observed Climate

Global climate models clearly show effect

of human-induced changes on global T.

blue band shows how global T would have

changed due to natural forces only .

pink band shows model projections of effects

of human and natural forces combined.

black line shows actual observed global

average temperatures.

Global climate models clearly show effect

of human-induced changes on global T.

blue band shows how global T would have

changed due to natural forces only .

pink band shows model projections of effects

of human and natural forces combined.

black line shows actual observed global

average temperatures.

Global climate models clearly show effect

of human-induced changes on global T.

Close match between black line and the

pink band indicates that observed warming

over last half-century cannot be explained

by natural factors alone, and is instead

caused primarily by human factors.

Global climate models clearly show effect

of human-induced changes on global T.

Close match between black line and the

pink band indicates that observed warming

over last half-century cannot be explained

by natural factors alone, and is instead

caused primarily by human factors.

800,000 Year Record of CO2 Concentrations800,000 Year Record of CO2 Concentrations

Measured from trapped air bubbles in Antarctic ice core

Energy from the Sun Has Not IncreasedEnergy from the Sun Has Not Increased

Solar energy has been measured by satellites since 1978.

Now, Now, Chapter 6Chapter 6Now, Now, Chapter 6Chapter 6

Our layer model to date assumes that

that surface temperature is the same

everywhere on Earth!

But, we know this is not true.

So, we have to add yet more complexity

to our climate change model!

Our layer model to date assumes that

that surface temperature is the same

everywhere on Earth!

But, we know this is not true.

So, we have to add yet more complexity

to our climate change model!

1. Daily & Seasonal cycles - drive surface

temperatures above and below average

values.

2. Energy budgets DO NOT balance locally.

– net heat input at low latitudes, transport

to high latitudes.

turbulent flows of air and water.

requires complex computer climate models.

1. Daily & Seasonal cycles - drive surface

temperatures above and below average

values.

2. Energy budgets DO NOT balance locally.

– net heat input at low latitudes, transport

to high latitudes.

turbulent flows of air and water.

requires complex computer climate models.

Daily Variability:Simplified Surface Energy Balance

Daily Variability:Simplified Surface Energy Balance

NET R = +SW (insolation) –SW (reflection) +LW (infrared) –LW (infrared)

NET R = +SW (insolation) –SW (reflection) +LW (infrared) –LW (infrared)

Figure 6.2

Radiation BudgetsRadiation Budgets

El Mirage, CA Pitt Meadows, BC

Seasonal VariabilitySeasonal Variability

Earth’s tilt is responsible for seasons. Earth’s tilt is responsible for seasons. Earth’s tilt is responsible for seasons. Earth’s tilt is responsible for seasons.

Earth’s tilt determines how much heat the surface receives from the Sun each day as a function of latitude

(y axis) and time of year (x axis).

Earth’s tilt determines how much heat the surface receives from the Sun each day as a function of latitude

(y axis) and time of year (x axis).

net heat input at low latitudes, transport to high latitudes

net heat input at low latitudes, transport to high latitudes

Global Latent HeatGlobal Latent Heat

Figure 4.19

Global Sensible HeatGlobal Sensible Heat

Figure 4.20

So we have to simulate the weather.So we have to simulate the weather.

In order to forecast global warming we have to In order to forecast global warming we have to

simulate the time and space variations and simulate the time and space variations and

imbalances in the energy budget.imbalances in the energy budget.

And the way the Earth’s climate responds by And the way the Earth’s climate responds by

storing or transporting heat around.storing or transporting heat around.

Our original layer model can’t do thisOur original layer model can’t do this.

Physics that simulate flows of air/water is

complex and difficult to simulate.

So we have to simulate the weather.So we have to simulate the weather.

In order to forecast global warming we have to In order to forecast global warming we have to

simulate the time and space variations and simulate the time and space variations and

imbalances in the energy budget.imbalances in the energy budget.

And the way the Earth’s climate responds by And the way the Earth’s climate responds by

storing or transporting heat around.storing or transporting heat around.

Our original layer model can’t do thisOur original layer model can’t do this.

Physics that simulate flows of air/water is

complex and difficult to simulate.

Global Circulation without RotationGlobal Circulation without RotationGlobal Circulation without RotationGlobal Circulation without Rotation

Coriolis effect - an inertial force described by 19th-century French engineer-mathematician Gustave-Gaspard Coriolis in 1835.

Effect is an apparent deflection of the path of an object that moves within a rotating coordinate system.

The object does not actually deviate from its path, but it appears to do so because of the motion of the coordinate system.

Coriolis effect - an inertial force described by 19th-century French engineer-mathematician Gustave-Gaspard Coriolis in 1835.

Effect is an apparent deflection of the path of an object that moves within a rotating coordinate system.

The object does not actually deviate from its path, but it appears to do so because of the motion of the coordinate system.

Global Circulation Global Circulation WithWith Rotation Rotation

With With Coriolis Coriolis EffectEffect

1. Energy Budget of the Earth fluctuates on daily

& seasonal timescales (in contrast to the layer

model).

2. Annual Energy Budget doesn’t balance locally

because excess heat is carried to higher

latitudes by winds and ocean currents.

3. Global warming forecast requires

simulation the weather – computational

challenge.

1. Energy Budget of the Earth fluctuates on daily

& seasonal timescales (in contrast to the layer

model).

2. Annual Energy Budget doesn’t balance locally

because excess heat is carried to higher

latitudes by winds and ocean currents.

3. Global warming forecast requires

simulation the weather – computational

challenge.