chapter 6: weather & climate. midterm exam 9:33 8: 22335778 7 : 5788 6:2335778 average score =...
TRANSCRIPT
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
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.