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New Core Curriculum Foundations of Scientific Process Factors that govern Global & Local Climate.
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Transcript of New Core Curriculum Foundations of Scientific Process Factors that govern Global & Local Climate.
New Core CurriculumNew Core Curriculum
Foundations of Scientific ProcessFoundations of Scientific Process
Factors that govern Global & Local ClimateFactors that govern Global & Local Climate
Life – Atmospheric Conditions – ClimateLife – Atmospheric Conditions – Climate
Proxies- needed to infer past climate-related changes
Time before present (billions of years)
Atmospheric CO2
Atmospheric O2
Development of the Habitable Conditions on Earth
The History of Life on Earth
Elements of Habitability
• Stability• Chemical Composition• Temperature
Temperature of a planet is determined from an energy balance:
Energy IN = Energy OUT
Star’s Luminosity Distance planet-star Tilt of planet’s axis,
eccentricity of planet's orbit
Reflectivity of planet, Albedo (cloud cover, surface ice, vegetation, aerosols)
Star’s Luminosity Distance planet-star Tilt of planet’s axis,
eccentricity of planet's orbit
Reflectivity of planet, Albedo (cloud cover, surface ice, vegetation, aerosols)
Planet’s atmosphere– Water vapor– Carbon dioxide– Methane– Nitrous oxides– Sulfur dioxide– Aerosols
Planet’s atmosphere– Water vapor– Carbon dioxide– Methane– Nitrous oxides– Sulfur dioxide– Aerosols
Elements of Habitability
• Stability• Chemical Composition• Temperature
Energy input = Earth output
1) Ein (from the Sun)
Eout
2) Reflectivity (Albedo)3) Greenhouse Concentration
How do we determine the energy into the climate system?
Distance from Sun
B = L/4πd2
Solar Max2001
Solar Min2006
Solar Max2011
Sunspots!
More sunspots = “brighter” sun
Small effect: 1-2 W/m2 of 1360 W/m2
Sunspot cycles occur over decades to hundreds of years
significant climate responses to sun spots
1 - 2
W/m2
Year
Precession is the change in the direction of the Earth's axis of rotation relative to the fixed star.
The angle of the Earth's axial tilt varies with respect to the plane of the Earth's orbit.
The eccentricity is a measure of the departure of this ellipse from circularity.
100,000
41,000 23,000
Milankovitch cycles
years years years
Green house gasesHow do we determine the energy out of the climate system?
Albedo
Clouds, ice, white aerosols reflect about 30% of incoming sunlight back to space
Albedo = Reflectivity fraction of incoming radiation that is not absorbed, yet just bounces back in space
Sample albedos
Surface Albedo
Fresh asphalt
0.04[1]
Conifer forest(Summer)
0.08[2]
Worn asphalt
0.12[1]
Bare soil 0.17[3]
Green grass
0.25[3]
Desert sand
0.40[4]
New concrete
0.55[3]
Fresh snow
0.80–0.90[3]
Venus ~ 0.65
Mars ~ 0.15Earth ~ 0.3Moon ~ 0.12Jupiter ~ 0.52
Europa ~ 0.67
Venus ~ 0.65
Mars ~ 0.15Earth ~ 0.3Moon ~ 0.12Jupiter ~ 0.52
Europa ~ 0.67
Volcanoes cool climate, briefly
Mt. Pinatubo - 1994
Big eruptions inject aerosols into the upper atmosphere.Earth becomes more reflective for 2-3 years
Natural effects that Increases
Earth’s Albedo
Greenhouse Effect:Greenhouse Effect: gases (H gases (H22O, COO, CO22,..) trap heat in the atmosphere,..) trap heat in the atmosphere
Greenhouse gases Greenhouse gases are highly influentialare highly influential
HH22O vapor constitutes the largest % of the O vapor constitutes the largest % of the
greenhouse effect (absorbs terrestrial radiation)greenhouse effect (absorbs terrestrial radiation)
How do we determine the energy out of the climate system?
Heat & TemperatureHeat & Temperature
• Heat: energy of atomic and molecular motion
• Temperature: measure of average kinetic energy of moving atoms and molecules
vavg 140(m /s)T
m
T (in Kelvin) m (atomic mass
unit, # protons + # neutrons)
T (in Kelvin) m (atomic mass
unit, # protons + # neutrons)
Ex: Room temperature
T = 293 K Air particles as
N2
(m = 2 x 14 g/mol)
vavg ~ 450 m/s
Ex: Room temperature
T = 293 K Air particles as
N2
(m = 2 x 14 g/mol)
vavg ~ 450 m/s
Climate: Climate: average weather (average temperature) for average weather (average temperature) for the whole planet that prevails over certain the whole planet that prevails over certain time-span; time-span;
it is variable with time;it is variable with time;
it is a sensitive system;it is a sensitive system;
3 factors 3 factors determining determining the global the global climate:climate:
1) Ein (from the Sun)2) Reflectivity (Albedo)3) Greenhouse Concentration
Complicated Feedback Complicated Feedback Loops “in-play”Loops “in-play”
What controls local climate?
differential heating What causes Seasons?
Temperature of a planet is determined from an energy balance:
Energy IN = Energy OUT
Star’s Luminosity Distance planet-star Tilt of planet’s axis,
eccentricity of planet's orbit
Reflectivity of planet = Albedo (cloud cover, surface ice, vegetation, aerosols)
Star’s Luminosity Distance planet-star Tilt of planet’s axis,
eccentricity of planet's orbit
Reflectivity of planet = Albedo (cloud cover, surface ice, vegetation, aerosols)
Planet’s atmosphere– Water vapor– Carbon dioxide– Methane– Nitrous oxides– Sulfur dioxide– Aerosols
Planet’s atmosphere– Water vapor– Carbon dioxide– Methane– Nitrous oxides– Sulfur dioxide– Aerosols
Elements of Habitability
• Stability• Chemical Composition• Temperature
Global TrendsGlobal Trends
Climate Change(global worming, sea-level rise, coastal flooding, extreme weather)
HOW DO WE KNOW?
The Earth’s Past (evidence from the geologic record)The Earth’s Past (evidence from the geologic record)
Proxies- needed to infer past climate-related changes
Time before present (billions of years)
Atmospheric CO2
Atmospheric O2
Natural Recorders of Temperature Natural Recorders of Temperature Paleo-climate ProxiesPaleo-climate Proxies
Ice Core
Glacial features
Tree Rings
Sedimentary Layers
Fossils
Retreating glaciers – Proxy for past climatic conditionsRetreating glaciers – Proxy for past climatic conditions
TODAY
Full extent was in ~1850 AD
Glaciers “clean” rock surfaceLeave hills or mounds of sediments (moraines) and discoloration
But this is with reference to Greenland. Is it applicable on the global
scale?
Retreating glacier in Greenland
Examine retreat of glaciers elsewhere on Earth
Franz Josef Glacier in New ZealandCompare size in 1880 AD and now
Retreat of glacier Climate much colder in the past
Retreating glaciers in the Southern hemisphere
Historical records of past conditions
Ref : IPCC Report 2001
Retreating glaciers worldwide
Glacial grooves and striations at the base of the Matterhorn
Glaciers as Proxies
Like in our backyard of Central Park!
Evidence that glaciers extended here in the past over 20,000 years ago
Ice Core Archiveshttp://www.pbs.org/saf/1505/video/watchonline.htm
movie of ocean sample
How glaciers trap bubbles samples of atmosphere
Snow falls Ice becomes closer packed Eventually pores are isolated and gas is trapped Gas is record of the atmosphere in the past and the content of various gases – CO2, CH4 etc. in it
2-5 km length
Data: CO2 content of air trapped in ice core
Earth’s paleoclimate
How was an estimate of temperature obtained?
How was an estimate of CO2 obtained?
Air bubbles trapped in the ice core
Ratio of Oxygen isotopes (atoms with different number of neutrons)
Calibration Curve
Homo Sapiens about 200 thousand years ago
Nature, June 2003 20,000 YEARS AGO
300
400
500
600
Mauna Loa
700
600
500
400
300
200
Mauna Loa
IPCCA1B scenario
1950 2000 2050 2100
Time (years)
CO2 concentrations (ppm)
IPCCA1B
300
400
500
600
Mauna Loa
Factors responsible for Climate Factors responsible for Climate Variation:Variation:
A) Natural A) Natural Causes Causes B) Anthropogenic Causes B) Anthropogenic Causes
Global Warming of Climate: Global Warming of Climate:
Who is responsible for the change? Who is responsible for the change?
Natural Natural Causes Causes
AnthropogeniAnthropogenic Causes c Causes
• addition of CO2
burn burning of coal/fossil fuels;
deforestation (vegetation decay);
• generation of Aerosols
• variations in Earth’s orbit
eccentricity, obliquity, precession
• movement of landmasses
• volcanic activity
So global climate is warming….So global climate is warming….
How can we distinguish between How can we distinguish between variations due to natural causes variations due to natural causes and those that are induced by and those that are induced by human activity?human activity?
Natural Natural Causes Causes
AnthropogeniAnthropogenic Causes c Causes
Climate Models as Climate Models as Evidence: used to Evidence: used to determine the amount of determine the amount of change anticipated by change anticipated by accounting for certain accounting for certain factorsfactors
Modern Climate Changes dominated by Human Influence
Climate Models as Evidence:Climate Models as Evidence:
Modern Climate Changes dominated by Human
Influence
Testing models against past climate: The last ~ 100 years
“Natural”
Influences
Human Influenc
es