Global Warming

011

Winter solsticeDec. 22Sun vertical at 23.5oS

Winter solsticeDec. 22Sun vertical at 23.5oS

Autumnal equinoxSep. 23Sun vertical at equator

Summer solsticeJune 21Sun vertical at 23.5oN

Vernal equinoxMarch 21Sun vertical at equator

Northern Hemisphere Names

Earth further from sun

Earth closer to sun

Solar irradiance-

What are some factors that effect exposure to irradiance?

The radiant energy emitted by the sun.

It is highest at the equator and lowest at the poles.

We are interested in conditions near the Earth’s surface

Convection cell model

Non-rotating Earth

Add rotation and add landmasses unequal heating and cooling of the Earth

Physical properties of the atmosphere: Density

• Warm, low density air rises

• Cool, high density air sinks

• Creates circular- moving loop of air (convection cell)

Physical properties of the atmosphere: Water vapor

• Cool air cannot hold much water vapor, so is typically dry

• Warm air can hold more water vapor, so is typically moist

• Water vapor decreases the density of air

Physical properties of the atmosphere: Pressure

• A column of cool, dense air causes high pressure at the surface, which will lead to sinking air

• A column of warm, less dense air causes low pressure at the surface, which will lead to rising air

ITCZ intertropical convergence zone= doldrumsLow pressure, wet climate

High pressure, dry climate

Low pressure, wet climate

30o

30o

60o

60o

90o

90o

0o

High pressure, dry climate

A) Idealized winds generated by pressure gradient and Coriolis Force.  B) Actual wind patterns owing to land mass distribution..

The Coriolis effect• The Coriolis effect

– Is a result of Earth’s rotation– Causes moving objects to follow

curved paths:• In Northern Hemisphere, curvature

is to right• In Southern Hemisphere, curvature

is to left

– Changes with latitude:• No Coriolis effect at Equator• Maximum Coriolis effect at poles

The Coriolis effect on Earth

• As Earth rotates, different latitudes travel at different speeds

• The change in speed with latitude causes the Coriolis effect

equator

Quito

Buffalo

79oW

North Pole

South Pole

N

Quito

Buffalo

equa

tor

Buffalo moves 783 mphQuito moves 1036 mph

15o

• Gyres are large circular-moving loops of water• subtropical gyres

• Five main gyres (one in each ocean basin):• North Pacific• South Pacific• North Atlantic• South Atlantic• Indian

• Generally 4 currents in each gyre• Centered about 30o north or south

latitude

Current GyresCurrent Gyres

Geostrophic flow and western intensification

• Geostrophic flow causes a hill to form in subtropical gyres

• The center of the gyre is shifted to the west because of Earth’s rotation

• Western boundary currents are intensified

Figure 7-7

Wind-driven surface currents

Global Warming

The E-M Spectrum

Fate of Solar Radiation Fate of Solar Radiation Reaching the EarthReaching the Earth

reflectionreflectioncloudsclouds

snow and icesnow and ice

the earth’s surfacethe earth’s surface

atmospheric dustatmospheric dust

reflectionreflectioncloudsclouds

snow and icesnow and ice

the earth’s surfacethe earth’s surface

atmospheric dustatmospheric dust

Fate of Solar Radiation Fate of Solar Radiation Reaching the EarthReaching the Earth

absorptionabsorptionatmosphereatmosphere

oceansoceans

landland

plant photosynthesisplant photosynthesis

absorptionabsorptionatmosphereatmosphere

oceansoceans

landland

plant photosynthesisplant photosynthesis

Fate of Solar Radiation Fate of Solar Radiation Reaching the EarthReaching the Earth

radiationradiationradiationradiation

The Greenhouse Effect

Greenhouse GasesGreenhouse Gases

Carbon DioxideMethane

Nitrous OxideWater Vapor

Ozone

                                                                                                          

                                               Thousands of Years Before Present

Tem

per

atu

re C

han

ge

(oF

)

Atm

osp

her

ic C

O2

(pp

m)

Year

Temperature

Carbon Dioxide

Tem

per

atu

re C

han

ge

(oF

)

Atm

osp

her

ic C

O2

(pp

m)

Atmospheric CO2 & Surface Temperature TrendsAtmospheric CO2 & Surface Temperature Trends

Sea level rise

Increased plant primary productivity

Shifts in the distribution of plants and animals

Water contamination and outbreaks of water-borne diseases

Increased storm severity

Potential melting or enlargement of polar ice caps

Changes to patterns of rainfall

More severe droughts or increased precipitation

changes to ocean circulation patterns

Predicted changes with increased greenhouse warming

Ice Age 18,000 years ago

Sea Level Changes due to Ice Ages and Ice Cap Melting

                                                                                                                    

                                     

Year

Ch

ang

es in

Mea

n S

ea L

evel

Mean Sea Level RiseMean Sea Level Rise

                                                                                                                   

                                      

Summer Arctic Sea Ice Decline Comparison between 1979 & 2005Summer Arctic Sea Ice Decline Comparison between 1979 & 2005

Early Fall Arctic Sea Ice ExtentEarly Fall Arctic Sea Ice ExtentS

ea Ic

e E

xten

t (m

illio

n k

m2 )

Year

    

                 

Greenland Seasonal Surface Melting

Surface melting

Permafrost

Permafrost

                 

                                   

Permafrost melting

Permafrost melting

Permafrost melting

Drunken forest

                                                                                                             

                                            

Year

North Atlantic Tropical Storms10-year running averageNorth Atlantic Tropical Storms10-year running average

Nam

ed T

rop

ical

Sto

rms

1 Meter Sea Level Rise Waikiki1 Meter Sea Level Rise Waikiki

http://www.soest.hawaii.edu/HMRG/FloodingOahu/index.phphttp://www.soest.hawaii.edu/coasts/sealevel/waikiki.html

Sea Level Rise

• Destroys coastal habitat (e.g. salt marshes, mangroves)

• Destroys human property• Increases pollution• Decreases freshwater supply

Effect on Marine Life• Phytoplankton bloom due to light and

temperature cues• Changes will impact food web• Hypoxia may result

Effect on Fisheries

• Migrations are in response to temperature• May impact fisheries

Effect on Corals• Coral bleaching • Leads to loss of habitat and food for reef-

dependent species

CurrentsOceanic conveyor belt may change ocean currents • Currents carry plankton• Bring food and oxygen• Distribute eggs and larvae• Remove wastes and pollutants

Salinity• Animals have a narrow range of tolerance• Glacial melting inputs lots of freshwater

Acidity• CO2 makes water acidic• Corals and other calcium carbonate species

can’t make skeleton• Impact on plankton development impacts food

web

Temperature• Higher temperature results in less O2

- Results in hypoxia• Ice melting leaves no resting/hunting areas for

polar bears• Antarctic Krill impacts food web

Invasive Species• Algae smothers coral• Invasive species out-compete natives

Weather Events

More severe weather patterns• El Niño• Hurricanes • Mudslides• Forest Fires• Drought

Sea Surface Temperature

July 24, 2012 http://www.elnino.noaa.gov/

Origin and paths of tropical cyclones

• Tropical cyclones are intense low pressure storms created by:

– Warm water

– Moist air

– Coriolis effect

El Niño-Southern Oscillation (ENSO)

• El Niño = warm surface current in equatorial eastern Pacific that occurs periodically around Christmastime

• Southern Oscillation = change in atmospheric pressure over Pacific Ocean accompanying El Niño

• ENSO describes a combined oceanic-atmospheric disturbance

El Niño

• Oceanic and atmospheric phenomenon in the Pacific Ocean

• Occurs during December• 2 to 7 year cycle

Sea Surface Temperature

Atmospheric Winds

Upwelling

Normal conditions in the Pacific Ocean

El Niño conditions (ENSO warm phase)

La Niña conditions (ENSO cool phase; opposite of El

Niño)

El NiñoNon El Niño

1997

Non El Niño

El Niño

thermocline

upwelling

El Niño events over the last 62 years

82-83

65-6672-73

57-5886-87 91-92

94-95

97-98

02-0309-10

Red - Strong El NinoBlue- Strong La NinaBlack – moderate (either)

50-5155-56

64-65

70-71

73-74

75-7688-89

98-9999-00

07-08 10-11

11-12

1969 1951 1957 1950 1955 1973

1976 1963 1965 1954 1970 1975

1977 1968 1972 1956 1998 1988

2004 1986 1982 1962 2007 1999

2006 1987 1997 1964 2010

1991 1967

1994 1971

2002 1974

2009 1984

1995

2000

El Niño La Niña

Weak Mod Strong Weak Mod Strong

2011

Effects of severe El Niños

1. What is a convection cell?2. What are current atmospheric CO2

levels?3. What is the fate of the majority of solar

radiation that strikes the Earth?4. What is a drunken forest?5. What is permafrost?6. Is global warming a natural event?

Inquiry