Climate Change

Chapter 18

Global Change

Population growth Distribution of water Distribution of food Climate change

Climate Change

Earth’s average surface temperature Distribution of rainfall Patterns of temperature change and

global conveyor belt

Factors Affecting Global Climate Change Relationship of Earth to Sun Anthropogenic causes

Anthropogenic Causes

Atmospheric change due to carbon dioxide emissions, methane emissions, destruction of ozone by providing more surfaces-free radicals for reactions to occur in stratosphere (SOX, NOX, CO2, CH4), changes in vegetative cover, water pollution - eutrophication

Thousands of years ago

Ave

rag

e su

rfac

e te

mp

erat

ure

(°C

)

900 800 700 600 500 400 300 200 100 Present9

10

11

12

13

14

15

16

17

Fig. 18.2a, p. 447

Average temperature over past 900,000 years

Years ago

Tem

per

atu

re c

han

ge

(°C

)

20,000 10,000 2,000 1,000 200 100 Now

-5

-4

-3

-2

-1

0

1

2

End oflast iceage

Agriculture established

Average temperature over past10,000 years = 15°C (59°F)

Fig. 18.2b, p. 447

Temperature change over past 22,000 years

Year

Tem

per

atu

re c

han

ge

(°C

)

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2101

-1.0

-0.5

0.0

0.5

1.0

Fig. 18.2c, p. 447

Temperature change over past 1,000 years

Year

Ave

rag

e su

rfac

e te

mp

erat

ure

(°C

)

1860 1880 1900 1920 1940 1960 1980 2000 2020

13.6

13.8

14.0

14.2

14.4

14.6

14.8

15.0

Fig. 18.2d, p. 447

Average temperature over past 130 years

How do we know?

Recent history-have sufficient data from a variety of sources (hot air balloons, buoys, satellite data, pollen records, coral...)

Ancient history- ice cores (Vostock), rocks, tree rings )

Geologic history-, deep ocean sampling(plankton & radioisotopes), rocks(fossils & radioisotopes)

Evidence of Global Change

How is this information processed? Modeling # factors, depth of data, period of time

Global cooling and warming cycles Global cooling, Ice Ages, last about

100,000 years Global warming, interglacial periods,

last about 10,000 to 13,000 years Currently, we are living in an interglacial

period

Climate and global warming Climate is statistics of meteorological

conditions, temperature, precipitation, winds, over a long period of time-at least 30 years

0.5C of warming has occurred in last 130 years with the 1980s the warmest during that period

Pattern parallels that of fossil fuel use and injection into the atmosphere of gases that can absorb radiation and lead to global warming

Greenhouse Effect

Molecules of atmospheric gases vibrate and transform the absorbed energy into longer wavelength infrared radiation in the troposphere

Convection currents distribute the heat

of greenhouse gases Atmosphere is good absorber

of infrared radiation (7.5 m) CO2 and H2O vapor limit

transmission to space at many

Variation of Temperature, pressure, and altitude above Earth’s surface

Global Energy Balance for Atmosphere

Numbers are %energy from incoming solar radiation

Greenhouse Effect Half of solar heat goes into latent heat,

absorbed by water changing to water vapor

Of 47% of initial solar energy absorbed at Earth’s surface, only 18% lost by radiation

The remainder is captured by atmosphere-surface cycling which causes Earth to be 33C warmer than is would be without an atmosphere

Tropospheric heating effect

Arrhenius !!!!! 1896 Not a guess, data supports Is THEORY in atmospheric science

Average Surface Temperature is about 15C (60F) Due to combination of greenhouse and

global cooling processes Cooling processes: heat absorbed by

evaporation of water, and water vapor stores heat in upper atmosphere (thermosphere)

Greenhouse Gas CO2 fossil fuel burning (75%), biomass

burning CH4 rice, cows, landfills, coal production, coal

seams, natural gas leaks, oil production N2O fossil fuel burning, fertilizers, livestock

wastes, nylon prod CFCs air conditioners, refrigerators, foams HCFCs-” “ Halons- fire extinguishers CCl4 cleaning solvent

Carbon dioxide

Temperaturechange End of

last ice age

160 120 80 40 0Thousands of years before present

Co

nc

entr

ati

on

of

carb

on

dio

xid

ein

th

e a

tmo

sph

ere

(p

pm

)

180

200

220

240

260

280

300

320

340

360

380

–10.0

–7.5

–5.0

–2.5

0

+2.5

Va

riat

ion

of

tem

pe

ratu

re (

˚C)

fro

m c

urr

en

t le

vel

Fig. 18.3, p. 449

Correlation between CO2 and Temp Change

Surface Ozone:Top is Preindustrial and Lower frame is current (2002)

Changes in atmosphere, geosphere, & biosphere from glacial to interglacial periods

Ozone over Antarctica 1979 to 1990

Measurement of Air pollution from satellite

Drought from June to August in global

climate model

Global Ocean Temp at depth of 160 m

(vol transport stream)

Year1990 2000 2025 2050 2075 2100

100

150

200

250

Ind

ex

(19

00

= 1

00

)Carbon dioxide

MethaneNitrous oxide

Fig. 18.5, p. 451

Projected emissions

Global warming is cyclical; the rate is not The rate of global warming is greater than past

interglacial periods The CO2 in troposphere is higher than probably the

last 20 million years 75% of CO2 since 1980 is due to fossil fuel burning;

remainder is human changes in land use Average global temp has >0.6C mostly since 1946 Since 1861 9 of 10 warmest years have occurred

since 1990 with the hottest in 1998 and 2001 Ice caps and glaciers shrinking Global sea level rise of 10-20 cm in 100 years Plants and animals are migrating north to meet

optimum temperatures

Global Change

Affect the availability of water resources by altering rates of evaporation and precipitation

Shift areas where crops can be grown Change average sea levels Alter the structure and location of the

world’s biomes

Positive feedback

More product results in more production-eg. “nothing succeeds like success”

Greater temp, more melting of snow, loss of albedo effect results in greater temp and still more melting of snow

Thawing soil results in more microbial activity; more microbial activity results in more CO2 and more thawing soil

Arctic circle, Greenland, and Antarctica all have thinning ice sheets, particularly Greenland

The influx of freshwater from melting glaciers on Greenland could stop the global conveyor belt in the Atlantic

Antarctica

Cold water melting fromAntarctica's ice cap and

icebergs falls to the ocean floor and surges northward, affecting

worldwide circulation.

Cold water melting fromAntarctica's ice cap and

icebergs falls to the ocean floor and surges northward, affecting

worldwide circulation.

GreenlandGreenland

Fig. 18.10, p. 456

Global conveyor belt

Year1860 1880 1900 1920 1940 1960 1980 2000 2010

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Observed

Model of greenhouse gases + aerosols + solar output

Tem

per

atu

re c

han

ge

(°C

) fr

om

198

0–99

mea

n

Fig. 18.7, p. 453

Climate Models and IPCC IPCC: Intergovernmental Panel on Climate

Change 2,000 climate scientists 90-95% chance that earth’s mean surface temp

will >1.4-5.8C between 2000 and 2100; change btwn 2000 and 2030 will equal that of entire 20th century

Many greenhouse gases show increases due to anthropogenic activities

Bush administration 2002 says climate changes anthropogenic and then reject Kyoto Treaty!

Climate models are only models & have limitations

Building models

Transect atmosphere mathematically Assign initial boundary condition for each

variable to each cell in layer (solar radiation, precipitation, heat radiated by earth, cloudiness, interactions btwn atmosphere and oceans, greenhouse gases, & air pollutants)

Develop equations that connect cells so vary together

Run model to simulate changes that can be verified and then run to project future changes

Reliability tied to accuracy of data inputs and magnification of errors over time, & chaos

Year

1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 21000

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

Ch

ang

e in

tem

per

atu

re (

ºC)

Fig. 18.8, p. 453

Measured vs predicted temperature changes

Change will not be evenly distributed Temp increases higher over land than

over oceans Greater in high latitudes near earth’s

poles than in lower latitude equatorial regions

Much higher in inland regions in the northern latitudes

• Increased deaths from heat and disease

• Disruption of food and water supplies

• Spread of tropical diseases to temperate areas

• Increased respiratory disease

• Increased water pollution from coastal flooding

Human Health

• Rising sea levels• Flooding of low-lying islands

and coastal cities• Flooding of coastal estuaries,

wetlands, and coral reefs• Beach erosion• Disruption of coastal

fisheries• Contamination of coastal

aquifiers with salt water

Sea Level and Coastal Areas

• Changes in forest composition and locations

• Disappearance of some forests

• Increased fires from drying

• Loss of wildlife habitat and species

Forests

• Changes in water supply

• Decreased water quality

• Increased drought

• Increased flooding

Water Resources

• Shifts in food-growing areas

• Changes in crop yields

• Increased irrigation demands

• Increased pests, crop diseases, and weeds in warmer areas

Agriculture

• Extinction of some plant and animal species

• Loss of habitats

• Disruption of aquatic life

Biodiversity

• Prolonged heat waves and droughts

• Increased flooding

• More intense hurricanes, typhoons, tornadoes, and violent storms

Weather Extremes

• Increased deaths

• More environmental refugees

• Increased migration

Human Population

Fig. 18.12, p. 458

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breakingoff a chlorine atom and leaving CFCl2.

UV radiation

Sun

Once free, the chlorine atom is off to attack another ozone moleculeand begin the cycle again.

A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2.

The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO).

The chlorine atom attacksan ozone (O3) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O2).

Cl

Cl

ClC

F

Cl

Cl

OO

Cl

OO

O

Cl

O

OO

ClO

O

Summary of ReactionsCCl3F + UV Cl + CCl2FCl + O3 ClO + O2

Cl + O Cl + O2

Repeated many times

Fig. 18.16, p. 466