Climate System

• Atmosphere– Nitrogen N2 78%

– Oxygen O2 21%

– Argon Ar 0.93%

– Carbon dioxide CO2 0.035%

– Other minor gases 0.035%

Greenhouse Gases

• CO2, H20 and methane (CH4):

• Absorb and re-radiate radiation

• Insulates and raises Earth temperature

GEOLOGIC RESERVOIRSGEOLOGIC RESERVOIRS

Fossilorganiccarbon

Fossilorganiccarbon

Rockcarbonates

Rockcarbonates

Fossil-fuel

burning(5.3 Gt/yr)

Fossil-fuel

burning(5.3 Gt/yr)

OCEANOCEAN

Cement production (0.1 Gt/yr)Cement production (0.1 Gt/yr)

Land-use change:

deforestation,agriculture(1.7 Gt/yr)

Land uptakeBy new plantgrowth(1.9 Gt/yr)

Ocean uptake by air-sea gas

exchange(1.9 Gt/yr)

Terrestrial biosphere

LANDLAND

ATMOSPHEREATMOSPHERE

The influence of Carbon on climate change

GEOLOGIC RESERVOIRSGEOLOGIC RESERVOIRS

Fossilorganiccarbon

Fossilorganiccarbon

Rockcarbonates

Rockcarbonates

Fossil-fuel

burning(5.3 Gt/yr)

Fossil-fuel

burning(5.3 Gt/yr)

OCEANOCEAN

Cement production (0.1 Gt/yr)Cement production (0.1 Gt/yr)

Land-use change:

deforestation,agriculture(1.7 Gt/yr)

Land uptakeBy new plantgrowth(1.9 Gt/yr)

Ocean uptake by air-sea gas

exchange(1.9 Gt/yr)

Terrestrial biosphere

LANDLAND

ATMOSPHEREATMOSPHERE

Human activities releasea total of 7.1 Gt of carbon into the atmosphere each year.

New plant growth andair-sea gas exchangeremove 3.8 Gt/yr,…

…yielding a netatmosphericincrease of3.3 Gt/yr.

Climate Change

Understanding Natural Climate Variability:

Use the geologic record to understand Earth Climate in the past

(Uniformitarianism)

Milankovitch cyclesRelated to variations in:

1. Eccentricity2. Tilt of axis3. Precession (wobble)

All of these variables change the earth-sun distance

Is Human-induced climate change

possible?

Long-term change can be assessed from ice cores, which record annual cycles of ice formation from snow.

Tem

pera

ture

rela

tive t

o p

resen

t clim

ate

(°C

)

Thousands of years before presentR

ela

tive c

arb

on

dio

xid

e a

nd

meth

an

e c

on

cen

trati

on

s

High

Low

Key:TemperatureCO2

Methane

Ice Ages Deglaciation

Climate has been relatively warm andstable during the last 10,000 years.

Years

Temperature

CO2 concentration

The 20th-century is clearly anomalous when compared with the last millennium.

Nort

hern

Hem

isp

here

tem

pera

ture

an

om

aly

(°C

)

CO

2 c

on

cen

trati

on

(p

pm

)

Keeling Curve

Years

Temperature

CO2

concentration

Glo

bal te

mp

era

ture

an

om

aly

(°C

)

A recent warming trend correlateswith the increase in CO2.

CO

2 c

on

cen

trati

on

(p

pm

)

Atmospheric CO2 Projections Under 3 Alternate Scenarios….

2000 2020 2040 2060 2080 2100

Year

….and Estimated Average Surface Temperatures for Those Scenarios

Uncertainty envelope due to lack of knowledge of climate system

Feedback enhances warming

• Positive Feedback: – Amplifies changes in the system.

– Temperature increase decreases Earth’s albedo by reducing snow and ice cover

Evidence for Warming

• Weather is highly variable*

• Glaciers provide long-term trends

1941

2004

Columbia glacier

Greenland

Greenland

Weather Related Hazards

1. Drought2. Desertification3. Heat waves4. Snow and Ice5. Global Warming6. El Niño

NMSU Rainfall

-2

0

2

4

6

8

10

12

14

1 19 37 55 73 91 109 127 145 163 181 199 217 235 253 271 289 307 325 343 361

Days since Jan 1

Cumulative Rainfall (Inches)

200620052004200320022001200020072008

Transition zones between desertsand humid areas are fragile

Soil gets eroded by wind and waterProductive land becomes degraded

Main culprits:OvergrazingOverplowing

Human activity can stress the ecosystem

• Grazing• Cutting trees for charcoal• Some agriculture

El Niño

• Pacific Ocean is pushed westward by trade winds

• Warm water off Peru is replaced by upwelling of cold, deep, nutrient-rich water

• Circulation reverses: El Niño

• 6 Year cycle

• Opposite extreme in weather patterns is La Nina

El Niño

Subtropical trade winds weaken

Warm surface water remains in east Pacific

Incessant rain to west coasts

Fisheries suffer (no cold, nutrient-rich upwelling water)

El Niño

• Drainage Basins

• Discharge

• Sediment load

• Meandering/Braided rivers

• Floodplains

• Flooding

Outline

SEA SEA LAND LAND+ 336 Runoff from land+ 398 Precipitation

over sea+ 434 Evaporation

+ 434 Evaporation– 398 Precipitation + 436 Excess to land

via precipitation

+ 107 Precipitation– 371 Evaporation

+ 436 Runoff toocean

+ 107 Precipitation– 336 Runoff to ocean

+ 471 Evaporation

Evaporation434

Precipitation398

Runoff 36

Groundwatertable Groundwater

flow

Infiltration

Surfacerunoff

Precipitation107

Evaporation71

Flux in and flux out over oceans is almost balanced.

Excess is moved toland and precipitates.Excess is moved toland and precipitates.

…or filters into soiland rock, where it moves as groundwater.

The precipitationruns off intolakes, streams,and oceans…

Drainage Basin/Watershed

Drainage Basins/Watersheds

• Rio Grande River basin includes:– Chama– Puerco– Pecos (and all of its tributaries)

• It doesn’t include the Gila, because it flows into Colorado

• Continental Divide (in NM) separates: – Rio Grande drainage– Colorado River drainage

Rio Grande

Rio Grande Pecos

ColoradoGila

San Juan

Rio Grande Watershed

• Q=VA

• Q is discharge

• V is average velocity (m/s)

• A is cross-sectional area (m2)

• units of Q?

Discharge/Total Flow

Discharge/Total Flow

Discharge/Total Flow

Stream profile depends on location

Sediment Load and Grain Size

• Streams can be provided with particles of any size from mud to giant boulders

• Volume and velocity of flow limit size and amount of sediment that stream can carry

Sediment Load and Grain Size

Alluvial fans have braided streams

Gravel delta at mouth of braided river, Cook Inlet, Alaska

Delta reworked by wave action, Cook Inlet, Alaska