Climate System Atmosphere –Nitrogen N 2 78% –Oxygen O 2 21% –Argon Ar 0.93% –Carbon dioxide CO % –Other minor gases 0.035%

Greenhouse Gases CO 2, H 2 0 and methane (CH 4 ): Absorb and re-radiate radiation Insulates and raises Earth temperature

GEOLOGIC RESERVOIRS Fossil organic carbon Fossil organic carbon Rock carbonates Rock carbonates Fossil- fuel burning (5.3 Gt/yr) Fossil- fuel burning (5.3 Gt/yr) OCEAN Cement production (0.1 Gt/yr) Land-use change: deforestation, agriculture (1.7 Gt/yr) Land uptake By new plant growth (1.9 Gt/yr) Ocean uptake by air-sea gas exchange (1.9 Gt/yr) Terrestrial biosphere LAND ATMOSPHERE The influence of Carbon on climate change

GEOLOGIC RESERVOIRS Fossil organic carbon Fossil organic carbon Rock carbonates Rock carbonates Fossil- fuel burning (5.3 Gt/yr) Fossil- fuel burning (5.3 Gt/yr) OCEAN Cement production (0.1 Gt/yr) Land-use change: deforestation, agriculture (1.7 Gt/yr) Land uptake By new plant growth (1.9 Gt/yr) Ocean uptake by air-sea gas exchange (1.9 Gt/yr) Terrestrial biosphere LAND ATMOSPHERE Human activities release a total of 7.1 Gt of carbon into the atmosphere each year. New plant growth and air-sea gas exchange remove 3.8 Gt/yr,… …yielding a net atmospheric increase of 3.3 Gt/yr.

Climate Change Understanding Natural Climate Variability: Use the geologic record to understand Earth Climate in the past (Uniformitarianism)

Milankovitch cycles Related to variations in: 1. Eccentricity 2. Tilt of axis 3. 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.

Temperature relative to present climate (°C) Thousands of years before present Relative carbon dioxide and methane concentrations High Low Key: Temperature CO 2 Methane Ice Ages Deglaciation Climate has been relatively warm and stable during the last 10,000 years.

Years Temperature CO 2 concentration The 20th-century is clearly anomalous when compared with the last millennium. Northern Hemisphere temperature anomaly (°C) CO 2 concentration (ppm)

Keeling Curve

Years Temperature CO 2 concentration Global temperature anomaly (°C) A recent warming trend correlates with the increase in CO 2. CO 2 concentration (ppm)

Atmospheric CO 2 Projections Under 3 Alternate Scenarios… 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

Weather Related Hazards 1. Drought 2. Desertification 3. Heat waves 4. Snow and Ice 5. Global Warming 6. El Ni ñ o

Transition zones between deserts and humid areas are fragile

Soil gets eroded by wind and water Productive land becomes degraded Main culprits: Overgrazing Overplowing

Human activity can stress the ecosystem Grazing Cutting trees for charcoal Some agriculture

El Ni ñ o 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 Ni ñ o 6 Year cycle Opposite extreme in weather patterns is La Nina

El Ni ñ o 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 Ni ñ o

Drainage Basins Discharge Sediment load Meandering/Braided rivers Floodplains Flooding Outline

SEA LAND + 336Runoff from land + 398Precipitation over sea + 434Evaporation – 398Precipitation + 436Excess to land via precipitation + 107Precipitation – 371Evaporation + 436Runoff to ocean + 107Precipitation – 336Runoff to ocean + 471Evaporation Evaporation 434 Precipitation 398 Runoff 36 Groundwater table Groundwater flow Infiltration Surface runoff Precipitation 107 Evaporation 71 Flux in and flux out over oceans is almost balanced. Excess is moved to land and precipitates. Excess is moved to land and precipitates. …or filters into soil and rock, where it moves as groundwater. The precipitation runs off into lakes, 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 Pecos Colorado Gila San Juan

Rio Grande Watershed

Q=VA Q is discharge V is average velocity (m/s) A is cross-sectional area (m 2 ) units of Q? 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