Climate & the Carbon Cycle

•Earth is a closed system. Carbon is not gained or lost, it just cycles through the different spheres (Atmosphere; Hydrosphere; Geosphere; Biosphere)

•Atmospheric CO2 is a GHG. It traps I.R. energy radiated from Earth’s surface; temperatures increase.

Climate Change: Global Warming

Global Warming = Increase in air and ocean temperatures.

Due to changes in Earth’s Energy Budget.

Greenhouse Effect & CO2

Greenhouse Gases = Gases that prevent I.R. wavelengths from E’s surface from escaping to outer space.

CO2 = GHG

Measuring Carbon Dioxide in the Atmosphere

•Ice Cores: Gas bubbles trapped in ice are miniature atmospheres that can be studied.•Measured directly from. Mauna Loa

Carbon Dioxide Levels

•CO2 levels are determined from gas bubbles trapped in ice (Vostock Lake, Antarctica)•Temperatures can be determined from 18O:16O ratios.

• CO2 levels are determined from gas bubbles trapped in ice (Vostock Lake, Antarctica)• Temperatures can be determined from 18O:16O ratios.

Evidence of Global Warming: Measured increases in Carbon Dioxide Levels

Modern CO2 levels measured at Mauna Loa Observatory, Hawaii

Evidence of Global Warming: Increasing Sea Surface Temperatures & Sea Level Rise

Evidence of Global Warming: Glacial Retreats

Carbon Cycle: Key IdeasReservoirs: a term used to describe the compartments that contain carbon in some form (e.g.: atmosphere, soil, water, in plants, etc)

Photosynthesis: CO2 from atmosphere turned into “sugar”

Respiration: cells convert sugars from food into CO2

Fossilization: processes involving extreme pressures that turn various kinds of carbon into fossil fuels (coal, crude oil, natural gas)

Sedimentation: material settles to bottom of aquatic system

Food Chain: carbon is transferred up the food chain as animals consume plants and other animals. Eventually, upon death, the carbon is returned to soil and sediments.

Volcanism: volcanoes can cycle carbon back to the atmosphere. As rock melts to form magma, carbonate (CO3

-2) is turned into CO2

Chemical Weathering: Carbon dioxide from air dissolves in water to form carbonic acid. Carbonic acid weathers rock surfaces.

Combustion: fires or burning of fossil fuels returns carbon to the atmosphere

Atmospheric CO2

Carbon in Trees, Plants,

Algae

CO2

Dissolved in Ocean

Carbon in Animals

Carbonate (CaCO3)

in shells, etcCarbon in Sediment

Carbon in Fossil Fuels

Carbon in Soil

Carbonate (CaCO3)

Rock (limestone)

uptake

dissolving

Uplift & Mt. Building exposes

new rock

Atmospheric CO2

Carbon in Trees, Plants,

Algae

CO2

Dissolved in Ocean

Carbon in Animals

Carbonate (CaCO3)

in shells, etc

Carbon in Sediment

Carbon in Fossil Fuels

Carbon in Soil

Carbonate (CaCO3)

Rock (limestone)

Resp

irationResp

iration

Bact

eria

l Res

pira

tion

photosynthesis

Food Chain

fossilization pressure

uptakeChem

ical

weathering

burn

ing

fires dissolving

Uplift/Mt. Buidling exposes

new rock

volcanoes

•Volcanism ADDS CO2 to the atmosphere.•Mt. Building & the chemical weathering of new rock REMOVES CO2 from the atmosphere.

Geosphere Atmosphere

Geosphere Atmosphere

Atmosphere Hydrosphere Geosphere

CO2 gas Dissolved CO2 used by plankton which die

Plankton settle to bottom of ocean floor. Sediment

layers become rock.

Biosphere Geosphere

•Plankton use dissoved CO2 in water for photosynthesis.•Plankton die (or are consumed/decomposed by other organisms, which die).•Dead plankton bring carbon to the ocean floor where it will become ROCK.

Warming or Cooling?

Increased volcanism? Increase in mountain building & weathering? Deforestation? Increased photosynthesis by marine plankton? Increased frequency of forest fires? Increased combustion of fossil fuels?Decreased volcanic activityIncreased use of solar energy or wind power.

Ways to Reduce atmospheric CO2?

Reduced volcanism? Mountain building & increased weathering? Increased photosynthesis? Increased absorption of CO2 by ocean? Changing land use (forests, urban areas, etc.)?Increase the amount or rate that carbon becomes rock?Decrease combustion of fossil fuels?

Results of increased levels of CO2

Increased atmospheric and sea surface temperature.Ice caps/glaciers melt.Flooding of coastal areas due to sea level rise.Droughts in some locations/increased productivity in others.Decrease in salinity of ocean water changes ocean circulation (& climate patterns).Ocean acidification (dissolved CO2 forms an acid in water) reef organisms dissolveIncrease in insect borne (tropical) diseases (Malaria, etc.)Economic loses.

Results of Global Warming•Flooding due to rise in sea level.•Change in “who” grows food.•Coral reefs die b/c acidification.