Geography 1001: Climate & Vegetation

Geography 1001:Climate & Vegetation

Instructor: Andrés HolzTeaching Assistant:

Eungul Lee

• Announcements– Yesterday’s lecture is online– First reading for guest lecture is

also online

– FIELD TRIP TO ISABELLE LAKE, INDIAN PEAKS

• Objective

– MEET AT THE REC CENTER TURN AROUND AT 9 AM. WE WILL DEPART PROMPTLY.

Agenda for Lecture 13: Thursday June 29


• Gear Requirements: – hiking boots (the trail is

muddy in places and there is still some snow on the ground)

– raingear– sun block & chap stick– Sunglasses hat, gloves– warm layers (fleece)– notebook and pen to take

notes

FIELD TRIP TO ISABELLE LAKE, INDIAN PEAKS

Access and Trail Description:• Lake Isabelle is one of the more

beautiful trails in the Front Range.

• The lake lies near timberline in a dramatic valley, offering views of high peaks such as Shoshone, Apache and Navajo Peaks

• Distance: 2.0 miles one-wayLake elevation: 10,868 feetTrailhead elevation: 10,480 feetNet elevation gain: 388 feet

• Today’s lecture:– Historical development of

the ecosphere• Biological processes that

changed the atmosphere– Anaerobic respiration– Photosynthesis– Aerobic respiration

• Atmospheric changes– Increase O & N– Stabilization of CO2– O3 layer


• Today’s lecture:– A bit of ourselves

• DNA• Earth colonization

– Changes on earth• Milanković


Be aware of..

• How the Ecosphere have developed over time: Timeline and processes occurring

• How Climate & Life on earth have co-evolved

• The fact that regardless of co-evolution, we still have large scale climate changes Milanković Theory

A bit of history here…

500 million years ago..






1 million year ago..

Less than a million year ago..•So far, we know that the Earth has experienced at least 8 ice ages•Last one?

Today•If we think of the earth life being a calendar year (i.e. from Jan 1 to Dec 31), when do you think we appeared?

But how have the conditions for life changed over these 4 billion years?

The solar system form 4.6 billion years ago.

4 billion years ago, the atmosphere was made of from volcanic emissions

• TIME– 4 billion yrs ago

• PROCESS– Water vapor– Ammonia (NH3)– Methane (CH4)– Hydrogen sulfide (H2S)

– Hydrogen gas (H2)– Carbon monoxide

(CO)– **Very little O2 & N2

All water was held in the atmosphere as vapor because of high temperatures (water vapor greenhouse effect).

• TIME– 4 billion yrs ago

– 3.1-3.5 billion yrs ago

• PROCESS– H2O, CO2, (N) dominant.

– CO2, H2O, N2 dominant O2 begins to accumulate.

– Cooling of the atmosphere causes precipitation and the development of the oceans.

– Break of H2O by ultraviolet rays H2O O2 + H

– Water vapor clouds common in the lower atmosphere.

– First single cell algae & bacteria

• TIME– 3.1-3.5 billion yrs ago

• PROCESS– Anaerobic respiration

• Single cells algae were able to – produce Energy without O2

– Take C-H20 (simple organic molecules food) & break down into CO2 + alcohols

energy

For ~800 millions of years, CO2 was released (as by-products of respiration) & built up in the atmosphere and oceans

There was enough CO2 in the atmosphere to sustain life….

• TIME

– 2.3 billion yrs ago….

• PROCESS

– Photosynthesis Single-cells (blue-green algae have chlorophyll)

CO2 + H2O CH2O + O2 built up

–Initially, the released O2 was lethal to the living organisms

energy

sunlight

food

• TIME


• PROCESS

– Ozone (O3) layer is being built in the stratosphere

Filters out the UV radiation make life possible on land development of O2 tolerant organisms

Aerobic life on the land took longer to start because it could only occurred after the ozone layer was formed

• TIME


• PROCESS

– Aerobic respiration

CH2O + O2 CO2 + H2O

energy

• TIME

– 600 mill yrs ago….

• PROCESS

– Life is widespread in the oceans• Single cells• Early fishes• Large algae

• TIME


• PROCESS

– Life is widespread on lands

• Earliest plants• Invertebrates• Vertebrates

• TIME


• PROCESS

– Development of tropical rainforest

• fossil fuel today’s oil

• TIME


• PROCESS

– Colonization of larger vertebrates

A bit of ourselves..

Date of Separation according to Mitochondrial DNA

Early Human Phylogeny

southern Africa

eastern Africa

eastern Africa

Asia

Africa Asia

Europe

Africa?

Europe & W Asia

Expansion of Human Habitat(old theory)

At 18,000 years ago, the Earth looked like this map from Earth and Life Through Time

Food Chain of Land Animals

World Population Trend from 10,000 B.C. to 200 A.D.

First civilization collapse..

• Eastern Island• Mayas Empire

UN, World Population Prospects:1992

Why has climate change?

• Meteorite impacts (very infrequent & random)

• Hugh Volcanic eruptions (more frequent, but still random)

• Enough evidence of glacial and interglacial periods for the last 2-3 mill yrs– Hypotheses, Theories, & Laws…the same?

Milanković cycles (Theory)

Performed detailed calculations concerning the periodicity of the earth’s orbital parameters

• Precession• Axial tilt• Eccentricity

Eccentricity

• During periods of high eccentricity higher differences between max & min distance from sun to earth more potential for extreme (cold & warm) climate

Orbit eccentricity

Tilt angle (or obliquity)

Tilt angle (or obliquity)

• The greater the angle of the tilt the greater the potential for extremes in seasonal climate (especially for polar regions)

Precession (or wobble)

Precession (or wobble)

• It’s a ‘slowing down’ of the rotation of the earth tilt of the earth point to various directions (like the axe of a spinning top)

Evidence of glaciations?

• Swiss hunter in the Alps (1815) associated scratch marks on rocks with the P of ice

Yosemite

How do scientists track glaciation?

• Stable-isotopes from zooplankton (tiny shells of calcite)

• Come from seawater• Once dead built up

on the ocean bottom as layers (~2.5 cm or 1” = 1,000 yrs)

Comparison between O2 isotope record & Milanković theory

How do scientists track glaciation?

Lighter Oxigen (16O) evaporates with water vapor (due to insolation) andthen precipitates as either:

a) rain and returns with rivers and groundwater to oceans seawater remains the ~same (interglacial) [e.g. now]

Or b) snow and accumulates and does NOT return to oceans seawaterchange rate between 16O & 18O

Documents

Geography 1001: Climate & Vegetation