Climate Change Midterm

How old is the universe?

13\.7 Billion years-when the big bang happened

When did the formation of sun & earth occur?

4\.57 billion years ago

Earth’s core

\-When the Earth was left it was a mixture of iron and silicates which was heated and melted by radioactive decay of U-238, U-235, and other radioactive species

\-Disassociation allowed the dense iron to sink to the center of the earth, forming an early core abt 15-30 million years after it formed

How was the moon formed?

Collision of early earth about 4.5 billion years ago

Early Atmosphere

* As the earth cooled so did the atmosphere and the water condensed on the surface - caused clouds and weather with an early atmosphere of ammonia, methane, water vapor, carbon dioxide, and nitrogen mostly formed by volcanoes (no oxygen until 2 billion years ago- formed through photosynthesis)


* Earth cooled and world oceans formed (4.1-3.6 Gyr ago)- this is time of the earliest documented life 
* Mass extinction - 65 million years ago

Composition of Earth’s atmosphere

78% N2

21% O2

0\.8% A

0\.042% CO2

0\.1-4% H20

Earth’s time line

First life forms (3.8 billion years ago)→ Complex Life(500-600 years ago): known as Cambrian explosion→ Major Ice Ages(700-550 millions years ago, 250 million years ago→ Dinosaurs (65 million years ago)→ Present ice age (40 million years ago)→ Homo sapiens (1 million years ago)

Sun’s luminosity

\-Getting larger

\-In 1-2 billion years Earth may be too hot for most life

\-In 5 billion years the Sun expands swallowing Earth.

Climate Forcers

Causers of climate change:

Astronomical(earth orbital changes and changes from the sun)

Tectonic: Continental drift

\-changes in ocean currents, mountain building, and volcanoes/outgassing

Atmospheric/Surface changes:

\-Albedo

\-Greenhouse gases

Anthropogenic Forcing

\-Greenhouse effect

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Positive Feedbacks

Reinforces the initial forcing

Example: Cold→more snow/ice→higher albedo→colder and more snow

Negative Feedbacks

Counters the initial climate forcers, many feedback loops are associated with changes in albedo or greenhouse gases.

Example: Warmer→increase in evaporation→increased clouds→higher albedo→colder

Albedo

% of incoming solar that is reflected.

A=1.0: Fully Reflected (white)

A=0.0: Fully Absorbed (black)

Albedo changes play a major feedback role in climate change

More clouds=more reflected

What is the average albedo of the Earth? Venus? Moon?

Earth: .3

Venus: .77

Moon: .08

Relation of angle of the sun relative to the horizon to climate

Near Equator: The sun is nearly overhead (hot)

Mid-Latitudes (at lat.= 40 degrees): Altitude from 26.5 degree winter to 73.5 degree summer

Artic: the sun is near horizon (cold)

Early Climatology

\-Clim=Klim=Slope/Inclination in Greek

\-First climatology book written by Hippocrates in -400 BC

\- “Meteorologica” by Aristotle was first meteorology treatise

\- Gailileo: Thermometer in 1593

\- Torricelli: Barometer in 1643

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The Winter of 1779-1780

Labelled “The harshest winter in American history”

Temp. was only above freezing once in Jan. of 1780 in Philly

General Washington’s troops were trapped for over a week in Morristown NJ

Solar Activity

Until 1990’s scientists thought that increasing solar activity was responsible for global warming.

Greenhouse Effect

* Sunlight gets in but outgoing heat (infrared) radiation is partially trapped, happens naturally but is enhanced by humans
* Since 1850s Greenhouse gases have been rapidly increasing causing the global temperature to rise nearly 1.8F

Greenhouse Gases

65%-Carbon Dioxides (fossil fuel and industrial processes)

11%-Carbon Dioxide (forestry and other land use)

16%-Methane

6%-Nitrous Oxide

2%-F-gases

Winners and Losers from the effects of climate change

Winners:

\-Warmer sub-artic→higher crop yields(ex. Canada, Northern US states, Russia, and Northern Europe)

Losers:

\-Warmer subtropics: IF DRIER→ less rain (ex. SW USA, S. California, South mid-west, Sub-Sahara Africa, Middle-East, and Australia)

\-Coastal Areas: Rising sea levels (ex. Florida, New Orleans, and Bangladesh

\-Warmer oceans could led to more and stronger tropical cyclones

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What causes the earth to have seasons?

\-seasons are the result of the tilt of the earths axis

\-earths axis is tilted 23.5 degrees

\-the number of daylight hours is greater for the hemisphere that is tilted toward the sun

\-summer is warmer than winter bc the suns rays hit earth at a more direct angle during summer

Cross Quarter Days (Groundhogs Day)

\-Occur mid-time between seasons, in the case of groundhogs’s day between the winter solstice(Dec. 21) and vernal equinox (Mar. 21).

\-Halloween is another example of a cross quarter day

Solstices

\-Occur twice a year, when the tilt of the earth’s axis is oriented at its extremes (tilted the farthest or closest)

\-Winter solstice is shortest day of the year, summer is the longest

Importance of Water/Oceans

\-The oceans cover 70% of the earth, hold 97% of the earth’s water, and hold over 1000 times the heat of the atmosphere.

\-Oceans absorb and release heat(affects sea lvl), transports heat over large distances(affects storm activity, and absorb and release CO2

\-*8-9 inch rise since 1850. 20-30-inches by 2100.*

Sea level rises come from:

\-Ocean thermal expansion

\-Melting of mountain glaciers

\-melting of Greenland(happening at an alarming rate) and Antarctic ice

A double whammy: positive feedbacks of sea ice

Sea ice as a reflector: bright ice is highly reflective and dark ocean is highly absorptive

Sea ice as in insulator: more ice=less heat while less ice=more heat

Both processes amplify thermally driven changes

\*Studies of past climates from ice cores

\-Earths ice sheets and glaciers preserve long, high resolution histories(such as ice caps in Peru)

\-they provide multiple lines of climatic and environmental evidence

\-ideal for revealing rapid climate changes

\-can explain: temperature, atmospheric chemistry, net accumulation, dustiness of atmosphere, vegetation changes, volcanic history, anthropogenic emissions, entrapped microorganisms.

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Ice shelves and the buttressing effect

Collapsing ice shelves dont directly raise sea level but..

\-increase in flow speed up to 8-fold

\-thinning by as much as 40 m in six months

\-glaciers that fed remaining parts of the ice shelf did not accelerate

Winners and losers of Ice-Free artic ocean

Ice-free artic ocean in summer may occur as early as 2040

Winners=Boats and Cruises can now access the waterway

Losers=Polar bears:(

Glaciers

\-the existence of year-round ice on a landscape

\-two types: continental (greenland) and alpine (Swiss alps)

\-Form whenever snowfall exceeds snowmelt year after year. The snow accumulates incrementally, pressure increases, and it is changed into neve and then ice by this pressure

\-Can cause erosion

Louis Agassiz

Swiss scientist who among the first to report evidence of prior ice ages(published in 1840)

Four Glacial Periods over the last million years

Most Recent: Wisconsin Glacial (110kyr-18 kyr) 1kyr=1,000 yrs

Illonian

Kansan Glacial

Nebraskan Glacial

\-named after the places where the moraines were uncovered

Paleoclimatology

The study of climate prior to the period of instrumental measurements

Dendrochronology

Tree rings-counting rings inwards gives date (1 ring=1 year)

Width of ring depends on growing weather conditions: precipitation, sunshine, temperature.

Ice Cores

\-limited to polar latitudes and mountain glaciers

\-darker and lighter layers are more or less blown in seasonally

\-measurements provide information on temp., snowfall, and atmospheric changes

Varved lake sediments

Varves=seasonal layers of sediment/dead organics

\-occur in deeper part of lakes that dont support bottom-dwelling organisms

\-layers usually result from seasonal alternation between light, mineral-rich debris and dark organic rich material brought in by run off

Other paleoclimate options

Corals, Pollen, Marine sediments, Fossils and Landforms

Conversions among temperature scales

K= C + 273

C= 5/9(F-32)

F= 9/5C + 32

Types of carbon sample

Charcoal

Wood

Seeds

Wall Painting and Rock Art

Hair

Pollen

Paper

Fish remains

Insect remains

Resins and glues

Antlers and horns

Carbon-14 dating

\-Carbon-14 is taken in by eating plants and created by cosmic rays hitting the upper atmosphere

\-Carbon 14 is radioactive and can be used to date things that were at one point living

\-Famous examples: Otzi the iceman and the Shroud of Turin

Carbon 14 dating example-*A bone is found to contain about 25% C-14/C-12 relative to living samples.  What is age of this sample?*

*50% = 1-Half-Life= 5730; while 25% = 2 Half-lifes = 2x 5730-yrs. =11,460yrs. Answer= 11,460 yr.*

Globergina Pachyderma

Coil left=cooler than 45 degrees

Coil right=warmer than 45 degrees

Japanese Cherry Blossoms

* Past dates of celebrations indicated when the cherry blossoms were in full flower and provide an estimate of the temperature in that year. ​
* Data available from records in Kyoto, Japan from the 11th century to the present time. ​

Bird Migrations

* Migrations of Swallows​
* Swallows fly south in the autumn going as far as South Africa and usually don’t return to Britain until late March​
* Swallow breeding in Europe-> they arrive earlier after their African migration, coinciding with earlier springs (have arrived as early as February 16th)​