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Climate and Climate Change Records Climate and Climate Change Records

Climate and Climate Change Records - PowerPoint Presentation

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Climate and Climate Change Records - PPT Presentation

Definitions Weather State of the atmosphere at a particular point in time Look outside Climate The accumulation of weather atmospheric state over a longer time period Look outside for a really long time and do statistics ID: 260625

ice climate cores years climate ice years cores record precipitation temperature tree energy www oxygen http growth ocean rings cover water classification

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Slide1

Climate and Climate Change RecordsSlide2

Definitions

Weather:

State of the atmosphere at a particular point in time.

Look outside.

Climate:

The accumulation of “weather” (atmospheric state) over a longer time period.

Look outside for a really long time and do statistics.

A combination of temperature and precipitation.

“Climate is what you expect … Weather is what you get.”Slide3

Climate VS Weather

Longer-Term (Years and longer)

B

road

composite of

average condition of a region (e.g., temp, rainfall, etc) snowfall, ice cover, winds)Mean state of a specific regionAn envelope of values

Shorter-term (minutes to

days).

State of

atmosphere (

temp, press, winds, sky

cover, rainfall

,

etc

).

Specific

location for specific

time.

A

single number Slide4

How do we classify current climate?Slide5

Climate Classification:

A consistent

climate classification

scheme to understand numerous climate

regions.

Earliest known scheme was used by the ancient Greeks about 2200 years ago.Morphed into the broad scheme to the right.

3 Major regions: Frigid, Temperate, Torrid.Slide6

Köppen climate classification

system

Based on a database of annual and monthly average temperature and precipitation

Four of five major groups classified by temperature

Fifth group classified by precipitation

Subdivided the five groups further based on temperature and precipitation relationshipsKöppen letter code systemThree letters; first describes group, second describes precipitation, third describes temperature

Used as a springboard for modified

Köppen

SystemSlide7

Modified

Köppen

Classification System

Designated by a descriptive name and a series of letters

First letter = major climate group

Second letter = precipitation patternsThird letter (if there) = temperature patternsSlide8
Slide9

How do we determine past climate?Slide10

Proxy Records

Sources

Tree Rings

Ice cores

Documentary data

ThermometersSlide11

Historical Record

Instrumental record ( ~150 years)

Written accounts

Art

PicturesSlide12
Slide13

Grinnell Glacier at Glacier National Park

1910

1997

Rate of Glacial melt in last 20 years = 4x historical rateSlide14

Portage Glacier: AlaskaSlide15

15

Snow Cover Reduced

Number of days per year with snow cover has reduced since early 1970’s

Water storage in snow pack is reduced

More precipitation is rainSlide16

Frozen River ThamesSlide17

Paleoclimatology

Definition: The study of past climates.

Why? To help understand current climates and future climates.

What about thermometers? They only go back a few hundred years.

So we use proxies, or substitutes, to reconstruct past conditions. Slide18

Dendrochronology

Tree rings!

Most trees increase trunk diameter by adding one concentric tree ring for each year of growth.

Count the rings to determine how old the tree is.

During more favorable years (mild temps. and/or more

precip.) tree rings are usually wider. Compare/correlating dead trees to living trees helps determine catastrophic events.Period of record: 10-100s of years. In rare cases 1000s of years. Slide19

Cross datingSlide20
Slide21

Southwestern US

Water is most precious, least abundant resource…Slide22
Slide23

Drought and the Anasazi

Populations expanded dramatically during wet years.

Sustainability of population = water

Population collapses related to

megadroughts

Number of habitation sitesSlide24

Pros and Cons

Dendrochronology

Pros

Well understood.

Direct correlation between growth and moisture.

Indirect correlations between growth and cloud cover, temperature.Location of tree is usually known.Local climate

Cons

Only record the growing season.

Tropical trees may not have obvious annual growth rings

No clear indication of when tree died, therefor harder to determine when it lived.

Other influences of growth other than climate.

Local ClimateSlide25

Ocean/lake sediments

Lake and ocean sediment cores.

Sedimentation rate.

Varves

: couplets of light (more energy) and dark bands (less energy) produced in some lakes. Thicker = more erosion.

Trapped organic matter (radio carbon dating)Seeds, leaves, charcoal. Little critters (Foraminifera or forams and diatoms) that die and sink to the bottom of the ocean and we measure their

18

O to

16

O

ratio.

Period of Record: 10s – 10,000s of yearsSlide26

Oxygen Isotopes

Oxygen Isotopes (atoms of the same element with different atomic weights because they have different numbers of neutrons) Oxygen 16 and Oxygen 18.

Both

16

O and

18O are found in common molecules such as water (H2O) and calcium carbonate (CaCO3

).

The ratio of

18

O to

16

O in the water changes based on the climate.

16

O

is lighter so it evaporates more easily, leaving the heavier

18

O in the ocean.Slide27
Slide28

Oxygen Isotope Cycle

More

18

O In ice because more heat energy

More

16

O In ice because less heat energySlide29

Ocean CoresSlide30

Lake coresSlide31

VarvesSlide32

Pros and Cons

Ocean/Lake Sediments

Pros

Relatively undisturbed by humans

F

airly consistent rates, especially in the oceanLong record. Local climate

Cons

Influences other than climate (biology and weather.)

Bioturbation

(worms borrowing!)

Can be expensive

Local climateSlide33

Ice Cores

Drilling ice cores in glaciers and ice sheets all over the world.

Dating from worldwide events like atom bombs.

The more

18

O in the ice the warmer it was because more heat energy was available to evaporate the heavier oxygen isotope. Wind blown dust can hint towards global air circulation patternsTrapped air bubbles enable scientists to measure concentrations of CO2

and other gasses that were present in the environment.

Historically, the more greenhouse gasses there were the atmosphere the less ice on earth.

Period of record: 10s to almost 1,000,000 yearsSlide34

Ice Cores

Age of ice (layers)

Isotope ratio (for temps)

Air bubbles (

atm

gas content)Dust content (wind)Salt content (wind)Sulphuric acid content (volcanism)Slide35

Ice CoresSlide36
Slide37

C : Tipping Point for Climate

Surface energy balance

Feedback processes rest on crossing the 0

˚

C thresholdAbove 0˚C , melt ensues, albedo change  positive feedback

Water storage

Below 0

˚

C , H2O can be stored, not utilized by plants, evaporate away etc.

Above 0

˚

C , H2O runs off, leads to plant growth, evaporation, etc.Slide38

Pros and Cons

Ice Cores

Pros

Actual bubbl

e

of past atmosphereMore global than other proxy records. Chemistry is pretty well understoodTemperature proxy and atmosphere bubble in same location. Easy to compare across different locations.

Cons

Can be hard to date.

Expensive and difficult to obtain and store.

Glaciers are melting all over the world.

Hard to find ideal locations

Cold and hard to get to locations.Slide39

Other

Coral reefs

Relic soils

Pollen

Cave deposits

Shell fishSlide40

Sources

Dr. Crystal

Kolden

Dr. John

Abatzoglou

(http://webpages.uidaho.edu/jabatzoglou/)More information:www.westernclimateinitiative.org/

Icenetmatrix.com

http://www.atmos.washington.edu/mm5rt

/

http://www.wrcc.dri.edu/research/jtwrcc/idaho-mon

/

http://www.wrcc.dri.edu/monitor/WWDT

/

http://www.cefa.dri.edu/Westmap

/

http://www.cpc.ncep.noaa.gov/products/predictions/90day

/