how long is teh quatershsary and when is it
- last 2.5 million years
- what were in now
- many changes have happene dwithin this period
list teh ways we can measure the wasys the cliamte has changed
- marine sediment
- ice cores
- fossils
- dendrochronology
- lake sediment
- historical records
what is it called when you examine tree rings to examine past climates
dendrochronography
what are teh tiny shells found in sea floor sediment
foraminifera
how can we tell past global tempertures from sea floor sediment
- layers of small shells of foraminfera. their chemical composition tells us about teh temperture of the coeans witch tehy formed
how can ice cores tell us about past cliamtes
- layers cut out of ice sheet shave layers of bubbles
- the gass compossition of teh bubbles tells us about teh composition of teh atmosphere when tehy were trapped.
- the realaltive frequency of stable hydrogen and carbon isotopes tells us how walm or cold cold it was. the more unstable isotope the wamer it was
how can lake sediemnt in terms of pollen tell us about the pats climate
- pollen and beetles
- polen granuals in sediemnt saples can tell us about teh type of vegitation tahst was about and thus the paleoclimatic conditions
how can dendrochronography tell us about past climates
- tree ring forms each year
- thinker tree ring means there was a walmer and wetter cliamate.
- only goes back thousands of years
how can historical records tell us about past climates
- past drawing and painting for example
- there are painting of markets and the thames river in the 1800s so we knwo it was colder back then
how do fossils tell us about past consitions
- planst an animals of differnt sepcise require differnt climates to thrive
- eg coral reifs are highly sentive to temperture, water depth (sea levels) and sunlight
- if corral fossils are fround in certain regins we know taht that place was one a walm troppical enviroment
- some dinosours we also know only survied in subtropical climates
- however aniamls are adaptable
list the ways natural forces have driven cliamte change
- plate tectonics and volcanic activerty
- Milankovitch cycles
- solar outputs (sun spots )
- matural green house gasses
list teh three parts to a milankovitch cycle
- Obliquity
- exentricity
- prossesion
what two ways do plate tectonics effect the climate
- volcanic erruptions
- change to global currenst
on an essay on the most important physical factors envolved in cliamte what shoudl you use
- Milankovitch cycles
- plate tectonics
- natural green house gasses
explain milankovitch cycles
obliquity
1. the tilt of teh earths axis varries from 22-24 degrees over a period of around 41,000 years
2. seasonal variation decreses when at 22degrees
3. this has teh secondry effect that ice sheets dont melt as much in the summer and therefore there is an incresed albedo cooling the palnet
Eccentricity
* this is how close or far the earth orbits to teh sun
* this varries about evey 100,000 year witch woudl expain teh glacial and inter glacial periods we see along this time frame suh as the holocene intergalcial period we entered 11,700 years ago
* when the earth reaches its greatest exentricity ( furtherst away for longest and ist most elyiptical orbit) it will be colder and there will be more ice coverage and thus albedo triggering an (ice age).
procession
* 26,000 years
* due to the graverty of the moon and jupiter the earth may also wabble on its axix
* this works teh same way obliquity does in altering seasonal changes
wjay was teh glacial peiod before the holocene and when did it end
- The Pleistocene
- ended 11,700 year ago to teh inter glacial period of the holocene
are we in an ice house or hot house period
- we are in the quaternary period and within that teh holocene.
- despite the holoceen being n intergalcial there is still ice on the panet so we can still call th elonger 2,5 million years of teh Quaternary an ice house
- it has invoved a numbre of 100,000 long glacia and interglacial cycles
when th eeath is furthest from the sun with its exentricity what is thsi called vs closes
- aphelion - furthest
- perihelion - closest
without GHG how mcuh colder would the earth be
- the global averge tempertre would be -20 C’
- a perpetual ice house earth
what are the natrally occuring GHG
- water vapur
- CH4
- CO2
- nitrous oxides
- CFC’s
whats the opersite to an ice house earth
Hot house
expain how natural GHG walm the earth ( the natural GHE)
- incoming short wave radistion heats the earth
- some is refelcted by albedo of the earth surface back to space
- the earth reradiate terrestrial long wave radistion
- some if the infared long wave raditio is emmitted to space but most is absorbed and remitted by GHG walming the atmosphere and the earths surface
expain how solar outputs change to golbal clime
- 11 year cyles
- teh more sun spots/solar falirs the walmer the climate
- minimum activert is 0.1% so would have a minor effect on cliamet
- this is throught to be the cause of the mini ice age in europe at teh start of teh 1800s
expain how plate tectonics have made change to golbal climate
ocean current curculation
* the positions of land effect from movement of tecntonic afefcts global currenst.
* where walm water flows walm air does too so teh whoel cliamte is walmer
* the carabene plate making it so north america and south america touch means that walm equatorial currets are redirrected up north to western europe.
* this means areas liek the Uk are significalty walmer
* this is known as teh Gulf stream
**volcanic activert **
* tectonic platemeovemtn aslso cause volcanic activerty
* they put huge aount of sulpher dioxide and well as ash into the atmosphere
* ash may cause a cooloing effect in the short term ( this is also thought to be a possible reason for the mini ice age of the start of the 1800s )
* sulpherdioxide causes a coolign effect in the long term as it forms sulphate aerosols witch refelct solar radistion back to space
