Long/short term causes of climate change Flashcards
how did the continental drift cause climate change
what did the collision cause?
North and south america tectonic plates collided which re-routed ocean currents so warmer carribean waters were forced northwest
»»creating the Gulf stream
how long ago was the continental drift
3 million years ago
does continental drift cause glacials or interglacials
glacial period as there is more evaporation so moist air goes to polar regions making the planet colder
what are glacials
cold , ice-house periods within the pleistocene
what are interglacials
warmer periods similar to present ie greenhouse conditions
what is the eccentricty of the orbit of earth
how long are the cycles and
what is the position of the furthest point earth can get from the sun
the changing of the earths orbit from circular to elliptical.
-the earth recieves less solar radiation in the elliptical orbit when the earth is farthest from the sun
these milankavich cycles last over 100,000 years
position is called the aphelion
how much does the tilt of the earths axis change
how long are these cycles
-21.5 degrees and 24.5 degrees
over 41,000 cycles
results in changes of severity of the seasons
does the change in eccentricty of the earths orbit cause glacials or interglacials?
glacial
less solar radiation recieved from sun with distance
does the axil tilt cause glacials or interglacials
glacial if tilted away
interglacial if tilt towards sun more
what is the wobble theory of climate change
how long do these cycles last
the earth wobbles as it spins on its axis
this means that the season the earth is closest to the sun (the perihelion) varies
»>atm the northern hemisphere winter is in a perihelion but in milder conditions
results in 21,000 year cycles and changes the severity of the seasons
does the ‘wobble’ of the earths axis cause glacials or interglacials
-interglacial as it gets closer to the sun
but glacial as dist. increases which we are at the moment as it spins away from sun
what are sunspots
dark areas of the sun caused by intense magnetic activity in the suns interior
an increase in the number of sunspots means that the sun is more active and gives off more energy
how often do sunspots last/ cycles
11 years or so
do sunspots cause glacials or interglacials
interglacials as more heat energy given off
how can volcanic activity be a cause of climate change
large eruptions of gas can eject large volumes of ash, sulfur dioxide, water vapour and carbon dioxide back into the atmosphere (volcanic aerosols)
> > > these get distributed by winds. the aerosols block the suns radiation, cooling the earth
does volcanic activity cause glacials or interglacials
glacials as blocks sun
however they do contribute to global warming too
how long can effects of volcanic activity last
ash tends to settle after a few months but sulfur dioxide can remain in atmosphere for 3 years which can reflect radiation back into space
name some long term causes of climate change
> continental drift
eccentricity of the orbit
axil tilt
wobble of axis
name some short term causes of climate change
> variations in solar output
>volcanic causes
explain the role of milankavich cycles in causing variations in relative ice volume
EXAM QUESTION
> gravitational pull between two gas planets saturn and jupiter causes the orbit to vary from more circular to more elliptical. This causes changes in the earths obliquity (rotation of earth on axis) as the greater the tilt the more extreme earths seasons are. Tilting away from the sun will cause more ice house conditions in glacial periods as well as the orbit of the earth being of a further distance from the sun so less solar radiation is obtained in winter (reference figure when these have been)
> causes lower ice volumes when the eccentricity of the earths orbit becomes more circular. This means the earth recieves higher amounts of solar radiation stimulating greenhouse conditions. Summers will eb around 4 days longer in these conditions which also means winters are shorter so there is less ice. (reference times there was less ice)
how long can milankavich cycles last
between 23,000 years to 100,000
