southern hemisphere Flashcards
what is Southern Annular Mode (SAM)?
a pressure gradient
what does +ve SAM show?
strong lows over Antarctica, stronger highs further north
what does upwelling in the S ocean cause?
increases atmospheric CO2
what isotopes are used in peatlands?
- stable
- 18O is a proxy for ppt source, atmospheric circulation
- 13O is a proxy for moisture balance, ppt
where is a good location to reconstruct a S hemisphere climate?
NZ because it is located at the boundary of low and high pressure zone and it is subject to both tropical and polar influences
why is Patagonia a good location to reconstruct change through time?
it is the core path of S westerlies
what is a key climate proxy?
Testate amoeba
why is Testate amoeba a good climate proxy?
- single celled to create a shell or test
- usually abundant in peat bogs
- around 60 common taxa
- microscopic
recent change in the Antarctic peninsula
- 3°C warming since 1950s
- ice shelf collapse
- glacier retreat
what can be analysed to provide long-term context in the Antarctic?
moss banks as they can form up to 3m deep and 5000 y/o
when did ice coring begin?
1950s
what is the oldest ice core?
Dome
800,000 years
3.2 km long
what is the atmospheric composition of ice cores?
CH4 and CO2
how old are the archaeology remains in S America?
14,500-14,250 y/o along west coast
what is peopling of the pacific?
- estimated first Australians arrived between 40,000-80,000 y/a
