Session 20 ( Paleoclimate) Flashcards
(39 cards)
Paleoclimate
Measuring the earths climate prior to human existence
Climate Proxies
indirect forms of evidence to infer climate.
Commonly used proxies
- Sediments (fossils)
- Ice cores
- Tree rings
- lake varves
- coral bed rings
- Speleothems
Dendrochronology (tree rings) (1000 years)
Wider rings = more growth. Vise Versa.
Anoxic Lakes ( Varves) (Century- Millenium)
Runoff sediment composition.
Light = Mineral rich
Dark = Organic rich
Speleothens (cave dripstones) (seasonal to millennium)
formed as a part of the meteoric water cycle
Corals (100+ years)
Lighter shade show fast growth (summer) dark layers show slow growth (winter)
Ice Cores (Poles) 800,000 years
Lighter layers in summer vs darker in winter
When do Ice ages happen?
when CO2 concentrations are low
Slow Carbon Cycle
Plates shift forcing CO2 from plankton to go under volcanos making them erupt and add more CO2 back into the atmosphere
What can cause the sediments to have different colors?
Oceans became acidic from the PETM causing the color change
Paleocene–Eocene Thermal Maximum (PETM)
a period of rapid global warming caused by a massive injection of carbon into the ocean and atmosphere
What did PETM Cause
Caused rainforest to flourish but marine life struggled with intense ocean acidification causing loss in calcium.
Methane Hydrates
Crystal like cages that enclose a methane molecules thriving at low temperature and high pressure.
How did PETM affect Methane release
The intense heating of the ocean released methane into the atmosphere
Milankovitch Cylces
Cycles of the sun and earth that cause warming and cooling in intervals over time
Precision of Equinoxes
When the northern hemesphere is tilted away or towards the sun (19 and 23 KY)
Aphelion
When the earth is furthest from the sun
Perihelion
When the earth is closest to the sun
Obliquity Cycle
Changes in tilt. More tilt will create more severe seasons and less tilt will create moderate seasons.
What is the Atlantic Meridional Overturning Circulation (AMOC)
A system of ocean currents that form a vertical loop that extends the whole length of the atlantic moving warm water to the poles and cold water to the equator
Why is AMOC reaching its tipping point
With ocean water becoming warmer, the AMOC weakens creating extreme weather
How the AMOC effects europe
Causes very severe cold temperatures in the north and very hot in the south.
What happens to the Antarctic ice sheet and southern polar jet stream because of AMOC
Causes warm water to stop going north and accumulates in the south causing western ice sheets to melt. Intense jet streams are caused due to the increase in temperture change between the poles and equator.
