Palaeoclimatology tools archive Flashcards
Climate change - holocene
Much smaller changes than magnitudes seen on other scales
2,000 yrs = influence of warming
Major ice sheet melt
Methane leaking in California
77,000 metric tons of methane in atmosphere. 25x more effective than CO2 - equivalent of adding 70 million cars over 20 years. 80x more powerful
Doesn’t stay in the atmosphere as long as CO2
Concentrations will stabilise but ice will continue to melt
Palaeoclimate archives
Natural place of collection, especially of information
High resolution
99% are sedimentary archives
Sedimentary archives
Best found in undisturbed aquatic environments
Good factors for sedimentary records
- Continuous deposition over
time - Preservation of fossils and
chemicals from the time of
deposition - High sedimentation rates
Ocean sediment
Ocean sediment drilling = 1874 - challengers expedition led to oceanography. Expense equivalent to expedition to the moon.
Loess
Accumulated sediments derived from wind blown silt e.g China
Picked up by strong winds and deposited in arid conditions. Produce 3Mya of records -several 100m of deposits over time
Kettle lakes
Provides annual records from seasons to seasons
Ice cores
Contains a variety of Palaeoclimate info: - temperature - ice volume - precipitation - atmospheric chemistry - atmospheric gas Ect
Corals
Similar to trees- seasonal info obtained by bands
Speleothems
Dated using uranium-thorium. Ring thickness and O-isotope determine pass climates
Found in wet environments
Tree rings
Confined to forestry areas
Variation in the closely separated rings of a bristlecone pine.
Comes respond to annual changes in rainfall and temperature
Radio metric dating
Measuring naturally occurring products of radioactive decay in an archive e.g. sediment basalt
c^14 readily oxides gets fixed into the atmosphere. Dates organic material
Other forms of dating
Annual layer counting - ice cores, tree rings
Volcanic events - tephra
Astronomical tuning - orbits
