past climate data Flashcards
how do we have records of past climate
proxy data
proxy data is data that is correlated to our desired data, but isn’t actually it
for climate these are historical data, tree rings, ice cores, lake sediments, fossil pollen, coral, ocean sediments, continental coastal sediments (in order of how far back they go)
what are isotopes
each element is decided by their number of protons, however they can have different number of neutrons. isotopic composition tells us details about climate, specifically oxygen and carbon isotopes
what can oxygen isotopes tell us about climate
O-16 is an oxygen isotope with an atomic mass of 16 amu. O-18 is an oxygen isotope with an atomic mass of 18 amu
both are found in water but O-16 is easier to evaporate
in nonglacial periods, O-16 evaporates and returns back to the water in runoff
in glacial periods, O-16 evaporates but stays frozen and does not return to the water, leading to isotopically heavier water
what do tree rings tell us about climate
patterns in tree ring width, density, and isotopic composition can tell us about climate
what do ice cores tell us about climate
ice cores are columns of ice taken in mountains or ice caps. the lower it goes the older it is unless there is some form of subduction
contain dust, air bubbles, and oxygen isotopes
what do fossil pollen tell us about climate
fossil pollen have distinct shapes based on species. can be found in sediment
use to determine plant type and infer climate
what do sediments tell us about climate
marine animals create skeletons and shells with calcium carbonate which contain oxygen
these shells and skeletons decay into sediments and therefore contain isotopic information about oxygen
what do corals tell us about climate
corals build their skeletons from calcium carbonate (CaCO3), which contain oxygen. scientists can use oxygen isotopes and trace metals to determine climate
what does historical data tell us about climate
historical data is historical recordings of data that is related to climate, e.g. farmers logs, travel diaries, newspaper accounts can all tell us things about climate
what does vostok ice core data tell us
vostok ice core data gives us an image of CO2 levels over time for the past 800000 years
what is the keeling curve
the keeling curve is CO2 data collected at mauna loa in hawaii
it shows the natural change in CO2 with seasons
in winter and fall, leaves shed and get decomposed, releasing CO2 and reducing photosynthesis. this aligns with northern hemisphere as there is more land with trees in the mid latitudes there
usually this oscillation is balanced but increased over time by humans causing upward trend
what does law dome ice core data
law dome ice core data gives us a record of CO2 levels from around 1000 ce to the late 1970s
what was the great oxidation event / oxygen catastrophe / oxygen holocaust (?????)
the great oxidation was an event around 2.3 billion years ago when the first photosynthetic organisms evolved, taking out carbon dioxide and adding oxygen at an extremely fast rate
