GEL 1 Lecture Notes - Lecture 26: Methane Clathrate, Basalt, Watt
Glaciers are fed by precipitation .. water from ocean evaporates. easier to evaporate water w/
O16, because O18 is a little more massive
therefore snow will be rich in O16, depleted in O18.
O18 is left behind in water, so seawater sediment records show enrichment in O18 during times
of large concentrations of glacial ice on continents
Carbon 13 is stable
● way to track where CO2 is sourced from
● critters that use carbon to make shells get carbon from volcanoes: mid-ocean ridge
basalt
● carbon emitted in atmosphere is C12
○ fossil fuels from plants are incredibly depleted in C13
■ plants don't use C13 to photosynthesize because it requires more energy
to use
○ more C12, diluting C13
■ relative amount of C13 is going down because we are adding so much
C12
Paleocene-Eocene boundary (55mya)
● PETM Paleocene-Eocene Thermal Maximum
● increase in oceanic and atmospheric temperature
● 2500-4000 Gt released during the PETM
○ ~ 1Gt per year
○ modern anthropogenic release ~2000 Ft since 1790
■ current release: 9.5Gt per year
● how fast does it take to get back to normal?
○ At current fossil fuel burn rates, we will release 5000 Gt by 2400 (end date, run
out of fossil fuels)
■ most will dissolve into the ocean
● warm up surface waters and then deep ocean
■ concentration of CO2 ~ 1800 ppm
● note: PETM was 1800-2500, (but it started out at 1000)
○ Ocean pH maximum effects calculated to last at least 5k years
■ Ocean temp increase by 3-7 degrees C
○ Best recovery/equilibrium by 10k years
■ full re-equilibration does not happen within 100k year
○ note: these data only for fossil fuels
■ does not include release of methane hydrates!!!
● mass extinction
Methane hydrate
● sources of large volumes of methane
Document Summary
Glaciers are fed by precipitation water from ocean evaporates. easier to evaporate water w/ O16, because o18 is a little more massive therefore snow will be rich in o16, depleted in o18. O18 is left behind in water, so seawater sediment records show enrichment in o18 during times of large concentrations of glacial ice on continents. Way to track where co2 is sourced from. Critters that use carbon to make shells get carbon from volcanoes: mid-ocean ridge basalt. Fossil fuels from plants are incredibly depleted in c13. Plants don"t use c13 to photosynthesize because it requires more energy to use. Relative amount of c13 is going down because we are adding so much. Modern anthropogenic release ~2000 ft since 1790. At current fossil fuel burn rates, we will release 5000 gt by 2400 (end date, run out of fossil fuels) Warm up surface waters and then deep ocean. Note: petm was 1800-2500, (but it started out at 1000)
