System Earth Ch 15 Flashcards
holocene epoch
the last 100,000 years
palynology
the study of pollen in sediment to establish an estimate of the plant population in an area and thus determine the climate.
what is radiocarbon dating used for?
date different levels of sediment coreto associate environmental change to certain periods. This is used in addition to palynology
dendrochronology
the study of tree rings using both the number of rings and their characteristics to determine climate every year.
since when do we have world wide accurate climate data?
1970
since when do we have temperature data
1850
where has temperature been affected the most in the last 1000 years?
mid and high latitudes
where has moisture content been affected the most in the last 1000 years?
tropics and sub-tropics
perspective on variability in temperature and the 20th century?
the small changes (eg. vikings) are fairly small (0.5K) but what we have predicted is similar to the change in temperature since the last ice age but then in the time scale of the next 100 years.
describe the world in the holocene climatic optimum
very stable (5,000 to 6,000 yrs ago)
warmer summers globally
northward shift of ITCZ
much more rainfall in sahara and savannah regions.
enhanced monsoon circulation
Medieval warm period
Greenland had farms in 1100
ended 1250-1350, sea ice expanded, lots of floods plus the plague, so 25% of Europe died
The Little Ice Age
1500-1850
much cooler, especially in Europe
causes of the little ice age
volcanoes and climate - lots of volcanoes in Iceland erupted
Solar variability
sunspot cycles
every 11 years
sharp increase in temperature and gradual decrease
sunspots increase earth’s temperature because warmer area around sunspot is larger
Maunder minimum
time of low sunspot activity
Some main carbon sources, sinks, and storages
vegetation, soils and detritus, terrestrail NPP, volcanism, atmosphere, fossil fuels, surface ocean, marine biota, dissolved organic carbon, intermediate and deep ocean, surface sediment
methane clathrate hydrate
CH4 in a lattice of H2O
organic matter decomposes anaerobically at great depths
rate of fossil fuel burning
keeps increasing and is not distributed evenly through the world
processes that remove CO2 from the atmosphere
reforestation
CO2 and N fertilization
dissolution in the oceans
dissolution of seafloor carbonate
weathering of continental rock
reforestation
mainly in the northern hemisphere, photosynthesis is our friend
CO2 and N fertilization
plants use water more efficiently under higher CO2 levels
if trees grow faster, they use more of the litter, which is wehere carbon is stored and thus there is less carbon stored in the ecosystem
nitrogen can be stored as nitric acid (acid rain) which fertilises plants. So increased rate of plant growth could be due to anthropogenic nitrogen emissions
dissolution of CO2 in the oceans
slows down when there is more CO2 already in the ocean - has to penetrate deeper
this also increases the acidification of the oceans.
dissolution of seafloor carbonates
in acidic oceans, the process of dissolution of carbonate sediments into the sea floor happens even faster. This is the long term sink for CO2.
weathering of continental rocks
silicate + CO2 -> CaCO3 + SiO2
CO2 is stored nearly permanently in the rocks
trace gases
methane and nitrous oxides
radiative forcing
basically the model and how that affected the energy balance
long-term climate warming
warming from an eightfold CO2 increase would make the earth warmer than it has been for tens of millions of year
possible change in THC
melting of greenland ice sheet would stop deep sea formation and slow/ stop the THC in the North Atlantic, changing the existence of the gulf stream. But also, on a shorter time scale, you increase the rainfall, which also reduces the THC
