Geography 1400F/G Lecture 11: 11 Lecture 26/10/2015

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Geography 1500F
The Carbon Cycle and Climate Change
Fossil Fuels: ‘Ancient Biomass/Buried Sunshine’
biomass in ancient life forms trapped, compressed, and ‘cooked’ (geothermal heating)
physics is clear: combusting this trapped carbon changes chemistry of the atmosphere
Bill Mckibben: “In 28 years of thinking about climate change, no single story has made
me as angry as today’s revelation about Exxon.”
even Exxon’s senior scientists told management that there is indeed climate change as
a result of burning fossil fuels, and that the temperature has risen by 3-4 degrees C
The Global Carbon Cycle
carbon naturally cycles between biosphere (and between biosphere and pedoshpere
(soils), and lithosphere) and atmosphere ((photosynthesis and respiration) (between
pedosphere and atmosphere)), oceans (photosynthesis and respirations), and within
oceans; it is constantly in motion
combining with oxygen to generate energy
there are reservoirs, or ‘sinks’
‘flux’ changes slowly over very, very long periods of time
very few large dramatic or sudden changes
change is relatively constant, but does change
fossil fuels is photosynthesizes energy (ancient biomass trapped) that has been formed
over hundreds of millions of years, and effectively sealed away
‘Hothouse Earth’ in the Mesozoic era (352-66 million years ago)
tropical climates
plankton abundant in oceans
Persian Gulf
edge of historic seaway, abundant tropical reefs
as sea closed, numerous ‘traps’ of oil and gas
GHGs
US dominant producer and exporter up to WW2
Texas and California was and still is largest sources of fossil fuels in US
humans are the new player in the carbon cycle in past 200 years, in that we are
combusting the fossil energy and releasing it into the atmosphere
land use change, especially deforestation, is humans changing cycle
soil degradation another component of humans changing cycle
it is clear, through empirical findings, that there are measurable changes in atmospheric
chemistry
buildup of CO2, rising PPM
1700: 278 PPM; 2013: 400 PPM
also, there is an increasing attention to measurable changes in ocean chemistry that
relate to the change in atmospheric chemistry
pH is decreasing
ocean is acidifying
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