1. Sources and Sinks Climate Change
Carbon
Sources and Sinks
Climate Change

2. Fossil fuels are not naturally a part of the fast cycle: every ton emitted changes the carbon cycle for thousands of years

3. Carbon Sources and Sinks
Places that provide carbon are called reservoirs.
Places where carbon settles are called sinks
Exchanges between sinks and reservoirs are called fluxes.
There are four major reservoirs for carbon
The atmosphere
The oceans
The biosphere
Fossil fuels
Ultimately the crust forms the basic sink for carbon via the deep oceans to carbonate rock and fossil fuels

4. Carbon Sink
This model shows the main carbon pools on Earth, limited to those that can exchange significant amounts of carbon in the short term (lime is thus not shown, though it constitutes the largest stock of carbon on Earth).
Figures are in gigatonnes of carbon (GtC).

5. Carbon Sink
Flows in black represent the "natural" exchanges, those that existed in 1750, before the beginning of our industrial activities and pool figures in black represent the amount of carbon stored in 1750.
Flows in red represent the human direct or indirect average contribution for the 1990's, and stock figures in red represent the net effect of human activities from 1750 to 1994.

6. What It Means This diagram means, among other things
Ocean sediments at the top of the ocean floor contain 150 billion metric tons of carbon, an amount that has not changed since the beginning of the industrial era
The intermediate and deep ocean contained billion metric tons of carbon in 1750, an amount that went up 100 billion metric tons since the beginning of the industrial era
Terrestrial ecosystems contained 2300 billion metric tons of carbon in 1750 (in the vegetation, soil and humus), an amount that went up 101 billion metric tons since the beginning of the industrial era because photosynthesis continuously increased since then, but in the same time went down 140 billion metric tons because of forest clearing

7. What it Means
The atmosphere contained 597 billion metric tons of carbon in 1750, an amount that went up 165 billion metric tons since the beginning of the industrial era because of our CO2 emissions.
The overall extractible fossil fuel reserves (oil, gas and coal, totaled billion metric tons of carbon in before we began to dig in it - and that at the end of 1994 we had extracted (and burnt, with CO2 going into the air) about 244 billion metric tons (note that between 1994 and 2005 this figure has risen by 30%).

8. The Carbon Cycle with and without humans
In 1750, WITHOUT industry & vehicles, there was around 280 CO2 molecules in every million air molecules
In 2010, WITH industry & vehicles, there is now 389 CO2 molecules in every million air molecules (35% increase)
Plants
Animals
Organic
Material
Atmosphere
Respiration
Decomposition
Photosynthesis
Fossil
Fuels
Plants
Animals
Industry &
Vehicles
Organic
Material
Fossil
Fuels
Atmosphere
Photosynthesis
Respiration
Decomposition
Burning
Pumping

9. Greenhouse Gas Concentrations
Compared to natural changes over the past 10,000 years, the spike in concentrations of CO2 & CH4 in the past 250 years is extraordinary.
Humans are responsible for the recent dramatic increase emissions. Fossil CO2 & CH4 lack carbon-14, and the observed drop in atmospheric C-14 is measurable.
Atmospheric concentrations of carbon dioxide, methane and nitrous oxide over the last 10,000 years (large panels) and since 1750 (inset panels). Measurements are shown from ice cores (symbols with different colours for different studies) and atmospheric samples (red lines). The corresponding radiative forcings are shown on the right hand axes of the large panels. {Figure 6.4}
(IPCC AR4 WG1, 2007)

10. Greenhouse Gas Concentrations
These figures show
Atmospheric concentrations of the key anthropogenic greenhouse gases were constant over hundreds of years until the industrial era.
Observed increases of 33%, more than a factor of two.
About15% are attributable to human activities.
These figures show that the atmospheric concentrations of the key anthropogenic greenhouse gases, carbon dioxide, methane and nitrous oxide were constant over hundreds of years until the industrial era. The observed increases in the atmospheric concentrations carbon dioxide, methane and nitrous oxide of 33%, more than a factor of two, and about 15% are attributable to human activities. Similarly, the atmospheric concentration of sulfate aerosols started to increase in the late 1800s due to the combustion of coal.

11. Greenhouse Gas Concentrations
Similarly, the atmospheric concentration of sulfate aerosols started to increase in the late 1800s due to the combustion of coal.
These figures show that the atmospheric concentrations of the key anthropogenic greenhouse gases, carbon dioxide, methane and nitrous oxide were constant over hundreds of years until the industrial era. The observed increases in the atmospheric concentrations carbon dioxide, methane and nitrous oxide of 33%, more than a factor of two, and about 15% are attributable to human activities.

12. Greenhouse Gases: CO2 The most plentiful greenhouse gas Results from
Combustion of fossil fuels
Gas (best)
Oil (medium)
Coal (worst)
Based on ratio of carbon to hydrogen in the molecules
Burning of vegetation/deforestation
Reduced uptake in plants/deforestation

13. Greenhouse Gases Methane
Methane concentrations have increased 2.5-fold since 1750
Sources
Coal mining
Oil production
Organic decomposition in landfills
Animal digestion (feedlots)
growing more crops such as rice to feed the world’s increasing human population
Resident in atmosphere about 10 years

14. Nitrous Oxide and Tropospheric Ozone
Anthropogenic Increase

15. Anthropogenic Aerosols
Particulate matter
Scatter sunlight back to space
Cause more, smaller cloud particles (increase albedo)

16. Chlorofluorocarbons (CFCs)
Nasty little gases – only anthropogenic
CFCs do not occur in nature – the Fluorine bond is too strong to break naturally.
CFCs come from
Refrigerants
Styrofoam, foaming agents
Cleaning electronics
Spray propellants

17. Global Warming Potentials
CO2 is the most abundant greenhouse gas in the atmosphere, it contributes more to the natural and to the anthropogenic greenhouse effect.
According to latest data, CO2 is exerting nearly six times more impact than methane, nitrous oxide, and halocarbons combined
Methane holds more heat, but because it is chemically more active, its atmospheric duration is about 10 years

18. Radiative Forcing
The amount of change in thermal energy that a given factor causes
1.6 watts/m2 (thermal energy) above what it was 250 years ago
I.E. the planet is receiving and retaining 1.6 watts/m2 more thermal energy than it is emitting back into space.