PowerPoint Presentation

Sources and SinksClimate ChangeCarbon

Fossil fuels are not naturally a part of the fast cycle: every ton emitted changes the carbon cycle for thousands of yearsCarbon Sources and SinksPlaces that provide carbon are called reservoirs. Places where carbon settles are called sinksExchanges between sinks and reservoirs are called fluxes.There are four major reservoirs for carbonThe atmosphereThe oceansThe biosphereFossil fuelsUltimately the crust forms the basic sink for carbon via the deep oceans to carbonate rock and fossil fuelsCarbon SinkThis 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).

Carbon SinkFlows 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.

What It MeansThis 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 eraThe intermediate and deep ocean contained 37100 billion metric tons of carbon in 1750, an amount that went up 100 billion metric tons since the beginning of the industrial eraTerrestrial 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

What it MeansThe 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 3700 billion metric tons of carbon in 1750 - 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%).

The Carbon Cycle with and without humansIn 1750, WITHOUT industry & vehicles, there was around 280 CO2 molecules in every million air moleculesIn 2010, WITH industry & vehicles, there is now 389 CO2 molecules in every million air molecules (35% increase)

PlantsAnimalsIndustry &VehiclesOrganicMaterialFossilFuelsAtmospherePhotosynthesisRespirationDecompositionBurningPumping

PlantsAnimalsOrganicMaterialAtmosphereRespirationDecompositionPhotosynthesisFossilFuelsGreenhouse Gas ConcentrationsCompared 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.

(IPCC AR4 WG1, 2007)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}9Greenhouse Gas ConcentrationsThese 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.

10Greenhouse Gas ConcentrationsSimilarly, 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. 11Greenhouse Gases: CO2The most plentiful greenhouse gasResults fromCombustion of fossil fuelsGas (best)Oil (medium)Coal (worst)Based on ratio of carbon to hydrogen in the moleculesBurning of vegetation/deforestationReduced uptake in plants/deforestation

Greenhouse Gases MethaneMethane concentrations have increased 2.5-fold since 1750SourcesCoal miningOil productionOrganic decomposition in landfillsAnimal digestion (feedlots)growing more crops such as rice to feed the worlds increasing human populationResident in atmosphere about 10 years

Nitrous Oxide and Tropospheric OzoneAnthropogenic Increase

Anthropogenic AerosolsParticulate matterScatter sunlight back to spaceCause more, smaller cloud particles (increase albedo)

Chlorofluorocarbons (CFCs)Nasty little gases only anthropogenicCFCs do not occur in nature the Fluorine bond is too strong to break naturally.CFCs come fromRefrigerantsStyrofoam, foaming agentsCleaning electronicsSpray propellants

Global Warming PotentialsCO2 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 combinedMethane holds more heat, but because it is chemically more active, its atmospheric duration is about 10 years

17Radiative ForcingThe amount of change in thermal energy that a given factor causes1.6 watts/m2 (thermal energy) above what it was 250 years agoI.E. the planet is receiving and retaining 1.6 watts/m2 more thermal energy than it is emitting back into space.