Its all about CARBON and thus the CARBON CYCLE and Carbon Cycle=carbon dioxide cycle
Climate Change Introduction…. Its all about CARBON and thus the CARBON CYCLE and… Carbon Cycle=carbon dioxide cycle Pool, or reservoir Place in biosph...
Climate Change Introduction…. Its all about CARBON and thus the CARBON CYCLE and… Carbon Cycle=carbon dioxide cycle Pool, or reservoir Place in biosphere carbon hangs out (shorter period of time). Sink is a place carbon is likely to stay for longer period of time. Flux Rate of movement between pools….. Example: Terrestrial plants are a pool for carbon, while photosynthesis represents a flux.
Overview • Occurs in the atmosphere at about .03% (see table in your text) (but huge amount stored in oceans) • Moves between organisms and atmosphere as a consequence of two reciprocal processes (photosynthesis and respiration) • Each year plants remove about 1/7th of the CO2 in atmosphere • Decomposition of that material recycles most of that back into atmosphere at some point in time..
• Largest fluxes between atmosphere and land vegetation and atmosphere and oceans • Some carbon cycles rapidly while other carbon is sequestered in relatively unavailable forms or places (sinks) • For ex. Carbon in peat, fossil fuels would normally be permanently sequestered or stored
Balancing the carbon budget.. “one of the most vexing problems in ecosystem ecology today” “The sizes of major sources and sinks for carbon are not well understood and we do not understand the processes that control carbon fluxes”
Where does carbon come from? Most comes from fossil fuels but... Are sources other than fossil fuels such as Shifting land use How does shifting land use affect carbon emissions??? (clearing of forests, burning of vegetation)
Land Use Change vs Fossil Fuel Release
Ha!
Anthropogenic release of C (that due to humans) to the atmosphere results from land use change(20%) and from burning fossil fuels (80%). Before mid 1800s deforestation was main contributor.
Review releases and then where does carbon go?
Another way of visualizing?
http://www.carboscope.eu
Temporal evolution of the atmospheric carbon balance over the years 1958-2006. Red line: CO2 emissions from fossil fuel burning. Brown line: total emissions (fossil emissions + emissions from land use changes). The colored areas show the uptake by the three carbon reservoirs: blue: ocean, light blue: atmosphere, green: land biosphere. Units: PgC.yr-1 (1 PgC.yr-1 = 1 billion tons of carbon = 3.7 billion tons of CO2).
I. Climate Change Uncertainties A. Feedbacks Uncertainties 1. Oceans 2. Water vapor and cloud cover 3. Polar ice 4. Air pollution 5. Effect of CO2 on photosynthesis B. Sink Uncertainties What is the role of Sinks? (oceans and vegetation, soils?)
There are uncertainties in the DETAILS OF Global Warming… How quickly will the earth warm? What parts of the earth will warm first? How will the earth respond? These issues are directly related to A. Feedback uncertainties B. Sink uncertainties
A. Feedbacks Uncertainties Will natural processes tend to…. • reduce the effects of warming (put the brakes on warming-negative feedbacks)?
• Or accentuate the effects of warming (positive feedbacks)?
1. Oceans *when warm release CO2 “bad” -positive feedback *but oceans also absorb CO2 and we don’t know how much can absorb? (sink uncertainty) *oceans might be able to absorb more heat *but deep ocean currents might be disrupted
2. Water vapor and cloud cover *warm temp increases evaporation-> creates more clouds, water vapor is a greenhouse gas --> could enhance warming-positive feedback-bad!
*but they could also reflect sunlight back into spacenegative feedback- good!
3. Polar ice *if warm temperatures melt some of the ice, more sunlight will be absorbed (darker earth exposed) -->then more ice would melt positive feedback Albedo effect *or early stages at some locations could increase snow in Northern latitudes and cover more of the earth -->reflect more sun and cool off the earth, creating a negative feedback
4. Air pollution *aerosols -tiny drops or particles of air pollution SO2 , NOX could reflect some heat *but at night added aerosols would hold heat in (most warming in atmosphere has occurred at night)
5. Effect of CO2 on photosynthesis *more CO2 may increase rate of photosynthesis which could remove more CO2 and slow warming--> negative feedback *others think that warmth would just increase feeding by insects and other animals which would mean no real gain in rate of photosynthesis *CO2 intake may slow dramatically over time
I. Climate Change Uncertainties A. Feedbacks Uncertainties 1. Oceans 2. Water vapor and cloud cover 3. Polar ice 4. Air pollution 5. Effect of CO2 on photosynthesis B. Sink Uncertainties What is the role of Sinks? (oceans and vegetation, soils?)
Oceans! Ocean surface water takes up CO2 from the atmosphere by diffusion. C is also transferred to deeper water mostly as organic detritus and carbonate shells. Then …Upwellings bring C-rich water to the surface, releasing CO2 to the atmosphere.
“If a moderately sized pulse of CO2 were added to the atmosphere today, about 85% of it would dissolve in the ocean, but the process would take more than 1000 years because of the sluggishness of vertical exchange between the surface and interior of the ocean. For example, the oldest ocean water in the world, which is found in the deep North Pacific, has been out of contact with the surface of the ocean for about 1000 years.” AIP
Vegetation! How much CO2 can vegetation take up? Early thoughts were plants would take up carbon-balance out After all grew 40% faster in chamber experiments with hi CO2 But…. 1. Run out of something that will constrain growth (nutrients, water) so this tends to level out over time 2. Vegetation respires too and much of it decomposes eventually!
So plants actually store only a small % of what they take in Also…. Heat seems to increase metabolic release of CO2 (plant material decomposes faster when temp higher)? Heat may also slow photosynthesis? (leaf temp above 33 degrees Celsius photosynthesis slows as rises above 36C “hits wall” stomata close to avoid dehydration)
I. Climate Change Uncertainties A. Feedbacks Uncertainties B. Sink Uncertainties What is the role of Sinks? (oceans and vegetation, soils?) II. A focus on CO2 levels and change over time (looking over first three links for Fri Oct 28th)
Why do levels measured at Mauna Loa rise and fall seasonally? Write your response on your own and THEN compare with a neighbor.
http://www.esrl.noaa.gov/gmd/ccgg/trends/history.html (NOAA Movie Historical Trends in CO2) https://www.youtube.com/watch?v=x1SgmFa0r04 (NASA CO2 Movie) http://www.bbc.com/news/science-environment-37729033 (CO2 this Year)
Questions related to video”What’s up with the weather?” What is the difference between weather and climate? Why is climate change the worst kind of problem? Would you say this video was dated? Yes because… No because… What kinds of ways do we understand the climate and CO2 levels of the past? They highlight several feedbacks, which ones?
