Biogeochemical Cycles
What are the 6 bioessential elements?
CHNOPS
What type/wavelength of radiation do greenhouse gases block?
Infared (IR) radiation
Why are there multiple atmospheric circulation cells? Why is there not just one big one from equator to pole?
Coriolis Effect
Why won't planting trees solve all our problems?
Carbon sequestration by trees/plants photosynthesizing is temporary (they are decomposed upon death).
The poles are warming faster than the rest of the globe due to the albedo effect. Because the ice melting is exposing darker surfaces, the more the ice melts at the poles, the faster the warming becomes in these regions.
What are chemical reservoirs? What role do they play in biogeochemical cycles?
Atmosphere (air), hydrosphere (oceans, lakes), geosphere (rocks), & biosphere (life)
These chemical reservoirs store elements or compounds as they move through their biogeochemical cycle.
Why is the C released from burning biofuels ‘cleaner’ or more renewable than C released from burning fossil fuels?
Biofuels are easier to replenish becuase we can plant more plants fast, but we cannot form new rocks very fast...
_________ __________ is the chemical alteration of rocks & minerals at Earth’s surface.
Chemical weathering
Extra 500 points to the team that can write the chemical equation of the reaction that occurs during chemical weathering of olivine (Mg2SiO2)?
What is it that gives soils their incredible ability to store carbon?
MICROBES!
Give 2 examples of climate solutions that do not involve lowering CO2 emissions or sequestering CO2.
2. Increasing albedo (through atmospheric sulfates, space based mirrors or sun shades, white roofs, etc.)
________ are necessary for the Nitrogen & Phosphorous biogeochemical cycles. Without them, we would not be able to get our nutrients.
MICROBES
Although photosynthesis & respiration control/balance the C cycle, there are many other processes that can throw the C cycle out of balance. Name 2 natual processes that release carbon, and name 2 that sequester carbon.
Release carbon: Volcanos, impacts, ice/permafrost melting (releases methane and other gases), burning fossil fuels.
Sequester carbon: continental weathering, algal blooms, ice/permafrost formation
Modern oceans are changing in many ways. Name 4 ways oceans are currently changing due to climate change.
Warming, acidification, anoxia, sea level rise, weakening circulation/vertical mixing, etc.
Why do we need to implement both short-term & long-term carbon sequestration methods?
Why? - because too much C in the atm & oceans is causing rapid warming, acidification, anoxia, etc., whereas C in the biosphere, just means for plants, and a healthy planet!
What is the Urban Heat Island Effect? And what kind of feedback mechanism is associated with this effect?
The UHI effect explains how cities are warming faster than surrounding regions due to lack of vegetation, dark surfaces, & waste energy from cars, power plants, etc.
The UHI effect is a positive feedback mechanism (warmer cities -> more energy use/C emissions-> faster warming)
How does the sun drive atmospheric & oceanic circulation?
The sun hits Earth at different angles, causing a temperature gradient from equator to poles, which leads to atmospheric circulation (warm air rises & cold air sinks).
Give an example of when life affected global climate (other than humans & modern climate change).
Acceptable answers:
1.Evolution of photosynthesis (cyanobacteria) caused oxygen rise & snowball earth events
2.Massive burial of fossil fuel deposits during very productive periods leading to cooling
3.Evolution of land plants & formation of soils, which increased both C sequestration & continental weathering rates & cooling
What are two major inputs of salts & gases to the ocean?
What are two major outputs?
Inputs: weathering & hydrothermal vents (underwater volcanos)
Outputs: Chemical & biogenic precipitation of minerals
What is one way we can address both water shortages/droughts & sequester more carbon?
Soil regeneration (healthy soils/humus sequesters & stores more carbon & water!)
1. Give an example of a positive feedback mechanism (from start to finish)
2. Give an example of a negative feedback mechanism (from start to finish)
1. Warming -> melting ice -> lower albedo -> more warming
2. Warming -> more evaporation -> more rain & chemical weathering -> C sequestration -> cooling
We talked a lot about how we are impacting the C cycle through modern agricultural practices, but what about other cycles? Explain how we are impacting phosphorous & nitrogen biogeochemical cycling through modern argicultural practices.
(HINT: think about what fertilizer is & its purpose)
We are killing the microbes in the soil that are necessary to take N out of the atmosphere & P out of the rocks, so we have to keep using more N & P-containing fertilizer to grow plants.
(In other words, we are weakening N & P cycling in soils)
In class, we talked about how the residence time of CO2 in the atmosphere is only about 3-10 yrs. So, why can’t we just wait 3-10 years for that CO2 to be removed from the atmosphere? Why won’t this solve our current climate change crisis?
The carbon we are releasing to the atmosphere today comes from the geosphere/rocks (fossil fuels), whereas the CO2 that is being removed from the atmosphere in 3-10 years is mostly going into the biosphere or hydrosphere (only a very tiny percentage is going back into the geosphere).
In other words, that relatively ‘short’ residence time is only referring to atmosphere-hydrosphere-biosphere transfer, not the transfer of carbon into the geosphere (rocks). And since the increase in atmospheric CO2 is coming from the geosphere, the extremely slow rate at which C-containing rocks re-form limits the amount and rate at which carbon can be permanently removed from the atmosphere after we release it.
What are the two major reasons that the deep ocean is becoming anoxic, especially near ocean margins?
And how do these mechanisms cause deep water O2 depletion?
Eutrophication/agal blooms (due to over-nutrification) causes deep water anoxia becuase organisms beneath the bloom use up all the O2 to decompose the over-abundance of organic material.
Weakened ocean circulation, particularly vertical mixing, slows down the rate of O2 replenishment in the deep waters, exacerbating the O2 depletion of deep waters.
How does silicate weathering combat both warming & ocean acidification?
Even if climate change was not an issue and we could release as much carbon as we wanted w/no consequences, we’d still have to switch to non-fossil fuel energy. Why?
Fossil Fuels are finite***
We will run out.
Extra 200 points to the team that can answer how many years of fossil fuels we have left assuming we continue using them at the current rate.