Atmosphere
formation & change
formation & change
What was missing from Earth's early atmosphere?
Molecular oxygen (O2)
Name three greenhouse gases.
CO2, CH4, H2O, etc.
_________ ________ make up ~90% of the Earth's lithosphere.
Silicate minerals
How did the oceans become salty?
Weathering & dissolution of rock
Global average temperatures have been higher in Earth's past during periods in which life thrived, so what makes modern global warming so dangerous for life on Earth?
Rate. Modern warming is so rapid that life cannot adapt quickly enough to keep up.
What was the major process that contributed to the formation of the atmosphere on early Earth?
Volcanic outgassing (release of gases from volcanos)
Troposphere, stratosphere, mesosphere, thermosphere, and exosphere
Silicate minerals weather ____________, meaning certain ions dissolve out of the mineral before others. These ions go on to react with other soluble constituents of the groundwater/seawater/etc.
incongruently
In the oceans (along mid-ocean ridges).
Why are the poles warming faster than the rest of the globe?
Albedo feedback mechanism
Sunlight heats up Earth's surface causing it to emit ____________ radiation, which gets absorbed by greenhouse gases in the atmosphere (blocking heat from escaping to space, and thus, heating Earth).
Why does the temperature of the stratosphere increase going up?
The ozone (O3) layer is in the stratosphere and heats it up due to its absorption of UV radiation.
What are the two main ways the lithosphere affects global climate.
Carbon burial & release (or carbon precipitation & dissolution)
What are the 4 main ways (as discussed in the lecture videos) that the ocean is changing due to global warming & increased CO2?
Ocean warming, ocean acidification, ocean anoxia, and sea level rise.
How do increasing CO2 levels cause the ocean to become more acidic?
<-- Precipitation <--> Dissolution -->
CaCO3 + H2O + CO2 <-> Ca + 2HCO3
Adding to the left side (e.g., CO2) will push the reaction toward the right (producing more carbonic acid & dissolving CaCO3).
How did the Great Oxidation Event effect Earth's climate? Did it cause cooling or warming, and why?
Cooling. (Oxygen increase was due to photosynthesis, which sequesters CO2 from the atmosphere, decreasing greenhouse effect)
What are the 3 main reasons we are not as worried about water vapor as were are about CO2 in terms of their relative greenhouse effects?
Water vapor has a shorter residence time, making its concentration in the atm highly variable and difficult to ascertain.
Water vapor is not something we are releasing and thus, we cannot control it as easily as we control C emissions.
Water vapor also contributes to cloud formation which cools Earth.
What is the reaction that occurs between the silicate mineral olivine and the CO2 & water? And why is it significant?
Mg2SiO4 + CO2 + H2O --> Mg + HCO3 + H4SiO4
Olivine + Carbon dioxide + Water -> Mg+ Bicarbonate + Silicic acid
This is significant because it sequesters carbon from the atmosphere (converts CO2 to bicarbonate) AND limits ocean acidification as bicarbonate increases pH.
Why did the oceans become more stagnant, stratified, & anoxic during past hothouse periods (periods in Earth's past during which there was no ice at the poles)?
Could this happen again?
Weakened ocean circulation & vertical mixing.
When there is no ice at the poles, the temperature gradient from equator to poles is not as strong, and thus, atmopsheric & oceanic circulation slows.
Moreover, vertical mixing is driven by temperature & density differences. Without ice at the poles, the difference in temperature & density between the water circulating to the poles and the water at the poles is not as strong.
Yes, it is happening again.
Why are we worried about global warming due to increased atmospheric CO2 over the coming decades if CO2 only has a ~3-10 year residence time in the atmosphere?
This residence time refers to the transfer of CO2 from the atmosphere to hydro- or bio-sphere (water & life). It takes much longer for carbon to go back into the geosphere (rocks), on the order of hundreds to millions of years.
Warming will continue until carbon transferred into the rocks (because that is where we are taking the carbon from in the first place).