Climate Change Through Time Flashcards
For Exam 3, May 6th
How does plate tectonics and supercontinents affect climate change?
Lots of continental rifting or subducting leads to extreme volcanism, which releases greenhouse gases that warm the atmosphere
What is a carbon sink? What is a carbon source?
Sink: removes CO2 from the atmosphere (e.g. photosynthesis, burying organic matter, absorption by ocean shells, rock weathering)
Source: adds CO2 to the atmosphere (e.g. decomposition, respiration, volcanoes, fossil fuels)
What is the difference between CO2, C13, and C14?
CO2 is a greenhouse gas with carbon in it
C13 and C14 are isotopes of carbon, meaning they’re the same element with a different number of neutrons
C13 is stable and used to make CO2
C14 is unstable and decays, so we use it in carbon dating
Why do we care about climate change today even though it occurred in the past?
It’s occurring at a significantly faster rate (almost 30x quicker) than at any time in history and the ecosystem can’t keep up
What are some effects of climate change happening today?
Glacial melting, sea level rise, ocean acidity leading to coral bleaching, spread of warm adapted animals to higher latitudes, more extreme weather and wildfires, etc.
What are solar radiation cycles (sunspots)?
Natural fluctuations in the sun’s temperatures that affect us here on earth
Tracked with sunspots - small regions of the Sun’s surface that are darker because they’re cooler than surrounding areas
Less sunspots = colder on earth
What are the factors controlling Milankovitch Cycles?
1- Eccentricity: how circular the earth’s orbit is (lower = more circular = slightly warmer)
2- Obliquity: tilt of the Earth’s axis (less tilt = weaker seasons + overall cooling)
3- Precession: wobble and direction of the axis’ tilt (one hemisphere receives more extreme seasons)
How do feedback loops work? How does this relate to the Albedo Effect?
Positive - actions reinforce one another and the process amplifies
Negative - actions counter one another and the process slows
Albedo: measuring how much sunlight is absorbed/reflected by a surface (low = more absorbed = higher temps = melting ice = less light surfaces = less reflection = higher temps….)
Which is the stronger greenhouse gas: carbon dioxide or methane? Why?
Methane because it has more molecules (CH4 > CO2)
How do ice cores and pollen tell us about climate change? What type of data is this considered?
Ice traps pockets of gas, dirt, and pollen
Getting samples can help us track historic levels of CO2 and the type of pollen present will tell us what kinds of trees were found (which tells us about the environment)
These are considered proxies or indirect measurements
How can rocks be proxies for climate change?
Type of rock present tells us what kind of environment used to exist there
For example, the presence of limestone indicates that the area used to have shallow, warm water
How can we track ocean conditions through time? What is the proxy data for this and where are we finding it?
Based on the proportion of isotopes O16 and O18 found in microscopic marine shells, which are made from surrounding water at the time of formation
What does O16 and O18 tell us about glaciers?
Glacier ice is made of O16 because it’s lighter and easier to transport
So, if there’s less O16 (more O18) found in the marine shells, that means that it must be trapped in ice, telling us that the climate was cooler at the time
How can isotope data about carbon be used to track levels of photosynthesis?
Plants break down C12 first because it’s lighter and easier to digest, meaning the sugar that plants create after photosynthesis is made of C13
Higher levels of C13 means more photosynthesis, more oxygen, and cooler temps
What is thermohaline circulation? Does it ever stop?
Oceans circulate based on density differences caused by temp and salt (colder, saltier water is denser sinks)
This process of cycling water also cycles nutrients and free oxygen
This process can slow down or stop if there’s very little density differences, which happens when the climate warms overall
What evidence do we have for the Paleocene-Eocene Thermal Maximum (PETM)? What were the possible causes?
Huge decreases in both C13 and O18 at this time, meaning less glaciers and less photosynthesis
We also saw interference with thermohaline circulation, leading to mass extinction of seafloor marine organisms due to anoxia (lack of oxygen in the water)
Potential causes: volcanism and methane release from melting glaciers
What similarities do we see between the PETM and today? What does this tell us?
Coral bleaching due to high temps and acidity + spread of warm adapted animals to higher latitudes
This is a warning sign that further climate change will continue to affect our ecosystems in negative ways
