Lecture 12: Climates of the Distant Past Flashcards
What is a climate trend vs rhythm?
Trends: global temperature change over a longer set period of time
Rhythms: repeating cycles of climate over a shorter period of time
What’s an ice age?
Persistent glaciers present
Whats an interglacial period?
Glaciers receding (now)
Whats a glacial period?
Glaciers are growing
What is hot house earth?
No persistent glaciers present
What are climate forcings?
factors which have been shown to influence global/regional climate?
What are feedbacks (in terms of earths climate)
A process which can amplify or dampen a climate forcing
What are tipping points?
When the physical/ecological state of an area crosses and “irreversible” threshold of climate forcings (irreversible on human timescales)
How/why are climate feedbacks so effective?
Most are positive! Aka not self regulating so small changes can lead to much greater effects.
How does solar radiation increase?
Gravity pushed the hydrogen atoms together. As they fuse together at the core, they’re converted into helium which is heavier, thus increasing the gravitational forces and increasing the rate of fusion (and therefore radiation in general).
How did the evolution of photosynthesis affect the earth’s climate?
Initially, high levels of CO2 trapped more solar radiation (which was only 80% of what it is now). With the emergence of photosynthetic organisms, this CO2 was depleted as the organic carbon cycle formed and O2 concentrations greatly increased.
What is snowball earth?
When the planetary surface was totally frozen.
What was the Huronian glaciation and what was the feedback loop that causes it?
A 300MY period of glacial and inter-glacial periods (possible snowball earth)
The ice-albedo feedback drove this: positive feedback loop between ice forming and increasing albedo, thus decreasing temperature.
How does continental drift affect climate?
Moving of tectonic plates influences ocean currents which transport heat around the globe.
How do plate tectonics (in terms of precipitation) affect climate?
Equatorial regions experience more rain, which means that the exposed rocks are older and have been exposed to more chemical weathering, meaning fewer carbonic acid molecules are released when it rains.
Plate tectonics also produce new surfaces and these new rocks have tons of carbonate and calcium to weather quickly.
