Lecture 18: The Holocene Flashcards
What was the climate like before the KT extinction?
Hothouse earth (no glaciers)
What is proxy data?
Data derived from sources that are not direct measurements of the variable of interest, but can be used to infer the measurements of the variable of interest
How do characteristic landforms provide proxy data for past climates?
Glaciers carve out characteristic valleys in landscapes as they form and deposits left at the melting end of a glacier are characteristic
How do ice cires provide proxy data for past climates?
Different layers in the ice core shows what the climate was like for a given time period
How do oxygen isotopes in ice cores work?
O16 is the most common isotope
When there is less heavy oxygen (less O18) in the frozen water means that temperatures were cooler –> hotter temperatures means there was more heavy oxygen (more O18)
Since oxygen is also part of caco3, the ratio in marine organisms is present too
How does pollen data work?
pollen doesn’t really degrade so by finding different types of pollen trapped in different areas, we can see what climate was like back then (since only certain plants can live in certain climates)
How do leaf fossils show climates?
Leaves with jagged edges are more common in high latitude climates with a marked seasonal change –> if fossils show jagged edged leaves, then climate must have been seasonal.
What is a mountain building event?
Formation of new elevated
regions of rock
How does precipitation affect global cooling?
Carbon is moved from rock to atmosphere through volcanism –> high precipitation causes the rock to be weather, there is less carbon entering the atmosphere causing cooling
How do ocean currents affect climate?
Heat falls unequally on the planet –> ocean currents pick up heat from the equator, and move it to higher latitudes
How did the isthmus of panama affect climate?
When the isthmus formed, hot was diverted upwards instead of across, warming the northern hemisphere
What is thermohaline circulation?
Global circulation of ocean currents driven by differences in temperature and salinity
How did the late Pleistocene glaciation affect waterways?
The Hudson Bay was a major drainage basin but after glaciers formed around the Judson Bay, the freshwater flowed to Mississippi instead
T or F: earth’s climate has been stable in the holocene.
True! Remarkably stable compared to other periods.
How did human civilization change during the holocene?
First agricultural revolution: switched to domesticated plants allowing civilizations to grow
