Climate change in the Cenozoic Flashcards
What does the cenozoic Era refer to?
The period since the dinosaurs were wiped out, the age of the mammals, last 55Ma (million years).
Describe the climate of the Cenozoic.
Had global long-term cooling.
What could have caused the Cenozoic’s long term cooling trend?
Decreasing CO2 emissions; Less volcanic activity, increased weathering, continental drift (position of continents influenced ocean circulation which transfers heat).
What happens when a tectonic plate with carbonate rock is subducted?
It melts and releases carbon dioxide via volcanoes (hence declining volcanic activity can cause global cooling)
What are carbonate rocks?
Any rocks that can take carbonate e.g. limestone.
What caused the closure of the Tethys Ocean?
Continental drift during the Cenozonic when India ran into Asia.
How did continental drift reduce warm water transportation to Antarctica?
It opened Drake Passage which led to changes in ocean circulation (reduced warm water transportation from tropics to Antarctica).
What is the albedo effect?
The albedo effect refers to the fraction of incoming solar energy that is scattered by Earth back into space. Darker surfaces e.g. grass absorb more of the suns energy, lighter surfaces e.g. ice reflect more of it back into space (Stephens et al., 2015).
What is Drake’s passage? When did it form?
A body of water between South America’s Cape Horn and Antarctica. It formed around 41-46 million years ago (Barker and Thomas, 2004).
What is the Tasman Gateway?
A slowly widening seaway between Australia and Antarctica (University of Tasmania, 2017).
What combined factors are believed to have caused Antarctica to have iced up?
Decline in atmospheric CO2 partly due to weathering and ocean circulation. Once some ice formed this also triggered the albedo effect.
Why is it harder to freeze the Arctic than the Antarctic?
The Arctic is not surrounded by an ocean current as land around it prevents this.
When does a cooling period class as an ice age?
When there is significant glaciation in the northern and southern hemispheres.
When did the Arctic permanently freeze up?
2.7-3.2 million years ago (Ma).
What explanations are there as to why the Arctic iced up 3.2-2.7 million years ago?
Closure of Panama seaway changing ocean circulation, uplift of mountains changing atmospheric circulation, ending of permanent El Nino, continued CO2 decrease.
