L28: The Ruddiman Hypothesis
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what is another term for The Ruddiman Hypothesis?
the early anthropogenic hypothesis
what change did the Neolithic transition cause to atmospheric CO2 levels?
drove CO2 levels up
how did the Neolithic transition cause CO2 levels to increase?
resulted from cultivation much earlier than the industrial transition
how did pre industrial cultivation impact the natural feedback relationship between orbital forcing and the carbon cycle within the current interglacial?
caused a deviation
what was the neolithic transition?
the shift from nomadic hunter-gatherer societies to settled agricultural systems
when did the industrial transition start?
about 1750
who proposed the early anthropogenic hypothesis?
William Ruddiman
what did the early anthropogenic hypothesis suggest?
human activities released GHGs thousands of years ago, altering the climate & preventing the natural cooling that would have occurred during the Holocene
where did the spread to agriculture occur?
spread from the Middle East and across Europe as well as occurring in China
what was the start of agriculture based on in the Middle East and Europe?
dryland grasses e.g. wheat, barley, oats. as well as the rearing and breeding of livestock
why was early agriculture different in China compared to the rest of the world?
adopted a very different style of agriculture
what was agriculture based on in the far east?
wetland grasses e.g. rice (paddy fields)
what did the agricultural transition cause?
a rise in atmospheric CO2 levels
what would have happened if there was no shift to agriculture?
the Earth would be transitioning because of the orbital position of the Earth in relation to sun periodicities. we would be starting to cool towards the next ice age
what does the primary relevance hypothesis argue?
argues that the Neolithic started the rise in atmospheric GHGs through human activity
what GHG are paddy fields often associated with?
the production of CH4
why do paddy fields release CH4?
waterlogged environment creates anaerobic conditions so sulphide production takes place, meaning you get CH4 production
why do cows produce vast amounts of CH4?
processes within their digestive system
what is the name given to the period of very low solar irradiance?
the Maunder Sunspot Minimum
what century was the Maunder Sunspot Minimum?
the 17th century
who were the first to notice the changes in sunspot cycles and solar irradiance?
Sporer and Maunder
when did Sporer and Maunder notice these changes?
during a period of low sunspot activity (1645-1715). known as the Maunder Minimum
when was the medieval warm period and the Viking colonisation of the North Atlantic?
700-1100 AD
what period was the golden age of the European cathedral construction?
the medieval warm period