Lecture 5: Ancient impacts of people on climate change

Question 1

Anthropocene: Human impacts push the Earth system (particularly ___ system) beyond its

Answer 1

climate system

natural range of variation

Question 2

when did the anthropocene begin?

Answer 2

DEBATE

• pre-industrial? (fire & hunting, origins of agriculture)
• industrial ? (industrial revolution, nuclear age?)

Question 3

holocene

Answer 3

last 10,000 years

Question 4

Industrial effects are obvious (CO2 + Methane)

Answer 4

Huge ‘hockey stick’ curves showing increase following industrial revolution

Question 5

earliest impacts of humans on the planet (4 points)

Answer 5

1) hunters and the megafaunal extinction
2) deglaciation & origins of agriculture
3) pre-industrial spread of agriculture
4) Climatic impacts of early agriculture

Question 6

Hunters & megafaunal extinction

Answer 6

• loss of wooly mammals etc
• on every continent (Johnson 2009)
• big animals more bias (more threatened)
• small animals thriving in modern world
• population sizes smaller in large animals, slower growth rates, breeding slower = more vulnerable to extinction

Question 7

causes of megafaunal extinction?

Answer 7

debate, extinction correlated with human arrival

Johnson 2009

Question 8

Agriculture: began? where? what does it allow?

Answer 8

• 10-12 thousand years ago
• began in multiple independent regions across the world
• allows society to support high no. of people in one place
• allows people to have diff jobs in society (farmers, not farmers, tax collectors)

Question 9

modern agriculture

Answer 9

• industrialised
• support cities (importation)
• free from need to go out and work and collect (hunter & gatherer)
• tech innovations stem from agriculture (people have time on their hands)

Question 10

hypothesis into why agriculture began?

Answer 10

• DEBATABLE –> lots of hypothesis

- - i.e. local resource availability, population growth, tech innovation, dietary breadth etc

Question 11

hunter gatherers ate …

Answer 11

• • were farming!
• a broad spectrum of wild grains
• Ohalo II, 10,000years BEFORE agriculture
• tool use (weapons, grindstones)
• wheat, barley & other things

Question 12

transition to agriculture involved specialisation from a large pool of wild species

Answer 12

to a few crops

- wheat, barley, pulses etc

Question 13

deglaciation probably allowed __ to begin

Answer 13

agriculture

Question 14

Was agriculture impossible during the glacial?

Answer 14

YES,
-necessary tech & intellect:
low & unpredictable plant productivity made it impossible to specialise on a narrow range of crops
- picking a few crops = runs risk of high crop loss

• so they go out, collect things in season, buffers you to environmental change

Question 15

domestication of crops allowed

Answer 15

• greater yields
  wild crops disperse their own seeds
• domesticated dont
  – they rely on us, we do them

Question 16

agriculture began & spread =

Answer 16

fertile crescent (iraq, iran, israel etc) and then spread through Europe and England in 5000 year ago 
- agriculture spread from where it began

Question 17

agriculture spread meant the __ of trees

Answer 17

deforestation

Question 18

from beginning agriculture (10,000) to now. Has tech innovations changed per capita land-use?

Answer 18

• productivity of crops has improved,
• shrinking per capita land-use
• land change occurred further back in time
• early anthropogenic view supports pre-industrial deforestation

Question 19

technological innovations in food production

Answer 19

• hunter-gatherer management of landscapes by fire
• food processing methods
• cultivation of sown seeds in intensive gardens
• agricultural economies (manuring, ploughing)
• irrigation, multiple cropping, rotations, fertilisers,
• industrial evolution
• green revolution

Ellis et al 2013

Question 20

indirect climatic impacts of pre-industrial agriculture

Answer 20

comparison of CO2 & CH4 in current interglacial (holocene) and past (eemian)
- Now in holocene, increase in CO2 and CH4 (slightly more recently)

Question 21

reasons for CO2 and CH4 holocene interglacial levels

Answer 21

• CH4 emissions from paddy rice & livestock
• CO2 emission from deforestation for agriculture
• RUDDIMAN 2013
• – debatable though!
• • prior to 3000 years ago, only half CO2 was from deforestation
• • CH4 nature variation explains CH4 conc changes