Human Activities & Climate Change 7.3

Question 1

Natural vs. Anthropogenic greenhouse effect?

Answer 1

Natural:
-milankovitch cycles, plate tectonics, volcanoes

Anthropogenic:
-the recent changing in greenhouse warming due to human activities, mans impacts.

Question 2

Anthropogenic Causes? (3 types)

Answer 2

1. Burning of Fossil Fuels
   - accounts 3/4 of increase in C02
2. Land Clering
   - forests absorb C02, clearing = more C02
   - farms/cows = methane
3. Cement Manufacture
   - roasting limestone to get lime for concrete productions > C02 production

Question 3

Feedback & Tipping Points:

Absorption of Extra C02

Answer 3

• When extra C02 released > naturally absorbed

- This feedback ‘works against’ the change occurring > negative feedback

Question 4

Feedback & Tipping Points:

Absorption by the Hydrosphere

Answer 4

-C02 dissolves & reacts with water, so extra amounts in air will dissolve into oceans > makes oceans acidic

Question 5

Feedback & Tipping Points:

Absorption by the Lithosphere

Answer 5

• Some rocks absorb C02 during weathering of rocks (very slow) > prolonging an ice age
• This exposes more rocks which weather by absorbing C02

Question 6

Feedback & Tipping Points:

Changes in the Earths Albedo

Answer 6

• Lower albedo > less reflection > more radiation absorbed > warming effect
• High albedo = reflective > more radiation > cooling

Question 7

Feedback & Tipping Points:

Methane Hydrates

Answer 7

-Sediments on continental shelves contain heaps of Methane gas > methane from rotting organic matter in sediment
> If glaciers melt > methane released > greenhouse effect

Question 8

Feedback & Tipping Points:

Methane in Permafrost

Answer 8

-Permafrost is frozen soil & wetland sediment
-Areas of Tundra in N America still frozen
> they contain heaps of methane gas > global warming is starting to release it!

Question 9

Impacts of Global Warming?

Answer 9

• Animals habitats > extinction
• seas rise
• earths albedo > less reflection = more absorption of heat
• thermohaline circulation in oceans slowed down

Question 10

Ocean Acidification?

Answer 10

carbonic acid is weak so it decreases oceans pH levels
-However, sea creatures sensitive to pH changes
> if pH drops, shell & skeleton creatures can’t maintain calcareous shells > it dissolves shells
e.g. great barrier reefs coral bleaching

Question 11

Ocean temperature Increase?

Answer 11

Lower Oxygen levels

• Oxygen that can dissolve in water, dissolves at temps rise
• Aquatic life need dissolved oxygen to survive
• Warmer oceans > less oxygen

Changing Ocean Currents
-temp increase affects rate of Ocean currents
-Evidence from sediments during ‘Great Dying’ 250 may
> ocean circulation was completely shut down

Question 12

Impacts on Biodiversity?

Answer 12

• Each of 5 mass extinctions proven to be caused by meteorite or volcano
• Mass extinction event NOW caused by humans

Question 13

Global Warming and Extinction rates

Answer 13

Earth is currently heading towards a mass extinction with global warming melting the ice caps. It is expected that 50% of earths species will be wiped out by 2100.
30 000 species are becoming extinct each year
Important as ecosystems all add up:
-rainforests are earths longs, absorbing C02 & producing Oxygen
-Ocean food chains give us HEAPS of our food
We will massively extinct humans at this rate

Question 14

Impacts on food production & water supply world wide?

Answer 14

• some places now too cold or dry for farming
• greatest worry is Africa, cannot grow food, too dry = starvation
• livelihoods of indigenous people in Arctic, Africa and in island communities are threatened

Question 15

Impact on human societies and Health?

Answer 15

• warmer temps will increase spread of tropical diseases & parasites
• changes to food & water supplies > cause people to become refugees to find food.
• every 1% temp rise, violence, warfare increases by 20%