human causes of climate change

Question 1

describe the changes to the climate over geological time

Answer 1

whilst there have been changes in the climate over geological time, the changes experienced over the last 200-300 years have been significant.

Question 2

describe CO2 levels throughout geological time

Answer 2

throughout geological time CO2 levels have remained constant, being between 260-280 ppm (parts per million) over the last 10,000 years. however, today these levels have risen to 420 ppm. the reason these levels have increased so dramatically is mainly to do with human activities

Question 3

what does flooding of rice fields cause

Answer 3

flooding off a rice field cuts off the oxygen supply from the atmosphere to the soil, resulting in a process called anaerobic fermentation.

Question 4

describe anaerobic fermentation

Answer 4

this is where the organic (living) matter in the soil starts to break down due to a lack of oxygen and is decomposed by a microorganism, methanogen archaea

Question 5

what product is produced from archaea

Answer 5

as archaea break down the organic matter, methane is the waste by-product produced from this process.

Question 6

how is the gas released from soil

Answer 6

the CH4 gas is released from the submerged soils to the atmosphere through the roots and stem of the rice plants (hallow like structure) or it is released directly from the field into the atmosphere when the water evaporates

Question 7

how much rice is produced each year

Answer 7

507 million metric tonnes of rice produced in 2020-2021

Question 8

which countries consume the most rice

Answer 8

rice is a staple food in many countries with China consuming more than any other country (155 million metric tonnes in 2021-2022) followed by India (104 million metric tonnes in 2021-2022)

Question 9

how much CH4 (methane) does rice cultivation produce

Answer 9

50-100 million tonnes of CH4 per annum

Question 10

is CH4 more potent then CO2

Answer 10

methane is 25 times more potent as a greenhouse gas then CO2

Question 11

what is the largest contributor to agriculture greenhouse gases

Answer 11

livestock

Question 12

how much emissions does livestock produce

Answer 12

it creates approximately 29% of global CH4 emissions. 9% of CO2 emissions (from respiration, land clearing, processing and transportation) and 65% of nitrous oxide emissions (from manure)

Question 13

how many emissions does livestock account for in Australia

Answer 13

in Australia, direct livestock emissions account for almost 70% of total national greenhouse gas emissions

Question 14

where does methane come from

Answer 14

methane is created from ruminant livestock, such as cows, sheep and goats, which are domesticated animals

Question 15

what is cud

Answer 15

regurgitated food that is continually chewed again

Question 16

what is the CH4 output dependent on

Answer 16

on the number of livestock that we have on earth at any given time.

Question 17

how many cows and sheep are there in 2022

Answer 17

1 billion cows and 1.2 billion sheep

Question 18

CH4 produced by each cow, sheep and pig

Answer 18

sheep=8kg of CH4
cow=60-120 kg of CH4
pig=1.5 kg of CH4

Question 19

how much of the national CH4 productioncis produced from livestock

Answer 19

66%

Question 20

how is methane produced from animals

Answer 20

from these ruminant livestock during their digestive process, which is called enteric fermentation

Question 21

where do methanogen archaea live

Answer 21

the methanogen archaea also live in the cow’s (and their ruminant animals) rumen, which is their first stomach and is responsible for breaking down the grass, making it inedible

Question 22

what is the by-product of this fermentation?

Answer 22

the by-product or waste product from eh archaea breaking down the cellulose in the grass is CH4 which is released through the mouth by belching or when the grass is regurgitated and chewed again

Question 23

what does this methane cause

Answer 23

this CH4 enters the atmosphere and increases the layer of greenhouse gases, trapping more terrestrial radiation- ultimately impacts on the heat budget and the enhanced greenhouse effect