Lesson 19: An Uncertain Future

Question 1

How much are temperatures predicted to rise by between 2000-2100?

Answer 1

2-6 degrees

Question 2

Give some physical factors making the climate uncertain

Answer 2

-Oceans and forests act as carbon sinks.
-Their response to increased GHG emissions and higher temperatures will continue to affect the global climate for possible hundreds of years
-Deforestation - overall the amount of forested land is on a global decline

Question 3

Give some human factors making the climate uncertain

Answer 3

-Economic growth
-Energy source
-Population change

Question 4

How much did emissions decrease by between 2008-2012/2013?

Answer 4

Down from 4% to 1%

Question 5

How much did emissions fall to by 2014?

Answer 5

0.5%

Question 6

How much did energy consumption grow by between 2008-14?

Answer 6

2%

Question 7

Renewables made up what fraction of the increase in electricity production in 2015

Answer 7

2/3

Question 8

How many more people could there be by 2050? Why?

Answer 8

An extra billion people
Increasing affluence and consumerist economy

Question 9

Who were the largest CO2 emitters by 2014?

Answer 9

China, USA, and India

Question 10

In terms of CO2 per capita, where is China ranked, and how many tonnes is this?

Answer 10

Ranked 55th
6.23 metric tonnes per capita

Question 11

In terms of CO2 per capita, where is the USA ranked, and how many tonnes is this?

Answer 11

USA 8th
17.6 metric tonnes per capita

Question 12

In terms of CO2 per capita, where is India ranked, and how many tonnes is this?

Answer 12

India 127th
1.7 metric tonnes per capita

Question 13

What % loss of soil organic carbon is lost from shallow and deep peat with a 4 degree rise?

Answer 13

40% shallow peat
86% deep peat

Question 14

What process occurs to peat with warming?

Answer 14

Warming causes peat to dry out as water tables fall, increasing decomposition rates and releasing methane

Question 15

Define tipping point

Answer 15

A climate tipping point is a critical threshold whereby a carbon sink could become a carbon source

Question 16

What two phenomena can lead to a tipping point?

Answer 16

Forest die back
Changes to the thermohaline circulation

Question 17

Describe how forest die back can cause a tipping point

Answer 17

Rainfall in the amazon basin is recycled from moisture within the forest. If the rainforest is subject to drought, trees die back.
A tipping point can be reached when the level of die back actually stops the recycling of moisture – resulting in further die back

Question 18

Describe how changes to the thermohaline circulation can cause a tipping point?

Answer 18

Cold, deep water in the North Atlantic forms part of the thermohaline circulation.
To keep the ‘conveyor belt’ of warm water heading from the Tropics towards Britain, heavy, salty water must sink in the north.
However, melting of ice sheets release large amounts of freshwater (less salty meaning its lighter) into the ocean – blocking and slowing the conveyor down.
As ice sheets melt, the ocean circulation is susceptible to a critical tipping point