Lecture 13: Climate Change

Question 1

Explain what the greenhouse effect is

Answer 1

Shortwave radiation (insolation) passes through the atmosphere to the surface where it is absorbed.

The surface emits longwave radiation which is selectively absorbed in the atmosphere (by greenhouse gases and clouds).

The atmosphere in turn emits longwave radiation, much of which is directed towards the surface.

Thus, the surface receives energy from the Sun and the atmosphere (as there is a cycling of energy between the surface and

Question 2

What is the outcome of the greenhouse effect?

Answer 2

An increase in radiant energy retained in the system and warming of the planet surface, oceans and the lower atmosphere, often called global warming

Question 3

What are the 5 primary greenhouse gasses?

Answer 3

• water vapour (H2O)
• carbon dioxide (CO2)
• methane (CH4)
• nitrous oxide (N2O)
• CFC’s and others

Question 4

Fossil-fuel combustion, industrial processes, deforestation and other human activities have increased our output of ______ to the atmosphere in recent decades.

Answer 4

carbon dioxide

Question 5

What are the 4 mechanisms of natural climate change?

Answer 5

Solar variability
Earth’s orbital cycles
Continental position and Topography
Atmospheric gasses and aerosols

Question 6

What are sources of methane related to human activities (anthropogenic)?

Answer 6

include livestock and rice cultivation, burning, natural gas delivery, landfills and coal mining.

Question 7

At what percent did the methane and nitrous oxide concentrations raise since the mid 1700s.

Answer 7

150% methane, 15% nitrous oxide

Question 8

How do we measure climate change?

Answer 8

Use instrumental records from climate stations and ocean observations

Question 9

How can we determine the significance of the current warming?

Answer 9

Examine climates of the past

Question 10

What are sources of paleoclimatic data that can be used to reconstruct climates in the past.

Answer 10

Tree-Rings, Pollen, Stable Isotopes, Speleothems, Lake Sediments

Question 11

How can we predict the likely future change in climate?

Answer 11

By modeling future climate, such as a GCM (general circulation models or global climate models)

Question 12

_____ is a technique for long-term climatic reconstruction that uses the atomic structure of chemical elements, specifically the relative amounts of their isotopes, to identify the chemical composition of past oceans and ice masses.

Answer 12

Isotope analysis

Question 13

When looking at tree rings, wider rings relate to ____ growth and narrow rings refer to _____ growth.

Answer 13

Good, bad

Question 14

The term radiative ______, also called climate ______, describes the amount by which some perturbation causes Earth’s energy balance to deviate from zero; a positive forcing indicates a warming condition, a negative forcing indicates cooling.

Answer 14

forcing

Question 15

True or False Volcanic eruptions generate aerosols which have a warming effect.

Answer 15

false, cooling effect

Question 16

What are some strategies you can employ to reduce climate change?

Answer 16

Reduce fuel consumption
Use CFL light bulbs
Eat less meat
Planting trees