Week 2: What is causing the climate to change and are humans responsible

Question 1

Earth is a closed system

Answer 1

: it exchanges energy within its environment, where all the existing matter on earth stays within the system, and no substantial matter is added from outside of the system boundary

Question 2

• Our energy: the sun

Answer 2

• Mass consists of hydrogen (three quarters) the rest mainly helium
  
  • Centre of the sun, pressure is so great that hydrogen atoms that bump into each other fuse together to create helium (nuclear fusion) releases massive amounts of energy that is so hot that it is sent out to space in the form of solar radiation

Question 3

Atmospheric trace gases:

Answer 3

• Water vapor, carbon dioxide CO2, methane CH4 (selective absorbers) as they let solar radiation through the atmosphere but they absorb the outgoing infrared radiation

Question 4

Radiation and energy flows- greenhouse effect

Answer 4

• Global average temperature without atmosphere -18°C
• Global average temperature with atmosphere +15°C
• Natural greenhouse effect +33°C
  
  • Key trace gases: WV, CO2, CH4

Question 5

What is changing in the energy fluxes to cause the observed changes
Three ways for changing the fluxes:

Answer 5

1. Change the amount of energy that in entering the system by changing the amount of radiation that is coming from the sun (change the amount of energy coming from the sun)
   
   2. Alter the concentration of the greenhouse gases in the atmosphere to change the amount of infrared radiation that is absorbed and re emitted by the atmosphere
   3. Alter the character of the earths surface to change how much of the incoming energy is reflected and how much is converted into heat
      Can have natural or human causes (anthropogenic)

Question 6

NEED TO KNOW NUMBER:

Answer 6

Current concentration of CO2 in the atmosphere: 425ppm
Ppm: Parts per million
Similar to percent: parts per hundred

Question 7

Summary
- Understand the basics of the greenhouse effect and the concept of climate forcing (natural + anthropogenic).
- CO2 concentration in atmosphere and its rate of change are unprecedented.
Computer model simulations indicate that our current observations of the climate system are not possible without the human interference.