What natural and anthropogenic factors affect climate...?
Interactive Study Guide
false
true
Guiding Question 22.3
What natural and anthropogenic factors affect climate, and which are implicated in the climate change we are experiencing now? How might positive feedback loops affect climate?
Why You Should Care
The Earth’s climate is a complex web of interactions between sun, air, land, and water. The temperature of the Earth has changed over time—just 10,000 years ago, the Earth was emerging from an ice age. The Earth’s temperature is kept warmer by gases that absorb sunlight and heat radiated by the Earth’s surfaces: This is the greenhouse effect.
The greenhouse effect is affected positively and negatively by both natural and anthropogenic factors. Positive factors increase warming by building on themselves and negative factors decrease warming by damping themselves down. Our recent focus on the planet shows us that there are natural cycles (called Milankovitch cycles) that vary over long periods and depend on the Earth’s orbit and tilt on its axis. These cycles can either warm or cool the Earth depending on where they are in the cycle. More recently, we have discovered that anthropogenic (human-caused) factors can affect the greenhouse effect (positively, by increasing greenhouse gas emissions), albedo (negatively, by releasing air pollution to create more clouds), and carbon storage (positively, by deforestation).
Today, the fact is that humans are emitting more greenhouse gases and changing both positive and negative forcers. Both natural and anthropogenic factors are changing, and scientists are working to understand each of these factors in more detail but the net value of the forcers is positive and growing.
Test Your Vocabulary
Choose the correct term for each of the following definitions:
Term
Definition
Molecules in the atmosphere that absorb heat and reradiate it back to Earth.
Changes caused by an initial event that trigger events which then reverse the response (for example, warming leads to events that eventually result in cooling).
Predictable variations in Earth’s position in space relative to the Sun that affect climate.
The ability of a surface to reflect away solar radiation.
Changes caused by an initial event that then accentuate that original event (for example, a warming trend gets even warmer).
Anything that alters the balance of incoming solar radiation relative to the amount of heat that escapes out into space.
The warming of the planet that results when heat is trapped by Earth’s atmosphere.
999
Try again.
Correct.
Incorrect.
1.
Which of the following emissions makes up the greatest percentage of CO2 equivalents?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
2.
What would be the effect of increasing greenhouse gas emissions?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
3.
Which of the following is NOT a major greenhouse gas?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
4.
Which of the following has the lowest albedo?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
5.
Which of the following traps more heat in the troposphere?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
6.
Which of the following demonstrate how positive feedback works?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
7.
Why do positive feedback loops speed up change compared to negative feedback loops?
Positive feedback loops cause more and more change to occur. The changes increase the intensity of the feedback loop and speed the rate of the change. Negative feedback loops decrease the intensity of the feedback and act to slow down change.
8.
Which of the following is NOT a positive forcer?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
9.
Which of the following is NOT a negative forcer?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
10.
If CO2’s positive forcer increased from 1.5 to 2.0 and no other forcer changed, what would the net value of the forcers change to?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
11.
How can positive and negative forcers be added together and have a net positive value?
The important point here is that the net value of all the positive and negative forcers is positive. Positive means an increase in global temperature—a warming. If the negative forcers had a larger value, then the net value would be lower (not as warm) or negative (cooler). Today, the forcers point toward a warming.
12.
Which of the following axial tilt angles causes the MOST heating for the Earth?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
13.
Which of the following cycles affects only one hemisphere?
A.
B.
C.
D.
999
Try again.
Correct.
Incorrect.
14.
Why do scientists say that none of the Milankovitch cycles are influencing the current climate warming?
All three cycles are in mid-phase between warming and cooling, so their net effect is neither warming nor cooling. So any warming must be coming from some other factors.
