Climate Sensitivity math problem

In summary: So I would use the maximum amount...In summary, the solar forcing has been .6 watt per square meter, which has increased the temperature by .9 c.
  • #1
courtneywetts
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0

Homework Statement



Using a climate sensitivity of 0.5K per watt per square meter, estimate how much of the .9 c global temperature increase since 1900 could be due to solar forcing who value is the range of .06 to .24 w/m2


Homework Equations





The Attempt at a Solution



I am not sure how to start this problem. I know the solar constant is 239 w/m^2 but don't know what to do with the rest.

I need help getting started
 
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  • #2
What is the minimum value for solar forcing since 1900?
What temperature difference would that account for?
 
  • #3
haruspex said:
What is the minimum value for solar forcing since 1900?
What temperature difference would that account for?

The minimum value for solar forcing would be .06 right?

But how would I know the temperature difference?
 
  • #4
courtneywetts said:
The minimum value for solar forcing would be .06 right?

But how would I know the temperature difference?
You are told climate sensitivity of 0.5K per watt per square meter.
That means, for each extra watt per square meter the temperature rises 0.5K.
If the solar forcing has been 0.6 watt per square meter, how much would that have increased the temperature?
 
  • #5
haruspex said:
You are told climate sensitivity of 0.5K per watt per square meter.
That means, for each extra watt per square meter the temperature rises 0.5K.
If the solar forcing has been 0.6 watt per square meter, how much would that have increased the temperature?

So would this mean I would do .5K x .06W/m^2 ?
 
  • #6
courtneywetts said:
So would this mean I would do .5K x .06W/m^2 ?
More precisely (tracking the units) .5K(Wm-2)-1 x .06(Wm-2) = .5 x .06 K
Now what about the maximum forcing?
 
  • #7
haruspex said:
More precisely (tracking the units) .5K(Wm-2)-1 x .06(Wm-2) = .5 x .06 K
Now what about the maximum forcing?

So for the maximum forcing would I do

.5K x .24 W/m^2?

Is there more to this problem though?
 
  • #8
courtneywetts said:
So for the maximum forcing would I do

.5K x .24 W/m^2?
Please try to get the units right.
Is there more to this problem though?
So how much of the .9C of warming can solar forcing explain? (Might be they're expecting it as a percentage - hard to know.)
 
  • #9
haruspex said:
Please try to get the units right.

So how much of the .9C of warming can solar forcing explain? (Might be they're expecting it as a percentage - hard to know.)

What do you mean by the right units?

And how would I find this as a percentage?
 
  • #10
courtneywetts said:
What do you mean by the right units?
See post #6. You wrote .5K x .24 W/m^2. The sensitivity is not .5K, it's .5K/(W/m2), which could also be written .5K(Wm-2)-1 or .5Km2W-1. When you multiply by solar forcing in units Wm-2 then Wm-2 cancels (Wm-2)-1 to give an answer in K.
And how would I find this as a percentage?
You don't know how to find one number as a percentage of another?
 
  • #11
haruspex said:
See post #6. You wrote .5K x .24 W/m^2. The sensitivity is not .5K, it's .5K/(W/m2), which could also be written .5K(Wm-2)-1 or .5Km2W-1. When you multiply by solar forcing in units Wm-2 then Wm-2 cancels (Wm-2)-1 to give an answer in K.

You don't know how to find one number as a percentage of another?

Would I do .06 W/m^2 x .5K =.03K

and .24 W/m^2 x .5K= .12 K

and then do .03K/.12 K= .25K or 25%?
 
  • #12
courtneywetts said:
Would I do .06 W/m^2 x .5K =.03K

and .24 W/m^2 x .5K= .12 K
No. You are given:
Climate sensitivity = .5K per W per m2. That means .5 K(Wm-2)-1, or more simply .5 KW-1m2.
Solar forcing = .24 Wm-2.
Climate sensitivity * Solar forcing = .5 KW-1m2 * .24 Wm-2, which simplifies to (.5 * .24) K. That's reasonable because the answer should be a temperature.
You wrote .24 W/m2 x .5K. That would give the result (.5 * .24) KWm-2, which is not a temperature.
Do you see the difference?
and then do .03K/.12 K= .25K or 25%?
No. You have calculated the minimum and maximum temperature rises that could have come from solar forcing. You are asked what portion of the observed .9 C rise could be a result of solar forcing, i.e. the largest possible portion.
 
  • #13
haruspex said:
No. You are given:
Climate sensitivity = .5K per W per m2. That means .5 K(Wm-2)-1, or more simply .5 KW-1m2.
Solar forcing = .24 Wm-2.
Climate sensitivity * Solar forcing = .5 KW-1m2 * .24 Wm-2, which simplifies to (.5 * .24) K. That's reasonable because the answer should be a temperature.
You wrote .24 W/m2 x .5K. That would give the result (.5 * .24) KWm-2, which is not a temperature.
Do you see the difference?

No. You have calculated the minimum and maximum temperature rises that could have come from solar forcing. You are asked what portion of the observed .9 C rise could be a result of solar forcing, i.e. the largest possible portion.



So I would use the maximum amount to find the ration? This would be .12K right?

How would I then use the .9 C. This is also in Celsius so would I need to convert?
 
  • #14
courtneywetts said:
So I would use the maximum amount to find the ration? This would be .12K right?

How would I then use the .9 C. This is also in Celsius so would I need to convert?

The .12K and the .9C are both changes in temperature. The K and C scales only differ by a constant, so a change of some number of degrees C is a change of the same number of degrees K. No conversion to be done.
 
  • #15
haruspex said:
The .12K and the .9C are both changes in temperature. The K and C scales only differ by a constant, so a change of some number of degrees C is a change of the same number of degrees K. No conversion to be done.

How would I go about finding this then?
 
  • #16
courtneywetts said:
How would I go about finding this then?
Finding what? .12 as a percentage of .9?
 
  • #17
haruspex said:
Finding what? .12 as a percentage of .9?

Would I put this into a ratio? If so how would I set this up?
 
  • #18
courtneywetts said:
Would I put this into a ratio? If so how would I set this up?
You don't now how to find a percentage? If you invest $100 and get back $105 you've made $5 profit. What percentage did you earn?
 

1. What is climate sensitivity?

Climate sensitivity refers to the amount of warming that can be expected from a doubling of carbon dioxide concentrations in the Earth's atmosphere. It is a measure of how sensitive the Earth's climate is to changes in atmospheric greenhouse gas levels.

2. Why is the climate sensitivity math problem important?

The climate sensitivity math problem is important because it helps us understand how much the Earth's temperature will change in response to increasing levels of greenhouse gases. This information is crucial for predicting and planning for future climate change.

3. How is climate sensitivity calculated?

Climate sensitivity is typically calculated using complex climate models that simulate the Earth's climate system. These models take into account various factors such as atmospheric composition, ocean heat uptake, and feedback mechanisms to estimate the amount of warming that can be expected from a doubling of carbon dioxide.

4. What is the current estimate for climate sensitivity?

The current estimate for climate sensitivity is between 1.5°C to 4.5°C, with a best estimate of around 3°C. However, there is still uncertainty in this estimate due to the complexity of the Earth's climate system and the limitations of climate models.

5. How does climate sensitivity impact climate change projections?

The higher the climate sensitivity, the more severe the projected impacts of climate change will be. A higher climate sensitivity means that the Earth's temperature will increase more in response to increasing greenhouse gas levels, leading to more extreme weather events, sea level rise, and other consequences of climate change.

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