Question about a warming latency study

[johnbbahm]

Maximum warming occurs about one decade after a carbon dioxide emission
In the study climate models are evaluated,not with an abrupt doubling of the CO2 level,
but with a 100 GtC pulse. There results show a medium sensitivity 0.2K for the 100 GtC pulse.

The question is if the 100 GtC is pre or post airborne fraction, as in did they inject 100 GtC but then realize
the post airborne fraction of ~44% or 44 GtC, or did they simulate the entire 100 GtC increasing the ppm count?

 

[samwinchester]

Forgive me for my stupid question, but is it possible to compensate for the release of carbon dioxide by increasing the number of trees - purely hypothetically

 

[johnbbahm]

Forgive me for my stupid question, but is it possible to compensate for the release of carbon dioxide by increasing the number of trees - purely hypothetically

I do not think you could plant enough trees to stay ahead of the curve.

 

[256bits]

fraction of ~44% or 44 GtC

where does that come from?

 

[johnbbahm]

There are a lot of sources but, NOAA Airborne Fraction describes it best, I think.

"The airborne fraction, AF, is defined as the fraction of anthropogenic carbon emissions which remain in the atmosphere after natural processes have absorbed some of them."

 

[pinball1970]

Forgive me for my stupid question, but is it possible to compensate for the release of carbon dioxide by increasing the number of trees - purely hypothetically

Short answer is no, longer answer below.
https://climate.mit.edu/ask-mit/how-many-new-trees-would-we-need-offset-our-carbon-emissions

 

[johnbbahm]

Short answer is no, longer answer below.
https://climate.mit.edu/ask-mit/how-many-new-trees-would-we-need-offset-our-carbon-emissions

I question the part about a single tree taking in 50 lbs of CO2 per year,
because I have read that the average dry biomass increase per year per tree is about 103kg per year.
This is 226 lbs, cellulose is 44% carbon, so a growing tree needs ~100 lbs of carbon per year.
Sourcing 100 lbs of carbon would require about 365 lbs of CO2.

 

[pinball1970]

I question the part about a single tree taking in 50 lbs of CO2 per year,
because I have read that the average dry biomass increase per year per tree is about 103kg per year.
This is 226 lbs, cellulose is 44% carbon, so a growing tree needs ~100 lbs of carbon per year.
Sourcing 100 lbs of carbon would require about 365 lbs of CO2.

I don’t how accurate those numbers are.

I think the point is while growing more trees and trying to protect ones we have will be helpful to the environment/biosphere, it will not make much of a dint in emissions.

 

[johnbbahm]

I don’t how accurate those numbers are.

I think the point is while growing more trees and trying to protect ones we have will be helpful to the environment/biosphere, it will not make much of a dint in emissions.

I agree, I was simply questioning the 50 lbs of CO2 per year per tree.
Perhaps they meant 50 lbs of carbon, which would be much closer to the 100 lbs of
carbon per year I cam up with.

 

[hutchphd]

I question the part about a single tree taking in 50 lbs of CO2 per year,
because I have read that the average dry biomass increase per year per tree is about 103kg per year.

Did you bother to check the reference? Usually a good plan
https://www.nature.com/articles/nature14967
Particularly note how they define a tree.

 

[johnbbahm]

Did you bother to check the reference? Usually a good plan
https://www.nature.com/articles/nature14967
Particularly note how they define a tree.

10cm diameter at breast height, is a very small tree.

 

[johnbbahm]

Did you bother to check the reference? Usually a good plan
https://www.nature.com/articles/nature14967
Particularly note how they define a tree.

The 50 lbs per year did not come from that reference but from this one.
Trees help tackle climate change
One tree planted has a decent scientific description.
One tree Planted

This was determined by reviewing the planting density of our projects around the world, with an average planting density rate of 1,000/trees per hectare. With carbon estimates, we like to err on the side of being conservative to avoid over inflating the potential benefits, which is why we selected 10 tons per hectare per year. Dividing 10 tons per hectare by 1,000 trees per hectare gets us an average value of 10 kilograms/22 pounds per tree per year.

 

[pinball1970]

where does that come from?

Top graph (max) after 30 years in the first post. Not sure I understand the data at all though. Could @StatGuy2000 have a quick look?

 

[StatGuy2000]

Top graph (max) after 30 years in the first post. Not sure I understand the data at all though. Could @StatGuy2000 have a quick look?

To @pinball1970 and @256bits ,

I see that you have flagged me with a question regarding the plot above. Are you asking me how to interpret the figure above, or where the quoted value of "~44% or 44 GtC" (from the OP) comes from?

If you are asking me the latter question, ~44 = 1 / 2.2 (where the 2.2 mK/GtC is the median value of temperature response, as per the original source code).

If you are asking me the former question, from my naive look, it appears to me that the simulated model indicates that warming peaks after the 30 year period and then gradually wanes with a steady state of approximately 1.8 mK/GtC after the 100 year period.

Please note: I am not an expert on climate models, nor do I have much experience in the statistical analysis on climatology. So I may not be best qualified to provide much input here.

 

[pbuk]

If you are asking me the latter question, ~44 = 1 / 2.2 (where the 2.2 mK/GtC is the median value of temperature response, as per the original source code).

I think that is just a coincidence.

The question is if the 100 GtC is pre or post airborne fraction, as in did they inject 100 GtC but then realize
the post airborne fraction of ~44% or 44 GtC, or did they simulate the entire 100 GtC increasing the ppm count?

If you can't work that out from the paper why ask us? In any case the question is pointless - the point of the paper is when is the peak response to a release of CO2, not how great is that peak in relation to the amount of CO2 released. So whether the median (not medium as you wrote) response of 0.2K [Edit: 0.02K (not 0.2K as you wrote)] is in relation to 100 Gt increase in atmospheric carbon or 100 Gt initial release attenuated to 44 Gt increase in atmospheric carbon (according to the OP's unreferenced assertion) is irrelevant.

 

[johnbbahm]

I think that is just a coincidence.If you can't work that out from the paper why ask us? In any case the question is pointless - the point of the paper is when is the peak response to a release of CO2, not how great is that peak in relation to the amount of CO2 released. So whether the median (not medium as you wrote) response of 0.02K (not 0.2K as you wrote) is in relation to 100 Gt increase in atmospheric carbon or 100 Gt initial release attenuated to 44 Gt increase in atmospheric carbon (according to the OP's unreferenced assertion) is irrelevant.

It goes to the climate sensitivity, it is 0.2K for 100 Gt, that would be a lower sensitivity
compared to 0.2K for a 44 Gt injection.
The graph has a unit of 2.0 per 1000 Gt, so 100 Gt is 0.2.
100 Gt would be an increase of about 47 ppm in the CO2 level,
but 44 Gt would only be 20.6 ppm.
The formulas would look like this is added to todays CO2 level 0.2C /ln(465/418)=1.877,
so 1.877 X ln(2) =1.30C per doubling, vs
0.2C /ln(438.6/418)=4.157, so 4.157 X ln(2)=2.88 C per doubling.
So the difference is sensitivity is quite large.

 

[pbuk]

It goes to the climate sensitivity, it is 0.2K for 100 Gt, that would be a lower sensitivity
compared to 0.2K for a 44 Gt injection.
...
So the difference is sensitivity is quite large.

But what has this got to do with the results and conclusions claimed by the paper which is how fast the climate responds not how much?

The graph has a unit of 2.0 per 1000 Gt, so 100 Gt is 0.2.

Yes of course, sorry (corrected).

 

[johnbbahm]

But what has this got to do with the results and conclusions claimed by the paper which is how fast the climate responds not how much?Yes of course, sorry (corrected).

The conclusion reached in the study is good, because the smaller size emission more closely
resembles how Humans emit CO2, if the average time to maximum warming is about a decade,
then there is minimal warming in the pipeline.
I was attempting to extract the sensitivity from their finding but was had a variable i did not know.

 

[johnbbahm]

I found the answer to my question, they are not counting the Airborne Fraction, but simulate
a 100 GtC pulse directly increasing the ppm level.
A second Study,
The time lag between a carbon dioxide emission and maximum warming increases with the size of the emission
had a footnote where they discussed the conversion from 100 GtC to ppm
Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: A multi-model analysis

The atmospheric CO2 concentration should be increased at the beginning of year 2015 by 47.1032 ppm (100 GtC/2.123 GtC/ppm) in all atmospheric grid cells.

This defines the sensitivity found in the smaller impulse studies.