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kassy

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Where are we now in CO2e , which pathway are we on?
« on: January 24, 2020, 11:45:57 PM »
Recently there was a request in the Moana Loa CO2 thread for a CO2e calculation and it looks like it can be done.

Basically it combines the updates from the CO2, NH4 and other greenhouse gas threads.

We can use this number and then maybe also use it to check which RCP we are following.

It might be interesting to include other metrics like the carbon clock.

*

First data post comes tomorrow.
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Ken Feldman

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #1 on: January 25, 2020, 01:09:16 AM »
Details of the RCPs are included in the technical annex to the IPCC Working Group I Report for AR5 published in 2013 available at this link:

 https://www.ipcc.ch/site/assets/uploads/2017/09/WG1AR5_AnnexII_FINAL.pdf

Tables for concentrations start on page 1422.

For CO2, the RCP 2.6 concentration in 2020 is 412.1 ppm and the RCP 8.5 concentration is 415.8 ppm.

According to NOAA, the global (which is what should be used, not the Mauna Loa which isn't comparable to global concentrations) CO2 concentration in January 2020 is about 411 ppm. 



So CO2, which is almost 2/3 of the radiative forcing, is under the RCP 2.6 concentration.  Unfortunately, methane, the next highest contributor to the greenhouse effect at 16%, isn't doing as well.

For RCP 2.6 the 2020 concentration of CH4 is 1731 ppb and the RCP 8.5 number is 1924 ppb.  According to NOAA, we're about 1870 ppb.



For N2O (about 6% of the GHG forcing)  the concentrations at RCP 2.6 and 8.5 are 323 and 332 ppb respectively.  NOAA shows us just above 332 ppb.

That's roughly 90% of the GHG forcings summarized.  The big one, CO2 is less than RCP 2.6 and is projected to decrease relatively rapidly compared to the RCPs due to the decline of coal.  CH4 is between RCP 2.6 and 8.5 and will also decrease rapidly as coal mining declines and natural gas and oil are phased out over the next three decades.  Since the lifetime of CH4 is about 12 years, when emissions decrease concentrations will quickly follow.  N2O is tied to agricultural fertilizers and isn't projected to stabilize until global populations level out (at 344 ppb in the later half of this century under RCP 2.6, it keeps growing under the other RCPs).

wdmn

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #2 on: January 25, 2020, 06:09:44 AM »
<snip, no need for this at all, don't do it again, please; N.>

You know Jan concentrations are not reflective of what the year average will be.
« Last Edit: January 27, 2020, 07:27:18 PM by Neven »

sidd

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #3 on: January 25, 2020, 07:42:55 AM »
Re: RCP 2.6 concentration in 2020 is 412.1 ppm and the RCP 8.5 concentration is 415.8 ppm.

We will not be able to tell which CO2 path we are on for a decade or so.
all RCPs are very close to each other, difference comparable to noise.

and i see no reason to denigrate Mr Feldman. nowhere does he say that january numbers are the ones to compare.

sidd

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #4 on: January 25, 2020, 07:57:55 AM »
and i see no reason to denigrate Mr Feldman. nowhere does he say that january numbers are the ones to compare.

This!

Is Ken overly optimistic? Imho yes. But is that a reason to be so harsh? Of course not. His arguments are mostly sound.
Unlearn things daily.

El Cid

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #5 on: January 25, 2020, 08:36:31 AM »
I think there is reason to be optimistic. During the past 10-15 years solar and wind became economically sound proposals and this shows up in the quickly changing expectations - noone expected such a strong change so quickly (the below chart is telling me that Co2emissions are likely topping out in the 2020s to start going down thereafter:

Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #6 on: January 25, 2020, 08:43:57 AM »
Re-posted from the 2020 Mauna Loa CO2 thread:
Thank you Stephan. Since you are regularly updating several GHG readings, would it be possible to add a CO2e figure?
In that way we'll have the cumulative GHG effect updated. I know it depends on assumptions but you can put those in.
nanning,
I will do it in the next time. I have the monthly reading of four gas concentrations (CO2, CH4, N2O and SF6) on my PC, in different files, and I can put them together.
I did it, but the sum differs from what I saw from gerontocrat's posting further upthread where he provides NOAA's annual table.
I took the monthly concentrations (beginning from 2000 on, before that date I do not have all the four gases) and multiplied CH4 with the factors 85 (20 years) and 28 (100 years), N2O with 264 (20 & 100 years), and finally SF6 with 17500 (20 years) and 23500 (100 years), using the conversion factors from the later IPCC report. Then I looked up the definition of these CO2 equivalents, which are not given in moles, but in kg and converted the numbers by taking their molecular weight.
I end up with the latest data (Sep 2019) with the following values (100 years equivalent):
CO2: 408.54
CH4:   19.05
N2O:   87.65
SF6    0.78
sum: 516.01
This sum is higher than the CO2 eq given further upthread. Also the proportions of the ratio CH4 to N2O differs completely from NOAA's table. Where is the error?
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #7 on: January 25, 2020, 11:19:20 AM »
I think there is reason to be optimistic. During the past 10-15 years solar and wind became economically sound proposals and this shows up in the quickly changing expectations - noone expected such a strong change so quickly (the below chart is telling me that Co2emissions are likely topping out in the 2020s to start going down thereafter:
The danger is that we may hit tipping points and feedbacks in this decade.
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wdmn

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #8 on: January 25, 2020, 01:33:57 PM »
...

and i see no reason to denigrate Mr Feldman. nowhere does he say that january numbers are the ones to compare.

sidd

He stated twice that we are below RCP 2.6 based on 411ppm
That is an inaccurate statement, and he knows it. How is it harsh to call him out on that? Ken's a smart guy, he knows what he's doing.

At this time of year the honest thing to do would be to report 2019 numbers, which would of course show that we are above RCP 2.6. I will call out such bullshit every time, and I would hope people would call me out for my bullshit too.
« Last Edit: January 25, 2020, 02:09:42 PM by wdmn »

nanning

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #9 on: January 25, 2020, 02:26:57 PM »
^^
I agree with wdmn.
But I don't like "... shit".
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nanning

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #10 on: January 25, 2020, 02:47:16 PM »
Stephan, could you please post your calculation and the numbers you used?

You mention different factors for GHG's but there is only 1 column in your table. I would have expected several CO2e numbers based on those factors.

Your CH4 seems much too low.
I have done it like this:

https://www.esrl.noaa.gov/gmd/ccgg/trends/monthly.html
dec2020 CO₂ 412 ppm                 =   412    ppm

https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/
sep2019 CH4    1.8705 ppm * 85 =  158.99 ppm (85)
                          1.8705 ppm * 28 =    52.37 ppm (20)

https://www.esrl.noaa.gov/gmd/hats/combined/N2O.html
dec2020 N₂O      0.332 ppm * 264 =   87.6 ppm

Total CO2e  equivalent                        -------- +
                                                      658.6  ppm CO2e (85)
                                                      552.0  ppm          (20)
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AbruptSLR

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #11 on: January 25, 2020, 03:37:22 PM »
...

and i see no reason to denigrate Mr Feldman. nowhere does he say that january numbers are the ones to compare.

sidd

He stated twice that we are below RCP 2.6 based on 411ppm
That is an inaccurate statement, and he knows it. How is it harsh to call him out on that? Ken's a smart guy, he knows what he's doing.

At this time of year the honest thing to do would be to report 2019 numbers, which would of course show that we are above RCP 2.6. I will call out such bullshit every time, and I would hope people would call me out for my bullshit too.

As far as I remember, the annual values for well mixed GHG atmospheric concentrations given in the RCP scenarios is for mid-year (i.e. the end of June not January), thus wdmn has a valid point as there is a clear trendline for WMGHG concentrations, so on average these concentrations will be higher in June than in January regardless of variability.  Thus going forward I would recommend that this thread evaluation values for June if it wants to compare with RCP values.

Edit:  With a hat tip to gerontocrat, the UK MetOffice has project the comparable Mauna Loa CO2 concentration value for 2020, see the red * on the attached image on the trendline at the end of June, from the linked website:

The complete MetOffice forecast is at
https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/long-range/forecasts/co2-forecast

Extract: "We forecast the annual average CO2 concentration at Mauna Loa to be 2.74 ± 0.57 parts per million (ppm) higher in 2020 than in 2019 (Figure 1). This will continue the rising trend in CO2 seen in the long-term record of measurements from the Mauna Loa observatory in Hawaii that date back to 1958 and are a good guide to global CO2 levels. As a result, we forecast the 2020 annual average CO2 concentration at Mauna Loa to be 414.2 ± 0.6 ppm. For the first time, monthly CO2 levels will exceed 415 ppm (during spring and summer) and will remain above 410 ppm for the entire year."
« Last Edit: January 25, 2020, 03:47:52 PM by AbruptSLR »
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kassy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #12 on: January 25, 2020, 08:59:05 PM »
Thus going forward I would recommend that this thread evaluation values for June if it wants to compare with RCP values.

Thanks , good point.

*

And on a general note please attack the arguments not the posters since that detracts from the discussion.

Trash the argument.

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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #13 on: January 25, 2020, 09:26:33 PM »
Stephan, could you please post your calculation and the numbers you used?
I re-calculate for June 2019 (recommended by ASLR)
CO2
concentration 413.92 ppm
factor 1
resulting 413.92 ppm CO2 eq

CH4
concentration 1.8596 ppm
factors 84 (20 y) and 28 (100 y)
resulting 156.21 or 52.07 ppm CO2 eq
adjusting mole weight 56.80 or 18.93 ppm CO2 eq.
→ this was one of my questions whether this has to be done or is it already implemented in the GHG factor? This makes my CH4 value so low


N2O
concentration 0.3318 ppm
factor 264 (I didn't use factor 265 for 100 y, so I used 264 for both times)
resulting 87.60 ppm CO2 eq
no adjust of mole weight necessary

SF6
concentration 0.00093 ppm
factors 17,500 (20 y) or 23,500 (100 y)
resulting 0.17 or 0.23 CO2 eq
adjusting mole weight 0.58 or 0.77 ppm CO2 eq
(same question as above, makes SF6 value much higher because it is so heavy)


The sum of the bold written black lines gives me the same value as yours, nanning (apart from the different month used) 657.90 ppm CO2 eq (20 y) or 553.82 ppm CO2 eq (100 y)
Including the mole weights the values are lower: 558.89 ppm CO2 eq (20 y) or 521.22 ppm CO2 eq (100 y)
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #14 on: January 25, 2020, 09:49:10 PM »
While writing these lines a further question came into my mind:
Is a simple addition right at all? Maybe the IR spectra of the molecules (especially CO2 and N2O) overlap and reduce each other by some interference?
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gerontocrat

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #15 on: January 25, 2020, 10:13:25 PM »

adjusting mole weight 56.80 or 18.93 ppm CO2 eq.
→ this was one of my questions whether this has to be done or is it already implemented in the GHG factor? This makes my CH4 value so low


The link seems to say the GWP ratio is based on WEIGHT
_____________________________________
https://climatechangeconnection.org/emissions/co2-equivalents/
The three main greenhouse gases (along with water vapour) and their 100-year global warming potential (GWP) compared to carbon dioxide are: (1)

1 x – carbon dioxide (CO2)
25 x – methane (CH4) – I.e. Releasing 1 kg of CH4 into the atmosphere is about equivalent to releasing 25 kg of CO2
298 x – nitrous oxide (N2O) – I.e. Releasing 1 kg of N2O into the atmosphere is about equivalent to releasing 298 kg of  CO2
__________________________________________

So I think this is the correct (?) result from your calculation
Including the mole weights the values are lower:
558.89 ppm CO2 eq (20 y) or 521.22 ppm CO2 eq (100 y)


ps: I have to go back to my spreadsheets to ciorrect them,

pps: The NOAA calculation of CO2e /AGGI does not include SF6 which is becoming significant,

ppps: CFC 11 & 12 that are in the NOAA CO2e /AGGI calculation and together as significant as N20. But how they do that I do not know.
https://www.esrl.noaa.gov/gmd/aggi/ & https://www.esrl.noaa.gov/gmd/aggi/aggi.html


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Tom_Mazanec

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #16 on: January 25, 2020, 10:24:38 PM »
Don’t forget the halocarbons.
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #17 on: January 25, 2020, 10:31:13 PM »
Don’t forget the halocarbons.
I didn't mention them because I only took the four "NOAA gases" that are reported on https://www.esrl.noaa.gov/gmd/ccgg/trends/index.html in a regular way. Of course the halocarbons are relevant and must be included into any realistic calculation of the GHG in Earth's atmosphere.
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RoxTheGeologist

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #18 on: January 25, 2020, 11:53:48 PM »
While writing these lines a further question came into my mind:
Is a simple addition right at all? Maybe the IR spectra of the molecules (especially CO2 and N2O) overlap and reduce each other by some interference?

The overlapping (or not) of spectra is already built into the GWP.

One think I am not sure of is if aviation emissions are counted correctly, as they are largely in the stratosphere.

AbruptSLR

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #19 on: January 26, 2020, 12:15:21 AM »
Don’t forget the halocarbons.

The total radiative forcings, RFs, from the linked ORNL website article by Blasing, T.J. (that updates such RF values reported in April 2016, see the attached table) are used in the linked Wikipedia article to calculate a CO2e value of 526.6ppm.  This relatively high value of for CO2e appears to be associated with RF associated with tropospheric ozone and its chemical interaction in the atmosphere with GHGs like methane.

https://en.wikipedia.org/wiki/Carbon_dioxide_equivalent


Extract: "To calculate the CO2e of the additional radiative forcing calculated from April 2016's updated data: ∑ RF(GHGs) = 3.3793, thus CO2e = 280 e3.3793/5.35 ppmv = 526.6 ppmv."

Title: "Recent Greenhouse Gas Concentrations" by Blasing, T.J., 2016, DOI: 10.3334/CDIAC/atg.032

http://cdiac.ornl.gov/pns/current_ghg.html
« Last Edit: January 26, 2020, 12:34:13 AM by AbruptSLR »
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #20 on: January 26, 2020, 08:00:26 AM »
If I use the radiative forcing from the table and compare that to the concentration of each GHG for 2016 I calculated the following factors with which the concentration has to be multiplied to achieve that radiative forcing:
CO2 = 1 (per definition)
CH4 = 57
N2O = 128
SF6 = 116,000
Using these factors one can adjust the concentration table to the radiative forcing of each gas.
_____________

Question: In the ORNL table there is the line: "increased radiative forcing". If I take this seriously, I subtracted the pre-industrial values from the actual values and receive new, modified factors:
CO2 = 1 (per definition)
CH4 = 28
N2O = 213
SF6 = 34,100
Is this a better way to calculate the CO2 eq?
« Last Edit: January 26, 2020, 08:41:59 AM by Stephan »
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nanning

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #21 on: January 26, 2020, 10:50:22 AM »
From: https://en.wikipedia.org/wiki/Carbon_dioxide_equivalent
    Carbon dioxide equivalent

Global warming potential

Carbon dioxide equivalency is a quantity that describes, for a given mixture and amount of greenhouse gas, the amount of CO
2 that would have the same global warming potential (GWP), when measured over a specified timescale (typically 100 years). Carbon dioxide equivalency thus reflects the time-integrated radiative forcing of a quantity of emissions or rate of greenhouse gas emission—a flow into the atmosphere—rather than the instantaneous value of the radiative forcing of the stock (concentration) of greenhouse gases in the atmosphere described by CO2e.

The carbon dioxide equivalency for a gas is obtained by multiplying the mass and the GWP of the gas
For example, the GWP for methane over 100 years is 34,[3] and for nitrous oxide, 298. This means that emissions of 1 million tonnes of methane or nitrous oxide are equivalent to emissions of 34 or 298 million tonnes of carbon dioxide, respectively.


Equivalent carbon dioxide

Equivalent CO2 (CO2e) is the concentration of CO2 that would cause the same level of radiative forcing as a given type and concentration of greenhouse gas. Examples of such greenhouse gases are methane, perfluorocarbons, and nitrous oxide. CO2e is expressed as parts per million by volume, ppmv.

    CO2e calculation examples:

The radiative forcing for pure CO2 is approximated by R F = α ln(C/C0) where C is the present concentration, α is a constant, 5.35, and C0 is the pre-industrial concentration, 280 ppm. Hence the value of CO2e for an arbitrary gas mixture with a known radiative forcing is given by C0 exp(R F/ α) in ppmv.

To calculate the radiative forcing for a 1998 gas mixture, IPCC 2001 gives the radiative forcing (relative to 1750) of various gases as: CO2=1.46 (corresponding to a concentration of 365 ppmv), CH4=0.48, N2O=0.15 and other minor gases =0.01 W/m2. The sum of these is 2.10 W/m2. Inserting this to the above formula, we obtain CO2e = 412 ppmv.

To calculate the CO2e of the additional radiative forcing calculated from April 2016's updated data:[5] ∑ RF(GHGs) = 3.3793, thus CO2e = 280 exp(3.3793/5.35) ppmv = 526.6 ppmv.
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Aporia_filia

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #22 on: January 26, 2020, 12:15:52 PM »
Here you have another unexpected parameter in the equation: HFC-23 the most potent greenhouse that should have been controlled under actual legislation.

https://www.nature.com/articles/s41467-019-13899-4

"Starting in 2015, India and China, thought to be the main emitters of HFC-23, announced ambitious plans to abate emissions in factories that produce the gas. As a result, they reported that they had almost completely eliminated HFC-23 emissions by 2017.

In response to these measures, scientists were expecting to see global emissions drop by almost 90 percent between 2015 and 2017, which should have seen growth in atmospheric levels grind to a halt.

Now, an international team of researchers have shown, in a paper published today in the journal Nature Communications, that concentrations were increasing at an all-time record by 2018.

Dr Matt Rigby, who co-authored the study, is a Reader in Atmospheric Chemistry at the University of Bristol and a member of the Advanced Global Atmospheric Gases Experiment (AGAGE), which measures the concentration of greenhouse gases around the world, said: "When we saw the reports of enormous emissions reductions from India and China, we were excited to take a close look at the atmospheric data.

"This potent greenhouse gas has been growing rapidly in the atmosphere for decades now, and these reports suggested that the rise should have almost completely stopped in the space of two or three years. This would have been a big win for climate.""

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #23 on: January 26, 2020, 06:58:17 PM »
If I use the radiative forcing from the table and compare that to the concentration of each GHG for 2016 I calculated the following factors with which the concentration has to be multiplied to achieve that radiative forcing:
CO2 = 1 (per definition)
CH4 = 57
N2O = 128
SF6 = 116,000
Using these factors one can adjust the concentration table to the radiative forcing of each gas.
_____________

Question: In the ORNL table there is the line: "increased radiative forcing". If I take this seriously, I subtracted the pre-industrial values from the actual values and receive new, modified factors:
CO2 = 1 (per definition)
CH4 = 28
N2O = 213
SF6 = 34,100
Is this a better way to calculate the CO2 eq?

In the Wikipedia approximation for the data published on April 2016 (but for 2015, from January 2015 through December 2015),  CO2e = 280 exp(3.3793/5.35) ppmv = 526.6 ppmv, the value of 280ppmv correlates the modern value of radiative forcing to the pre-industrial condition.  Thus to determine CO2e for 2019 one can wait until April 2020 when NOAA publishes their radiative forcing values for well mixed GHG and add in the radiative forcing for tropospheric ozone into this formula and you will have a value for 2019 to compare with the RCP values
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #24 on: January 26, 2020, 08:18:26 PM »
….
In the Wikipedia approximation for the data published on April 2016 (but for 2015, from January 2015 through December 2015),  CO2e = 280 exp(3.3793/5.35) ppmv = 526.6 ppmv, the value of 280ppmv correlates the modern value of radiative forcing to the pre-industrial condition.  Thus to determine CO2e for 2019 one can wait until April 2020 when NOAA publishes their radiative forcing values for well mixed GHG and add in the radiative forcing for tropospheric ozone into this formula and you will have a value for 2019 to compare with the RCP values

For example, the attached NOAA table gives the radiative forcing for well mixed GHG in 2018 as 3.101 and adding the radiative forcing for tropospheric ozone as 0.4 gives 3.5101, which per the equation gives CO2e, in 2018, an approximate value of 538.7 ppmv
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oren

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #25 on: January 26, 2020, 10:08:16 PM »
Quote
Carbon dioxide equivalency is a quantity that describes, for a given mixture and amount of greenhouse gas, the amount of CO
2 that would have the same global warming potential (GWP), when measured over a specified timescale (typically 100 years). Carbon dioxide equivalency thus reflects the time-integrated radiative forcing of a quantity of emissions or rate of greenhouse gas emission—a flow into the atmosphere—rather than the instantaneous value of the radiative forcing of the stock (concentration) of greenhouse gases in the atmosphere described by CO2e.
I normally don't question established science but I think this 100-yr approach is wrong. As we track GHG concentrations, none of them has been faliing. We are obviously on a path where new emissions (both anthropogenic and natural feedbacks) are sufficient to maintain and even increase concentrations, regardless of sinks and destructive processes in the atmosphere. Thus the proper calculation should be the "instantaneous value of the radiative forcing of the stock (concentration) of greenhouse gases in the atmosphere". Assume this level is maintained going forward, to understand our current situation.
« Last Edit: January 27, 2020, 01:23:26 AM by oren »

Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #26 on: January 26, 2020, 10:46:39 PM »
oren,
I strongly support your opinion about the "instantaneous" GHG effect as all GHG concentrations (not sure whether this is true for all the halocarbons) increase for many decades now.
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #27 on: January 27, 2020, 05:21:20 AM »
I, too, agree, Oren.  Half-life (or equivalent) calculations are useful when 'exposure' will decline at known rates but when 'exposure' (e.g., continued release of methane and other greenhouse (GH) gasses by industry, etc.) is expected to go up or stay somewhat steady, half-life calculations don't make much sense ... unless the calculations include both expected new releases (all sources) and half-life attributes of those GH gasses.  However, our handle on future emissions of the various greenhouse gasses is probably not very clear (1.5 to 4 ppm or whatever CO2 levels?).

Remember those algebra problems about the bathtub with the open drain and turned-on faucets, only with ACC we don't know how the inflows will change over time, and some outflows get less efficient the warmer the ocean gets.
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wolfpack513

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #28 on: January 27, 2020, 01:43:02 PM »
Instantaneous CO₂ equivalent is basically why NOAA/ESRL created AGGI.  The AGGI is made up of all the major GHGs and even the 15 minor GHGs.

2019 data hasn't been added yet but through 2018, radiative forcing is currently 3.1 Watts/m² above pre-industrial.  https://www.esrl.noaa.gov/gmd/aggi/aggi.html
 
« Last Edit: January 27, 2020, 02:32:26 PM by wolfpack513 »

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #29 on: January 27, 2020, 03:59:40 PM »
So we added as much forcing in the last 40 years as in the entire previous history.
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #30 on: January 27, 2020, 04:37:04 PM »
Well all of these measures are helpful I think it's important to consider the CO2e assuming a higher multiplier.

RF is a great measure (and reminds us to account for negative forcings), but most people have been trained to think in terms of a doubling of CO2 concentration, and all the modelling is done around ECS and TCR. We need to know how close we are to doubling, (or how long ago we doubled) to start making sense of how much risk we've already exposed ourselves too, I think... Otherwise why do we keep looking at CO2 concentration? We should just be looking at RF.

oren

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #31 on: January 27, 2020, 05:03:48 PM »
Thing is, while we haven't doubled CO2 (yet) we have greatly increase methane concentration and are busy maintaining it in the face of atmospheric destruction processes. The big question in calculating CO2eq is and has always been the methane question. So a higher multiplier is in order, but what should the multiplier be?

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #32 on: January 27, 2020, 05:08:44 PM »
I doubt this is taken into account here, but as the air warms it can hold more water vapor, which is itself a GHG, right?
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #33 on: January 27, 2020, 05:21:18 PM »
Thanks wdmn, very good observation in my view.
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #34 on: January 27, 2020, 05:48:08 PM »
Well all of these measures are helpful I think it's important to consider the CO2e assuming a higher multiplier.

RF is a great measure (and reminds us to account for negative forcings), but most people have been trained to think in terms of a doubling of CO2 concentration, and all the modelling is done around ECS and TCR. We need to know how close we are to doubling, (or how long ago we doubled) to start making sense of how much risk we've already exposed ourselves too, I think... Otherwise why do we keep looking at CO2 concentration? We should just be looking at RF.

First, while it may be the case that this thread was created to focus on CO2e as calculated as a well mixed gas, and on the increasing emissions of methane and nitrous oxide; I note that CMIP6 models do consider scenarios with increasing methane and nitrous oxide emissions (such as SSP5) which provide projections of GMSTA that are relatively high in the coming decades (see the first attached image).

Second, the CMIP6 projections significantly underestimate the RF from ice-climate feedback mechanisms (say from a release of relatively warm & fresh water from the Beaufort Gyre in the next decade, or so, triggering a collapse of significant portions of the WAIS via the bipolar seesaw mechanisms) as indicated by the second attached image (see the gold curve assuming a 5-year doubling time).  Which this indicated increase in RF from such large freshwater hosing events might only last for a few decades, that period of time might be sufficient to push the NH atmosphere into an equable pattern before 2100.

I plan to stop posting in this thread after this post (so as not to highjack the main focus) but I think that it is important to realize that RF threat from ice-climate feedback is real (the already large amount warm fresh water still accumulating in the Beaufort Gyre will be released before too long) and is not fully accounted for by any consensus climate model projection.
« Last Edit: January 27, 2020, 06:55:06 PM by AbruptSLR »
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Ken Feldman

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #35 on: January 27, 2020, 06:23:35 PM »
...

and i see no reason to denigrate Mr Feldman. nowhere does he say that january numbers are the ones to compare.

sidd

He stated twice that we are below RCP 2.6 based on 411ppm
That is an inaccurate statement, and he knows it. How is it harsh to call him out on that? Ken's a smart guy, he knows what he's doing.

At this time of year the honest thing to do would be to report 2019 numbers, which would of course show that we are above RCP 2.6. I will call out such bullshit every time, and I would hope people would call me out for my bullshit too.

As the point of this exercise it to attempt to get a more current estimate of total forcings, I thought I would use the most current data available.  On NOAA's website, the most recent annual data is from 2018 (which is a global average of 407.38 ppm).

Mauna Loa is in the northern hemisphere which has the largest GHG emitters.  The Southern Ocean, which is one of the largest CO2 sinks, is in the Southern Hemisphere.  And the difference between the annual global average at Mauna Loa and the global average reported by  NOAA is evident from the data.

Year   Mauna Loa Avg (ppm)  Global Avg (ppm)
2019             411.44             Not yet available
2018             408.52                       407.38 
2017             406.55                       405.00
2016             404.24                       402.85
2015             400.83                       399.41

You can see that the Mauna Loa average is consistently higher than the global average, but that the amount differs from year to year.  So if you want to use the Mauna Loa data, you'd have to correct to get the global forcings.  However, the correction factor wouldn't be available until the global average is reported in spring of the following year.

Ken Feldman

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #36 on: January 27, 2020, 06:29:55 PM »
Either I missed this before or NOAA just added it, but there's a new feature on their website for Trends in CO2 covering the daily Global CO2.  It shows the global average as well as readings from several observation sites.

https://www.esrl.noaa.gov/gmd/ccgg/trends/gl_trend.html


kassy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #37 on: January 27, 2020, 07:52:30 PM »
I plan to stop posting in this thread after this post (so as not to highjack the main focus) but I think that it is important to realize that RF threat from ice-climate feedback is real

Thanks for some key remarks (#11). Do post here if something pertinent comes up.

I am really interested in the difference between our scenarios and the actual earth systems but more of that on the other thread. Nice timing on the Beaufort Gyre reposts btw.  :)

You can see that the Mauna Loa average is consistently higher than the global average, but that the amount differs from year to year.  So if you want to use the Mauna Loa data, you'd have to correct to get the global forcings.  However, the correction factor wouldn't be available until the global average is reported in spring of the following year.

Basically the comparison is yearly.

All the non CO2 updates were monthly and they do not vary that much.

Technically that looks like less work (or a whole lot more if you really want to dive into it).

I normally don't question established science but I think this 100-yr approach is wrong. As we track GHG concentrations, none of them has been faliing. We are obviously on a path where new emissions (both anthropogenic and natural feedbacks) are sufficient to maintain and even increase concentrations, regardless of sinks and destructive processes in the atmosphere. Thus the proper calculation should be the "instantaneous value of the radiative forcing of the stock (concentration) of greenhouse gases in the atmosphere". Assume this level is maintained going forward, to understand our current situation.

It would be interesting to see the difference between using the two values.


 

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #38 on: January 27, 2020, 09:49:29 PM »
Either I missed this before or NOAA just added it, but there's a new feature on their website for Trends in CO2 covering the daily Global CO2.  It shows the global average as well as readings from several observation sites.
I do not see a fundamental difference in these readings. Barrow has a much larger intra-year fluctuation than the very smooth South Pole data. But in the end the slope of all these graphs is identical. I do not think that we should discuss whether the global average is 408.53 or 407.92 or 406.05 ppm. It is the annual increase (and the positive 2nd derivative of it) that must worry us all.
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #39 on: January 27, 2020, 11:05:37 PM »
And on a general note please attack the arguments not the posters since that detracts from the discussion.

Trash the argument.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #40 on: January 28, 2020, 07:36:19 PM »
oren
I fully concur.


100 year numbers can only apply if we expect CH4 emissions to suddenly end & the atmospheric concentrations fall over that time period.
Since we're currently replacing each molecule as rapidly as one fails, the "instantaneous" value is the only one of concern.
The PPM numbers represent the CH4 present at this instant, not the CH4 that will have survived over a 100 year period.


If our blanket were being devoured by moths, we'd measure the heat radiated today rather than fretting over the fact that in 100 years it would be a thin rag, providing very little comfort. Nor would we be concerned about calculating the average heat radiated back over that period.


In 20 years, or 100 we could again measure the blanket's remaining efficiency - at that particular instant.
Today we're adding more wool than the moths are devouring. The longer, lower numbers are simply pulling wool over the sheep's eyes. ::)
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #41 on: January 28, 2020, 09:39:50 PM »
Same applies for biomass burning. If we fell a tree, or a forest, and burned it as firewood it would take 50 years or so for the trees to grow back.

All this time the co2, although slowly diminishing, would stay in the atmosphere warming the planet.

And who knows, maybe the forest won’t grow back at all.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #42 on: January 28, 2020, 10:46:50 PM »
It seems to me that discarding the 100-year time horizons neglects the fact that there are (at least) two different problems to be solved. Each problem has their own metrics that work well within the domain of that problem but which are problematic when applied out of context.

The first problem is that of modelling the response of the climate system to future radiative forcing from GHGs and feedbacks. The solution to this problem requires (among other things) an estimate of the time evolution of GHG concentrations from initial conditions; this is what the RCPs are designed to serve.

The second problem is to provide a metric for use by policy makers to estimate and account for the cumulative future effect of their current actions. Implicit in any solution to this problem is the need to integrate an effect over time: it is a cumulative result that is being estimated. This is the problem that GWPs are intended to help with and why, by definition, they require a time horizon to serve as the limits on the integral.

So GWPs are not intended as a tool to project future concentrations with. They are simply an accounting mechanism to quantify and compare from one jurisdiction to the next behaviour that’s happening today.

Ken Feldman

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #43 on: January 31, 2020, 07:38:06 PM »
One way to track which pathway we are on is to look at the annual change in the concentrations of each greenhouse gas and compare them to the RCPs.  This will capture both the anthropogenic and natural emissions, so would include feedbacks from climate change (such as increased ghg emissions from wetlands drying or permafrost thaw).

Here's the link to the RCPs:

https://www.ipcc.ch/site/assets/uploads/2017/09/WG1AR5_AnnexII_FINAL.pdf

For CO2, the concentrations are projected to be:

Year    RCP 2.6    RCP 8.5
2010     389.3       389.3
2020     412.1       415.8
2030     430.8       448.8

The average annual change from 2010 to 2020 was projected as 2.28 ppm under RCP 2.6 and 2.65 ppm under RCP 8.5.  The actual average annual (using the global avg annual data from NOAA) change was (411.44 - 389.9)/10 = 2.15 ppm.

Data available here.

https://www.esrl.noaa.gov/gmd/ccgg/trends/data.html

While all of the RCPs are very close up to the 2020s, in the future, the projections really start to differ.  For the next decade, RCP 2.6 projections average annual increases in CO2 of 1.87 ppm while RCP 8.5 projects annual changes of 3.3 ppm.
« Last Edit: January 31, 2020, 07:51:53 PM by Ken Feldman »

Ken Feldman

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #44 on: January 31, 2020, 08:00:28 PM »
The linked commentary in the January 29, 2020 issue of Nature makes it clear that the RCP8.5 scenario (updated to SSP5-8.5 for the upcoming AR6 report) is unrealistic.

https://www.nature.com/articles/d41586-020-00177-3

Quote
COMMENT 29 January 2020
Emissions – the ‘business as usual’ story is misleading
Stop using the worst-case scenario for climate warming as the most likely outcome — more-realistic baselines make for better policy.
Zeke Hausfather & Glen P. Peters

More than a decade ago, climate scientists and energy modellers made a choice about how to describe the effects of emissions on Earth’s future climate. That choice has had unintended consequences which today are hotly debated. With the Sixth Assessment Report (AR6) from the Intergovernmental Panel on Climate Change (IPCC) moving into its final stages in 2020, there is now a rare opportunity to reboot.

In the lead-up to the 2014 IPCC Fifth Assessment Report (AR5), researchers developed four scenarios for what might happen to greenhouse-gas emissions and climate warming by 2100. They gave these scenarios a catchy title: Representative Concentration Pathways (RCPs)1. One describes a world in which global warming is kept well below 2 °C relative to pre-industrial temperatures (as nations later pledged to do under the Paris climate agreement in 2015); it is called RCP2.6. Another paints a dystopian future that is fossil-fuel intensive and excludes any climate mitigation policies, leading to nearly 5 °C of warming by the end of the century2,3. That one is named RCP8.5.

Quote
Assessment of current policies suggests that the world is on course for around 3 °C of warming above pre-industrial levels by the end of the century — still a catastrophic outcome, but a long way from 5 °C7,8. We cannot settle for 3 °C; nor should we dismiss progress.
Plan for progress

Some researchers argue that RCP8.5 could be more likely than was originally proposed. This is because some important feedback effects — such as the release of greenhouse gases from thawing permafrost9,10 — might be much larger than has been estimated by current climate models. These researchers point out that current emissions are in line with such a worst-case scenario11. Yet, in our view, reports of emissions over the past decade suggest that they are actually closer to those in the median scenarios7. We contend that these critics are looking at the extremes and assuming that all the dice are loaded with the worst outcomes.

Quote
For policymakers, mitigation policies that depend on the assumptions underlying high-emission baseline scenarios such as RCP8.5 will seem exorbitant, because they do not incorporate the plummeting costs of many low-carbon technologies over the past decade. The marginal investments required to move from 3 °C of warming to well below 2 °C (the main Paris goal) will be much less than moving from 5 °C to well below 2 °C. A narrative of progress and opportunity can make the Paris targets seem feasible, rather than seemingly impossible.



Quote
Finally, we suggest that climate-impact studies using models developed for AR6 should include scenarios that reflect more-plausible outcomes, such as SSP2-4.5, SSP4-6.0 and SSP3-7.0 (see ’Possible futures’). When RCP8.5 or its successor SSP5-8.5 are deployed, they should be clearly labelled as unlikely worst cases rather than as business as usual.


wdmn

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #45 on: January 31, 2020, 08:28:15 PM »
One way to track which pathway we are on is to look at the annual change in the concentrations of each greenhouse gas and compare them to the RCPs.  This will capture both the anthropogenic and natural emissions, so would include feedbacks from climate change (such as increased ghg emissions from wetlands drying or permafrost thaw).

Ken, while it's a good idea, it's actually not true since those feedbacks are not included in CMIP5 models.

This is exactly what the debate over the article you shared from Glen Peters and Zeke Hausfather is about: Glen and Zeke are confident antrho emissions won't follow RCP 8.5; scientists like Michael Mann and Gavin Schmidt have pointed out (and Glen and Zeke concede) that without RCP 8.5 there's nothing capturing higher emissions scenarios from non-anthro sources unaccounted for in the models.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #46 on: January 31, 2020, 10:58:32 PM »
Quote
The average annual change from 2010 to 2020 was projected as 2.28 ppm under RCP 2.6 and 2.65 ppm under RCP 8.5.  The actual average annual (using the global avg annual data from NOAA) change was (411.44 - 389.9)/10 = 2.15 ppm.
Silly me is having trouble understanding how the actual 2020 value was 411.44 if 2020 hasn't finished yet.

Ken Feldman

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #47 on: January 31, 2020, 11:00:04 PM »
One way to track which pathway we are on is to look at the annual change in the concentrations of each greenhouse gas and compare them to the RCPs.  This will capture both the anthropogenic and natural emissions, so would include feedbacks from climate change (such as increased ghg emissions from wetlands drying or permafrost thaw).

Ken, while it's a good idea, it's actually not true since those feedbacks are not included in CMIP5 models.

This is exactly what the debate over the article you shared from Glen Peters and Zeke Hausfather is about: Glen and Zeke are confident antrho emissions won't follow RCP 8.5; scientists like Michael Mann and Gavin Schmidt have pointed out (and Glen and Zeke concede) that without RCP 8.5 there's nothing capturing higher emissions scenarios from non-anthro sources unaccounted for in the models.

The observed concentrations include all emissions (as well as all sinks).  There is no need to rely on climate model assumptions for the observations. 

And if you compare the actual observations to the projected concentrations for each RCP, you also avoid the problem.  You're just looking at how much of each greenhouse gas is needed to get to the radiative forcing assumed by the RCP, it doesn't matter whether the emissions are from fossil fuels or burning forests. 

Ken Feldman

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #48 on: January 31, 2020, 11:01:59 PM »
Quote
The average annual change from 2010 to 2020 was projected as 2.28 ppm under RCP 2.6 and 2.65 ppm under RCP 8.5.  The actual average annual (using the global avg annual data from NOAA) change was (411.44 - 389.9)/10 = 2.15 ppm.
Silly me is having trouble understanding how the actual 2020 value was 411.44 if 2020 hasn't finished yet.

I took the 10 years from 2010 through 2019 for Mauna Loa data (the global number for 2019 isn't reported yet). If you went to the link I posted, you would've known that.

oren

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #49 on: January 31, 2020, 11:17:30 PM »
I did click on the link, but these numbers were not immediately apparent while browsing it. I did not download any data files though.
Be that as it may, average of 2010 to average of 2019 sounds like 9 years to me, rather than 10. What am I missing?
Why not take the last actual available annual global average (2019? 2018?), compare it to the annual global average of 2010, and compare these numbers and their diffs to what the RCPs had to say about the same timespan (2018-2010 or 2019-2010)? Sounds liks a more proper comparison to me.