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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #200 on: October 10, 2020, 10:00:51 PM »
Is there a way to change the final value to CO2e, in ppm?
And a way to compare the sum of them with what we have, by example, versus 1980?

Here you go, Juan:

I converted the radiative forcing back into CO2 equivalents. Please find the values for each January of the following years. Please also keep in mind that these numbers only represent the four "NOAA gases" CO2, CH4, N2O and SF6. Therefore the "true" value is higher than that.

Jan 1980 372.2 ppm
Jan 1990 394.8 ppm (+22.6 ppm or +6.1%)
Jan 2000 415.7 ppm (+20.9 ppm or +5.3%)
Jan 2010 440.4 ppm (+24.7 ppm or +5.9%)
Jan 2020 473.4 ppm (+33.0 ppm or +7.5%)

The latest value (June 2020) represents a CO2 equivalent of 477.1 ppm (annual increase of 3.6 ppm). I will report this equivalent in future, once a month, when NOAA adds the latest monthly averages to its website.

It is obvious that we are on an exponential track. The smaller increase during the 1990s is a consequence of the breakdown of the Soviet Union's and its allies' economy after the revolutions of 1989/90. 
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kassy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #201 on: October 11, 2020, 01:34:03 AM »
That is quite the progression.

Now there were always two ways of looking at it. OK so 1 you have got a number for  the CO2eq but what does it actually mean.

What does it mean for the actual world?

For this you can look to graphs and theories or alternatively you look out of the window and see what is already happening.

We will lose the arctic ice some time the next decade , we have already comittted to a whole lot of sea level rise. Somewhere out there we are comitting to a protocol to stop some dangerous undefined future climate change while ignoring where we already are.

And we are on the edge of going from ice house to hot house earth. So much things will change so drastically before we do anything meaningful.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #202 on: October 11, 2020, 09:48:10 AM »
Thanks for that, Stephan.
What CO₂e factor do you use for methane?
I would expect the total to be more than a bit above 500ppm, using a short-term factor of 80.

--

I agree with kassy and oren.
But 'we' do meaningful stuff, we aren't doing nothing. But it is not mitigation but the opposite; worsening the problem even more. Year in year out. We can't even stop deforestation. Governments have no power over large international companies and these companies WILL NOT STOP WITH DESTRUCTION because their investors want more profit of them. Nice system eh? Out of control, just like the climate and biosphere destruction.
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
"It is preoccupation with what other people from your groups think of you, that prevents you from living freely and nobly" - Nanning
Why do you keep accumulating stuff?

Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #203 on: October 11, 2020, 06:59:19 PM »
I do not use a factor for methane, but I convert the actual concentration into radiative forcing (values listed in my posting). I sum up all the radiative forcings of the four "NOAA gases" and re-convert them into CO2 equivalents using the same formula I use to convert CO2 concentrations into radiative forcing.

There has been a lengthy discussion how to do it some months ago in this thread, because before that I had used the factors 28 and 80. But this is scientifically not correct as I was told.
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #204 on: November 06, 2020, 07:42:33 PM »
To finalize my update on greenhouse gases here is the summary of the four postings in the individual gas concentration threads.

More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in July 2020 than in July 2019, but less than in June 2020, because CO2 and CH4 reach their seasonal maximum in May.

The values [W/m²], change to June 2020 and change to July 2019:
CO2 2.136    (- 0.025)    (+ 0.034)   
CH4 0.519    (- 0.000)    (+ 0.005)
N2O 0.206   (+ 0.001)    (+ 0.004)
SF6  0.0054 (+ 0.0001)  (+ 0.0002)
sum  2.865  (- 0.026)    (+ 0.043) (rounding differences)

The relative annual increase is 1.49 %, a little bit higher than June 2020.

This recalculates to a CO2eq of 474.8 ppm (annual increase of 3.7 ppm).
« Last Edit: November 06, 2020, 07:51:59 PM by Stephan »
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Tom_Mazanec

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #205 on: November 06, 2020, 10:45:00 PM »
But aren't there other GHGs, Stephan, like CFCs and HFCs?
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #206 on: November 06, 2020, 10:50:22 PM »
Yes, of course. See my posting Oct 10, where I state that the true value is higher than that I had just posted. I only take care of these four "NOAA gases" because their concentration is followed on a daily (CO2) or monthly basis (CH4, N2O, SF6) by NOAA.
In the end I think that the absolute value itself is not too interesting. So I focus on the increase which I think is concerning, and please do not forget the slightly exponential development of all of these four gases, where we all should have taken a U-turn decades ago...
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Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #207 on: November 09, 2020, 06:46:12 PM »
But aren't there other GHGs, Stephan, like CFCs and HFCs?

SF6 represents the "15-Minor" greenhouse gases that NOAA tracks.  As you can see by the image below,  CO2 represent the bulk of the warming and CH4 most of the rest.  The 15 minor, with the CFCs that have been reduced due to the Montreal Protocol to protect the ozone layer, combined with N2O roughly equal the forcing from CH4.

« Last Edit: November 09, 2020, 06:55:44 PM by Ken Feldman »

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #208 on: November 13, 2020, 05:37:56 PM »
So i ran into this article:

Quote
Science journal U-turns on claim that global warming cannot be stopped after British experts cry foul

Richard Betts, a professor of climate impacts at the University of Exeter:
 'While the press release suggests that global warming may now be unstoppable for centuries, the model result in this paper is not convincing as support for that message.

Andrew Watson, a Royal Society research professor at the University of Exeter, said that he did not agree with the press release describing global warming as potentially catastrophic, 'given that it occurs over 500 years'.

Some scientists hailed Scientific Reports' findings as significant. 'This study provides evidence for what we don't want to hear: that global heating may have already become self-reinforcing, and that we have therefore passed the point of no return for halting long-term climate change,' Phillip Williamson of the University of East Anglia said.

https://www.dailymail.co.uk/sciencetech/article-8942619/Ending-greenhouse-gas-emissions-not-stop-global-warming.html

The actual article:
An earth system model shows self-sustained melting of permafrost even if all man-made GHG emissions stop in 2020

https://www.nature.com/articles/s41598-020-75481-z

The model they use is fairly simple to put it mildly:
Abstract. We have made a simple system dynamics model, ESCIMO (Earth System Climate Interpretable Model), which runs on a desktop computer in seconds and is able to reproduce the main output from more complex climate models. ESCIMO represents the main causal mechanisms at work in the Earth system and is able to reproduce the broad outline of climate history from 1850 to 2015.

https://esd.copernicus.org/articles/7/831/2016/


What did they find? Some background:

Quote
Method
We used ESCIMO to simulate the development of the global climate system from 1850 to 2500 under different assumptions concerning the emission of man-made GHGes. ESCIMO is a system dynamics model that includes representations of the world’s atmosphere, oceans, forests (and other land types), biomass—and their interactions. It is described here5. The source code with documentation is available online6.

In the first simulation reported here, “Scenario 1”, we assume that humanity reduces man-made GHG emissions to zero by 2100. In the second simulation, “Scenario 2”, we assume that emissions are cut much faster—to zero in 2020. In both cases man-made emissions remain zero thereafter.

Results
The result is shown in Fig. 1. In both scenarios the global temperature keeps rising for hundreds of years—to around + 3 °C in 2500—after a temporary decline in this century in conjunction with the decline in man-made emissions (Fig. 1c).

So where does effect come from:


Scenario 1
Scenario 1 describes the result when we assume that man-made emissions peak in the 2030s and decline to zero in 2100 (see Fig. 1, solid lines). This is the “most likely” scenario as described here7.

Quote
The historical part of the simulation (1850–2015) and the ensuing 60 years (2015–2075) are intuitive and understandable. Rising emissions of man-made GHGes lead to an increase in the concentration of GHGes in the atmosphere (Fig. 1b,d). This, in turn, leads to a rise in the global average surface temperature because GHG molecules block outgoing long-wave (heat) radiation from the surface. The warming is enhanced by the increased amount of water vapour which accumulates in a warmer atmosphere because H2O is a strong greenhouse gas which blocks other frequencies (Fig. 1f). The warming leads to rising sea levels because of thermal expansion and glacier run-off. Difficult to detect, but of great significance for the years beyond 2150, surface albedo starts a slow and smooth decline as the ice and snow cover melts, making the planet darker and leading to more absorption of short-wave (SW) radiation in the surface (Fig. 1h).

So what happens in the realistic scenario:

Quote
In Scenario 1 the temperature passes a temporary peak around 2075 at + 2.3 °C above pre-industrial times. The temperature then falls for 75 years (2075–2150) to + 2 °C. There are two reasons: (a) the concentration of GHGs in the atmosphere declines, and (b) heat is used to melt on-land glaciers and Arctic ice.

Furthermore, the concentration of CO2 declines (from its all-time peak of 450 ppm in 2050) through two processes: (a) CO2 is gradually absorbed in the ocean surface (and later transported into the deep ocean), and (b) CO2 is gradually absorbed in the biosphere. CO2 in the atmosphere is converted through photosynthesis into biomass in living matter and soils at a rate that is determined by the temperature and the amount of CO2 in the atmosphere. By 2150 all on-land snow and ice are gone in ESCIMO Scenario 1 (except in Greenland and Antarctica, which require thousands of years to melt).

While the developments to 2150 are understandable, developments in ESCIMO beyond 2150 are more surprising (counter-intuitive). As shown in Fig. 1 the temperature once more starts rising. The surprising fact is that this rise takes place 50 years after man-made emissions have ceased, and after the concentration of CO2 in the atmosphere has been significantly reduced through absorption in oceans and biomass.

The explanation (in ESCIMO) is as follows. While GHG concentrations—and thus their forcings—fall from 2070 to 2150, the effect of surface albedo continues on its smooth upward path throughout this period. Its time development is much slower than that of GHGes. It is the result of mainly Arctic ice melting—but it has enough ‘momentum’ to push the climate system back onto a path of rising temperatures, with its secondary effects of raising humidity and permafrost melting, which then in turn help the system become warmer and warmer, even if man-made GHG emissions are zero. A cycle of self-reinforcing processes is established. See Fig. 2a.

So the model is really simple but is there anything in the IPCC models to counter these effects? Or to put it more simply what do they show for the same trajectories?

Essentially this a very simple general model that shows us we are already in dangerous territory because we overshot whatever the goal was to keep the permafrost stabile.

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wehappyfew

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #209 on: November 13, 2020, 05:51:14 PM »
Assuming we retain any kind of technology, we're going to end up doing some kind of solar radiation blocking, either stratospheric aerosols, or space based shades.

What will be the consequences? Who knows.

The chief source of problems is solutions to previous problems.

Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #210 on: December 08, 2020, 09:53:41 PM »
To finalize my update on greenhouse gases here is the summary of the four postings in the individual gas concentration threads.

More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in August 2020 than in August 2019, but less than in July 2020, because CO2 reaches its seasonal maximum in May.

The values [W/m²], change to July 2020 and change to August 2019:
CO2 2.112    (- 0.024)    (+ 0.034)   
CH4 0.521    (+ 0.002)    (+ 0.006)
N2O 0.206   (+ 0.000)    (+ 0.004)
SF6  0.0054 (+ 0.0000)  (+ 0.0002)
sum  2.844  (- 0.021)    (+ 0.043) (rounding differences)

The relative annual increase is 1.54 %, a little bit higher than July 2020.

This recalculates to a CO2eq of 472.9 ppm (annual increase of 3.8 ppm).

Compared with 1980 [average was 1.578 W/m²] the increase since then sums up to 80.2%.
« Last Edit: December 08, 2020, 10:02:35 PM by Stephan »
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #211 on: January 12, 2021, 10:39:28 PM »
To finalize my update on greenhouse gases here is the summary of the four postings in the individual gas concentration threads.

More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in September 2020 than in September 2019, but less than in August 2020, because CO2 reaches its seasonal maximum in May.

The values [W/m²], change to August 2020 and change to September 2019:
CO2 2.095    (- 0.017)    (+ 0.035)   
CH4 0.523    (+ 0.002)    (+ 0.005)
N2O 0.206   (+ 0.000)    (+ 0.004)
SF6  0.0054 (+ 0.0000)  (+ 0.0002)
sum  2.830  (- 0.014)    (+ 0.045) (rounding differences)

The relative annual increase is 1.62 %, a little bit higher than August 2020.

This recalculates to a CO2eq of 471.7 ppm (annual increase of 3.9 ppm).

Compared with 1980 [average was 1.578 W/m²] the increase since then sums up to 79.3 %.
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Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #212 on: January 21, 2021, 06:22:07 PM »
To finalize my update on greenhouse gases here is the summary of the four postings in the individual gas concentration threads.

More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in September 2020 than in September 2019, but less than in August 2020, because CO2 reaches its seasonal maximum in May.

The values [W/m²], change to August 2020 and change to September 2019:
CO2 2.095    (- 0.017)    (+ 0.035)   
CH4 0.523    (+ 0.002)    (+ 0.005)
N2O 0.206   (+ 0.000)    (+ 0.004)
SF6  0.0054 (+ 0.0000)  (+ 0.0002)
sum  2.830  (- 0.014)    (+ 0.045) (rounding differences)

The relative annual increase is 1.62 %, a little bit higher than August 2020.

This recalculates to a CO2eq of 471.7 ppm (annual increase of 3.9 ppm).

Compared with 1980 [average was 1.578 W/m²] the increase since then sums up to 79.3 %.

Stephan does a great job in calculating the changes to radiative forcings from greenhouse gases each month.

It's important to remember to subtract 1 from that number (the combined forcings from aerosols and land use changes as estimated in the IPCC AR5 published in 2013) to compare them to the RCPs.  So the most recent calculated radiative forcing would be 1.83 W/m2 (the 2.83 from greenhouse gases -1 for aerosols and land use changes).  This is still within the RCP 2.6 pathway.

Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #213 on: January 21, 2021, 09:20:45 PM »
Ken,
please remember that I only cover the "NOAA gases" (CO2, CH4, N2O, SF6) that are regularly reported about on the NOAA website (https://www.esrl.noaa.gov/gmd/ccgg/trends/index.html). There are other (and not too unimportant) greenhouse gases like chlorinated and/or fluorinated hydrocarbons which must be added to the list which make the real CO2 eq higher than I calculate it.
There are some posts about this, including figures and graphs, further up in this thread.

I am no expert in judging the effect of black carbon, soot, aerosols, land use change etc on the CO2eq evaluation so I can not comment this part of your post.

kind regards from Germany Stephan
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #214 on: January 21, 2021, 10:16:31 PM »
Just in addition to my previous post I want to confirm that the increase of CO2eq from these four "NOAA gases" is of slightly exponential nature, although the calculation of the radiative forcings has a square root function in it (a four fold increase of CO2 means a doubling of additional radiative forcing). I doubt that this behaviour is compatible with a RCP2.65 path.

See attached picture.
« Last Edit: January 22, 2021, 06:50:13 AM by Stephan »
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Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #215 on: January 21, 2021, 11:30:29 PM »
While it's interesting to track the forcings from other greenhouse gases, CO2 is the one that will determine how much global warming we'll experience.  The others don't add up to much, and once fossil fuel extraction is shut down, methane concentrations will decrease, leading to a cooling that offsets the minor warming from the other long-lived greenhouse gases.

https://www.worldenergydata.org/ghgs/

Quote
Greenhouse gas emissions

Rapidly increasing CO2 emissions, mainly from our energy systems, almost solely determine Earth’s long term warming commitment. These emissions continue to grow with no peak in sight, at a rate unprecedented in the past 66 million years.

February 18, 2018 (Updated: September 26, 2020)


Quote
Chart 2. Annual change of radiative forcing by greenhouse gas, 1980-2019. Data: NOAA ESRL3

Quote
Chart 3 shows the same data as chart 2, but by share. The share of annual change caused by civilisation’s CO2 has been greater than 70% for every year since 1993, and reached 90% or more in 2003, 2005 and 2013.


Quote
Chart 3. Annual change of radiative forcing by greenhouse gas, as share of total annual change, 1980-2019. Data: NOAA ESRL.3

Quote
Our long term warming commitment is almost solely determined by cumulative CO2 emissions (nitrous oxide (N2O)7 is also a long-lived greenhouse gas that contributes to our warming commitment, but as shown in chart 1(a) above, it’s contribution is much smaller than that from CO2).



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Re: Where are we now in CO2e , which pathway are we on?
« Reply #216 on: January 22, 2021, 03:30:54 AM »
once fossil fuel extraction is shut down, methane concentrations will decrease, leading to a cooling that offsets the minor warming from the other long-lived greenhouse gases.
I find this statement to be optimistic on a couple of levels, however I'd rather not distract from Stephan's excellent tracking of CO2eq which will eventually tell us if and when the trends actually start to reverse.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #217 on: January 22, 2021, 06:23:07 AM »
nitrous oxide as long lived ?

I would have thought oxidation from N20 -> NO -> NO2  followed by dissolution in watervapour as HNO3 and rainout would make it fairly short lived ...

sidd

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #218 on: January 22, 2021, 08:52:41 AM »
nitrous oxide as long lived ?

I would have thought oxidation from N20 -> NO -> NO2  followed by dissolution in watervapour as HNO3 and rainout would make it fairly short lived ...

sidd
Lifetime of N2O exceeds 100 years . . . . . I.e. not short lived.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #219 on: January 22, 2021, 01:18:03 PM »
http://www.bbc.co.uk/climate/evidence/nitrous_oxide.shtml
Nitrous Oxide
Nitrous oxide makes up an extremely small amount of the atmosphere - it is less than one-thousandth as abundant as carbon dioxide. However, it is 200 to 300 times more effective in trapping heat than carbon dioxide.

Nitrogen is removed from the atmosphere by plants and converted into forms such as ammonia, which can then be used by the plants. This is called nitrogen fixation. At the same time, micro-organisms remove nitrogen from the soil and put it back into the atmosphere - denitrification - and this process produces nitrous oxide. Nitrous oxide also enters the atmosphere from the ocean.

Nitrous oxide has one of the longest atmosphere lifetimes of the greenhouse gases, lasting for up to 150 years.

tractor sprayingBurning fossil fuels and wood is one source of the increase in atmospheric nitrous oxide, however the main contributor is believed to be the widespread use of nitrogen-base fertilisers. Sewage treatment plants may also be a major source of this gas.

Since the Industrial Revolution, the level of nitrous oxide in the atmosphere has increased by 16%.

Due to the long time it spends in the atmosphere, the nitrous oxide that we release today will still be trapping heat well into the next century.
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #220 on: January 23, 2021, 12:48:58 AM »
Thanks for the detail on N2O lifetime. I see that I misremembered lifetime against oxidation/dissolution/rainout for nitrogen oxides.

sidd

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #221 on: February 03, 2021, 09:56:35 PM »
The Terrifying Warning Lurking in the Earth’s Ancient Rock Record

Our climate models could be missing something big

https://www.theatlantic.com/magazine/archive/2021/03/extreme-climate-change-history/617793/?scrolla=5eb6d68b7fedc32c19ef33b4

" But our trajectory as a civilization is headed well beyond the warmth of the last interglacial, or any other interglacial period of the Pleistocene, for that matter."

"In the Miocene, this volcanic CO2 warmed up the world to at least 4 degrees Celsius and perhaps as much as 8 degrees above modern temperatures. As a result, there were turtles and parrots in Siberia. Canada’s Devon Island, in the high Arctic, is today a desolate wasteland, the largest uninhabited island in the world—and one used by NASA to simulate life on Mars. In the Miocene, its flora resembled Lower Michigan’s."

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #222 on: February 04, 2021, 08:37:56 PM »
2 hyper-pertinent questions that nobody ever seems to discuss...


A)If the radiative forcing from the "NOAA 4" was 100 in 1700, what is it today?

B) What percent increase is this of the total greenhouse effect (aka: including H2O)?


There is so much detail and random specifics on this thread, but I feel like there is no consensus on the foundational viewpoint. Forget the path... the first step is to figure out where we were and where we are. Without that, guessing at the path is meaningless.
big time oops

Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #223 on: February 04, 2021, 11:41:41 PM »
2 hyper-pertinent questions that nobody ever seems to discuss...


A)If the radiative forcing from the "NOAA 4" was 100 in 1700, what is it today?

B) What percent increase is this of the total greenhouse effect (aka: including H2O)?


There is so much detail and random specifics on this thread, but I feel like there is no consensus on the foundational viewpoint. Forget the path... the first step is to figure out where we were and where we are. Without that, guessing at the path is meaningless.

According to the IPCC 5th Assessment Report, Working Group 1, published in 2013, the concentrations of three of the "NOAA 4" in 1755 (oldest date shown in the tables):

CO2: 276.7 ppm
CH4: 723 ppb
N2O: 272.8 ppb

SF6 is a man-made gas that was first produced around 1901.

NOAA sets their annual greenhouse gas index at 1.0 in 1990 and has a graph showing how the concentration of gases has changed from 1750 to 1990.




Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #224 on: February 05, 2021, 06:25:03 PM »
Adding the three "1755" concentrations into the formula with which I calculate the radiative forcing the result is zero.
This proves the formula I use to be correct, as the radiative forcing I calculate is the additional radiative forcing coming from the man made GHG which are in the atmosphere in addition to the naturally abundant concentrations.
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #225 on: February 05, 2021, 09:32:30 PM »
To finalize my update on greenhouse gases here is the summary of the four postings in the individual gas concentration threads.

More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in October 2020 than in October 2019 and in September 2020.

The values [W/m²], change to Sep 2020, change to Oct 2019 and change to Oct 2010:
CO2 2.095    (± 0.000)    (+ 0.036)    (+ 0.322)
CH4 0.526    (+ 0.003)    (+ 0.006)    (+ 0.031)
N2O 0.207   (+ 0.001)     (+ 0.004)    (+ 0.031)
SF6  0.0054 (+ 0.0000)   (+ 0.0002)   (+ 0.0017)
sum  2.833  (+ 0.003)     (+ 0.046)     (+ 0.386)  (rounding differences)

The relative annual increase is 1.65 %, a little bit higher than in September 2020.

This recalculates to a CO2eq of 472.0 ppm (annual increase of 4.0 ppm).

Compared with 1980 [average was 1.578 W/m²] the increase since then sums up to 79.5 %.
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Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #226 on: February 08, 2021, 06:57:31 PM »
For some perspective, here is a peer-reviewed science article by a team of modelers on the forcings from pre-industrial to present day.

https://acp.copernicus.org/articles/21/1211/2021/

Quote
O'Connor, F. M., Abraham, N. L., Dalvi, M., Folberth, G. A., Griffiths, P. T., Hardacre, C., Johnson, B. T., Kahana, R., Keeble, J., Kim, B., Morgenstern, O., Mulcahy, J. P., Richardson, M., Robertson, E., Seo, J., Shim, S., Teixeira, J. C., Turnock, S. T., Williams, J., Wiltshire, A. J., Woodward, S., and Zeng, G.: Assessment of pre-industrial to present-day anthropogenic climate forcing in UKESM1, Atmos. Chem. Phys., 21, 1211–1243, https://doi.org/10.5194/acp-21-1211-2021, 2021.

Abstract

Quantifying forcings from anthropogenic perturbations to the Earth system (ES) is important for understanding changes in climate since the pre-industrial (PI) period. Here, we quantify and analyse a wide range of present-day (PD) anthropogenic effective radiative forcings (ERFs) with the UK's Earth System Model (ESM), UKESM1, following the protocols defined by the Radiative Forcing Model Intercomparison Project (RFMIP) and the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). In particular, quantifying ERFs that include rapid adjustments within a full ESM enables the role of various chemistry–aerosol–cloud interactions to be investigated.

Global mean ERFs for the PD (year 2014) relative to the PI (year 1850) period for carbon dioxide (CO2), nitrous oxide (N2O), ozone-depleting substances (ODSs), and methane (CH4) are 1.89 ± 0.04, 0.25 ± 0.04, −0.18 ± 0.04, and 0.97 ±  0.04 W m−2, respectively. The total greenhouse gas (GHG) ERF is 2.92 ± 0.04 W m−2.

UKESM1 has an aerosol ERF of −1.09 ± 0.04 W m−2. A relatively strong negative forcing from aerosol–cloud interactions (ACI) and a small negative instantaneous forcing from aerosol–radiation interactions (ARI) from sulfate and organic carbon (OC) are partially offset by a substantial forcing from black carbon (BC) absorption. Internal mixing and chemical interactions imply that neither the forcing from ARI nor ACI is linear, making the aerosol ERF less than the sum of the individual speciated aerosol ERFs.

Ozone (O3) precursor gases consisting of volatile organic compounds (VOCs), carbon monoxide (CO), and nitrogen oxides (NOx), but excluding CH4, exert a positive radiative forcing due to increases in O3. However, they also lead to oxidant changes, which in turn cause an indirect aerosol ERF. The net effect is that the ERF from PD–PI changes in NOx emissions is negligible at 0.03 ± 0.04 W m−2, while the ERF from changes in VOC and CO emissions is 0.33 ± 0.04 W m−2. Together, aerosol and O3 precursors (called near-term climate forcers (NTCFs) in the context of AerChemMIP) exert an ERF of −1.03 ± 0.04 W m−2, mainly due to changes in the cloud radiative effect (CRE). There is also a negative ERF from land use change (−0.17 ± 0.04 W m−2). When adjusted from year 1850 to 1700, it is more negative than the range of previous estimates, and is most likely due to too strong an albedo response. In combination, the net anthropogenic ERF (1.76 ± 0.04 W m−2) is consistent with other estimates.

By including interactions between GHGs, stratospheric and tropospheric O3, aerosols, and clouds, this work demonstrates the importance of ES interactions when quantifying ERFs. It also suggests that rapid adjustments need to include chemical as well as physical adjustments to fully account for complex ES interactions.

They define the present day as 2014, so this would need to be adjusted slightly for the current forcings.  Even with that caveat, SSP 2.6 is still within reach.

Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #227 on: February 08, 2021, 09:19:52 PM »
I checked the data I have collected over the years.
For 2014 (yearly average) I calculate the additional radiative forcing for
CO2   1.92 W/m²             vs. 1.89 ± 0.04
CH4   0.501 W/m²           vs. 0.97 ± 0.04
N2O   0.187 W/m²           vs. 0.25 ± 0.04
SF6    0.0043 W/m² (no UKESM value given).
My values are lower, especially for nitrous oxide and methane.
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #228 on: February 14, 2021, 08:57:41 PM »
For those who are interested in historical values of additional radiative forcing (baseline 1750 = 0 W/m²) I invite you to visit https://www.esrl.noaa.gov/gmd/ccgg/ghgpower/ whereannual averages from 1800 to 2019 are published. I added the values into my Open Office file and will do some evaluations.
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #229 on: February 14, 2021, 10:10:05 PM »
The first evaluation done.
Please find the additional radiative forcing, separated into four main compounds (CO2, CH4, N2O and all CFC&Co together) in the first graph.
The second graph shows the decadal increase rates. They were all quite small before 1950. The first peak is mainly contributed by the increase in CO2 and (70s-90s) by the CFC (green circle). After their increase has more or less stopped, the increase rate didn't go down too much. Instead it rose again, mainly due to an ever increasing CO2 content, supported by CH4 and N2O (red circle).
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Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #230 on: March 05, 2021, 08:26:36 PM »
To finalize my update on greenhouse gases here is the summary of the four postings in the individual gas concentration threads.

More radiative forcing of the "NOAA gases" (CO2, CH4, N2O, SF6) in November 2020 than in November 2019 and in October 2020.

The values [W/m²], change to Oct 2020, change to Nov 2019 and change to Nov 2010:
CO2 2.116    (+ 0.021)    (+ 0.034)    (+ 0.323)
CH4 0.526    (+ 0.000)    (+ 0.006)    (+ 0.031)
N2O 0.207   (+ 0.000)     (+ 0.004)    (+ 0.030)
SF6  0.0054 (+ 0.0000)   (+ 0.0002)   (+ 0.0017)
sum  2.855  (+ 0.022)     (+ 0.044)     (+ 0.387)  (rounding differences)

The relative annual increase is 1.57 %, a little bit lower than in September 2020.

This recalculates to a CO2eq of 473.9 ppm (annual increase of 3.9 ppm).

Compared with 1980 [average was 1.578 W/m²] the increase since then sums up to 80.9 %.
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vox_mundi

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #231 on: March 15, 2021, 11:25:11 PM »
Study Predicts Oceans Will Start Emitting Ozone-Depleting CFCs
https://phys.org/news/2021-03-oceans-emitting-ozone-depleting-cfcs.html

The world's oceans are a vast repository for gases including ozone-depleting chlorofluorocarbons, or CFCs. They absorb these gases from the atmosphere and draw them down to the deep, where they can remain sequestered for centuries and more.

Marine CFCs have long been used as tracers to study ocean currents, but their impact on atmospheric concentrations was assumed to be negligible. Now, MIT researchers have found the oceanic fluxes of at least one type of CFC, known as CFC-11, do in fact affect atmospheric concentrations. In a study appearing today in the Proceedings of the National Academy of Sciences, the team reports that the global ocean will reverse its longtime role as a sink for the potent ozone-depleting chemical.

Since its phaseout, levels of CFC-11 in the atmosphere have been steadily declining, and scientists estimate that the ocean has absorbed about 5 to 10 percent of all manufactured CFC-11 emissions. As concentrations of the chemical continue to fall in the atmosphere, however, it's predicted that CFC-11 will oversaturate in the ocean, pushing it to become a source rather than a sink.

The researchers project that by the year 2075, the oceans will emit more CFC-11 back into the atmosphere than they absorb, emitting detectable amounts of the chemical by 2130. Further, with increasing climate change, this shift will occur 10 years earlier. The emissions of CFC-11 from the ocean will effectively extend the chemical's average residence time, causing it to linger five years longer in the atmosphere than it otherwise would. This may impact future estimations of CFC-11 emissions.

"By the time you get to the first half of the 22nd century, you'll have enough of a flux coming out of the ocean that it might look like someone is cheating on the Montreal Protocol, but instead, it could just be what's coming out of the ocean," ...

"Generally, a colder ocean will absorb more CFCs," Wang explains. "When climate change warms the ocean, it becomes a weaker reservoir and will also outgas a little faster."

Peidong Wang el al., "On the effects of the ocean on atmospheric CFC-11 lifetimes and emissions," PNAS (2021).
https://www.pnas.org/content/118/12/e2021528118
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Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #232 on: March 16, 2021, 09:24:41 PM »
NOAA has posted the preliminary 2020 average global CO2 concentration at this webpage:

https://www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2/co2_annmean_gl.txt

The global average for 2020 is 412.48 ppm.

RCP 2.6 for 2020 is 412.1 ppm
RCP 8.5 for 2020 is 415.8 ppm

Full RCP data is available at this webpage:

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

CO2 concentrations for the RCPs are on page 1422.

oren

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #233 on: March 17, 2021, 01:40:38 AM »
I note this thread is about CO2e, not just CO2. How are the RCPs doing in regards to the other gases?
Also I've been wondering if all RCPs started with the then correct CO2 concentration when they were defined? The charts always seem to be a bit off at the beginning.

Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #234 on: March 17, 2021, 05:08:29 PM »
The RCPs track each individual forcing separately, they don't lump them into CO2eq. They were developed around 2007 for the model runs that produced the AR5 report that was published in 2013. The tables in AR5 list the concentrations starting in 2010 and then every 10 years. 

So far NOAA hasn't released the annual averages for 2020 for the other gases yet.  Once they do, we can list them here and calculate a CO2 eq for those four gases.  However, the RCPs track many more gases and also land use and aerosols, so we're not quite tracking the RCPs exactly in this thread.  The forcings for the RCPs are around 1 w/M2 less than what we report in this thread because the negative forcings for land use and aerosols aren't reported here.

However, CO2 is the main driver of the greenhouse gases.  CH4 is second, but it's short-lived and once it starts to decrease (as is expected when coal mining and oil and gas use decline) it will lead to cooling.  Those two gases will control how much warming we experience in the future.

Edited to clarify that a decrease in methane concentrations will lead to lower temperatures.
« Last Edit: March 17, 2021, 08:39:33 PM by Sciguy »

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #235 on: March 17, 2021, 06:21:44 PM »
Quote
CH4 is second, but it's short-lived and once it starts to decrease (as is expected when coal mining and oil and gas use decline) it will be a cooling forcing.

How does it become a cooling forcing?

Quite a lot of methane sources are not mining related (rice, livestock, african spikes due to more rainfall and whatever poofs out of the ESAS and northern permafrost) so we will be stuck with some methane emission baseline.

I totally fail to see how it could become a cooling forcing while just decreasing.
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #236 on: March 17, 2021, 06:52:38 PM »
Quote
CH4 is second, but it's short-lived and once it starts to decrease (as is expected when coal mining and oil and gas use decline) it will be a cooling forcing.

How does it become a cooling forcing?

Quite a lot of methane sources are not mining related (rice, livestock, african spikes due to more rainfall and whatever poofs out of the ESAS and northern permafrost) so we will be stuck with some methane emission baseline.

I totally fail to see how it could become a cooling forcing while just decreasing.
CH4 breaks down in the atmosphere. So the hope is that if CH4 emissions decrease enough then CH4 emissions added will be less than CH4 broken down so CH4 ppb in the atmosphere will therefore decrease.

Thus CO2e will decrease, or at least reduced CH4 ppb will partially offset increased CO2e from CO2 emissions.

That is the hope. We certainly are not there yet.
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Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #237 on: March 17, 2021, 07:24:49 PM »
Methane is a short lived greenhouse gas with an average residence time in the atmosphere of 11 to 12 years.  From the late 1990s until 2007, concentrations of methane in the atmosphere were nearly stable.  Recently, it's been determined that fugitive emissions from coal mines and oil and gas drilling and pipelines are responsible for the increases in methane concentrations since 2007.  A large portion of the methane emissions from fossil fuels are leaks that occur from the active infrastructure while the fuels are produced and transported. 

Abandoned fossil fuel infrastructure also contributes to the methane emissions.  Methane emissions from abandoned coal mines and oil and gas infrastructure can be ended quickly by flooding the coal mines and plugging leaks in the oil and gas infrastructure.  Once that happens, methane concentrations will begin to decrease.

Here is a paper on what will happen when methane concentrations start to decrease.

https://link.springer.com/article/10.1007/s10584-020-02794-3

Quote
Smith, S.J., Chateau, J., Dorheim, K. et al. Impact of methane and black carbon mitigation on forcing and temperature: a multi-model scenario analysis. Climatic Change 163, 1427–1442 (2020). https://doi.org/10.1007/s10584-020-02794-3

Abstract

The relatively short atmospheric lifetimes of methane (CH4) and black carbon (BC) have focused attention on the potential for reducing anthropogenic climate change by reducing Short-Lived Climate Forcer (SLCF) emissions. This paper examines radiative forcing and global mean temperature results from the Energy Modeling Forum (EMF)-30 multi-model suite of scenarios addressing CH4 and BC mitigation, the two major short-lived climate forcers. Central estimates of temperature reductions in 2040 from an idealized scenario focused on reductions in methane and black carbon emissions ranged from 0.18–0.26 °C across the nine participating models. Reductions in methane emissions drive 60% or more of these temperature reductions by 2040, although the methane impact also depends on auxiliary reductions that depend on the economic structure of the model. Climate model parameter uncertainty has a large impact on results, with SLCF reductions resulting in as much as 0.3–0.7 °C by 2040. We find that the substantial overlap between a SLCF-focused policy and a stringent and comprehensive climate policy that reduces greenhouse gas emissions means that additional SLCF emission reductions result in, at most, a small additional benefit of ~ 0.1 °C in the 2030–2040 time frame.

Quote
A second set of auxiliary reduction mechanisms are physical effects related to changing methane concentrations. Decreasing methane emissions decreases temperatures, the oxidation of CH4 to CO2, the production of tropospheric ozone, and the production of stratospheric water vapor (all included in MAGICC). All of these forcing mechanisms contribute to the auxiliary forcing reductions and their magnitude is quantified in the lower set of model auxiliary results noted above (e.g., ~ 0.03 W/m2 in 2050). The largest contributor to the CO2 decrease is smaller carbon-cycle feedbacks due to decreased global temperatures. Note that there is additional forcing uncertainty for some of these mechanisms as compared with methane forcing itself. We also note that in the configuration used here, all anthropogenic methane is assumed to be oxidized to CO2, where in reality only fossil CH4 emissions should be considered to add to atmospheric CO2 concentration (Boucher et al. 2009), which will lead to an overestimate of the effect of CH4 oxidation.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #238 on: March 17, 2021, 07:39:24 PM »
Yes that´s methane but that does not equate to a cooling forcing.
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Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #239 on: March 17, 2021, 08:29:22 PM »
To clarify, the decrease in the radiative forcing from methane as it's concentration decreases in the atmosphere will lead to a decrease in the CO2eq radiative forcing, as the CO2eq for methane is 28 to 80 times (depending on the timeframe assumed) the radiative forcing from CO2.  That's why the temperature starts to decrease as the methane concentrations decrease.


Stephan

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #240 on: March 17, 2021, 09:05:56 PM »
I do not get your point so far.
Let's assume that the CH4 concentration increase may slow down in some years when there is less oil and gas fracking and less coal mining. But rice will be grown and cows will live in great(er) numbers, and the permafrost won't stop thawing. Therefore a reduction of CH4 concentration in the atmosphere is unlikely to happen.
One major product of CH4 decomposition is the formation of CO2 which is also a greenhouse gas. As CO2 is held responsible for about 70% of the total radiative forcing its proportion will rise slightly. The net effect of all of this might be a slow down of the increase of radiative forcing compared to its actual rate. But a cooling is not in sight.
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oren

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #241 on: March 17, 2021, 09:47:53 PM »
As long as the forcing is not in balance with outgoing radiation there will be no cooling. Even if forcing decreases, as long as it doesn't reach equilibrium level it simply means warming slows down. No cooling.
Besides, talking about methane concentrations dropping does not equate actual drops. Sure it's short lived, and yet its concentration is not only growing but accelerating.

Sciguy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #242 on: March 17, 2021, 11:18:00 PM »
The number of cows, rice paddies and permafrost thaw are not responsible for the increased methane emissions since 2007, coal mining and oil and gas drilling are.

A recently published study found that human emissions (from coal mines in China and oil and gas fields in North America) are responsible for the recent uptick in methane emissions (since 2007).  They found "There is no evidence of emission enhancement due to climate warming, including the boreal regions, during our analysis period."

https://www.jstage.jst.go.jp/article/jmsj/advpub/0/advpub_2021-015/_article

Quote
Emissions from the Oil and Gas Sectors, Coal Mining and Ruminant Farming Drive Methane Growth over the Past Three Decades
Naveen CHANDRA, Prabir K. PATRA, Jagat S. H. BISHT, Akihiko ITO, Taku UMEZAWA, Nobuko SAIGUSA, Shinji MORIMOTO, Shuji AOKI, Greet JANSSENS-MAENHOUT, Ryo FUJITA, Masayuki TAKIGAWA, Shingo WATANABE, Naoko SAITOH, Josep G. CANADELL

Abstract

 Methane (CH4) is an important greenhouse gas and plays a significant role in tropospheric and stratospheric chemistry. Despite the relevance of methane (CH4) in human-induced climate change and air pollution chemistry, there is no scientific consensus on the causes of changes in its growth rates and variability over the past three decades. We use a well-validated chemistry-transport model for simulating CH4 concentration and estimation of regional CH4 emissions by inverse modelling for the period of 1988-2016. The control simulations are performed using a seasonally varying hydroxyl (OH) concentrations and assumed no interannual variability. Using inverse modelling of atmospheric observations, emission inventories, a wetland model, and a δ13C-CH4 box model, we show that reductions in emissions from Europe and Russia since 1988, particularly from oil-gas exploitation and enteric fermentation, led to decreased CH4 growth rates in the 1990s. This period was followed by a quasi-stationary state of CH4 in the atmosphere during the early 2000s. CH4 resumed growth from 2007, which we attribute to increases in emissions from coal mining mainly in China and intensification of ruminant farming in tropical regions. A sensitivity simulation using interannually varying OH shows that regional emission estimates by inversion are unaffected for the mid- and high latitude areas. We show that meridional shift in CH4 emissions toward the lower latitudes and the increase in CH4 loss by hydroxyl (OH) over the tropics finely balance out, which keep the CH4 gradients between the southern hemispheric tropical and polar sites relatively unchanged during 1988-2016. The latitudinal emissions shift is confirmed using the global distributions of the total column CH4 observations by satellite remote sensing. There is no evidence of emission enhancement due to climate warming, including the boreal regions, during our analysis period. These findings highlight key sectors for effective emission reduction strategies toward climate change mitigation.
There are ways to decrease the methane emissions from rice paddies (using biochar as a fertilizer), landfills (adding biochar to the soil cap), and even ruminants (adding seaweed to cattle feed).  These decreases in emissions could offset any future growth in numbers as population grows.

The big decreases in methane emissions will occur as the coal mines are closed and the oil and gas wells are capped.  Many nations have adopted net zero goals that range from 2050 to 2060.  So emissions related to fossil fuel production will be dropping quickly in the next decade.

oren

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #243 on: March 18, 2021, 01:46:56 AM »
Quote
Many nations have adopted net zero goals that range from 2050 to 2060.  So emissions related to fossil fuel production will be dropping quickly in the next decade.
I wish I could share your optimism, especially the derivation of sentence B from sentence A.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #244 on: March 18, 2021, 01:51:21 PM »
Quote
Many nations have adopted net zero goals that range from 2050 to 2060.  So emissions related to fossil fuel production will be dropping quickly in the next decade.
I wish I could share your optimism, especially the derivation of sentence B from sentence A.

Sentence B demands on how quickly sentence A is implemented.  Perhaps adding an "s" to decade would make the logical equation a tad truer.

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #245 on: March 18, 2021, 06:09:03 PM »
Quote
Many nations have adopted net zero goals that range from 2050 to 2060.  So emissions related to fossil fuel production will be dropping quickly in the next decade.
I wish I could share your optimism, especially the derivation of sentence B from sentence A.

Sentence B demands on how quickly sentence A is implemented.  Perhaps adding an "s" to decade would make the logical equation a tad truer.

Look at what happened to coal in the UK.  Even with a fairly mild government policy, it pretty much crashed to near zero usage in just a few years.

Look at individual Cities, States and utilities in the USA.  A lot of the renewable plants installed between 2010 and 2020 were due to local commitments.  And the trend has increased (made easier by the fact that solar is now the cheapest energy in history).

Also look at China.  2060 looks a long way out and they have a lot of coal plants.  But they've started a carbon cap and trade market.  Check out what happened in Shanghai as a result of the pilot cap and trade program and expand it to the whole country.

Look at EV adaptation rates.  Check out what happened in Norway due to government programs there.  Consider what governments (especially the US and China).

Check out the ESG investment movement.  Private equity is moving away from fossil fuels and into renewables.  And the fossil fuel companies are finding it harder to find banks or investment firms to loan them money for new projects.

The energy transition is well underway and picking up steam. Global coal use has peaked in 2013 and has plateaued soley due to China.  In a few years, coal use in China will be mirroring the last few years of coal use in the US and UK.  Oil use probably peaked in 2019 although it may grow slightly in the 2020s after the Covid recovery and before EVs are the dominant form of surface transportation before it crashes to a fraction of it's current level.  Natural gas use will be peaking this decade as investors realize that any new projects started now wont operate long enough to pay back the initial investment.

Human Habitat Index

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #246 on: March 25, 2021, 12:14:30 AM »
Can someone please rebutt the latest article by Sam Carana ?

http://arctic-news.blogspot.com/
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Re: Where are we now in CO2e , which pathway are we on?
« Reply #247 on: March 25, 2021, 06:28:15 PM »
Can someone please rebutt the latest article by Sam Carana ?

http://arctic-news.blogspot.com/

It's been done before, many times, in various posts here and elsewhere on the web.  But I'll take a look at the first doozy I noticed, in his second paragraph:

Quote
The trend highlights that the 1.5°C threshold was crossed in 2012 (inset), while the 2°C threshold looks set to be crossed next year and a 3°C rise could be reached at the end of 2026.

The IPCC published a special report on warming of 1.5C in 2018.  Here is what they said about warming to date:

https://www.ipcc.ch/sr15/

Quote

*Box SPM.1 Core Concepts Central to this report

A.1. Human activities are estimated to have caused approximately 1.0°C of global warming
 above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. (high confidence) (Figure SPM.1) {1.2}

So you can see that SC is starting with a bogus statement and going from there.

BeeKnees

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #248 on: March 25, 2021, 10:15:31 PM »
This may not be the right place

Important new research measuring the effects of greenhouse gases and aerosols in near real time

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL091585

Quote
Changes in atmospheric composition, such as increasing greenhouse gases, cause an initial radiative imbalance to the climate system, quantified as the instantaneous radiative forcing. This fundamental metric has not been directly observed globally and previous estimates have come from models. In part, this is because current space‐based instruments cannot distinguish the instantaneous radiative forcing from the climate’s radiative response. We apply radiative kernels to satellite observations to disentangle these components and find all‐sky instantaneous radiative forcing has increased 0.53±0.11 W/m2 from 2003 through 2018, accounting for positive trends in the total planetary radiative imbalance. This increase has been due to a combination of rising concentrations of well‐mixed greenhouse gases and recent reductions in aerosol emissions. These results highlight distinct fingerprints of anthropogenic activity in Earth’s changing energy budget, which we find observations can detect within 4 years.

NASA have done an explainer
https://twitter.com/NASAEarth/status/1375096176320581638?s=20

kassy

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Re: Where are we now in CO2e , which pathway are we on?
« Reply #249 on: March 25, 2021, 10:28:15 PM »
But what is bogus?

https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement

Quote
The Paris Agreement is a legally binding international treaty on climate change. It was adopted by 196 Parties at COP 21 in Paris, on 12 December 2015 and entered into force on 4 November 2016.

Its goal is to limit global warming to well below 2, preferably to 1.5 degrees Celsius, compared to pre-industrial levels.

To achieve this long-term temperature goal, countries aim to reach global peaking of greenhouse gas emissions as soon as possible to achieve a climate neutral world by mid-century.
What is missing is an exact definition.

When are we going to stop? What is our maximum output? Why do we not have such a simple number, a practical target?

The reference year IPCC uses for pre industrial is known to be incorrect so we probably should correct that.

Now the questions are:
Why do we actually use a wrong base line? Are the reasons science or politics?

Another related question is why we ever shifted to 1,5C as a target instead of 1C? Science or politics?

Why do we use 4 different predictions for this century which all do not account for the loss of Arctic sea ice along the way? Would that be science or politics?


Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.