Trajectories of the Earth System in the Anthropocene

[Lord of Planar]

You've got it backwards.

I mean... You do understand that there is currently about 220 times more CO2 than methane in the atmosphere, yes? And despite that, the RF of CH4 is more than half that of CO2. That wasn't lost on you, right?

My God man. Changes in forcing since 1750 is not the same at total forcing. The total forcing for CO2 at 278 ppm is around 30.2 W/m^2, and the total forcing for CH4 at 722 ppb is around around 0.55 W/m^2. This represents 1750 levels. Today, with around 400 ppm CO2, and 1865 ppb CH4, these values represent around and 32.2 W/m^2 and 1.07 W/m^2. By these calculation that fit the IPCC projections, CO2 forcing increased by 2.0 W/m^2 and CH4 by 0.52 W/m^2. That's using the IPCC methodology, which I disagree with, but I'll stick with that for debate.

Forcing change is not the same as total forcing.

CO2 traps less energy than CH4. However, the total radiative forcing is higher because it is more abundant (400 ppm CO2 vs 1804 ppb CH4). If there was a consistent level of 410ppm of both CO2 and methane in the atmosphere, the methane would be causing significantly more warming than CO2.

Not true at all. If both gasses were 410 ppm, CO2 would have a calculated forcing of 32.3 W/m^2 and CH4 would be 6.1 ppm. That's using the AR4 curves. The AR5 curves would make the differences greater yet.

I suggest you do the math sometime from what they claim for forcing changes at what levels.

To illustrate this, U of Chicago has the "Slugulator," which is a climate model which compares the effects of a pulse of CO2 and CH4. When we simulate a pulse of 1 gt and look at the effects over 100 years, the CH4 traps almost double the amount of energy as CO2, even though CH4 concentrations fall much more rapidly than CO2. You can play with the numbers, but it's pretty clear that ton for ton, CH4 is a stronger greenhouse gas than CO2.

First of all, 1 gigaton of CH4 is 2.75 times the molecules of C)2 at 1 gigaton. Then you have to consider the instantaneous slope. Greenhouse gas sensitivity is based on doublings. When we are at about 400 ppm for a doubling of CO2, and about 2 ppm for a doubling of CH4, there is already a 200 to 1 ratio in play. Iff we were to add 2 ppm to each, now there is only about a 100 to 1 ratio. You cannot use the instantaneous slope of a greenhouse gas to project future levels. That is only for that one ppb of change. Look closely at the graph I presented in post 45. The slope for CH4 is calculated to 0.3664 vs. 0.0141 for CO2. For the gas levels used, that indicates that one ppb of CH4 will increase warming by 36.64 microwatts while CO2 increases warming by 1.41 microwatts. This means that 1 ppb of CH4 warm 26 times greater than 1 ppb of CO2. When used in mass, fot GWP numbers, multiplied by 2.75 makes that GWP year zero number at 71.4. However, notice that the warming does not follow the straight line calculations. For every doubling, since these are log functions, the Radiative Efficiency is halved. RE for CH4 at AR5 levels table 2.1 for CH4 is 3.63 x 10[SUP]-4[/SUP] for 1803 ppb. 1.37 x 10[SUP]-5[/SUP] for CO2. Doubling this to 3.606 ppm would make that number half. Half again for each doubling. After seven doublings, CH4 would be at 231 ppm and have only a 5.67 x 10[SUP]-6[/SUP] This is now less than half the RE for CO2. At the 8th doubling, is we had 462 ppm of CH4, the RE would be down to 2.84 x 10[SUP]-6[/SUP].

This is not controversial. This is fairly basic climate science.

So why do you fail to comprehend it? Did you flunk math?

GWP is based on reality. Its goal is to illustrate an abstract concept, namely the relative strengths of different GHGs. It's based on radiative efficiency, current amounts of the various gases in the atmosphere, and rates of absorption of the gases over time; it's updated periodically as well. The "unreal" part is that it's based on the effects of emitting 1 ton of each gas. This is because it is specifically designed to indicate the impacts of different gases on the atmosphere.

But after that 1 ton of gas, the next ton is less. The next ton less again. That's why GWP is meaningless. It is not a variable than can be used for gas level projections. It only represents that first ton.

It is not a problem for GWP to show that CH4 is a more powerful GHG than CO2. That's part of its job, to give policy makers an insight into relative strengths of GHGs, so they can tailor their policies appropriately.

It is deceptive to those who don't understand what it really represents, and added ambiguity to science instead of clarity. RE and GWP are deceptive numbers unless only fully comprehends what they mean.

You clearly do not comprehend.

 

[Visbek]

Where the people who put out nonsense like GWP get confused, or intentionally attempt to confuse people, it that a gigaton is a fixed amount
in relationship to the atmosphere, is a much larger change for CH4 at 1.8 ppm than for CO2 at 410 ppm.

They're not confused. At all.

They are well aware that there is more than 200 times more CO2 in the atmosphere than there is CH4.

The point is that when you compare the two gases, you do not compare them based on doubling their current amounts. That's an absurd standard that no one uses to compare the relative strengths of greenhouse gases.

 

[Visbek]

I am sorry, but that is how the forcing of greenhouse gasses are calculated.
As to no one using the doubling method, I suspect James Hansen, would not like being deprecated, to "No One".
https://pubs.giss.nasa.gov/docs/1997/1997_Hansen_ha01900k.pdf

lol

So where in that paper does he propose using 2x as a comparative measure to other GHGs? Oh wait, he doesn't. The point of the paper is to show that factors like the altitude and latitude of the forcing changes its impact on the atmosphere as a whole.

And no, I didn't say "no one ever used 2xCO2 for any purpose whatsoever." What I'm saying, repeatedly, is that "doubling current concentrations of GHGs is an absurd standard to measure the relative strengths of different GHGs, which no one uses."

Better luck next time.

 

[longview]

They're not confused. At all.

They are well aware that there is more than 200 times more CO2 in the atmosphere than there is CH4.

The point is that when you compare the two gases, you do not compare them based on doubling their current amounts. That's an absurd standard that no one uses to compare the relative strengths of greenhouse gases.

It is the way forcing is calculated, BY Hansen, By the IPCC, buy just about everyone.
In reality CH4 has a much lower potential, then even what simple doubling cure conveys,
because the CH4 will quickly become CO2, but lets run the numbers to see what happens.
Assume that we double the CH4 level from 1.8 ppm to 3.6 ppm.
this would force an imbalance of .510 X ln(2)= .35 Wm-2, but the CH4 will break down into C02 within about a decade,
so that 1.8 ppm of CH4 would become 1.8 ppm of CO2, increasing the CO2 level from say 410 to 412,
so the forcing would be 5.35 X ln(412/410)= .0260 Wm-2.

 

[Visbek]

My God man. Changes in forcing since 1750 is not the same at total forcing. The total forcing for CO2 at 278 ppm is around 30.2 W/m^2, and the total forcing for CH4 at 722 ppb is around around 0.55 W/m^2. This represents 1750 levels. Today, with around 400 ppm CO2, and 1865 ppb CH4, these values represent around and 32.2 W/m^2 and 1.07 W/m^2. By these calculation that fit the IPCC projections, CO2 forcing increased by 2.0 W/m^2 and CH4 by 0.52 W/m^2. That's using the IPCC methodology, which I disagree with, but I'll stick with that for debate.

Forcing change is not the same as total forcing.

sigh

Yet again... You're missing that small increases of trace gases are capable of having a significant impact on warming. The fact that a relatively small increase in CH4 still makes a big impact is... wait for it... an indicator that CH4 is a more powerful GHG than CO2.

You're so caught up in the idea of doubling that you are missing the obvious.

Not true at all. If both gasses were 410 ppm, CO2 would have a calculated forcing of 32.3 W/m^2 and CH4 would be 6.1 ppm. That's using the AR4 curves. The AR5 curves would make the differences greater yet.

Or, not. Remember, CH4 is removed faster from the atmosphere, meaning you'd need much higher levels of emissions of CH4 to keep it at 410ppm. If you tried to get it to that level in a single pulse, it'd require over 900 gigatons of CH4 added to the atmosphere, and it won't stay at that level for long -- most of it will be cleared after about 40 years. That pulse alone would send temperature anomalies to over 7C in about 15 years; RF from that pulse would start at over 16 Wm^, falling to 0 after about 60 years. That's not including any feedbacks resulting from the increased temperature.

I'm gonna guess that you missed something in your math. Maybe you need, oh, I dunno... A specialized model which could better calculate the actual emissions required to keep CH4 at 410ppm, and the subsequent impact on the atmosphere? Just a thought. Something sort of like.... what I have snapshots of? Yep, whacking CH4 up to around 400ppm would require an annual increase of around 26gt per year might increase its RF to nearly 30 Wm^2 after 50 years. (To put that increase in perspective, natural + anthropic CH4 emissions are around 0.5 gt/yr.)

First of all, 1 gigaton of CH4 is 2.75 times the molecules of C)2 at 1 gigaton.

Uh huh

So, what happens when we compare the IR absorption of CO2 and CH4 on a molecule-per-molecule basis? Gosh, I have no idea. Oh, wait, someone figured that out, decades ago. Per mole, CH4 causes 3.7 times more warming than CO2. I'm sure subsequent research has refined those original results.
https://www.nature.com/articles/344529a0

You cannot use the instantaneous slope of a greenhouse gas to project future levels.

So... I take it you missed how GWP recognizes the non-linear absorption of IR for gases like CO2, CH4 and N2O?

But after that 1 ton of gas, the next ton is less. The next ton less again. That's why GWP is meaningless. It is not a variable than can be used for gas level projections. It only represents that first ton.

GWP is not used for real-world gas level projections. Its job is to give policy makers an idea of the relative impacts of different GHGs over different time scales. It isn't used to make real-world projections of adding 10 or 20 or 100 tons of CH4. We have other tools for that purpose, and I even used a basic one in my previous post. Did you miss it?

I thought you understood what GWP is for. Ah well.

It is deceptive to those who don't understand what it really represents, and added ambiguity to science instead of clarity. RE and GWP are deceptive numbers unless only fully comprehends what they mean.

Zomg.... They tell you exactly what GWP is for.

Your accusation is hilarious. If you failed to understand it, that's on you, not the IPCC.

 

[Visbek]

It is the way forcing is calculated, BY Hansen, By the IPCC, buy just about everyone.

It's a convenient benchmark that we use for the impact of CO2. It's not used to compare GHGs. And again, it wasn't used in that paper as a means to compare the effects of GHGs.

Yet again: If we compare by equivalent mass, or equivalent number of particles, in both cases CH4 absorbs more IR than CO2. It's a trace gas, and increases by small amounts relative to CO2 will have a big impact. This really is not that complex.

In reality CH4 has a much lower potential, then even what simple doubling cure conveys,
because the CH4 will quickly become CO2, but lets run the numbers to see what happens.

I already have. And running the numbers the wrong way multiple times doesn't change anything.

 

[longview]

It's a convenient benchmark that we use for the impact of CO2. It's not used to compare GHGs. And again, it wasn't used in that paper as a means to compare the effects of GHGs.

Yet again: If we compare by equivalent mass, or equivalent number of particles, in both cases CH4 absorbs more IR than CO2. It's a trace gas, and increases by small amounts relative to CO2 will have a big impact. This really is not that complex.



I already have. And running the numbers the wrong way multiple times doesn't change anything.

CO2 and CH4 respond to the same type of natural log curve, and can both be fitted to the same type of curve.
The forcing is a ratio of the new level divided by the new level, and CH4 is both weak and short lived.
Both factors make CH4 almost insignificant in terms of a greenhouse gas.
While the empirical data of forcing for CO2 is weak and minimal, it is almost non existent for CH4.
with only a 10 year lifetime, one has to wonder how it could ever be accurately measured, as portions
are breaking down almost as fast as they are emitted.

 

[Empirica]

The ad hominem is the refuge of those without an argument.

A refuge commonly inhabited by liberals with an intense propensity for defending the progressive ideology.

Maybe you need a little more understanding of those with 'no argument' until you've walked a mile in their shoes.

Although that "walk" may not come none too soon Jack, considering you usually have a pretty solid argument. :thumbs:

 

[Lord of Planar]

sigh

Yet again... You're missing that small increases of trace gases are capable of having a significant impact on warming. The fact that a relatively small increase in CH4 still makes a big impact is... wait for it... an indicator that CH4 is a more powerful GHG than CO2.

That BS. Microwatts of change per square meter is not significant.

You're so caught up in the idea of doubling that you are missing the obvious.

No, I'm pointing out a reality of which you fail to comprehend.

Or, not. Remember, CH4 is removed faster from the atmosphere, meaning you'd need much higher levels of emissions of CH4 to keep it at 410ppm. If you tried to get it to that level in a single pulse, it'd require over 900 gigatons of CH4 added to the atmosphere, and it won't stay at that level for long -- most of it will be cleared after about 40 years. That pulse alone would send temperature anomalies to over 7C in about 15 years; RF from that pulse would start at over 16 Wm^, falling to 0 after about 60 years. That's not including any feedbacks resulting from the increased temperature.

Your rationalization does not change reality.

So, what happens when we compare the IR absorption of CO2 and CH4 on a molecule-per-molecule basis? Gosh, I have no idea. Oh, wait, someone figured that out, decades ago. Per mole, CH4 causes 3.7 times more warming than CO2. I'm sure subsequent research has refined those original results.
https://www.nature.com/articles/344529a0

Per mole at current levels. It isn't a straight line. You fail to comprehend how the amount of warming CH4 causes is insignificant, because it's a log function. Not linear.

So... I take it you missed how GWP recognizes the non-linear absorption of IR for gases like CO2, CH4 and N2O?

Inly for that one ton. The next ton is smaller. The next smaller yet.

It is nonlinear as the levels increase.

GWP is not used for real-world gas level projections. Its job is to give policy makers an idea of the relative impacts of different GHGs over different time scales. It isn't used to make real-world projections of adding 10 or 20 or 100 tons of CH4. We have other tools for that purpose, and I even used a basic one in my previous post. Did you miss it?

It is used to put fear in the uneducated of these sciences.

I thought you understood what GWP is for. Ah well.

I understand completely what GWP is. You obviously do not.

 

[Visbek]

CO2 and CH4 respond to the same type of natural log curve, and can both be fitted to the same type of curve.
The forcing is a ratio of the new level divided by the new level, and CH4 is both weak and short lived.
Both factors make CH4 almost insignificant in terms of a greenhouse gas.

Whatever, dude. You do you.

 

[Visbek]

Your rationalization does not change reality.

I'm not offering any rationalizations or changing anything. I'm simply stating what the models show -- models based on the same exact claims about the properties of greenhouse gases that you claim you're using.

I mean, really. For just a moment, think about it. An increase in concentration of CH4 by about 1ppm caused as much radiative forcing as, what, a 50ppm increase in the concentration of CO2? And CH4 is the weaker greenhouse gas? C'mon, man. Get it together.

And as usual, I'm summarizing the documented and published work of thousands of climate scientists, while you are... piggybacking on their work, as though you found something that all those PhD's missed, by doing no actual work whatsoever, and citing no research whatsoever.

Bored now.

 

[Lord of Planar]

I mean, really. For just a moment, think about it. An increase in concentration of CH4 by about 1ppm caused as much radiative forcing as, what, a 50ppm increase in the concentration of CO2? And CH4 is the weaker greenhouse gas? C'mon, man. Get it together.

If they were to both increase by 1 ppm, from AR5 numbers, then CH4 would go from 1803 ppb to 2803 ppb and increase warming by 0.48 W/m^2. From 722 to 1803 ppb, we can extrapolate that forcing change equals 0.524 x ln(ch4 ratio). This addition 1 ppm would equal 0.231 W/m^62. Yes, the CO2 increase in minimal. CH2 changes would be 5.35 x ln(391.5/390.5) = 0.0137 W/m^2. A 16.9:1 ratio. Notice that it is no longer around 20:1. The added 50 ppm would give us a 0.645 W/m^2 increase. Almost three times that of the 1 ppm increase to CH4. These changes ar not linear! When increasing by 1 ppm, we increased CH4 by 55.5%, and only increased CO2 by 0.256%. As a percentage, CH4 was increased 217 times more to get that 16.9 ratio. It doesn't take 50 ppm of CO2 to equal a 1 ppm increase of CH4. It only takes a 17.2 ppm increase. 5.35 x ln((390.5+17.2)/390.5) = 0.231. That RE number is real slippery and useless in a dynamic calculation.

In the natural system, we would never see such a large deviation between percentage changes. Even with man-made increases, the concept you provide is unreal.

It took us over 250 years to increase CH4 from 722 ppb to 1803 ppb. During that time, CO2 went from 278,000 ppb to 390,500 ppb. These changes reflect an additional 1,081 ppb of CH4 to the additional 112,500 ppb for CO2. It is realistic to assume that CH4 will only increase by about 1 ppm for every 100 ppm of CO2, and will never be too far from this.

I get why you alarmists like translating small changes in a linear fashion. It's deceptive, and you approve of deception.

 

[longview]

Whatever, dude. You do you.

It occurred to me that comparing what CH4 might do compared to what CO2 might do for an equal impulse is unnecessary,
because the ACS has published how much radiative forcing a change in CH4 has caused.
https://www.acs.org/content/acs/en/climatescience/atmosphericwarming/climatsensitivity.html
For the increase of CH4 from about 375 to about 675 ppb, ΔFCH4 ≈ 0.3 W·m–2.
ACS also published the formula for radiative forcing for a change in CO2. (ΔFCO2 = (5.35 W·m–2) ln(265/185) = 1.9 W·m–2)
Now we can compare exactly, the radiative forcing for an equal change in CH4 and CO2.
5.35 X ln(675/375)=3.14 W·m–2, wow that sure doesn't look like CH4 has more effect, 0.3 W·m–2 vs 3.14 W·m–2.