Guest post by David Middleton
Featured image borrowed from here.
Nearly every catastrophic global warming doomsday scenario, particularity those involving icecap failures and Noah-size sea level rises are based on the “RCP 8.5” scenario.
Representative Concentration (or Carbon)Pathway 8.5 assumes a “rising radiative forcing pathway leading to 8.5 W/m² in 2100.” It is generally assumed, with little dissent, that each doubling of the atmospheric CO2 concentration will add 3.7 W/m² to the net infrared radiative flux.
A doubling of the supposedly stable pre-industrial CO2 level (280 ppmv to 560 ppmv) should yield 3.7 W/m² of additional forcing to the net infrared radiative flux. In order to get 8.5 W/m², the atmospheric CO2 concentration would have to rise to 1,370 ppm…
Note: Yes. The above is from SkepSci. I checked the math. It’s close enough.
Does any sane person really believe that the atmospheric CO2 concentration could rise from the current 400 ppm to 1,370 ppm over the next 85 years? (*)
Using BP’s Statistical Review of World Energy 2015, I built a “model.”
This “model” derives two equations:
- CO2 (ppm) = 0.0002*(MTOE) + 320.87 (R² = 0.9986)
- MTOE = 142.16*(Year) – 275,639 (R² = 0.9698)
Note: MTOE = Millions of Tonnes of Oil Equivalent.
Note to nitpickers: Yes, I know the top and bottom charts and equations 1 and 2 should have been listed in the opposite order.
These two equations enable me to project fossil fuel use and atmospheric CO2 into the distant future (beyond my retirement date… which with oil at $30/bbl is either very far off in the future or sooner than I would prefer). Using the assumption that the mix of crude oil, natural gas and coal would remain at a constant ratio (that of the period 2005-2014), I come up with an atmospheric CO2 concentration of 683 ppm in 2100, about half of RCP 8.5 (Venus) and comparable to RCP 4.5 (non-catastrophic).
The Peak Oilers in the WUWT community will quickly notice that crude oil production in 2100 would have to be about four times that of 2015 for this model to work… In other words, Peak Oil would be delayed again. My “back of the envelope” calculation says that we would have to find and produce about 4 trillion barrels of crude oil between now and 2100 to comply with this model… Since that is about twice the sum of global proved crude oil reserves and the current estimate of technically recoverable resource potential, I better get back to work finding more oil… 🙂
I didn’t do the calculations for natural gas and coal… because I had to get back to work. My best guess is that there is more than enough coal and natural gas in the ground to make it to 2100 without us having to freeze in the dark.
Disclaimer: These models are based on a whole lot of assumptions… But probably not nearly as many assumptions as RCP 8.5.
(*) Addendum
It has been brought to my attention that RCP 8.5 references “CO2-equivalent,” not pure CO2 and that the CO2-only concentration in 2100 is posited to *only* be 930 ppm, not 1130. 930 is still a lot (36%) higher than 683… And 683 was based on the assumption that the ratio of crude oil, natural gas and coal remains constant. Since natural gas will very likely continue to displace coal and eventually crude oil, 683 is probably unrealistically high as well.
So I will revise and extend my question:
Does any sane person really believe that the atmospheric CO2 concentration could rise from the current 400 ppm to 930 ppm over the next 85 years? Does any sane person really believe that the atmospheric CO2-equivalent concentration could rise from the current 478 ppm to 1,370 ppm over the next 85 years? Why would the non-CO2 GHG’s rise at a 25% faster rate than the already improbable RCP 8.5 rate for CO2?
It is not and never has been about facts , it is and always has been about politics
with that in mind you can see why wild claims are made .
To be fair , many working in this area have such low scientific ability , along with low levels of personal honour and massive ego’s , that even if they wanted to they could not support their arguments on the basis of facts.
David Middleton, thank you for your short, focused essay.
You will. In the 34 years between 1980 and 2013 average annual increase of known crude oil reserves was 2.61%, while production only increased by 1.05% per year. The net result is, in 1980 proven reserves were enough for 29 years at constant rate of production, while in 2013 they covered twice that much time, 59 years.
Not the kind of behavior one would expect from a resource on the brink of final depletion.
Even under Hubbert’s 1956 assumptions, crude oil wouldn’t be “on the brink of final depletion.” Peak resource production generally occurs around the mid-point of the depletion of that resource.
This “model” derives two equations:
->This “model” derives of two equations:
‘Does any sane person really believe that the atmospheric CO2 concentration could rise from the current 400 ppm to 930 ppm over the next 85 years? Does any sane person really believe that the atmospheric CO2-equivalent concentration could rise from the current 478 ppm to 1,370 ppm over the next 85 years? Why would the non-CO2 GHG’s rise at a 25% faster rate than the already improbable RCP 8.5 rate for CO2?’
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problem is: such belives are inherent in midst of society.
midst of society tries to stay sane by adhering to such believes.
After reversing back the global average temperature curve and from this removing the other components other than anthropogenic greenhouse gases that contributing to global average temperature rise, what will be the real temperature rise at global level — although global average is a misnomer & hypothetical in nature as this factor is not going to affect nature but the localized change only affect it.
CO2 & anthropogenic greenhouse gases — there are several other sources other than fossil fuel use. Prior to 60s we have practically no measurements of greenhouse gases around the world. Yet, with all this the so called global warming is less than 0.15 oC by 2100.
Dr. S. Jeevananda Reddy
Details of the RCP 8.5 scenario can be found at this link. Annual CO2 and CH4 emissions will plateau in 2070 at triple today’s level. Despite burning all that coal, sulfate aerosol emissions will drop by 75%.
http://tntcat.iiasa.ac.at:8787/RcpDb/dsd?Action=htmlpage&page=compare
Thanks. I may gin up a sequel to this post.
So…RCP 8.5 is even worse bad science fiction than previously believed.
I see the CO2-equivalent issue has been addressed. But also consider yourself making this calculation in 1916. You would draw a linear trend line through fossil fuel emissions from 1865-2014 and project that linear growth into the future, finding a year-2015 concentration of about 340ppm. You would conclude with the question: “Does any sane person really believe that CO2 will reach 400ppm by 2015?”. That apparently wouldn’t have been a controversial view at the time. From what I understand Arrhenius initially believed it would take millennia to double atmospheric CO2.
Linear growth calibrated to the period 1965-2014 is a plausible assumption. It’s actually pretty close to what happens in RCP6.0, the low-end “Business-as-usual” scenario, which reaches 670ppm in 2100. But an increasing growth rate is also plausible – it’s been the norm in the historical record to date.
The scenarios are calibrated to a historical emissions inventory and diverge from 2005. Going on from 2005 the same emissions inventory is so far showing growth tracking slightly above RCP8.5, way above RCP6.0. Early days obviously, but no sign that 8.5 is insane from a demand perspective at least.
The problem is that fossil fuel consumption cannot follow the growth rate required by RCP 8.5 very far into the future. It can’t even follow RCP 6.0 very far into the future.
Figure 5. Natural sources probably account for 40-60% of the rise in atmospheric CO2 since 1750.[/caption]
Had atmospheric CO2 simply followed the preindustrial trajectory, it very likely would have reached 320-345 ppmv by 2010…
[caption id="" align="alignnone" width="479"]
The problem is that fossil fuel consumption cannot follow the growth rate required by RCP 8.5 very far into the future.
Cannot? There’s certainly enough material to burn. It’s a question of whether it can be extracted economically, which is a function of technology, economics and will. It seems absolutely plausible that the demand is going to be there, absent policy changes.
Re: your natural CO2 analysis.
Firstly, your training period of 1788 to 1944 substantially overlaps the industrial era (historians would argue it’s entirely within the industrial era – 1760 is commonly considered the start date), so claiming it as a pre-industrial trajectory is clearly wrong. Why not train it using 1000-1760CE?
Secondly, it looks like your cumulative emissions curve is fossil fuel-only. In the early-industrial era land-use change was by far the largest source of anthropogenic CO2 emissions. At 1850 land use change emissions were plausibly about 10x that from fossil fuel sources, bigger multiples prior to that, and it was only around the 1930s-60s that fossil fuels took over as the larger source.
Crude oil production simply can’t keep up with RCP 8.5. While it may not actually reach “peak oil” for a long time, the growth rate can only decelerate. The Hubbert Equation is actually valid. His estimate of recoverable resources was wrong. Natural gas and coal may be able keep up with RCP 8.5. However, gas is steadily displacing oil and coal, largely due to economics. So, the emissions projection in RCP 8.5 is not even remotely realistic as a “business as usual” scenario. Yet, it is the basis of almost every catastrophic forecast of what is expected to happen if we don’t drastically reduce emissions.
Prior to 1960, atmospheric CO2 was rising faster than emissions. I suppose that could be a function of land use changes.
Can any sane person really believe Armageddon will occur when atmospheric CO2 reaches 900 ppm at some unknown year in the future, when atmospheric CO2 was at least 5,000 ppm in the past (and helped create the oxygen based world we live in). Yes, alarmism sells magazines, papers, votes, funding but c’mon folks, take a deep breath and get back to reality.