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The first five years of the RCPs

Further to yesterday's post on butterflies and RCPs, I wondered just how things were panning out for the RCPs since they were issued five years ago. I wasn't really expecting very much from this analysis since five years is not very long, but it turned out that there is more of a difference than might be expected.

The RCP data is for the mid-year carbon dioxide concentration and it turns out that the June figure from Mauna Loa has just tipped the 400ppm mark. RCP8.5 predicted that 2015 would be the first year in which the 400ppm mark was breached at the mid-year point, so at first glance we are indeed on the RCP8.5 pathway.

However, it turns out that at the point the RCPs were issued Mauna Loa was already several PPM ahead of the RCPs, so it is necessary to put everything on the same baseline to get a meaningful comparison. Here's the result - a graph which shows the growth in CO2 concentrations for each time series since 2010.

As you can see, RCP8.5 carbon dioxide concentration is already more than 1ppm more than reality. That's not a great deal in absolute terms but is quite a lot given we have only had five years for any divergence to show itself. We actually seem to be tracking RCP4.5 most closely. (Slightly counterintuitively, RCP6 produces the lowest carbon dioxide concentrations for the first few decades before accelerating in the second half of the century.)

Of course it's really a bit early to draw strong conclusions from such an analysis. The big question is over what happens in the middle of the century, when RCP8.5 and RCP6 start to curve upwards and RCP4.5 heads the other way. But, as Matt Ridley and Blair King have so ably described, a brief look at the assumptions behind RCP8.5 suggests that it is more a rather implausible worst case scenario than anything else. Certainly any suggestion that it represents "business as usual" is likely to mislead the lay reader.

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Reader Comments (40)

I am puzzled by the calibration of the CO2 concentration axis as it does not tally with the 400 ppm range described in the text. Is it a misprint or have I missed something?

Aug 11, 2015 at 10:05 AM | Registered Commentermikeh

Mike H

That's the growth since 2010.

Aug 11, 2015 at 10:15 AM | Registered CommenterBishop Hill

Is five years a long enough period to evaluate anything?

No, I don't think it is.

Aug 11, 2015 at 10:16 AM | Registered CommenterM Courtney

Another alarmist wet dream?

Isn't "OMG 400ppm!!!!!!!!!!!!!!!!!!!!!"

ergo............ "we're all doomed, doomed I say............... DOOMED!"............. rather too convenient, what wiv Paris coming up and all?

CO², we love it and so do the plants - naturally!

Aug 11, 2015 at 10:16 AM | Unregistered CommenterAthelstan.

So CO2 is 'on track' with RCP8.5. Doesn't mean a thing if all the prophesized disasters associated with that model fail to materialize.

Aug 11, 2015 at 10:26 AM | Unregistered CommenterClimateOtter

Why does my co2 meter show a reading of 364 ppm and has done with slight variation for the past year or is rural Somerset different than the top of an extinct volcano the other side of the world

Aug 11, 2015 at 10:32 AM | Unregistered Commentermark

Is 5 years too long or too short?

I look at it from a different perspective. There is no real reason to think that their projections should or would be correct. They don't understand the carbon cycle well enough, other than saying that the missing CO2 is probably in the land vegetation, or probably in the oceans, but definitely hasn't left the planet. Otherwise they would not be still looking for missing sinks.

The current projections are at the level of a sales director who tells the shareholders that sales are going to be 10% higher next year because this year was 9% higher than last year, and that's what the shareholders want to hear. He doesn't actually know, but might end up being right. Until the year that sales go down, when he won't have to worry about being sales director any more.

Aug 11, 2015 at 11:26 AM | Unregistered Commentermichael hart

The RCPs have been out for 5 years. The RCPs are scenarios of concentrations only, and cannot be interpreted without the corresponding scenarios, so-called SSPs, of emissions, energy use, economic activity and so on.

The SSPs were released in March 2013, but only population and per capita income. Energy use and energy supply were released, as draft, in May 2015 -- and are currently being revised.

So, five year after their release, we still do not know where the RCPs come from, and whether they are at all realistic.

Recall that David Henderson's conversion to climate skepticism began when he had a close look at the previous set of scenarios. Fortunately for the IPCC, David's example cannot be followed because there is, literature, nothing to see here. For five effing years, this crucial bit of the IPCC work has been hidden.

Aug 11, 2015 at 11:34 AM | Unregistered CommenterRichard Tol

So it'll be a while before it gets to 1600ppm in my greenhouse thats connected to my warm broom cupboard brewery?

Anything about instrumentation errors in this stuff? Or is it an averaging of a bunch of readings that may have values like here today, gone tomorrow and back next week...or something? Or is the trend(s) tweaked by the professional hand?

Aug 11, 2015 at 11:39 AM | Unregistered CommenterEx-expat Colin

M Courtney
Possibly not, but if I'd written an application which was showing an error of 10% after a relatively short time I think I might have started to look for a reason why. My boss might be asking why too (some definitely would).

Aug 11, 2015 at 12:03 PM | Unregistered CommenterSandyS

The link goes to RCP Concentration Calculations and Data. At the bottom is the heading Further Information.

1 20th Century Mixing Ratios. This is how they mixed it up to get what they wanted

2. Harmonised Emissions. Their adjustments sound nicer

3. RCP post 2100 extensions. This is their computer modelled guesswork

What did they say the funding was supposed to achieve with scientific accuracy? A nice annual seafront holiday?

Aug 11, 2015 at 12:11 PM | Unregistered Commentergolf charlie

Who cares?

The OCO2 satellite which measures the atmospheric CO2 content, has shown that maximum CO2 is formed in the SOUTHERN hemisphere not north. There are hot spots of extreme production in Africa. Very little actually comes from the industrial north.

Yes I was surprised as well but reality is reality.

Aug 11, 2015 at 12:37 PM | Unregistered CommenterJohn Marshall

John Marshall, do not confuse computer modellers and science fiction projectionists with actual facts. This would make climate science seem like nothing more than a Hollywood disaster movie from start, to eternity.

Aug 11, 2015 at 12:52 PM | Unregistered Commentergolf charlie

It's an ill wind?

How Agriculture Is Booming In Africa

" We regularly hear that it is places like Africa which are suffering most from climate change.

When we look at agricultural statistics, however, there is no evidence of this. On the contrary, as the official UN figures show, cereal production and yields, meat production and the gross value (at constant prices) of all agricultural output have all been rising steadily since 1970.

There may be all sorts of reasons for this, but it is evident that, as far as agriculture is concerned, Africans are much better off than they were a few years ago........"

Aug 11, 2015 at 1:00 PM | Registered CommenterGreen Sand

Aug 11, 2015 at 1:00 PM | Registered CommenterGreen Sand

Given that Zimbabwe used to be a major player in African agriculture but has done its utmost to ruin its own farm industry, does that suggest the rest of Africa is doing even better than is thought?

Aug 11, 2015 at 1:16 PM | Unregistered CommenterDaveS

I have never known Richard Tol swear before.
I think that tells us all we need to know about the deviousness or downright dishonesty that is being perpetrated in the name of climate "science".
Would that there were someone of integrity in that cesspit prepared to break ranks and let us know exactly what is going on.
Any time between now and mid-November would be nice. We can't promise you a Nobel Prize but we can try to make sure you do have the proper recognition in due course as the Man/Woman Who Saved the Sanity of Science.

Aug 11, 2015 at 1:25 PM | Registered CommenterMike Jackson

We are also behind the projected CO2 concentration of the 'standard' AIB scenario of the AR4. By 2015 the concentration was to have been 405ppm.

Aug 11, 2015 at 1:25 PM | Unregistered CommenterDB

Given climate sensitivity to CO2 is probably somewhere between <1C and zero, who cares about 400ppm? It's merely symbolic of the total failure of CAGW theory. The total failure of atmospheric temperatures to be noticeably influenced by rising CO2 for around 20 years nails it.

The theory doesn't say there's a lag in warming, rather that CO2-driven warming is effective immediately. Annoyingly for them that hasn't happened and in a sane world that would be game over for alarmists. The IPCC are imo literally lying through their teeth when they continue to claim a possible ECS range of 1.5C-4.5C. There is NO observed evidence whatsoever to support the latter number, which is there purely to maintain hysteria. Meanwhile the former figure allows them their wriggle room to continue the blag.

Aug 11, 2015 at 1:36 PM | Unregistered Commentercheshirered

DaveS, Zimbabwe has been damaged by political climate change. It is a warning to the world about the unintended consequences of destroying modern farming technology and infrastructure, irrespective of the rights and wrongs of colonial rule and its end.

Climate alarmists do not even try to blame the starvation and unrest on global warming, but still preach the virtue of the Green subsistence economy.

Aug 11, 2015 at 1:50 PM | Unregistered Commentergolf charlie

"So, five year after their release, we still do not know where the RCPs come from... For five effing years, this crucial bit of the IPCC work has been hidden" Richard Tol

Erm, no. It was all published in a 2011 special edition of the journal Climatic Change. The paper detailing RCP8.5 is even open access:

You weren't aware of this?

Aug 11, 2015 at 2:04 PM | Unregistered Commentertilting@windmills

Tilting (if I may): That's RCPs, which have been available to anyone for a number of years now. The SSPs are still not there.

Aug 11, 2015 at 2:38 PM | Unregistered CommenterRichard Tol

SandyS, in my industry if you haven't achieved anything after five years then you would have been out the door for a couple already.

But the climate is slower. By definition, it's not weather.
So can you really say there's anything to worry about after five years? No. I don't think so.

And that means there's nothing to worry about their accuracy or, therefore, their predictions.
It's all too early to tell - one way or the other.

(If anyone wants to call on the Precautionary Principle raise it as a Discussion and we can knock that down then).

Aug 11, 2015 at 3:05 PM | Registered CommenterM Courtney

M Courtney, on the basis of the Precautionary Principle, we should not spend anymore taxpayer funds on climate science, and see if any taxpayers notice the improvement to their own wealth and the economy as a whole.

Squeals of indignation from climate scientists won't be heard, if they are all on a top secret, life long mission to record the precise moment the North Pole melts.

Aug 11, 2015 at 3:25 PM | Unregistered Commentergolf charlie

Professor Tol, you claimed we don't know where the RCPs "come from". Hence my reply.

The RCPs were derived from a bunch of population, GDP, energy system, land-use and other parameters that have been available to look at since 2011. How else could Matt Ridley be criticising the population and coal use assumptions in RCP8.5?

The SSPs weren't used to derive the RCPs. They are subsequent attempts by model groups to come up with alternative ways of realising them.

But then you know all this, surely...

Aug 11, 2015 at 3:45 PM | Unregistered Commentertilting@windmills


Sorry, could you explain to what you mean by "attempts to come up with alternative ways of realising them". Not sure what that means.

Aug 11, 2015 at 3:50 PM | Registered CommenterBishop Hill

Couldn't you just look at CO2 emissions?

For claiming five years is too short a time period, Raupach et al had no problem doing so with AR4 numbers.
They claimed a faster growth rate than the model scenarios, and there were disputes as to the methodology.
Particularly, they chose to use compound continuously when calculating the growth rate, and they averaged across all scenarios within a family. The dispute is that IPCC assigned no probability to the individual scenarios, and Raupach chose to interpret that as they have equal probability, making an average possible.

Aug 11, 2015 at 4:13 PM | Unregistered CommenterMikeN

Different socio-economic futures could give rise to the same path of atmospheric concentrations (RCP).

More info can be found by Googling "Shared Socioeconomic Pathways" and clicking on the top result.

Aug 11, 2015 at 4:16 PM | Unregistered Commentertilting@windmills

Ms Windmills:
The RCPs are scenarios of concentrations and loads, and of radiative forcings. The corresponding emissions, energy use, diets, economic activity etc were NOT released with the RCPs -- and a large part is yet to be released.

I'd happily eat my words, as I've been trying to get hold of the missing parts for some five years now. Analyzing these data is much more fun than bitching about their inaccessibility.

Aug 11, 2015 at 4:22 PM | Unregistered CommenterRichard Tol

Ms Windmills
Closer inspection shows that the IIASA database looks great but does not contain any data ... the .csv files that can be downloaded have population only.

Aug 11, 2015 at 4:32 PM | Unregistered CommenterRichard Tol

The appending of Mauna Loa CO2 measurements on to a curve of Ice Core air bubble CO2 data is as scientifically unacceptable as Mann's appending of recent air temperature series onto a tree ring proxy temperature re-construction and should be questioned and treated with the same skepticism as Mann's Hockey Stick.

No study has yet demonstrated that the content of greenhouse trace gases in old ice, or even in the interstitial air from recent snow, represents the atmospheric composition.

The selection of ice core data by Calendar skewed results to match the theory. The values G.S. Callendar chose to use are a small and unrepresentative selection from the available chemical measurement data. He rejected both higher and lower values, to arrive at a figure that supported his hypothesis.
( see S. Fonselius, et al., 1956. Tellus, Vol. 8, p. 176)

In presenting measurements of CO2 concentrations in the pre-industrial ice core from Byrd Antarctica, Neftel, et al.,in 1982 showed maximum values up to 500 ppmv. In 1988, the same authors published measurements for the same section of the Byrd ice core, but left off the high readings published previously,reporting a highest concentration of 290 ppmv, in agreement with the ( CO2 driven global warming) theory

Measurements of CO2 in pre-industrial ice and CO2 as measured in the atmosphere at Mauna Loa, Hawaii were matched in the so called "Siple Curve" In this exercise the original data was subjected by Callendar to an arbitrary “correction” of 83 years in the age of the air, to make the ice core CO2 content match the Mauna Loa atmospheric concentration of CO2 in 1957 . No technical justification of this correction has been demonstrated then or since.

Using the real age of the air, would indicate that the CO2 concentrations in the latter part of 19th century were the same as those in the 1970s. The “corrected” data were published by Neftel et al. 1985; Friedli, et al. 1986; and IPCC, 1990.

Aug 11, 2015 at 4:39 PM | Unregistered CommenterPaleoclimate Buff

Dear Professor, if we didn't love bitching why would we be here? ;)

So you are aware of the population data. The emissions data are also easily findable. Some of the other things you mention are plotted as charts in the published paper.

Hiding? I guess RCP data is a bit like Kim Kardashian - plenty is on show for most people, even if some want more...

Aug 11, 2015 at 5:16 PM | Unregistered Commentertilting@windmills

Even if Kim Kardashian is a climate scientist, this still makes no sense of the nonsense above.

Aug 11, 2015 at 5:48 PM | Unregistered Commentergolf charlie

Er, what's an RCP, please?

a unix remote copy command?
a Reinforced Concrete Pipe?
a Respiratory Care Practitioner?

Beats me.

Aug 11, 2015 at 5:51 PM | Registered CommenterMartin A

Ms Windmills: Thanks for confirming that you do not know where the data are located either.

Aug 11, 2015 at 6:17 PM | Unregistered CommenterRichard Tol

Martin A.,
scenarios for climate change modeling = Representative Concentration Pathway

Key ideas --

Aug 11, 2015 at 6:40 PM | Unregistered CommenterJohn F. Hultquist

Thank you JFH.

Aug 11, 2015 at 6:56 PM | Registered CommenterMartin A

It all depends on what the temperatures do, as the rate of change of atmospheric CO2 is proportional to temperature anomaly (with appropriate baseline)

If temperatures decline in the next ten years, the rate of change of atmospheric CO2 will decline with it, which will cause a huge divergence with these silly RCP models.

Aug 11, 2015 at 8:40 PM | Unregistered CommenterBart

To clarify what I mean by the probability error made by Raupach and others, first pointed out to me by Ian at The Blackboard, consider that someone gives you a list of the Republican candidates for President, and tells you he is not assigning a probability to each one's chance of victory.
Should you take that to mean that Lindsay Graham has the same chance of victory as Scott Walker?

Aug 11, 2015 at 8:50 PM | Unregistered CommenterMikeN

That's not an error. It's the Principle of Insufficient Reason. If you only have a list of names, and you know nothing about the candidates, then indeed you should assign each of them an equal probability (1/17 if I'm not mistaken). Any deviation from that indicates that you know something about them that would affect their electoral success.

Aug 12, 2015 at 6:49 AM | Unregistered CommenterRichard Tol

I thought the Principle of Insufficient Reason was what impelled Donald Trump to declare his candidacy... ;-)

Aug 12, 2015 at 2:44 PM | Registered CommenterHaroldW

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