Guest Post by Willis Eschenbach
There’s a new study out claiming that tropical forests are losing their ability to sequester carbon dioxide. Bad forest, no cookies for you! The study is entitled “Asynchronous carbon sink saturation in African and Amazonian tropical forests”, and is available through Sci-Hub here. In their press release it says:
In the 1990s intact tropical forests removed roughly 46 billion tonnes of carbon dioxide from the atmosphere, declining to an estimated 25 billion tonnes in the 2010s.
The lost sink capacity in the 2010s compared to the 1990s is 21 billion tonnes carbon dioxide, equivalent to a decade of fossil fuel emissions from the UK, Germany, France and Canada combined.
Overall, intact tropical forests removed 17% of human-made carbon dioxide emissions in the 1990s, reduced to just 6% in the 2010s.
Now, the first thing I noticed was that this study falls under what I modestly call “Willis’s Rule Of Authors”, which states that
Q ≈ 1/N2
Where “Q” is the quality of a scientific study, and N is the number of study authors. In English, this means that the quality of a study decreases in proportion to the inverse of the square of the number of authors … which in this case is … wait for it … no less than one hundred and six authors.
So … how did the one hundred and six authors determine that the tropical forest are no longer sequestering as much as they used to sequester?
According to the study, they used both observations and models. How much of each? Well, a clue is that the word “model” appears 158 times in their study, while “observations” appears only 44 times … here’s a typical comment.
A statistical model including carbon dioxide, temperature, drought, and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly.
Now, it turns out that we can actually measure roughly how much human-generated CO2 is sequestered each year. The calculation is not all that complex. We know how many gigatonnes (“GT”, 109 metric tonnes) of carbon are emitted each year from the burning of fossil fuels plus cement manufacture. We know that for every 2.13 GT of carbon emitted, the atmospheric carbon dioxide level increases by one part per million by volume (ppmv). We routinely measure the atmospheric carbon dioxide level at the Mauna Loa Observatory.
So we take a look at how much carbon is emitted in a given year and we calculate how much the CO2 level should have increased. We subtract from that the actual increase in CO2 during that year, and the difference is the amount sequestered in that year by various carbon sinks around the planet.
Using that calculation, Figure 1 shows the amount of CO2 sequestered by year since 1959.
Figure 1. Percentage of anthropogenic CO2 sequestered by year.
There are some interesting things about this graphic. First, the amount sequestered varies widely year by year. This depends on two factors, the amount of natural emissions of CO2, and the variations in the natural carbon sinks. These are weather-driven. Some years there’s a lot of green growth on land and at sea, and other times there’s much less, which varies the amount of the carbon sinks. On the other side of the ledger, El Nino years like 1998 show an increase in natural CO2 emissions, so the percentage sequestered is smaller. With very large El Ninos, the amount of CO2 released may actually overwhelm the sinks, as in 1967.
Next, the smoothed value (blue/black line) varies between about 40% and 50%. It has hit both 40% and 50% twice in the past and most recently is about in the middle. There is no statistically significant long-term trend in the data (a least-squares analysis shows sequestration increased by 9% over the period, but the p-value is 0.20, far from significant).
Of interest for our purposes is the average for the 1990s and the 2010s mentioned in the study. In the 1990s the average sequestered was 49.8%. In the 2010s the average was 46.0%. The difference indicates the reduction in sequestration is 3.8%, but again it is not statistically significant …
But the one hundred and six authors say that forest loss reduced the amount sequestered by 11%. Hmmm …
Ah, well, I guess we shouldn’t expect models to actually agree with reality, that would be far too boring. In any case, we’re left with several possibilities, which include:
- The new paper is correct, forest sequestration has decreased by 11%, and coincidentally some other unknown carbon sink has increased by 7.2%, or …
- The new paper is wrong, or …
- The uncertainty is too great to come to any conclusion.
My conclusion? I’m not taking firm sides in this question, although option 2) seems most probable, followed by option 3). In any case, there’s no indication of a long-term reduction in the sequestration rate. And finally, I find it … well … discouraging that the authors didn’t include the actual sequestration calculations and discuss the implications of reality as opposed to models.
My best to everyone from a very dry hillside near the ocean in Northern California,
w.
As Usual: I politely request that you quote the exact words you are discussing, to avoid at least some of the misunderstandings that are the bane of the internet.
Technical Note: As you might imagine, there is a lag between when CO2 is emitted at the surface and when that surface CO2 affects the background CO2 as measured at Mauna Loa. This lag is on the order of ten months, and it has been adjusted for in Figure 1 above.
At least 106 vitas got enhanced in the process.
Hi Willis – This paper by David Motes takes a new approach.
Guest blog by David Motes; GW driven by Plant Evapotranspiration Reduction
http://www.warwickhughes.com/blog/?p=6729
Shameless hijack. Would you please provide monthly updates on the communication between you and your reviewers about the peer reviewed paper you’re writing? If it has already been published, then my bad, and I’ll find it and read it. We would be better served if we saw ALL of the exchanges, both ways. Feel free to comment to us, but I would think that those comments would also be sent to your reviewers.
There is much written here about the perversion of the peer reviewed process to keep skeptics in subterrannea, and this might be a good example of it.
Thanks in advance
During low solar periods, particularly during centennial solar minima, El Nino conditions increase and the tropical forests become drier and release massive plumes of CO2. Ideally seen as a natural negative feedback.
If you care about too much CO2 in the atmosphere plant a tree. If it turns out that the amount of CO2 in the atmosphere doesn’t matter, we still get the tree. If you reduce the amount of fossil fuels you consume, the price goes down and someone somewhere else uses more.
Thanks, Willis. Tropical forests are jungles, and I have mentioned before they stink when you walk (or cut your way or push against stinging plants or turn around) through them. The stink is from accumulated rotting vegetation on the ground. Rotting is an oxidation process, therefore what is the balance between CO2 uptake in the green leaves, then oxygen outgassing, and finally consumption of oxygen in the rotting process?
The swing in sequestration was about 80% from 1985 to 1990. Really? How does that happen globally?
WE, your skepticism (ridicule) of this paper is well deserved.
I went and looked at the paper in Nature. It is WORSE that you pointed out.
The paper is paywalled (and I did not waste my money), but as usual the SI is not. The alarmist tell is in SI table 5 footnote 1, explaining their final conclusion methodology.
They took two 20 year intervals and calculated the centered delta T means—1985 and 2050. Now 2050 hasn’t arrived yet. So they took the mean of 19 CMIP5 models for that interval. Then they regionally downscaled that mean to ‘match’ the regional forest plots in the study. Then they used that downscaling to project their erroneous models of African and Amazonian forest plot observations forward to 2050 to ‘prove’ it will get worse in the future.
Just three little problems. CMIP5 provably runs hot. Regional downscaling is very unreliable (discussed in essay ‘The Last Cup of Coffee’ in ebook Blowing Smoke). And as you show, their model of ‘observations’ is off by about a factor of 3 high. Not science, nonsense.
Mother Nature is calling for more, otherwise she wouldn’t sequester any.
The study conclusion seems counter intuitive. If the earth is indeed “greening” and increasing amounts of CO2 is being pumped into the atmosphere, wouldn’t we expect the sequestered CO2 to be increasing as well? I must be missing a piece of this cycle in my understanding.
Hi Willis, thank you for this very interesting post. Hope you are enjoying the very dry hillside near the ocean in Northern California.
Willis, the post reads, “With very large El Ninos, the amount of CO2 released may actually overwhelm the sinks, as in 1967.”
Is 1967 a typo?
1967 was the ebb year of the 1966/1967 La Nina and the start year of the 1967/1968 La Nina. In other words, it was in the middle of back-to-back La Ninas. It was not an El Nino year, according to NOAA’s Oceanic NINO Index (ONI):
Climate Prediction Center – ONI (noaa.gov)
Regards,
Bob
I recall a paper from long ago that contended that tropic forests hold all of their nutrients and carbon in the living biomass. Little to none is in the soil. They based the conclusion on how poor the soil was for growing crops after clearing.
It doesn’t take 106 authors to know that when you burn down a tropical forest, the forest loses it’s ability to sequester CO2.
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https://www.usgs.gov/center-news/satellite-data-shows-value-monitoring-deforestation-forest-degradation
Seems like a long-winded way for “scientists” to deny world-wide “greening.” Do you suppose that NASA will be their next victim to be ousted from the cult?
“Why 100? If I were wrong, one would have been enough. [In response to the book “Hundred Authors Against Einstein”]”
Willis, you said:
[Spoiler Alert!]
I can provide some input on that. In my next submission I’ll show that the Summer drawdown of CO2 has been remarkably constant for at least the last 30 years, and not much different 60 years ago.
Another equation determining quality is the number of papers cited published from 2000 and earlier divided by the number since minus the number of no choke shotgun graphs. I calculate that Q= 1/49-6 (from Fig. 2) whatever negative number that comes out to be.
If I had to find fault with your analysis *of the paper*, it would be that they are only talking about tropical forests, whereas your analysis is looking at total carbon sinks.
So I suppose that if we take their “analysis” at face value, we should probably be asking what exactly has changed in the other sinks to take up all this excess C02 no longer being absorbed by tropical forests?
If the Carbon emissions by human activity per year have significantly increased since 1959 (comparing to Fig1) and the multiyear smoothing cycles around 40 to 50% sequestered, then the GTonnes of carbon sequestered per year has significantly increased.
Looking at Fig1 shown above, the average % sequestered has stayed the same or has a slight upward trend.
The climate models probably assume constant Gtonnes absorbed by nature per year but this study highlights the influence of natural greening despite AGW. Large natural variations per year but long term trends are not alarming.
Proof that Willis has no clue, RE: Q ≈ 1/N2 (I could have have said he is full of $*** but that is disrespectful)
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N=5154
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https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.191803.
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https://marketbusinessnews.com/higgs-boson-physics-paper-has-mega-record-5154-authors/95442/
Willis,
You are comparing apples to oranges. You state for example that “In any case, there’s no indication of a long-term reduction in the sequestration rate. ” which the authors agree with since they state in their abstract that:
“the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked”
Secondly you also distort the amount of measurements that the authors did to calculate the amount of carbon sequestered in the forests. For example consider the following:
“Height of individuals from ground to the top leaf, hereafter Ht, was measured in 204 plots, using a laser hypsometer (Nikon forestry Pro) from directly below the crown (most plots), a laser or ultrasonic distance device with an electronic tilt sensor, a manual clinometer, or by direct measurement, that is, climbing the tree.”
or
“In all plots, all woody stems with ≥100 mm diameter at 1.3 m from the base of the stem (‘diameter at breast height’, DBH, in mm), or 0.5 m above deformities or buttresses, were measured, mapped and identified using standard forest inventory methods64,65. The height of the point of measurement (POM) was marked on the trees and recorded, so that the same POM is used at the subsequent forest census.”
and they did this for over 200 seperate plots in various forests. And the fact that the plots were scattered across Africa and studied by different researchers accounts for the large number of authors.
Willis: “Now, it turns out that we can actually measure roughly how much human-generated CO2 is sequestered each year. The calculation is not all that complex. We know how many gigatonnes (“GT”, 109 metric tonnes) of carbon are emitted each year from the burning of fossil fuels plus cement manufacture. We know that for every 2.13 GT of carbon emitted, the atmospheric carbon dioxide level increases by one part per million by volume (ppmv). We routinely measure the atmospheric carbon dioxide level at the Mauna Loa Observatory.
So we take a look at how much carbon is emitted in a given year and we calculate how much the CO2 level should have increased. We subtract from that the actual increase in CO2 during that year, and the difference is the amount sequestered in that year by various carbon sinks around the planet.”
This analysis presumes that the natural sources of CO2 did not change during the year, which is a big assumption. We cannot assume that nature produces CO2 at a steady state. The stated uncertainties in the major sources of non-anthropogenic CO2 are as large as what humans produce. we do not have an accurate material balance of CO2 inputs and removals from the atmosphere.
You are using a mass balance that does not include a year-to-year increase in natural emission rates which allows the IPCC to claim about half of anthropogenic emissions accumulate in the atmosphere. The truth is that every molecule that reaches the surface of cold polar waters will be absorbed, and most will be food for phytoplankton. There is no global accumulation in the atmosphere beyond a year. The increase in atmospheric concentration is the result of year-to-year increases in natural emissions. During each year, concentrations do build up as sea-ice effectively closes the sinks. That buildup is completely consumed when the ice melts.
a
“We routinely measure the atmospheric carbon dioxide level at the Mauna Loa Observatory.”
True, but . . .
For monitoring carbon dioxide concentration in the atmosphere, the Total Carbon Column Observing Network (TCCON) was formed in 2004, and by 2015, consisted of 23 monitoring stations worldwide. TCCON is a global network of stations that measure the amounts of CO2, CO, methane, nitrous oxide and other trace gases in the atmosphere.
Elsewhere, I have read that Mauna Loa and 6 (?) other sites are continually checked against each other. All this is costly and well documented – and I’m not going to search it up again.