The NZ Herald reports a new study showing that since 1988 there has been a sudden increase in the absorption of CO2 over land. It’s in the order of a billion tons of CO2 a year and amounts to 10% of all human emissions. As usual, the spinmeisters frame it in terms of our guilt instead of their ignorance. “Look! Things would have been worse and even warmer if not for this new unknown factor.”
But globally plants already emit about 80Gt per year. Finding one extra Gt of absorption is both predictable and largely insignificant. What this episode really shows is just how far the alarmist PR departments will go to find any excuse to cover up for two decades of poor predictions.
Dr David Evans, formerly a carbon modeler for the Australian Greenhouse Office calls the new discovery “just noise”:
Sounds impressive, but it’s not significant. Rough numbers: there are currently 800GtC (gigatonnes, or billion tonnes) of
CO2 carbon in the atmosphere, and each year: plants oceans absorb 80GtC and emit 80GtC, oceans plants absorb 120GtC and emit 120Gt, and human emissions are 8GtC. (Notice that the total turnover in CO2 carbon each year is about a quarter, which fits with the observed residence time in the atmosphere of an individual CO2 molecule of about 4 to 5 years — here are delays due to inadequate mixing). The atmospheric CO2 levels have been going up at about 2ppm (or 4GtC) per year for decades.
[Apologies for the mix up between C and CO2. Carbon accountants work in C but often report in CO2 because that is what many "clients" expect. Having seen umpteen sets of figures each way I have lost any sense of what is "normal", and simply check context every time to see what is meant. The carbon accounting software I wrote, FullCAM, works in C internally, and converts to CO2 or CH4 or whatever as required. It is the C atoms that accountants track, because they combine and recombine with O (as CO2) and H (as CH4) and numerous organic compounds as they move from air to plants to soil to microbes and back to air, and so on. As for the ocean-plant mix up, it was late, oops. There is a good diagram in AR4 page 515, Figure 7.3, although for the 1990's. The rough figures here are round numbers which will let you understand and check any of these global carbon flow discussions. - David]
This study purports to find an extra 1Gt of CO2 absorbed by plants. That’s just noise, less than the uncertainty in the other figures, and makes no significant difference to anything. Their suggestion that the earth would have warmed faster without this absorption is true, but the extra warming is miniscule and unmeasurable. The unmistakable conclusion is this paper is transparently qualitative boasting to suck in those ignorant of carbon accounting (which is just about everyone), and simply distracts attention from the failure of their predictions that the world would warm quickly from 1990 on due to rising CO2 levels (awkward reminder: 0.30C per decade was the 1990 IPCC estimate).
On a side issue, there’s a bit of a red flag: one of the study’s authors, DrSara Mikaloff-Fletcher said “We applied some really exciting statistical techniques …”. Oh I hope you’re not overindulging in numerical wishful thinking like Dr Mann, of whose hockey stick Professor Wegman famously said: “It is important to note the isolation of the paleoclimate community; even though they rely heavily on statistical methods they do not seem to be interacting with the statistical community.”
Patrick Moore: (Greenpeace founder) says Long live plants and humans, increase CO2!
Climate Depot asked Patrick Moore to comment on the new results.
Ecologist Dr. Moore pulled no punches in commenting on the new study: “These people are either completely naive about the relationship between CO2 and plants or they are making this up as a way of deflecting attention from the lack of warming for the past 15 years.”
Moore told Climate Depot: “Plants grow much faster when CO2 is higher, the optimum concentration is between 1500-2000 ppm so there is a long way to go before plants are happy. CO2 levels in the atmosphere have continued to rise despite plants absorbing more CO2. So what is the ‘scientists’ point? It is to obfuscate, confuse, and otherwise muddy the waters with disinformation.
Moore continued: “We should challenge them to admit that CO2 is the most important nutrient for all life on earth and to admit that it is proven in lab and field experiments that plants would grow much faster if CO2 levels were 4-5 times higher in the atmosphere than they are today. This is why greenhouse growers pipe the exhaust from their gas and wood heaters back into the greenhouse to increase CO2 levels 3-5 times the level in the atmosphere, resulting in 50-100% increase in growth of their crops. And they should recognize that CO2 is lower today than it has been through most of the history of life on earth.
“There is no ‘abrupt’ increase in CO2 absorption, it is gradual as CO2 levels rise and plants become less stressed by low CO2 levels. At 150 ppm CO2 all plants would die, resulting in virtual end of life on earth.
“Thank goodness we came along and reversed the 150 million-year trend of reduced CO2 levels in the global atmosphere. Long live the humans,” Moore concluded.
Moore is the author of the book, “Confessions of a Greenpeace Dropout: The Making of a Sensible Environmentalist,” where he explains why he left the organization.
Lubos Motl’s points out that it was obvious trees would use more CO2 as more CO2 became available:
I find it obvious that the absolute amount of carbon absorbed by the atmosphere inevitably increases if the CO2 concentration does. If a substance is easier to get, then the consumers will consume more of it. Is that shocking? It’s true for CO2 much like it’s true for water, marijuana, or anything else.
There is a lot more CO2 around now than there was 20 years ago:
These days, the average CO2 concentration is about 393 ppm. Twenty years ago, it could have been 357 ppm or so. That means an increase by 10 percent. However, it’s more interesting to compare the “excess CO2″ in the atmosphere. The CO2 concentration that is in equilibrium with the current temperatures (and believe me, it makes no difference whether you mean “before global warming” or “after global warming” because this difference in tenths of a degree is negligible relatively to the difference between ice ages and interglacials which is almost a dozen of degrees) is about 280 ppm. So twenty years ago, it was 77 ppm above the equilibrium value; now it is 113 ppm above the equilibrium value. This “excess CO2″ therefore rose by 47% in the recent 20 years.
Humans would increase global CO2 by 4ppm per year if it wasn’t for plants and trees pegging that back:
Our CO2 emissions these days, if they were just being added to the atmosphere, would increase the CO2 concentration by 4 ppm per year or so (i.e. by 1% a year, using the current concentration). The actual increase is something like 1.9 ppm (0.5%) so 2.1 ppm is absorbed by the oceans and the biosphere. This amount of 2.1 ppm is approximately proportional to the “excess CO2 in the atmosphere”…
Lubos estimates trees would take about a century to remove all the CO2 humans may have added (I think that sounds a bit slow):
…So if we stopped all CO2 emissions tonight, the CO2 concentration would continue to decrease by the rate of approximately 2.1 ppm per year; this number was derived above. The rate would be slowing down as the concentration would be returning back to those 280 ppm and the CO2 consumers’ boom would be fading away but it’s still true that within a period comparable to a century, the CO2 concentrations would be almost exactly back to the equilibrium value.
H/t Climate Depot