One has to wonder though, since CO2 residence time has been said to be anywhere from five year to hundreds, or even thousands of years, with no solid agreement yet, how they can be so sure of themselves?
From the University of Cambridge
4 degree rise will end vegetation ‘carbon sink’
Latest climate and biosphere modelling suggests that the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ – is the key “uncertainty” in predicting how Earth’s terrestrial plant life – and consequently almost all life – will respond to higher CO2 levels and global warming, say researchers.
Carbon will spend increasingly less time in vegetation as the negative impacts of climate change take their toll through factors such as increased drought levels – with carbon rapidly released back into the atmosphere where it will continue to add to global warming.
Researchers say that extensive modelling shows a four degree temperature rise will be the threshold beyond which CO2 will start to increase more rapidly, as natural carbon ‘sinks’ of global vegetation become “saturated” and unable to sequester any more CO2 from the Earth’s atmosphere.
They call for a “change in research priorities” away from the broad-stroke production of plants and towards carbon ‘residence time’ – which is little understood – and the interaction of different kinds of vegetation in ecosystems such as carbon sinks.
Carbon sinks are natural systems that drain and store CO2 from the atmosphere, with vegetation providing many of the key sinks that help chemically balance the world – such as the Amazon rainforest and the vast, circumpolar Boreal forest.
As the world continues to warm, consequent events such as Boreal forest fires and mid-latitude droughts will release increasing amounts of carbon into the atmosphere – pushing temperatures ever higher.
Initially, higher atmospheric CO2 will encourage plant growth as more CO2 stimulates photosynthesis, say researchers. But the impact of a warmer world through drought will start to negate this natural balance until it reaches a saturation point.
The modelling shows that global warming of four degrees will result in Earth’s vegetation becoming “dominated” by negative impacts – such as ‘moisture stress’, when plant cells have too little water – on a global scale.
Carbon-filled vegetation ‘sinks’ will likely become saturated at this point, they say, flat-lining further absorption of atmospheric CO2. Without such major natural CO2 drains, atmospheric carbon will start to increase more rapidly – driving further climate change.
The researchers say that, in light of the new evidence, scientific focus must shift away from productivity outputs – the generation of biological material – and towards the “mechanistic levels” of vegetation function, such as how plant populations interact and how different types of photosyntheses will react to temperature escalation.
Particular attention needs to be paid to the varying rates of carbon ‘residence time’ across the spectrum of flora in major carbon sinks – and how this impacts the “carbon turnover”, they say.
The Cambridge research, led by Dr Andrew Friend from the University’s Department of Geography, is part of the ‘Inter-Sectoral Impact Model Intercomparison Project’ (ISI-MIP) – a unique community-driven effort to bring research on climate change impacts to a new level, with the first wave of research published today in a special issue of the journal Proceedings of the National Academy of Sciences.
“Global vegetation contains large carbon reserves that are vulnerable to climate change, and so will determine future atmospheric CO2,” said Friend, lead author of this paper. “The impacts of climate on vegetation will affect biodiversity and ecosystem status around the world.”
“This work pulls together all the latest understanding of climate change and its impacts on global vegetation – it really captures our understanding at the global level.”
The ISI-MIP team used seven global vegetation models, including Hybrid – the model that Friend has been honing for fifteen years – and the latest IPCC (Intergovernmental Panel on Climate Change) modelling. These were run exhaustively using supercomputers – including Cambridge’s own Darwin computer, which can easily accomplish overnight what would take a PC months – to create simulations of future scenarios:
“We use data to work out the mathematics of how the plant grows – how it photosynthesises, takes-up carbon and nitrogen, competes with other plants, and is affected by soil nutrients and water – and we do this for different vegetation types,” explained Friend.
“The whole of the land surface is understood in 2,500 km2 portions. We then input real climate data up to the present and look at what might happen every 30 minutes right up until 2099.”
While there are differences in the outcomes of some of the models, most concur that the amount of time carbon lingers in vegetation is the key issue, and that global warming of four degrees or more – currently predicted by the end of this century – marks the point at which carbon in vegetation reaches capacity.
“In heatwaves, ecosystems can emit more CO2 than they absorb from the atmosphere,” said Friend. “We saw this in the 2003 European heatwave when temperatures rose six degrees above average – and the amount of CO2 produced was sufficient to reverse the effect of four years of net ecosystem carbon sequestration.”
For Friend, this research should feed into policy: “To make policy you need to understand the impact of decisions.
“The idea here is to understand at what point the increase in global temperature starts to have serious effects across all the sectors, so that policy makers can weigh up impacts of allowing emissions to go above a certain level, and what mitigation strategies are necessary.”
The ISI-MIP team is coordinated by the Potsdam Institute for Climate Impact Research in Germany and the International Institute for Applied Systems Analysis in Austria, and involves two-dozen research groups from eight countries.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
wuwt makes itself ridiculous by repeating this mantra.
it would help, if the guys here educate themselves a bit. Is this hopeless?
1. there is no “single” CO2 residence time, as there are several.
2. would be there a “single 5..10 years residence time”, CO2 would not be steadily rising in the atmosphere. Unfortunately, it does.
DirkH says:
December 17, 2013 at 12:55 am
An infinte number of models that all fit the past equally well, with wildly different outcomes in the future, are possible.
===========
that is the difference between Victorian age physics and modern physics. classical physics holds that there is only 1 future for any given past. modern physics holds there are a near infinite number of futures for any single past.
while this may seem an abstract notion, it has profound consequences when trying to predict the future. the models are trying to deal with the future as though classical physics was correct. it isn’t. at a fundamental level the models do not and cannot represent the future.
bobl says:
December 17, 2013 at 5:29 am
3. The Ocean does not exchange one for one, even with a constant partial pressure of CO2, some of the CO2 is removed to the lower ocean,
============
the oceans are continually turning CO2 into limestone. Ca + CO2 + O2 ===> CaCO3
via plate tectonics, the earth is continually turning limestone into hydrocarbons, recycling calcium back to the oceans.
CaCO3 + H2O + Fe ======> CxHx + Ca + FeOx
Life is turning the hydrocarbons back into CO2 and H2O
CxHx + O2 ======> CO2 + H2O
Re: Apparently, 4 degrees spells climate doom
The lead paragraph says,
Latest climate and biosphere modelling suggests that the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ – is the key “uncertainty” in predicting how Earth’s terrestrial plant life – and consequently almost all life – will respond to higher CO2 levels and global warming, say researchers.
IPCC defines Mean Residence Time thus:
Turnover time (T) (also called global atmospheric lifetime) is the ratio of the mass M of a reservoir (e.g., a gaseous compound in the atmosphere) and the total rate of removal S from the reservoir: T = M / S. For each removal process, separate turnover times can be defined. In soil carbon biology, this [Turnover time, T] is referred to as Mean Residence Time. Bold added, AR4, Glossary, p. 948.
IPCC also provides a model for Earths global carbon cycle in the 1990s. AR4 Ch 7, p. 515, Figure 7.3. http://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-7-3.html. For vegetation, M_veg = 2261 GtC, S_veg = 121.6 GtC/yr, so T_veg = 18.7 yrs. For the ocean, M_oc = 918, S_oc = 232.4, so T_oc = 3.95 yrs. And for the atmosphere, M_atm = 782, S_atm = 215. So T_atm = 3.64 yrs.
However, IPCC also reports another flux not included in Figure 7.3, nor specified as being included in the vegetation reservoir:
The total amount of CO2 that dissolves in leaf water amounts to about 270 PgC/yr [GtC/yr], i.e., more than one-third of all the CO2 in the atmosphere. Citations deleted, TAR, ¶3.2.2 Terrestrial Carbon Processes, ¶3.2.2.1, p. 191.
Since the leaf water reservoir is uncertain, the residence time for vegetation cannot be immediately fixed. However, leafwater is a flux to the atmosphere which increases S_atm to 485 GtC/yr without affecting M_atm, so it reduces T_atm to 1.6 years.
• Either IPCC’s (1) formula, (2) its carbon cycle estimates, or (3) its conjecture that CO2 is long-lived (and hence well-mixed, so MLO CO2 is global, etc., etc.) is wrong. We can rule out the formula, (1), because it’s high school physics. And we can rule in (3) from the latest images of lumpy atmospheric CO2 concentration. E.g., http://www.giss.nasa.gov/research/news/20080910/272733main_peakoil20080910_CO2Image_HI.jpg ; http://climate.nasa.gov/system/news_items/main_images/newsPage-205.jpg .
Dikran, I answered your question. I don’t know. But now I looked into it again. From this source:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/annex1sglossary-e-o.html
“Carbon dioxide (CO2) is an extreme example. Its turnover time is only about four years because of the rapid exchange between the atmosphere and the ocean and terrestrial biota. However, a large part of that CO2 is returned to the atmosphere within a few years. Thus, the adjustment time of CO2 in the atmosphere is actually determined by the rate of removal of carbon from the surface layer of the oceans into its deeper layers. Although an approximate value of 100 years may be given for the adjustment time of CO2 in the atmosphere, the actual adjustment is faster initially and slower later on.”
So, the figure given in the article above mixes the two terms, the turnover and the adjustment time.
You say:
“The adjustment time cannot be shorter than the residence time, if you think that is the case, you do not understand the meanings of these terms. The residence time depends on the rate CO2 is taken out of the atmosphere. However the rate at which an excess of CO2 is removed from the atmosphere also depends on the rate at which it is being added by the natural environment, which is why adjustment time is inevitably longer.”
I don’t understand what you’re trying to say. Increasing the carbon dioxide concentration of the atmosphere will cause the ocean to take up more carbon dioxide. Since the oceans contain much more, they will hardly notice it. Individual molecules are another story, they have to wait for their turn to be taken up.
The adjustment time is shorter than the turnover time. What is there to prevent the CO2 flux into the oceans when you increase the atmospheric pCO2? This is fast, even the consensus agrees, but they claim that the oceans are “getting full”. That’s laughable.
The model speculations above about doom are a pack of lies. The paleo recored contradicts this for the neotropical forests which warmed up to 7C. They not only persisted, they thrived. What about vegetation as you head towards the poles? Some will shrivel, while warm climate vegetation comes in and takes their place. On balance, no catastrophe. Why don’t these modellers take an honest look at the past and actually carry out long term, empirical based experiments without going into immediate extremes such as 5,000ppm in 24 hours or 15C maintained rise for tundra plants in 12 hours.? 😉
Previous references
Edim, so you would agree that the figure at the top of the article is misleading as it suggests that the IPCCs estimate of residence time is at odds with a range of other studies, when in fact it isn’t, and this fact is very easily verified? Do you not find it odd that nobody seems to have questioned, and that it seems to have been automatically accepted as the truth?
The fact that you are still concentrating on the sinks and completely ignoring the natural sources, shows that you are still not listening to the explanation already given.
Yes, it’s misleading.
Your explanation is wrong and so is IPCC. The adjustment time is shorter than the turnover time of an individual CO2 molecule. If you increase the atmospheric pCO2, you create a gradient and CO2 will be taken by the oceans. The oceans are not ‘getting full’, not even close.
More doom on the horizon.
Edim wrote “Your explanation is wrong” sadly this is all too common in discussion of climate on blogs. If you want to be able to say that an explanation is wrong, you need to actually engage with the explanation provided, rather than steadfastly refusing to address the key element, which is that you need to consider the sources as well as the sinks to understand adjustment time.
If Professor Cox and calm down, why can’t we?
Slowly but surely people are seeing the light. There will be no catastrophic warming. This 4C is taken from the Brother Gimm fairy tales. Climate sensitivity has booted the 4c to the kerb. Let’s just move along?
How good are the models they used? I hope they fine tuned their models.
From Hockeyschtick:
Thursday, August 29, 2013
“New paper finds global carbon cycle datasets may be biased”
http://hockeyschtick.blogspot.com/2013/08/new-paper-finds-global-carbon-cycle.html
Wednesday, September 4, 2013
“New paper finds another problem with global carbon-cycle models: plant respiration is ‘as different as night and day’ ”
http://hockeyschtick.blogspot.com/2013/09/new-paper-finds-another-problem-with.html
So the carbon sink ended during the PETM? The Arctic had palm trees, did they contain carbon? The tropical rainforests persisted and even thrived. Am I missing something here?
One look at the Keeling curve shows that a 100 year residence time is wrong. The annual net May to October CO2 draw-down seen in the curve is about 1.7%. The curve is dominated by northern hemisphere plant growth, and by absorption in a cooling southern ocean, but also includes a smaller counteracting cycle from plants in the southern hemisphere, plus a smaller release from a warming northern ocean. As such, 1.7% is a gross underestimate of the annual atmospheric CO2 exchange. If we assumed for the sake of argument that the Keeling curve captured 100% of the annual CO2 exchange, it would imply a 40 year residence half-life as a strict upper bound. Given the C-14 data implies a 10 year residence half-life, the Keeling curve serves as independent confirmation that the number is reasonable, and that it captures a remarkable 25% of the actual CO2 exchange.
ferdberple says:
December 17, 2013 at 6:13 am
“that is the difference between Victorian age physics and modern physics. classical physics holds that there is only 1 future for any given past. modern physics holds there are a near infinite number of futures for any single past.
while this may seem an abstract notion, it has profound consequences when trying to predict the future. the models are trying to deal with the future as though classical physics was correct. it isn’t. at a fundamental level the models do not and cannot represent the future.”
It has nothing to do with mechanistic determinism versus Quantum uncertainty. Rather, the models do not and cannot, for reasons of complexity, be a one to one mapping of reality. Would take a computer with at least as many atoms as the modeled system, for obvious reasons. They model statistically. It is possible to create good statistical models, but predictive skill has to be demonstrated. As always these people fail to do so because they just don’t care. I have in fact never seen one single instance where researchers of the climate complex did it. All you get is a Trust us we’re scientists.
DirkH says:
December 17, 2013 at 8:01 am
“It is possible to create good statistical models, but predictive skill has to be demonstrated. ”
I mean that in a general sense; an example would be a statistical model for the behaviour of a gas in a container. Whether it is possible for the Earth’s climate remains to be seen, as no attempt has been demonstrated to be successful by now. The existence proof has not been delivered.
Dikran, all is considered. The time needed to remove individual molecules is longer than the time needed for removal of the partial pressure gradient at the air-water interface. Think!
Edim, you clearly are not considering all, as otherwise your argument would include a mention of the sources as well as the sinks, but it has not done so at any point. Do yourself a favour and get a book on the carbon cycle and read it (David Archer’s primer is a good start), and learn the basics, rather than having the hubris to think that you know better than the leading scientists.
Dikran, your belief in the ignorance of experts is very weak. Nature will demonstrate.
The model and these assumptions don’t take into account how the 4c would be spread around the planet because if they did we would have very different outcomes.This kind of rise affects many different local climates differently. The deserts aren’t there because of warm temperatures, but due to weather circulation patterns unable to give precipitation to those areas. The colder the planet, the increased risk these weather circulation patterns fail to deliver due to lack of water vapour in the atmosphere..
With the planet warming 4c in past for example the tropics warm less than 1c, mid latitudes about 2-3c and the poles around 7-9c. Therefore little change would occur in the tropics, mid-latitudes benefit from a modest warming and the poles greatly benefit from major warming. Hence, plants would flourish in a warmer world where leaves would grow bigger with higher CO2 levels, higher water vapour and more warmth. Vegetation in sub Arctic would spread up towards the poles, so the model doesn’t even behave like the real world, no wonder it is wrong.
“The norway/red pines common in north central minnesota and wisconsin have a very narrow range whereby the species has a very definite upper and definite lower temp limits.”
How narrow can it be if they regularly survive annual 100-degree swings? I say the effect is not discernible from noise.
bobl
good points but a few problems with that post:
yes about 1/2 of all CO2 emitted by human sources is removed each year, leaving about half to increase the earth’s concentration an additional 1% above the previous years concentration.
so, say 2 molecules of CO2 are emitted by human sources in a year. within that year 1 will go away and the other will be absorbed and another emitted by a saturated ocean surface within about 5 years.
over about 1000 years, the thermohaline current will have caused enough upwelling of low-saturation CO2 water (that descended before the industrial revolution at 270ppmv) This, and other CO2 fertilizer and expanding woodland growth into the boreal areas will cause a slow and growing sink to carbon dioxide.
However, this will take a very very very long time to return to 270 ppmv
Define what you mean by “adjustment time”. The key issue is how long it will take for the ‘pulse’ of CO2 added over the past century or so (and over then next century or so) to be removed from the atmosphere should CO2 from fossil fuel burning cease.
Currently CO2 atmospheric CO2 concentrations are about 400 ppm, i.e. about 120 ppm has been added over the past 150 years or so. The question then is this: If all fossil fuel burning ceased tomorrow how long would it take before the excess 120 ppm is removed. from the atmosphere.
It would certainly take longer than 5 years.
In theory, it could take thousands of years to remove the lot but, in practice, most would probably be gone within 100 years. 50% would be re-absorbed within about 40 years and around 37% (1/e) would remain in the atmosphere after about 55 years.
I believe Lubos Motl has performed a very rough calculation to show that it would take at least 60 years before the total excess was removed. This assumed that the current rate at which the excess is absorbed (~2 ppm per year) remains constant leading to the simple calculation that T = 120/2 = 60 years. However, the rate of ‘excess re-sequestration’ is likely to be a function of the actual excess so will reduce as the excess declines. Some form of negative decay function might, therefore, be more appropriate.
jai mitchell says “yes about 1/2 of all CO2 emitted by human sources is removed each year” and then later “over about 1000 years, the thermohaline current will have caused enough upwelling of low-saturation CO2 water …”
When I see that kind of “logic” being applied, I cringe. But its all too common amongst the warming enthusiasts to embrace non-logic to support their views.
Edim says:
December 17, 2013 at 8:26 am
Dikran, all is considered. The time needed to remove individual molecules is longer than the time needed for removal of the partial pressure gradient at the air-water interface. Think!
It is you who needs to think, it appears that you don’t understand the mechanism of gas exchange with the ocean! The atmosphere and ocean are in near dynamic equilibrium, CO2 molecules are constantly being dissolved in the ocean and constantly being outgassed at an approximately equal rate, the ratio between the two reservoirs is given by Henry’s law. Thus individual molecules which dissolve are replaced by ones from the ocean so the lifetime of individual molecules in the atmosphere is necessarily less than the time for removal of the excess. If the rate of solution is Rs and the rate of dissolution Rd the individual gas molecules are depleted at Rd whereas the excess is depleted at Rd-Rs.