The advocate will pick up any piece of apparently useful data and without doing any analysis, decide that their pet theory perfectly explains any anomaly without consideration of any alternative explanations. Their conclusion is always that their original theory is correct.
The scientist will look at all possibilities and revise their thinking based on a thorough assessment of all issues – data quality, model quality and appropriateness of the the comparison. Their conclusion follows from the analysis whatever it points to.
Mike #286 the answer is, it depends. If you have an established forest the overall carbon sequestered is very significant. One individual tree may possibly decay and release all its carbon to the atmosphere, but one tree is not interesting. You need to consider the whole system. Collectively, forests sequester carbon not only in the timber but also in the ground (where do you think coal comes from?). The actual amount depends on the type of forest and the local climate.
The major reason that there is confusion about this issue is logging interests have sowed confusion. Growing trees long-term and leaving them growing is a significant carbon sink.
Here’s a slide show that covers the common myths: http://www.slideshare.net/dougoh/forest-carbon-climate-myths-presentation
The inaptly named “truth” writes:
As mentioned several times in this blog, including in threads you claim to have read, the cause of the ice ages is NOT unknown. Google “Milankovic Cycles.” And we know it’s not operating now because the present warming is extremely rapid and Milankovic cycles takes tens of thousands of years to operate.
walter crain writes:
Lab measurements first made by John Tyndall in 1859 show that carbon dioxide largely passes visible light but absorbs infrared. Put more of it in the air and the ground must warm, all else being equal.
Rick Brown writes:
That doesn’t sound right. I recall deforestation accounting for about 16% of artificial CO2 increase. It’s overwhelmingly fossil-fuel burning. But of course deforestation also hurts and we have to control that as well.
Shorter greenhouse: Sunlight heats the ground, the ground radiates infrared, greenhouse gases absorb the infrared, and they radiate themselves–half of it right back down to the ground. The greenhouse effect is “atmosphere shine” adding to the sunshine which heats the ground.
“The estimates that business as usual will lead to from about 2ºC to 5.5ºC global increase in temperature by 2100 is predicted with about 95% confidence. That means that there’s about 2.5% chance that the warming will be less than 2ºC. That appears to be where Dyson is placing his bet. That doesn’t necessarily make him crazy” – Leonard Ornstein
Yes, it does – if you include “recklessly irresponsible” in your definition of “crazy”. If there was merely a 1% chance that BAU would lead to more than 2ºC global increase by 2100, it would be recklessly irresponsible not to take urgent action to control GHG emissions.
Hi folks. Can we have an update please on the Wilkins Ice shelf and Pine Island Bay? Might also be timely to have some commentary regarding sea level changes associated with ice shelf collapse; I’m thinking here more about the impact of local isostatic rebound rather than the more usual melt volume vs displacement issues. Thanks.
Christopher Booker, writing in the Telegraph, is one of the UK’s main climate sceptic journalists, writing for the Sunday Telegraph (a paper that tends to be read by upper middle classes, especially Conservative party members and politicians.
His latest diatribe is on sea levels – any comments (See link below). I’m going to use this as a basis for an MSc essay (I am a mature p/t student MSC Architecture: Advanced Energy & Env. Studies at CAT, Wales.
http://www.telegraph.co.uk/comment/columnists/christopherbooker/5067351/Rise-of-sea-levels-is-the-greatest-lie-ever-told.html
[Response: This would be the least likely source material for an academic thesis that I’ve ever heard. I’d strongly recommend basing your research on something that was actually true. – gavin]
Paul writes:
That is FAR from accurate. I’ve been called a “Denialist” many times because I’ve argued both that GCRs affect the weather, as well as that a number of scenarios are unfeasible for economic reasons.
On the GCR front, it’s been pro-RC people who’ve just waved their hands like there is nothing to the claims that the strength of the solar wind, etc. affects climate. And here it is, 30 days since the last sunspot, a couple years into the deepest solar minimum in decades, and I’m freezing my butt off waiting on the weather to finally warm up. It’s April in Central Texas — why is it 45F outside and I’m sleeping under an electric blanket?!?
[Response: But you completely miss the point that because the sun or a volcano or factor X might also affect climate, it has no impact on the radiative impact of CO2. – gavin]
On the fossil fuels front, y’all can explain to me how the planet is going to afford to burn all that coal, gas and oil. Before the financial meltdown, people were already going broke trying to consume fossil fuels.
Glen Morton #233, 275:
Let me give you an example of how the planet’s emergence of the planet from the last climate optimum impacted severely on hunter gatherer societies.
In south-east Australia (and throughout much of the rest of the continent), the Aboriginal people were members of clans who identified with specific areas of landscape (which some anthropologists now clumsily refer to as clan estates). In my state of Victoria at the time of European settlement there were at least 300 clans, speaking at least 30 distinct languages and many dialects between these. (For example, this map shows the approximate location of known clans of the Wada Wurrung speakers of the volcanic plains, coasts and ranges west of Melbourne.) In every day life people lived and travelled in groups that anthropologists refer to as bands. Band membership was fluid and would included members from a number of clans. Bands were able to travel through and access the lands and resources included clans, and of other clans with whom they had negotiated agreements. In all such negotiations, laws and ceremonies passed down generation upon generation had to be adhered to. The members of a clam were obligated to conduct ceremonies and pass on sacred knowledge which were specific to features of the landscapes of their estates, most of which they understood to have been created by ancestoral creator beings in the time before time which is now known as the Dreamtime. Although many clans were allied, others were at time in conflict. Particularly where there were large language and cultural differences.
Now consider Australia during the ice age. The sea level was 130m lower and vast areas of continental shelf which are now inundated were then productive land and were inhabited by tens of thousands of people. The current coastline was far inland and our magnificent heathlands, eucalyptus woodlands, forests and rainforests stretched into what is now ocean.
Have a look at this map to orientate yourself with my part of the World.
The Tasman sea between the mainland and Tasmania was a wide peninsular (and when the sea level was higher was a large bay bounded by a peninsular stretching up through Phillip Island at the north-east corner of Tasmania. You can see this in this Interactive map of the Australian coast with sea level adjustable to any time in last 140,00 years
Now picture what would have happened to the landscape as sea levels rose. Between 20,000 and 8,000 years before present, sea levels rose by 117 metres. That’s an average of 0.7mm/year. During Meltwater Pulse A, which took place between 14.7 & 14.2 thousand years ago, it rose by about 4mm per year. Melbourne is build around the Yarra river. At the height of the ice age the river fell into the Great Australian Bight west of the Tasman Peninsular. Over the course of 12,000 years the river advanced up it’s valley at a rate of about 17m per year. During Meltwater Pulse A it would have been something like 90 metres per year.
* Post glacial sea level rise plot at the CSIRO
* Post glacial sea level rise plot at Global Warming Art
Now ponder what the Aboriginal people would have experienced. Clearly there at times there will have been a lot of conflict as coastal groups were pushed into the lands of adjacent peoples and they into the lands of people further inland. This would have particularly occurred during lean years. It seems that the situation of the Bunwurrung people at the time of settlement may have reflected the inundation experience. They laid claim to the shoreline of Port Philip Bay (into which the Yarra flows and around the shores of which Melbourne now stretches). To this day this claim to land is contentious to descendants of the clans immediately inland of the Bay. At that time of settlement they were also in deadly conflict with clans of the east of Victoria. The Bunwurrung may in fact have originally been people of the now submerged Tasman Peninsular who lost their sacred lands and were forced to take possession on those further inland.
Glen, you contend that nothing bad happen. That’s easy to say from where you sit. Some very very bad things probably happened at the tips of flint edged war spears. Some of the tensions over land will have been resolved by negotiation and intermarriage, but there will inevitably been innumerable conflicts over thousands of years.
Now consider the disruption that will ensue as sea level rise relentlessly in response to global warming in future centuries. And for that matter as spreading deserts render whole regions and countries uninhabitable. How will the US deal with half of Mexico’s population being forced to migrate north for example? Or Canada with the migration of the US plus Mexico?
Nick writes:
Very little? The volume of water which is relocated twice daily from tidal effects dwarfs the volume of melt water from an ice shelf collapse.
More to the point, those ice sheets were already floating.
[Response: Tidal effects are irrelevant. But floating ice shelves do make a small difference to sea level when they melt because they are fresh water. When floating, they displace salt water which is slightly denser than the fresh water that they supply when they melt. The difference in density is small (about 3%), and so the extra sea level can approximated at 3%*height of the ice (~500m?)*area of ice shelf (~20,000 km2)/area of the ocean (3.6×10^14 m2). If I did the unit conversions right, that is a little under 1 mm. (note that this is for when the ice has fully melted, not just when it’s collapsed, and for the whole Wilkins ice shelf, not just the little bit that is collapsing now). The exact answer isn’t that different – details left for the readers…. – gavin]
“And here it is, 30 days since the last sunspot, a couple years into the deepest solar minimum in decades, and I’m freezing my butt off waiting on the weather to finally warm up. It’s April in Central Texas — why is it 45F outside and I’m sleeping under an electric blanket?!?” – FurryCatHerder
Meanwhile in the UK March 2009 mean temperatures were 1.4 C above the 1961-90 average. Maybe sunspots only affect the US of A, or even Texas – or is it that what happens anywhere else doesn’t really count? Seriously, what on earth do you think your anecdote about one tiny patch of the Earth’s surface means?
Please continue any discussion about Wilkins Ice Shelf on the relevant post. Thanks. – gavin
Glenn Morton says “I am a geophysicist, that is why I know these things.”
It would appear that most geophysicists disagree.
http://www.agu.org/sci_soc/policy/climate_change_position.html
Agricultural yields suffer in a substantially warmer climate than we have at present. Do you advocate going back to a hunter-gatherer lifestyle in a world of 9 billion hungry souls?
Leonard Ornstein, I think that Dyson is betting that technology will save us more than he is betting on low climate sensitivity–or perhaps he’s betting that it will save us IF climate sensitivity is not low. The problems with this position are manifold. First, the probability distribution for CO2 sensitivity is skewed significantly toward higher values. Second, a 95% confidence does not equate to a 5% probability of being wrong–that is confidence and probability are different measures. Third, assuming technology will save us seems dubious, since a changing climate will strike at economic prosperity and render us less likely to be able to support the infrastructure demanded by such an effort. Fourth, technology takes time to develop solutions, and we have wasted a whole lot of time doing nothing
No one denies Dyson is brilliant. He is, however, well outside his field of expertise, and some of his comments make it clear he has not devoted copious study to the issue. That is a pretty good way for a brilliant person to be flat-assed wrong.
speaking of technology…have you heard of “carbon-eating” man-made “trees” that somehow “draw” co2 out of the air? i read somewhere (sorry…no citation/link/anything…) of these plastic plates or fins or something that attract co2, which is periodically “washed” off with water and magically “sequestered” somewhere. was i smokin’ something or did i really read that? what do you think?
…to continue “technology”…is there anything “good” we can do with “captured” co2? anything useful we can make it into? in theory? i mean, like mockton or maybe shimkus said, “it’s plant food…”
RE: Bill DeMott #296 6 April 2009 at 12:31 AM (and BPL #305)
Gavin’s inline response addresses current contributions of deforestation; as for the historic component:
“The intensity and scale of human alteration of the biosphere has accelerated since the industrial revolution, and by 1990 ca. 20-30% of original forest area had been lost. This loss of forest cover has contributed 45% of the increase in atmospheric CO2 observed since 1850.”
Malhi, Y., P. Meir, and S. Brown. 2002. Forests, carbon and global climate. Proceedings of the Royal Society A 360:1567-1591.
[Response: Thanks for the citation. But the number still seems too high – let me look into it some more. – gavin]
[Response: On further reflection this seems reasonable (though there is some uncertainty). I learn something new every day. – gavin]
Sue – one hopes your essay is some kind of examination of the reliability of mainstream media and shall-we-say ‘outlying’ scientists in the determination of scientific principles. As background reading you might want to check out Mr Booker’s equating of white asbestos to talcum powder, and the views on dowsing of Nils-Axel Mörner.
http://richardwilsonauthor.wordpress.com/2008/09/23/bookers-38-bogus-claims-about-white-asbestos/
http://www.monbiot.com/archives/2008/09/23/the-patron-saint-of-charlatans/
http://www.randi.org/hotline/1998/0012.html
I realise that a belief in water-divining does not of itself negate Morner’s reliability, however to establish Morner’s credentials, Booker cites his past presidency of INQUA; here the opening of that body’s current position statement on climate change …
There is now strong evidence that significant global warming is occurring1. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and, indirectly, from increases in average global sea levels, retreating glaciers, and changes in many physical and biological systems.
Any old how … Good luck with the essay. BTW does CAT = Centre for Alternative Technology? I had no idea those guys were offering academic courses these days …
JP
RE: Bill DeMott #296 6 April 2009 at 12:31 AM
Regarding Vermont: Starting in the early 20th century, forests have indeed grown on former pasture land, but what were these lands before they were pasture? Forests. I have no data at hand, but I think it likely that current forests in Vermont, and other areas reforested willy-nilly after abandonment of farms, store less carbon than they did prior to the initial deforestation.
Gavin responds
It’s my understanding — correct me if I’m wrong — that the impact of increases in CO2 are computed from historical climate data, not deduced directly from the underlying physics? If the past 30 or 40 years have been a period of abnormal solar activity (and both SC22 and SC23 were well above normal, compared to the record), would or wouldn’t that affect the calculations, if GCRs are being ignored?
[Response: No. The impacts of greenhouse gases (and aerosols, and the sun and volcanoes and orbital forcings) are mostly derived from direct calculations. Any GCR effect might have some impact on studies of the solar cycle, but since GCR hasn’t increased since the 1950s (pretty much as long as we’ve been measuring), it isn’t likely to have any impact on recent trends. But rather than deal with this again, please see our previous posts on the issue. – gavin]
While I am almost certain the first few posts are confusing or blending “activist” and “advocate”, I’m not sure either is right here. An “activist” attempts to bring about action for an existing view – this probably matches your description better, but is not always disconnected from new facts. An “advocate” tries to raise the profile of an issue and attempts to convince people to take a view, which doesn’t quite match as well, and is also not always (or even often) bad.
The closest words I can think of that matches your description is “fundamentalist” or “selectively deaf”. But I have to admit that I think it’s very close to just a strawman; “generic idiot” matches fairly well.
“rhetoric.” those denialists are master rhetoricians.
but it doesn’t have to be “vs” as in “science vs rhetoric”, it can, should, be science and rhetoric. we have to do better science AND better rhetoric.
#295 walter crain
The question is too limited. Are you talking about optimal for humans or for life in general? For my money, optimum time was the Cambrian for the formation of life in general.
I like the Holocene myself, but lacking anything to compare it too, since humans have not been around long, I’m not sure how I would like an ice age. I suppose if we were in an ice age human would be hanging out near the equator though and of course year round skiing is a bonus.
Our current forcing has us heading into Jurassic temps. Ideal is a relative term. How easy is it to move all the people that own land in the southern part of the US to the northern part… doesn’t sound very ideal… what about moving 3/4’s of Africans into Europe and Russia… How ideal does that sound? What about Mexico moving up in to America? How ideal is that?
You are bringing up a contrarian point. The silly ‘optimal’ question was brought up by none less that Michael Griffin the former head of NASA. I will refrain from stating what I think of his dedication to honor regarding science.
http://www.uscentrist.org/videos/word-items/airogance
http://www.uscentrist.org/videos/word-items/mission-control
He apologized for his remarks but he did not do it publicly, he did in over at JPL.
http://www.msnbc.msn.com/id/19058588
I also did a piece on the general idea in response to some of the silliness
http://uscentrist.org/news/2007/docs/demand-debate/
and related
http://uscentrist.org/news/2007/word-play
Rick Brown, thank you (again, I recall I’ve been thanking you on and off for years for what you do).
Your link above has a trailing period incorporated in it by mistake and won’t load — this works:
http://www.defenders.org/climatechange/forests
Implications of Climate Change for Conservation, Restoration and Management of National Forest Lands
By Rick Brown
Published September 2008
Highly recommended forestry reading, folks. As Gavin says, always something new to learn. Good source.
Rick, Hank thanks for the comments.
You two have given conflicting answers regarding whether a tree removes carbon from the atmosphere. I’m going to assume Rick is right, given that he agrees with me.
I think I see the point. So an individual tree being planted doesn’t help in the long term, or even 1 million trees in isolated locations, but having the constant replanting, or a forest with its own natural regrowth does help reduce CO2 in the atmosphere.
johnp,
nice articles about “framing”. i realise it could be thought of as politically incorrect. i’m not at all advocating we try to adjust earth’s temps to this “optimum”. i like it just fine the way we’ve had to the past 10,000 years too. i was really just musing about some theoretical optimum for life on earth in gerneral. i know that’s open to interpretation, but maybe that’s the fun.
Uh, you might want to discuss that with NASA. [edit]
[Response: Oh yeah. Maybe I know something about that. Perhaps you would like to look at the cosmic ray data instead. No more on this – it is OT. – gavin]
Bias in science towards the results that are wanted?
The head of the British Antarctic Survey, or rather, he who is heading up the Wilkins Camp there, was interviewed on the box tonight. That’s BBC in UK.
I guess this post is about potential bias in science (it happens other places/skills I a sure) in that he was saying the split-off could be due to regional warming or could be due to global warming. But they were working on things, and expected to be able to show it is due to global warming. He was a tad excited (in my own personal opinion) about it being “global” and I got the impression that that’s what he wanted to show. (My partner is an ex-toxicologist PhD – who sometimes has done work for Greenpeace UK – and says people should be aware of bias towards the results they want).
My interest in this particular event is actually to see how the even is reported and how the event is seen by nay-sayers and professional deniers (as opposed to merely confused like me)
————-
Who was this bloke, Wilkins, anyway, who has shot to fame after years in the shadows? ;-)
> Rick, Hank thanks for the comments.
> You two have given conflicting answers
Nope. You misread or didn’t read. Did you follow any of the links and do any of the reading I suggested? All of that body of research supports the same point Rick makes.
walter crain (295) — Being partizan for Homo sapiens, I find best a temperature at which glaciers neither melt back nor advance, etc. This suggests that around 290–300 ppm CO2e would be ideal.
RE #26 MikeN 6 April 2009 at 1:23 PM
Maybe we should just let this OT thread end, but I think the conflict between Hank and my answers is more apparent than real; we just interpreted your question somewhat differently. I took it literally as being about the fate of individual trees, the references Hank cited have more to do with the ability of even very old stands of trees to continue to sequester and store carbon.
Avoiding deforestation has the most immediate benefits for carbon storage, since the forest will continue to absorb carbon while maintaining existing stores (absent disturbance). Planting an individual tree will provide benefits for its lifespan, but these will begin to reverse once the tree dies and starts to decay. Planting a forest with native species on a previously forested site (one that’s been clearcut logged, for instance) will be beneficial, but it may be a decade or two before the rate of sequestration by the new, young trees exceeds the rate of carbon loss from decaying stumps, roots, etc. Planting trees/forests where they didn’t occur before is questionable, not only because there will be an initial carbon loss from disturbing e.g., a native grassland, but also due to losses of native habitat and biodiversity.
artificial trees? any good?
http://news.bbc.co.uk/2/hi/programmes/6374967.stm
> artificial trees? any good?
1) hypothetical
2) source of sodium hydroxide?
3) transportation?
4) put the result where?
5) You can buy a lot of tree seeds for the money you’d spend putting those things up on poles.
6) Where are you planning to get the poles?
7) cost it out and we’ll see, but I doubt it.
Hank, I asked a question, and you answered nope and Rick said yes. Based on the articles you posted, I think you were answering a different question, and maybe agree with Rick about individual trees having no net carbon sink.
Rick, your response brings up another question. You say there is a carbon loss for many years if you plant a tree on a previously forested site. How is that? Shouldn’t a tree be a carbon sink from the moment of planting? And isn’t a stump a carbon ’emitter’?
MikeN
Yes, decaying stumps emit carbon, as will the remnants of any ecosystem (including their soils) disturbed in the course of planting trees. Grassland soils are notably rich in carbon, a good deal of which will be emitted subsequent to planting trees. The young planted trees are a very small store of carbon and it will be a while before they store more than was released by the initial disturbance.
May I humbly suggest you download my paper, which I’m told is a fairly easy read, as I think you’ll find many of your questions answered there or in the cited references. No doubt it will raise other questions. Let’s see if I can get it right this time (thanks Hank for catching the previous error): http://www.defenders.org/climatechange/forests
(And, getting back to the original theme of this post, yes Defenders of Wildlife is an advocacy organization, but I hope you will find that I’ve done my level best to be an honest broker of the science.)
An individual tree is like an individual dog — you find them around humans, but not in the wild. They’re social organisms, fundamentally so.
For an individual tree, how long it’s a carbon sink, and how much of one, depends entirely what you do with it . It’s your decision, on an ongoing basis.
Are you raking and mulching or composting the leaves or needles? Is something eating the fruit or nuts?
Will wood removed be used for some longterm purpose, or chipped and composted?
The part of a tree that you burn is neutral. All the rest of it can be a carbon sink. Don’t mistake ‘rot’ for releasing carbon dioxide rapidly. Most “rot” is consumption by other species.
Once a live tree falls, it very rapidly becomes full of life — all the dead wood inside the thin living surface layer gets consumed and mostly turned to living material, starting with fungi, then beetles.
The fungi are there and waiting.
http://www.jstor.org/pss/1943154
But what falls is the part above the ground. What’s cut down for lumber is the part above the ground. What gets killed off is often the part above the ground.
The American Chestnut is still alive — underground — and still putting up shoots in circles that mark the size of the giant trees. If anyone ever finds a cure for the Chestnut blight that can be inserted into those trees where they’re still living, they’ll grow back. The numbers are astonishing:
“… the fungus cannot grow well in the tree’s root system, and so sometimes does not completely kill a large tree, numerous small and medium-sized clumps of chestnut survive, with living stems growing from root collars of old, once large trees. Throughout the US, there are probably hundreds of millions of American chestnuts, but few reach a size and age when they can flower, and the blight continues to kill them back to the ground level in repeating cycles of disease. In Maryland forests, larger-sized, weathered American chestnut logs and stumps can still be found today. The great trees that once dominated the canopies and produced an abundance of edible nuts are absent, but the chestnuts continue to resprout from living roots and thereby survive in significant numbers in our forests…. there were as many as 4 billion chestnuts growing in North America at the time of blight introduction. That would have been 25% of the trees….”
http://www.mdinvasivesp.org/archived_invaders/archived_invaders_2008_04.html
But to serve as a serious carbon sink, yes, you need trees growing longterm with the associated soil organisms. Once you’ve done a few soil profiles, and used a hand lens or dissecting scope and looked at all the material from the fresh dry leaves at the top to the mineral soil at the bottom, you know how the carbon cascades through many different forms of life, and that’s how topsoil gets built.
http://www.ent.orst.edu/moldenka/Conservation/survey.htm
Removing all the fallen branches and “litter” starves the soil and longterm harms the forest.
Unasylva – No. 174 – Forest resources assessment –
The term “Waldsterben” (forest death, forest decline) sprang up in Germany in the early ….. especially the discontinuation of litter and humus removal, …
http://www.fao.org/docrep/v0290e/v0290e07.htm
Air pollution and forest decline in Central Europe – Elsevier
INTRODUCTION The concept of ‘Waldsterben’ (forest death, forest decline) arose ….. the practice of litter removal was discontinued in the 1930s to 1950s. …
http://linkinghub.elsevier.com/retrieve/pii/026974919500006D
So — single tree? It’s up to you.
Forests? It’s up to you.
http://www.cdra.org.za/creativity/The%20Man%20Who%20Planted%20Trees%20-%20Jean%20Giono.htm
http://search.barnesandnoble.com/Wildwood/Roger-Deakin/e/9781416593621
Rick Brown Says (6 April 2009 at 3:04 PM):
“Planting trees/forests where they didn’t occur before is questionable, not only because there will be an initial carbon loss from disturbing e.g., a native grassland, but also due to losses of native habitat and biodiversity.”
However, the world is full of places that were previously forests, and are not now – and the same is true for places that were grassland/savanna, and are now desert – due (arguably) to human activity. Much of the western US, North Africa & the Middle East, Australia, etc. Revegetating those places would, IMHO, be a good thing in itself. If doing so also sequesters an appreciable amount of CO2, that’s an added bonus.
The countries across the Sahel will like some financial help is starting a long, wide belt (forest) to fend off the advance of the Sahara to the south.
http://en.wikipedia.org/wiki/Sahel
http://en.wikipedia.org/wiki/Sahara_Desert
One last thought on this — it’s not the tree, it’s the forest including the soil where carbon is tied up.
Look at an area recently burned hot enough that even the topsoil burns, as happens in a really big forest fire when an area has been “protected” for 40 or 50 years and has a huge fuel load. You end up with lots of burnt rock and black silt that blows and washes away. Opportunistic plants grow really successfully in that first flush of available minerals, for a year or two. Same thing happens downwind of a volcano in volcanic ash — it’s enormously rich in available minerals for a few years, before the soluble and mobile nutrients wash away. After that, it can take decades for soil to begin to build up again. You have to stop erosion, break up sheet flow so biological material blowing in the wind and washing in the surface water can be captured and dropped and tied up slowly by microorganisms. It’s doable — in several human lifetimes.
e: #320 Rick
Well, actually:
VT (and much of NorthEast):
forest
(some) cleared for agriculture by native Americans
disease kills natives, forests regrow, somewhat
European settlers clear forests again
(some) farming is abandoned, forests grow back
N. American history didn’t start with European settlers…
See book.
When my father stopped farming, in 20 years trees covered a pasture that had been there for 100+ years.
“Alan Millar wrote in 222:
In a dynamic system you have to have a very clear understanding of all possible significant climatic factors and processes and how they relate to each other and in combination and how they drive further changes and we just don’t at this point.
Actually we do, more or less. They are called climate models — and they take into account ocean circulation and atmospheric circulation according to fluid dynamics, gravitation, radiation transfer theory (including non-Local Thermodynamic Equilibrium conditions), soil types, plant species, you name it all within a 1.25 ° by 1.25 ° grid with forty levels of atmosphere and forty levels of ocean and time increments of fifteen minutes. Or there-abouts. No, they don’t take into account every possible detail but they don’t need to in order to be a good approximation — a far better one that Barton Paul Levenson’s quite useful approach.
Moreover, uncertainty is not your friend. The likelihood of climate sensitivity being considerably greater than the 3 °C per doubling of CO2 is greater than that of it being considerably smaller — with the currently accepted range of 2-4.5 °C”
Hi Timothy
I see that we generally agree about what is important in the consideration of climatic matters.
We seem to differ in respect that you seem to consider that Climate Science is generally settled and is well described by current Climate Models and I don’t.
Fair enough! I must admit that ‘differ’ is not a strong enough term to describe our differences.
I am amazed that anyone, with any good grasp of Mankinds current knowledge of climatic factors, as you seem to have, could think that the science is basically settled.
It appears that mine and yours definitions of scientific certainty are poles apart. I see huge gaps in our knowledge eg are clouds a net positive or negative factor and you don’t apparently.
You also state that probability suggests that, the current estimates of the effect of doubling CO2, are ‘considerably’ smaller than expected reality.
I don’t know how you have calculated these probabilities however these calculations can be tracked.
If as you say reality means that 21st century warming has a greater probability of exceeding 3 degrees centigrade than not then we can check out the current confidence level of this prediction.
e.g. If I was to say that, in the next 100 coin tosses, heads had the same probability of exceeding 50 as tails then I would be be speaking the obvious truth.
If however the first 20 tosses come out tails in this sequence then this statement has hardly any chance of being true.
That is because real data will always trump any theoretical data in any particular sequence.
So in the 21st century we could create 1200 monthly data points towards the final alleged result of > than 3 degrees warming. Well we can now fill in the first 100 data points of this sequence with real data.
http://www.woodfortrees.org/plot/uah/from:2001/to:2010/trend/plot/uah/from:2001/to:2010
Now what does that say about the probability of “greatly exceeding” 3 degrees warming by 2100? Obviously it will be reduced.
Perhaps you can recalculate your calculations and tell us what the difference is now in the probability of your statement for the 21st century as compared to the start of the sequence in 2001.
Indeed, if you have a free day, it would be good if you could post a model, which updates monthly on receipt of global temperatures, in respect of the changing probability of the forecast. It would be quite fun to watch the trend of probability as real data fills in the sequence.
Alan
[Response: I’ve already done this, if you look at the probability distribution of long term trends based on the trend over an 8 or 9 year period in the IPCC models you get almost exactly the same pdf as if you use all of the runs. That is to say that the short term trend in a single realisation doesn’t provide much information (if any) about longer term trends driven by long term forcings. – gavin]
Alan, why be so obvious about stretching to make a bogus claim?
If you were to base your statistics on say the last five coin-tosses, that’d be like basing your trend on ten years of temperatures, given how much variation there is in coin-tossing compared to climate.
Why pick just a handful of cherries, when you can have the entire basketful? Just set the low year to less than the beginning and you get all the data:
http://www.woodfortrees.org/plot/uah/from:1800/to:2010/trend/plot/uah/from:1800/to:2010
__________________
“rubber publication” says ReCaptcha
Well, I guess you should publish your chart. Try E&E.
RE Hank Roberts 6 April 2009 at 5:30 PM
Hank, nice post. I am currently in Maryland sitting in my living room (nee parlor) in which I am stripping the paint that covered our chestnut casework. The woods here have occasional chestnut trees growing to almost 2 meters high, about the thickness of a pencil. Sometimes we can think of the forests not only being good carbon sinks, but areas of great beauty.
RE Alan Millar 6 April 2009 at 7:15 PM:
Alan, you should look at this post by Andrew Revkin and this analysis by Tamino to see the pitfalls of basing conclusions on short-term data.
James # 331 6 April 2009 at 5:44 PM
I don’t see much disagreement between what you say and what I said above. I think it can generally be a good idea to reforest areas that were previously forest, including those that have been converted to agriculture, often marginally so. However, I do not think it would be desirable to establish forests on what are naturally non-forest vegetation – grasslands, prairies, shrub-steppe. These vegetation types are often in short supply, provide important habitat and often store substantial amounts of carbon. Even with a narrow focus on carbon, it’s essential to consider what some have called the “time value of carbon.” Carbon stored, or emissions avoided, now are more important than the same thing in the future. The certain emissions now from converting a grassland need to be balanced against the uncertain projected storage from planted trees.
(As an aside, thank you for your suggested experiment for Glenn Morton in comment #300, which was as good an expression of the “rate of change” issue as I’ve seen.)
John Mashey # 341 6 April 2009 at 6:33 PM
Far be it from me to enter into debate about New England vegetation before the Mayflower, a topic on which I claim no expertise. I’ll note that I believe the science on it is not settled and that the narrative in the book you link to doesn’t appear to provide sufficiently quantified information to compare pre-Mayflower circumstances with those of the early 20th century. Earlier I feared that the discussion risked veering in this direction. I wonder whether focusing overly on one state or small section of the country runs the risk of getting into something similar to discussing weather rather than climate.
Although I too grew up in New England, saw the evidence of previous pasture abandonment in some of the woods on our farm and have since seen trees reclaim the rest of it since we stopped farming in the 1950s, I have to rely on the published, peer-reviewed literature, such as:
Houghton, R.A., and J.L. Hackler. 2000. Changes in terrestrial carbon storage in the United States. 1: The roles of agriculture and forestry. Global Ecology and Biogeography 9:125–144.
Abstract:
1 Changes in the areas of croplands and pastures, and rates of wood harvest in seven regions of the United States, including Alaska, were derived from historical statistics for the period 1700–1990. These rates of land-use change were used in a cohort model, together with equations defining the changes in live vegetation, slash, wood products and soil that follow a change in land use, to calculate the annual flux of carbon to the atmosphere from changes in land use.
2 The calculated flux increased from less than 10 TgC/yr in 1700 to a maximum of about 400 TgC/yr around 1880 and then decreased to approximately zero by 1950. The total flux for the 290-year period was a release of 32.6 PgC. The area of forests and woodlands declined by 42% (160 x 106 ha), releasing 29 PgC, or 90% of the total flux. Cultivation of soils accounted for about 25% of the carbon loss. Between 1950 and 1990 the annual flux of carbon was approximately zero, although eastern forests were accumulating carbon.
3 When the effects of fire and fire exclusion (reported in a companion paper) were added to this analysis of land-use change, the uptake of carbon calculated for forests was similar in magnitude to the uptake measured in forest inventories, suggesting that past harvests* account for a significant fraction of the observed carbon sink in forests. * [RB: this might be more clearly stated as recovery from past harvests — see quote from p. 139, below]
4 Changes in the management of croplands between 1965 and 1990 may have led to an additional accumulation of carbon, not included in the 32.6 PgC release, but even with this additional non-forest sink, the calculated accumulation of carbon in the United States was an order of magnitude smaller than the North American carbon sink inferred recently from atmospheric data and models.
Notes:
p. 135 “Since 1950 the net flux has been close to zero, varying between ± 50 TgC/yr. Emissions of carbon from harvest of fuelwood peaked at about 60 TgC/yr around 1870. The reduced use of fuelwood was responsible for the largest continued sink for carbon in regrowing forests. Emissions of carbon associated with the harvest of industrial wood, including the storage of carbon in products and their oxidation, were generally small, but since 1960 these emissions have been the largest source of carbon to the atmosphere.”
p. 139 “One of the primary reasons for calculating the land-use flux, despite its not being the total terrestrial flux, is that it enumerates one of the mechanisms responsible for a carbon sink; that is, the accumulation of carbon in forests recovering from past harvests or abandonment of agriculture.”
I never would have imagined that I would ever post such a long comment, especially one off-topic . . . Sorry about that.
Rick (320):
“I have no data at hand, but I think it likely that current forests in Vermont, and other areas reforested willy-nilly after abandonment of farms, store less carbon than they did prior to the initial deforestation.”
Without question. Not just Vermont but virtually all cleared forests in North America. They haven’t had time to recover, and/or are under continuous entry for partial harvest. On the other hand, there are also substantial areas that now store more carbon due to things like fire suppression and horticultural plantings in irrigated drylands. For example, the South Platte river across eastern CO, (and presumably the main Platte across NE) had no tree corridor at settlement time, but now has a ~ 1/2 to 1 mile wide corridor of large cottonwoods for long distances. Some unlogged ponderosa pine forests now have double to triple their pre-settlement carbon levels. But such areas do not balance the tremendous losses due to clearing, particularly in the midwest.
Rick’s understandably hesitant to promote his own work, but I’m free to say that it is an outstanding and comprehensive effort that ties together numerous relevant topics in forest mgt.
MikeN: Exposing the forest floor, especially after crown fire, greatly increases litter and soil carbon decomposition rates due to greatly increased surface and subsurface T.
Off topic? Oh, I think Philip made clear
https://www.realclimate.org/index.php/archives/2009/04/advocacy-vs-science/langswitch_lang/fi#comment-118349
that attention to trees is pertinent — we’re going to see lots of “advocacy science” claims about carbon sequestration putting money in one pocket or another, from everyone who has a tree or could plant one, or could cut one down and plant another and sell the lumber.
Here’s a survey from China indicating that they have less carbon in soil and speculating that they could qualify for credits for sequestration in topsoil:
http://www.cababstractsplus.org/abstracts/Abstract.aspx?AcNo=20053153660
Oh man! I’ve been doing my best engage with rational discussion with the clowns on that WUWT Lindzen thread, but it’s like trying to wrestle eels. Those people are utterly immune to rational discourse. They never ever answer a straight question.
I must say though that I am very impressed with the rate at which Watts flings up articles. He does it at the rate of a regular news media Goliath.
>As I read your graph, you are predicting better than 50/50 odds than there will be a new record temp set in the next 2 years. Would you be interested in a wager on this?
I see this in another RC post form May 2008. I think you are missing Alan Millar’s point. For example, are you as likely to take this bet now, as you were then?
Wouldn’t the odds of a new record change with lower temperatures?