Just quick questions, what is the value ($ per ton or whatever) of carbon in the USA, overseas under Kyoto, and in Europe?  

Also, given the elasticity of energy, how much carbon tax do you feel will be required?

I don't have a strong opinion about carbon markets or carbon offsets. However it is a turn-off to hear that anyone who criticizes them sure seems to hate carbon markets, so much so that he's not going to let a few gaps in economic or evidentiary logic stand in the way of a good screed. Maybe I'm old-fashioned, but I would like to see analysis, arguments pro and con, and a certain amount of objectivity.

My skepticism about carbon offsets just went way up.

It's a new phenomenon, so maybe it'll be short lived, but it's fascinating to see the extreme hostility to carbon markets.  Even Bart, normally thoughtful, goes straight to knee-jerk mode on an issue he claims to have no strong opinion about (hint, Bart: Adam does not make that criticism of 'anyone who criticizes [carbon markets]'.  He's specifically addressing a single author, Gar Lipow).

I thought Adam's blogpost was well thought out and respectful for the most part, and enjoy seeing point by point rebuttals in any argument.  Have fun, looking forward to the usual flameworks.

I'll give some detailed rebuttal later. In the meantime:

>Sure, it might be possible, for example, to calculate the amount of super-regulatory landfill methane flaring that would occur in the absence of carbon offsets (none).

No one every burns landfill methane to produce electricity, or to improve air quality? That would be a big surprise in California even under Reagan.

>Emissions markets have been phenomenally successful in the past.

>When the U.S. wanted to reduce sulfur dioxide emissions in the early '90s, it did so using an emissions market. Results came more quickly and cheaply than even the program's designers dared to hope.

Phenomenally successful? The SO2 program is expected to cut SO2 emissions by only about 35 percent by its 20th anniversary in 2010. In contrast, Germany cut power plant emissions by 90 percent from the first proposal in 1992 to completion of its program in 1998--all without trading.

>by necessity CDM projects always reduce carbon emissions from what would have happened otherwise.

To make that statement you have to assume that there is never a reason other than CDM credits to improve efficiency or use renewables.

>Carbon is mispriced, you see, because the bureaucrats in Brussels are tinkering with supply, and the public relations value of the reductions distorts the demand curve.

Oh come on. You can make your argument without mistating mine. My objection is not to tinkering, but to tinkering without feedback. I support Carbon Taxes of a type other than trading, regulation and public initiatives - all forms of bureaucratic tinkering. The problem with offsets is that most of them  require a greater level of detail than we have access to. Because they are granted at an extremely micro-level you need to measure results at a micro level. Also because they require all sorts of economic assumptions. With forms of carbon taxation other than emissions trading, and with regulation, you can adjust according to measured results at the macro level - region, nation or even world if the appropriate treaty can be negotiated. With carbon trading, especially offset trading, your precision is greater than your accuracy.

>Carbon markets are not the only or the exclusive means by which to address global warming. Carbon taxes, energy policy, regulation -- all have a role.

OK -here is where you need to understand something. Emission trading IS a form of carbon tax. Both emission trading and carbon taxes are pigovian. They both put a price on carbon. The difference is that carbon taxes as actually carried out tend to be applied largely to fossil fuels when extracted. Yes they would have to be applied to some point sources as well cement factories, landfills and so on. But overwhelmingly you could tax GHG sources at the point of extraction, or the point of manufacture of stuff like HFC. In contrast emission trading as actually done tends to apply almost entirely at the point of use - where it is much more difficult to measure.

If you are reacting to feedback, any engineer can tell you that you need to scale your reactions to the actual precision with which you can measure - so you can react to information, not noise. The Kyoto market saw carbon prices drop by half recently. That volatility is reflection of a very noisy market indeed.

Incidentally you may sneer at me for citing Mises all you like.  I agree with almost nothing he stands for, but when I cite an idea that is widespread today that he invented, I'm going to give him due credit. The idea of prices as information is an important one. When you support "carbon markets" or any Pigovian system you are indirectly making use of Mise's insight.

I would just like to offer a comment that the discussion of forest offsets has been somewhat imprecise.  Not all forest offsets are tree-planting offsets, although most are.  I will not argue Caldeira/Livermore right now, but (just) for the sake of argument will accept the idea that tree-planting doesn't provide a net benefit because of decreased albedo relative to grassland.

However, forest carbon offsets from managed forests are albedo-neutral.  That is to say, changes in management of existing forests in order to store additional carbon do not result in significant changes in albedo.  So the albedo argument is moot when it comes to managed forest offset projects.  And, contrary to the assertions of some in this space, means of measuring the additional sequestered carbon are quite well established.  And, there are well-established means of establishing additionality and permanence to these offsets.

Anyone curious can go explore the California Climate Action Registry's Forest Protocols.  Rigorous, verifiable, permanent, additional.  Groovy.

I was fully expecting the line-by-line dissection, although I notice it's silent on the topic of those trees. In response, I'd like to try to avoid getting excessively caught up in the minutia of Gar's arguments. I suspect we could spend a lot of time shouting about CDM protocols without shedding a lot of light on the topic of carbon markets. Instead I'd like to address some of the broader outlines of his comments.

It seems to me that there are three main strands of criticism, each problematic in its own way:

A heavy use of anecdotes that highlight specific implementation problems rather than fundamental issues with carbon markets.
Appeals to abstruse economic principles that ostensibly show carbon markets can't work even in principle.
Massive rhetorical overreach that ignores the history of debate on these topics.

Taking each in turn:

Anecdotes. Gar doesn't seem overly interested in sticking up for his claims about tree-planting projects, so I won't rehash this debate. It is worth mentioning, though, that these types of criticisms have provided most of the read meat to those who seem reflexively suspicious of carbon markets, so I hope critics aren't losing their nerve on this one.

Economics. Regarding the abstruse economic principles, Gar suggests that I've mistated his argument. I'm going to come clean here and make an admission: I can't respond directly to his economic argument because I don't understand it. To avoid an possible misstatement, here's a version of it in direct quotation:

Project-based credits subvert the entire advantage normally claimed for market means over regulation -- namely, feedback. How do you know a project will reduce emissions? Some bureaucrat evaluates the paperwork and says so. How do you know after the fact that the project has reduced emissions? Another bureaucrat evaluates the claim. At no point does a market provide micro-information, comparable to sales figures telling a store owner she has mispriced an item. Feedback comes through political means, or (as happened recently) through the collapse of the entire carbon market.

I'm sure I'm missing something here, but I just can't parse this. Carbon markets have a supply curve and a demand curve, much like any other other market. Where the curves intersect, you get a carbon price. That carbon price contains useful information about the cost of carbon reductions, which businesses, governments, and project developers can use to make judgments about how to allocate their money for future carbon reductions.

Suggesting that the project-based carbon reductions are a fiction created by "bureaucrats" is a bit like suggesting that corporate profits are a fiction created by accountants. Pollution markets have worked phenomenally well in the past (really, they have), so I see no a priori reason to believe they can't work in principle.

Scams, etc. The third line of criticism is not really criticism at all, so much as outright condemnation:

Carbon offsets are almost always either an honest error or a scam.
The problem is that claims of carbon neutrality based on offsets are almost certainly false.
We've discussed problems with carbon offsets from an economic viewpoint, and from their abuse as a misleading public relations tool. But perhaps we should focus on the awesome cruelty of their human costs.

I know blogs aren't the most nuanced medium in the world, but statements like these can't stand on their own. There are a lot of people out there who seem to hold contrary opinions, so it is incumbent upon the author to actually support these statements. A grab bag of criticisms don't add up to an argument.

Let's look again at additionality. I mention above a category of project called super-regulatory landfill methane flaring, which are generally regarded to be highly additional. Gar responds, "No one every burns landfill methane to produce electricity, or to improve air quality? That would be a big surprise in California even under Reagan."

To answer his question, plenty of people do burn landfill gas for electricity, but that isn't relevant. The relevant question is, "How difficult is it to distinguish additional from non-additional landfill methane projects?" And the answer is: not very difficult. There are two additionality tests that come in quite handy here. The first is the regulatory test. If the flaring happens due to regulatory requirements, it can't be additional. The second is the financial test. If the project couldn't be profitable in the absence of offsets, then it's most likely additional. It's pretty easy to spot non-profitable projects - they're the ones that aren't producing electricity.

Getting back up out of the weeds here, the bigger point is that a lot of thinking has been put into how to address issues such as additionality, carbon pricing, etc. Of course, that doesn't mean the questions have been fully resolved - they haven't - but to read these out-of-hand dismissals of carbon offsets as a scam, you'd think no one had ever thought about these issues before.

191 countries are already signed up for some form of carbon trading. The U.S. is rapidly heading in the same direction. Carbon markets may or may not work. But I'm pretty confident that they're not just some elaborate hoax.

Hello.

Thank you very much for this post.

I had the impression that this particular Grist kerfuffle started because someone cited evidence suggesting that boreal forests are not appropriate for carbon sequestration. This lead to some discussion about the overall value of planting trees and whether growing them in place of other vegetation is really a net gain. My major concern is that if planting trees will be used to reduce net carbon emissions, we should make sure that there is a real benefit, especially if the trees will replace a different biome. I did not question the value of other means for countering carbon emissions.

Adam Stein wrote...

"A quick survey of the pipeline of offsetting projects submitted for approval under Kyoto reveals that, out of 1,661 total projects, exactly 5 involve forestry. Exactly zero involve clean coal, because such technology is still experimental. So much for sequestration."

Could someone direct me to information about the other 1,656 carbon offset projects? How do they work?

I was looking at only one aspect of this issue, an aspect that happens to conflict with other environmental concerns that I do follow closely. Otherwise, I know very little about this issue.

It just seems that we hear primarily about planting trees. Calculators that suggest how one might compensate for carbon emissions often tell you how many trees you should plant. Environmental organizations tell us to plant more trees. They will even send out free trees (though not appropriate for the region). Maybe trees are simply something the carbon offset people think the public will best understand. So I have this image that planting trees is the primary tactic when, in fact, it is a very small element of the overall strategy.

I would like to suggest reducing the emphasis on and marketing of planting trees. Plesase tell us more about the othe projects.

[This was probably discussed elsewhere on the Grist site, but I did not follow the discussion until the tree kerfuffle emerged. Sorry! There is just so much valuable information here, I can't read all of it.]

Forward!

Sorry to be repetitive here, but:  not all forest offsets are tree-planting (aka afforestation).  There are also offsets from forest management and conservation, that have very different characteristics.  Lumping them all together isn't helpful.

Hi Jangal,

You're absolutely right. This is a problem in general when discussing these topics - it's very hard to generalize. This is another reason arguments from anecdote aren't very compelling.

Adam

Hi sunflower,

I appreciate your comment, but it's not really possible to draw many conclusions from prices on the CCX, which is a voluntary exchange. I think the CCX is a worthwhile experiment, but we need a carbon market that is mandatory and encompasses the entire economy.

Also, a $50/ton surcharge will be politically difficult to achieve in the near-term via any mechanism - carbon markets, carbon taxes, or otherwise - so I'm not sure this criticism is really specific to any one approach.

I am far more radical than that example, which would be self sustaining solar w/o credits.

I want $0.30/lb C tax ($600/ton) as soon as possible.  That would only increase the price of gasoline about $1.50/gallon, but hopefully would sharply curtail coal.

Yep, that's it. Sorry the URLs got munged, but if you click the links in my comment, they'll take you to the right place.

Bart, just so you know, I'm not actually all that angry. Bemused is probably a better word to describe my current emotional state of being. I do enjoy me a good blog kerfuffle, though.

Happy to answer additional questions...

My grandmother used to make a wonderful kerfluffle, from a recipe she brought from the Old Country.  Aah, Grandma's Kerfluffle...

Even though it seems no one but me is interested in forests, I will assert that forest-based offsets have very significant potential to help with global warming solutions. Huge, in fact.

Did you know, that North American forests currently store only a small fraction of the carbon they stored before European occupation began?  These forests can again store massively greater amounts of carbon.  I am talking about standing forests that pre-date the global warming problem and that not even Ken Caldeira is proposing we cut down.  

Since they pre-date global warming, and Dr. Caldeira agrees we shouldn't cut them down (because of their many lovely and useful properties), they are effectively albedo-neutral and we should be thinking of ways for landowners to store more carbon in them, no?  Wasteful and foolish not to, don't you think?  

If only we could measure the forests' storage of carbon...guess what, we can!  Quite well!  

OK, well, too bad we don't have a crystal ball or really powerful truth serum in order to divine a producer's motivations and make absolutely sure there's no rewards for the undeserving...guess what, we don't need one!  

The proper way to measure additionality is not to say, simplistically, that nothing should count that can not be proven to have been done solely because of the offset incentive.  That speculates about motivations for no reason.  The better way to define additionality is to carefully define prevailing business-as-usual conditions in a given region and to reward those who exceed the baseline.  That is what is known as a performance standard.  Those who are opposed to performance standards seem obsessed with eliminating excess rewards for a few, at the risk of removing a powerful incentive for the many.

So, to return to trees, trees store more carbon as they get bigger and older, and our North American forests can store massively larger amounts in some cases than they do presently.  But they don't, presently, because of financial pressures that shorten rotations and simplify structures.  So, incentives are needed to encourage private landowners to grow bigger trees, manage less intensively, and therefore store more carbon.  Forest carbon offsets, in the form of avoided or reduced timber harvest, in perpetuity.  (Please don't get hung up on senescence- I'm not talking about specific trees, but the forest inventory over time, which in many forests can continue to rise for much longer than you'll be on this planet, while individual trees are still being harvested).  You thereby get not only a small part of the solution for global warming, but you also protect nature and put more money in the pockets of the wonderful stewards of our nation's forests (that crook Charlie Hurwitz excepted).

Lots of good stuff here, now.

But for those of us with IQ < 190, would it be possible to have this info in a more structured form?  For example, like the Guide to GW Skeptics that Gar wrote.

Since Gar and Adam seem to be the heavy hitters here, perhaps something like:

Points of agreement
Points of partial agreement (with short summary of each side)
Points of total disagreement.

Or perhaps a list from Gar of "If these things were done, I would sign on"

For some reason, I don't think the sides are as far apart as it seems at first.

>If only we could measure the forests' storage of carbon...guess what, we can!  Quite well!  

Most of this takes place in nations without carbon caps. So if there is no limit to the amount of carbon they can produce performance standards get harder to set.

Also, unfortunately, when it comes to forest storage it is not just a matter of getting a convincing business as usual scenario. Forests t hat do store carbon vary a lot from year to year. They vary a lot from acre to acre. And guess what? actual measurement is pretty iffy in a case like this. So you have to depend on averages.

Does this mean that you can't provide incentives for various types of sequestration (including tree sequwestration)? Of course not! It means that any subsidies for things of this sort should not be in the form of credits. If you want to encourage people to grow more trees in an area set up those performance standards and offer cash! That way they don't have to generate their own cash by selling doubtful carbon credits to others as permission not keep burning fossil fuels. Support PV, and wind generators and carbon conserving agriculture, and carbon conserving siva culture. If done right emissions reductions from these thing are real. But you still don't know how great that emission reduction was. So don't depend on knowing the magnitude. If you can determine that something is worthwhile even if you can't put an exact number on , provide the incentive in some form other than permission for someone else to burn emit carbon.

Yeah - I responded quickly, cause I did not want to let too much of this sit there unanswered. Sometime in the forseeable future I will do a reply post, where I can answer more quickly. But I think one of the keys is what I answered above. Offset schemes vary. Some are truly awful consisting of supporting stuff like the Ugandan plantation I described, or buying up spare credits where coal utilities were granted more credits than they needed based on too high projected demand. Some support decent things. But even the latter don't know how much emissions they have reduced, even if they think they do.

I would like to see all the voluntary offset schemes converted into certificates that don't claim to offset X emissions, but simply state what they help support. You could still use "offset" guesses as the best (if not very good) way to compare one such scheme to another, but you would name the unit something else so as not to confuse it with an actual hard number to apply  GHG emitted.

I like this topic because this is what I think about, so thank you, Jangal, for bringing it back up. I don't feel like writing a lot, so I would like to suggest that the primary reason that carbon offsets are not properly implemented with forestry projects is because foresters are not contacted. I would think that there are zero foresters who are concerned with this issue right now in the NE. They do their best and do a pretty good job (the ones that are standing by their ethics), but communication and incentives for landowners and agencies are required to make this work.

There needs to be a unified forest policy in the United States and other forestes countries, which would promote carbon sequestration in forest management (let's start with having forest management).

I'm sorry, Gar, but the kitchen sink approach still isn't adding up to much.

Note that you conceded that tree planting is difficult to do right and that Terrapass avoids tree projects for just that reason. To be brief, my objection was not tree planting, but to A) Carbon plantations which so far have proven evil things in terms of human rights affects and to B) counting offsets from trees - which whether or not they sequester carbon (and usually outside they tropics they apparently don't) are very hard to measure in terms of what they sequester.

No, your objection is not to A or B. Your objection is to carbon markets. That is very clear from your numerous posts on the topic. Tree-planting projects are simply a convenient way to bash carbon trading. We all agree that there are problems with tree-planting projects, but to me that isn't a fundamental problem. I simply don't purchase tree-planting offsets. And because forestry makes up only a tiny portion of real-world projects, I can't make out why they're so crucial to the validity of carbon trading in the abstract.

If your objection were to A or B, you might advocate stricter guidelines for tree-planting projects or removing them from offset regimes altogether. But it's more convenient to elide implementation problems - which everyone admits are numerous - with fundamental problems.

There are a number of landfills in South Africa which local people were lobbying to shut down, and which carbon credits played a large role in keeping open. Without these carbon credits, loss of landfill might have resulted in waste reduction programs, along with concentration of remaining wastes in landfills where methane burning would have been economical on its own.

This is your refutation of the additionality of landfill gas flaring projects? If offsets didn't exist, some landfills in South Africa might have been shut down, which might have led to waste reduction programs, and also might have led to a situation in which more economically viable flaring programs rose up in their place?

If this isn't reaching, I don't know what is. Carbon offsets are the only value stream for landfill gas flaring projects. This is as close to 100% additionality as one could hope for. A counterfactual universe in which alternative value streams spring up to replace carbon offsets doesn't count as a refutation. (Question: why aren't those value streams spontaneously springing up now all over South Africa?)

Your comments also betray a misunderstanding of additionality. There is no such thing as an ironclad additionality test, and some non-additional projects are always going to slip through even the best screen. They goal of well-designed additionality tests is to favor additional projects without being so onerous as to restrict any projects from ever happening. Asking for "certainty in additionality" or "100% additionality" is missing the point.

There's a further point here which might seem minor but does have some relevance: TerraPass doesn't purchase offsets from South African landfills. We purchase from US landfills that we're quite sure local villages didn't lobby to close down. The issue, again, is whether the problems you raise are implementation-specific or fundamental to carbon trading.

The CDM absolutely is flawed. But Kyoto expires in 2012 and the US is only just starting to draw up carbon legislation. Can we learn from the mistakes of the CDM? I believe absolutely we can, and one of our goals at TerraPass is to make sure that future markets do draw on the lessons of the past.

Information doesn't come from the magic intersection of supply and demand. It comes from that intersection representing real phenomena in the real world.

I understand better now what you're saying. To paraphrase: if additionality doesn't exist and carbon reductions are impossible to measure, then offsets don't have any meaningful value and can't be priced correctly.

On this we can agree. If either of those two conditions are true, then offsets have no value. Of course, it is my strong hope and belief that neither of those conditions is true, because the converse statement is quite joyful: if additionality is real and carbon reductions measurable, then offsets could be one of the most powerful tools we have to fight climate change.

A) Carbon plantations which so far have proven evil things in terms of human rights affects and to B) counting offsets from trees - which whether or not they sequester carbon (and usually outside they tropics they apparently don't) are very hard to measure in terms of what they sequester.

I agree with Adam Stein that you are over-reaching your argument. There are several aspects I would prefer not getting into because of personal reservations and lack of time, specifically carbon trading and markets. I do think that there is potential in these aspects, and I do not see you providing any solution, just armchair criticism of people who are working on these issues.

To the point of the quotation: carbon plantations, in some cases, have been socially unacceptable and somewhat undesirable. This is not a reflection on the nature of carbon plantations, but on the companies' social vs. profit-driven agenda. If you want to criticize the companies for their poor practices, go right ahead. You are currently arguing the wrong angle.

I think what you meant to say for the second bullet was: 'We can tell how much carbon the trees in the northern latitudes are sequestering, but at the current time, it is difficult to say exactly how much of an influence this is having on the climate'.

Clearly you do not know much about forest mensuration, silviculture and plant ecology. Please stay out of arguments that you know next to nothing about, i.e. trees. It is very possible to know the amount of carbon stored in trees, especially in the northern hemisphere where there is a long-standing forestry tradition and lots of long-term research established and maintained. Any profesional forester, let alone a researcher, can let you know the amount of carbon currently present in standing biomass and create a good projection of how much will be stored in the forests and taken out with harvests.  

Personally, I am not as familiar with tropical forestry, and I assume that carbon accounting will be more difficult, but I have no specific knowledge of this. I know several people that are working on this topic right now, and I believe that it is still a work in progress.

What I think is currently important is the climatic aspect of re-planting or maintaining forests in the north, specifically the amount of influence that albedo exerts vs. evapotranspirative cooling vs. carbon sequestration. This appears to be a very 'hot' area, into which I am hoping to shift my research at this moment, provided funding opportunities.

Atregar

>Please stay out of arguments that you know next to nothing about, i.e. trees. It is very possible to know the amount of carbon stored in trees, especially in the northern hemisphere where there is a long-standing forestry tradition and lots of long-term research established and maintained. Any profesional forester, let alone a researcher, can let you know the amount of carbon currently present in standing biomass and create a good projection of how much will be stored in the forests and taken out with harvests.  

Carbon stored BY trees includes more than carbon installed in trees.  Lets look at what a couple of other experts say on the topic:

Larry Lohman, author of Fate of the Forests:

Measuring and predicting the net carbon sequestration of the most managed plantation
projects according to the requirements of carbon trading would involve not only better data and a better understanding of carbon flows among
soil, vegetation and water in a warming climate than we have today, but also a magical way of anticipating all conceivable future scientific
discoveries about, e.g., the relative strength of albedo effects, outgassing from streams, long-term effects on regrowth, etc., etc., as well as surveillance and calculation about the carbon behavior of each and every person whose lives had been affected by the plantation project, whether it's the guy in the shack on the farm who had to move to the city or the investor who changes his carbon planning as a result of reading about the project in a newspaper, for a century or more.
That's not even to mention the unsolvable issue that afflicts forestry projects just as much as any other carbon offset project -- they have to
prove how much less carbon they are emitting than would have been emitted in a singular "otherwise" scenario. Apart from the first, relatively trivial physical data problem within a test-plot geographical boundary (a boundary which the foresters may not realize is largely irrelevant to the requirements of carbon accounting), which possibly could be solved although it hasn't been yet to the degree required, no one has the slightest idea how to do any of this. The foresters are probably confusing what they have been trained to DO in their professional lives to date with what is REQUIRED by the new carbon market. The two are different. Yet even within their closed professional community, they are giving wildly different estimates of how much carbon might be "sequestered" by any given plantation or forestry project even on their own inadequate assumptions about accounting.

The other person I was about to quote was Jutta Kill, but since she said essentially the same thing, I'm going to spare the bandwidth.

Gobbledygook, another one's of Grandma's wonderful treats from the Old Country.   Yum!

What exactly are Larry Lohman's credentials for being considered an "expert" on forestry?  That he's an activist?  That he wrote a book?  Does he manage forests?

I noticed a lot of big words and sweeping statements in the quote, but actually what he is saying is not accurate, from a practical standpoint.  What matters, in terms of measuring forest carbon for offset purposes, is not the behavior of every last molecule of carbon at 3am on the north side of a black spruce in a ravine on the western slope 5 miles from the coast on a slightly windy day in March...What matters is the larger amounts, for which measurement is significantly more straightforward.    

Do you honestly believe that billions of dollars are invested in timberland without foresters knowing how to measure how much wood they can produce and how that is affected by management and other inputs?

That reminds me of the time more than ten years ago when I was showing someone around my totally solar powered home and talking about how we didn't have to skimp too much on amenities, and he insisted that solar power can't work because of too much moisture and other particles in the atmosphere limiting the poor well-intentioned photons, and he knew this because he was an ENGINEER.  Theory getting in the way of being able to observe reality.

Gar, foresters CAN measure what's going on in forests.  In fact, they do!  And they don't have to count every last tree, and root, and piece of duff and humus, at each moment continuously, to 5 decimal places, to do it.  It's called statistical sampling.  If you don't like that degree of certainty for the small stuff, then you can just say only the big pools or the pools that can be measured well should get full credit.

Many of these problems are not solved by sampling:

1) - Maybe the most significant is your base case - how to hell do you know what the forest would have sequestered if left to itself.

2)Methane. That is not trival. You sample at interveral. So have carbon at time A and Carbon at time B. There have been fluctations in between, that produced leaves and bark that rotted on the ground. Some of that turn into CO2 - which is covered in your inventory. Buts some of it turned into methane, and your inventories don't tell you that. Nor can methane sampling solve that problem. (Not that many people are doing it.) Methane production varies a lot over time. So samples at points in time months apart won't tell you much. You could do continous monitoring instead of interval monitoring - but that really is expensive.

3)Carbon sampling can detect part of the carbon in soils. But there are new studies constantly on carbon fluxes. So our understanding of carbon storage in soils is nowhere near that of carbon in plants - because it is not as straighforward. Estimate the biomass, use knowledge of the plant or samplign to estimate carbon stored per kilogram and you have a pretty good gross number. Soil estimatation is not that straighforward. And when you consider methane and other fluxes even net sequestration in the plants themselves is not that straightfoward.

4) Soil carbon is extremely heterogeneous. That affects the sampling process. This is trivial compared to the other points I mentioned but still important because these errors get multiplied by the other factors.

As Atreyger and I have both said, forest mensuration in North America is very well-developed, and in other countries as well.

Baseline: You make a projection of where carbon storage will be over a period, say 50 years, based on where it is now, and expected management and growth rates, etc.  Expected growth rates depend on site factors such as species, soil, climate, etc. and management factors such as thinning etc., and are not a total mystery as some would suggest.  Your management assumptions for the baseline would be set based on prevailing practices for that region and forest type, and very importantly, what is allowable under law.  You can set that baseline tighter or looser, but it's important to make sure it isn't so tight or onerous that it's not actually an incentive to participate, and not so loose that it credits normal activity by the average actor.

The increase is measured by comparing the baseline storage to storage projected under a more conservative case, call it the "offset case".

You can then go back and check storage in the "offset case" against your projections at periodic intervals.  Ideally, you only "bank" and sell offsets as they actually accrue, rather than selling futures.  Just my opinion.

As to methane, are you suggesting that forests are generally net emitters of carbon, or that methane release via decay is very significant compared to sequestration through growth?  

I think we can both agree that trees get bigger by storing carbon dioxide, and that a bigger tree contains more carbon than a smaller tree of the same species, and that it would be worthwhile to encourage landowners to grow bigger trees and try to store more carbon than they currently do, because that would benefit our poor little overworked climate.  Yes?  I think we could further both agree on my earlier post that many forests in North America are harvested WAY before their carbon storage potential is reached (think NW coastal rainforests, for example), and that such forests might be good candidates for projects to encourage greater carbon storage.  Yes?  Finally, I think you would agree that we can quantify and certify what we think is sufficiently measurable, and discount or disqualify what we think is not sufficiently measurable, and in so doing we can capture the major part of the carbon balance and not have to throw the baby out with the bathwater.  I can sense you're feeling agreeable on that, yes?  If we can agree on all that, then I am confident that we can work out the details of how to make sure there are not perverse outcomes or benefits to the undeserving and how to protect the consumer so they know they're consistently buying what they think they are.

Then we can be done, and move on.  Great!