CO2

Permafrost@29

Where boreal carbon is increasing or decreasing, according to models, in Eurasia.
BG - Abstract - Assessment of model estimates of land-atmosphere CO2 exchange across Northern Eurasia

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Certain aspects of the carbon cycle are interesting enough for Scientific American
Higher CO2 Levels in Atmosphere May Speed Soil Emissions - Scientific American

 

Tree growth rates affect CO2 on the trapping side. This is not a climate thread, excluding many interesting possible discussions based on a new publication. Its citation details are in the figure below.

Slowest growth follows large volcanic eruptions and persists for a few years. The main point of the study was to provide a better record of when and how large those were. Some will have heard of Tambora 1815. It was ‘out-blasted’ 5 times in 2500 years.

Other than that, tree growth looks rather complacent over this time, until the recent CO2 increase.

This is work related for me, not just PC play. Tree growth ultimately provides the dead wood I study. Previous compilations have a lot more century-scale variations than this one does, and that deserves to get sorted out.

 

CO2. Plants make CO2 go down

1. when their growth outpaces decomposition.

2. by increasing surface area of minerals that consume CO2.

3. by producing some material that gets buried into ‘decomposition-proof’ settings (low-oxygen soils and sediments, land, lake, or marine).


Soils store a small fraction of the carbon cycled by plants growing in them. However, this carbon pool is now 3 or 4 times larger than the atmosphere. Plants and soils operate on very different time scales. Certainly the soil carbon pool was larger before ‘planet forest’ was (partially) converted to ‘planet agriculture’.


Geologic uplift puts minerals into erosion-prone environments, and thus makes CO2 go down. Himalayas are famous for that.


Volcanoes (a special case of geologic uplift) emit CO2 directly and also deliver minerals that may consume CO2. So they are complicated. If a large field of volcanoes has the (bad) luck to erupt up through a coal deposit, a lot of CO2 will be released. Siberian traps are famous for that.


The ocean is a much larger pool of CO2 than the atmosphere. Any process that leads to CO2 release there has a lot of ‘upside potential’. I consider all such processes to be incompletely understood.


The ups and downs in paleo CO2 are the shifting balance of all these processes over time. We understand them imperfectly at present, but that is sure to improve.

 

Here is a CO2 vs long time graph. The CO2 axis is as doublings compared to 200 ppm, but any other chosen value would only slightly move the vertical axis. Time is log (base ten) because my friends here assert that everyone understands.

After (if) active posters sign off on this, we can move on to T vs Co2 in a separate thread, because here we only do CO2. Any CO2 doubling leads to + 2 oC, or maybe less, or maybe more.

 

I would never have made all this work without PC nudge. Love youse guys. hate you too! Now, how can we do something useful with all this stuff.

 

My graph @44 can easily add a second y axis of CO2 ppm. PC is my boss. How should it look?

 

That is Excel, and logs in reverse is optional check boxing. I use a bitmap based editor to add labels.

Sigma plot is my favorite, I use it for 'difficult' plots $500 software!

Forgot to take that 0 off the x axis

 

Before 'microcomputers' and spreadsheet programs were readily available, I needed them. So with help from a serious computer science guy, I implemented the necessary functions (fr me) on a mainframe in BASIC.

But GUI makes is a lot easier

 

Flux towers.

Let’s say you have a crop field, or a forest, and want to know how fast carbon goes in and comes out, on timescales from minutes to multiple years. You can do.

First, construct a tower that is about 1.5 times taller than the vegetation. For crops, that is not much of a tower. Next, buy gadgets to measure temperature, airflow, water vapor and CO2 at high accuracy and importantly, with quick response times. Campbell Scientific of Logan, Utah will happily take your money, and they do have a few competitors.

Plug the gadgets into your computer, and start the (included for free) software. Thirty years ago eddy flux and flux gradient and flux accumulation were ‘experimental’, now it’s all off the shelf. Your post doc (or advanced grad student; hereafter, minion) will know what to do.

Don’t forget lightning protection, as some of your predecessors have, or melted hardware awaits you.

The minion artfully deletes periods of ‘bad data’, infills with ‘reasonable approximations’, and your net carbon fluxes are there to behold.

It works like this, more or less. Air is a bunch of small parcels, moving either upward or downward, past your tower sensors. The software keeps track of how much CO2 moves down, and up. Also many other related things. Your minion adds them up. This is a vague explanation of flux accumulation. The others require matrix math. Ewww.

You will certainly find that at day, CO2 is trapped, while at night it is released. The balance, over time, is the net carbon flux.

Your tower will join >300 worldwide, and will provide local detail far better than the OCO2 lookdown satellite.

Where are the ‘holes’? Where can your tower provide the most new information?

Ecosystems undergoing massive changes (take yer pick).
Tropical peatlands converted to oil-palm plantations.
The entire ocean, where structures (oil-extraction platforms) already exist.

It is my intention to introduce how these things are done, and shock you to realize where they have not been.

 

CO2 is removed from the atmosphere by what may seem an unlikely process – reacting with calcium-rich desert soils.

Some of you may have had the experience of attempting to dig a hole in central Texas or west of there. Less than a foot down, you hit hardpan. Caliche. Further excavation is best done with dynamite. At least, it is the most entertaining option.

This stuff is calcium carbonate, formed in place when there is not enough soil water to keep it dissolved. It is very stable, not just with reference to your shovel. As yet it is unknown how much CO2 has been trapped this way. Studies of its formation rate have been over just the last decade or so. It is largely non biological, as it can happen in soils where no plants are rooted.

It adds to the list of ‘places where CO2 can go’. If deserts become larger from non-constant climates (as some of them are trying to do), it would constitute a negative feedback on atmospheric CO2. Any high-calcium soil could act as a CO2 sink, if they dry enough so that CaCO3 cannot stay dissolved.

 

My graph@44 would be improved with closer linkage between EPICA and instrumental. Later, I would still wish to show a gap. People hate it when dissimilar records are linked.

Because I used log (time), very regular EPICA glaciations are still squished, I don't like that either.

The main intended message is that by way of fossil-C burning, we have already reverted to 3 Mya CO2, and in this century we will revert to 20 or 30 Mya. Not all results from that will be favorable. It obviously take us out of the range of 6000 years of agriculture and 300 thousand years of human existence. Y'all good with that?

 

Tallest trees in the world are a Sequoia and a Eucalyptus. They reach about 120 meters which is as high as you can 'capillary' water under Earth's gravity. Most other tall trees are about half that. It is quite a large discontinuity.

Meanwhile these two tall boys could scarcely be more different. Very distantly related, and with dissimilar xylem 'plumbing'. One grows fast (in a fire prone forest) and the other very slowly (coastal cloud forest). To test a hunch about why they are this way, I am shopping (elsewhere) for a collaborator with a different skill set.

Aside from one fellow named Tng, this oddity of treeness has attracted scarcely any attention.

Hasten to add that 60-m tall trees are still very impressive. Especially if you try to climb them. Or fall out.

 

CO2 effects on planetary temperature. Without turning this into a climate-change thread, we can take a general look. I wish to do so because as so often, mojo raised an interesting issue. This time it was in the ‘choose your poison’ FHO Politics thread @20. He asserted that Venus’ high surface T was strictly due to much more atmosphere, and not at all to CO2 IR absorption. This is an interesting question and resolvable with general knowledge of Venus, Earth and physics. Venus’ climate has been invoked, one way or another, many times at PC. Perhaps we can set it to rest here.

Mars plays a minor but interesting role, to be revealed later.

First, to Venus. As correctly stated, her atmosphere is massive (about 92 times Earth), and dominated by CO2 (96.5%). If all the earth’s carbonate rocks turned to CO2, and if such a heavy atmosphere could persist, Earth could ‘catch up’. This is much more than all burnable carbon compounds, about 222 thousand times as much CO2 in Venus total atmosphere than Earth’s. Or, to say it in a less shocking way, 17.76 doublings. Venus is also very short on water; yet another reason NOT to make this imaginary visit. How it got (and stays) that way is beyond my scope here.

Besides CO2, all 3 of these planets have known characteristics (distance to Sun, Bond albedo, surface T) that are needed to calculate ‘effective temperatures’, which are radiation balances based on solar flux and planetary albedo. That follows below.

First I reference
How Hot is Venus?, by Roger Bourke White Jr., copyright May 2006
Mr. White’s website considers Venus temperature at an altitude corresponding to Earth’s atmosphere (of 1 bar). This addresses mojo’s concern about atmospheric pressure differences, which indeed at the surfaces would be like comparing grapes to watermelons.

White finds that at 1 bar, Venus is only 20 oC warmer than Earth (surface), after correcting for the greater solar flux to Venus, etc. He considered 20 oC to be trivial, but let’s suspend judgment on that. Importantly, he worked ‘up from the surface’ using adiabatic expansion, and did not show all his work.

I went the other way, down from the top of atmosphere, and used ‘effective temperatures’ based on equation 7 from here:
Black-body radiation - Wikipedia, the free encyclopedia
Ignoring atmospheric effects (beyond albedo) I found Venus and Earth effective Ts are 26.2 and -18.8 oC respectively (top of the atmospheres). The attached spreadsheet explains what I did. Comparing 1 bar atmospheric levels, Venus is 26.8 oC warmer than Earth, with solar fluxes and albedos considered. White says 20. Thus, we differ, but perhaps not by a lot.

Comparing atmospheres above 1 bar levels (White did not do this), Venus has about 2400 times more CO2 than Earth. This could also be called 11.24 doublings. Dividing (as you knew I would), the apparent +T per doubling is 2.4 oC. Compare this to values summarized by IPCC which range from about 1.7 to 4 oC per CO2 doubling.

Thus we see that removing pressure effects of the Venusian atmosphere, as mojo advised us to do, gives a ‘CO2 sensitivity’ value which would seem reasonable to folks only studying Earth. It may be the only comparison of CO2 effects over such a wide range (11.24 doublings). It is more than enough to silence “CO2 absorption is saturated on Earth”, but already there has been enough physics on about that.

It would simply be impossible to double Earth CO2 11 times from fossil C; not enough exists, and we’d all be anaesthetized long before.

Earth says doubling CO2 give +T of something like 2 oC, and Venus/Earth comparison AGREES. This is progress. Put your ‘likes’ on mojo, and we can only hope that his next pronouncement will be equally fruitful.

Now we have to go to Mars. My calculations led to something unexpected. Mars atmosphere contains >15 times more CO2 than does Earth’s. !f my calculations are not wrong, it is something that no one else is saying. I also found the greenhouse effect on Mars to be nothing, zero, diddly.

Think about that. A ‘low-atmosphere’ planet like Mars has no GGE. My Venus-surface T calculations gave CO2 doubling sensitivity of 25; much more than 2. I can’t explain these pressure differences, and I don’t see that anyone else has even tried to.

For us on Earth, this is not a matter of concern because the atmospheric mass (pressure) can’t change over ‘species timescales’. We have more important things to do here. Human enterprise needs more energy and food and water, even as T slowly increases, crop production changes, and shipping ports are obliged to slowly move inland.

Yet if we manage to persist, and later think about other planets very far away, how much atmosphere they have may matter just as much as the IR-absorbing gas concentrations. I had no idea that mojo’s comment would affect me thus. You go. Never fear being shown wrong. Push.

 

Standing on the surface of Mars (in your special suit), 1 m2 of the atmosphere above you has 15 time more CO2 than thus on Earth. Tellin' ya I was shocked and plead for somebody to check my spreadsheet.

 

Terraforming Mars would be quite a large project

Just 43% of Earth's solar flux, and 38% of gravity to 'hold your gases in place'. Works in the movies though.

See the wiki page
Terraforming of Mars - Wikipedia, the free encyclopedia
Where I note ref. 9 with interest. Those fluorocarbons with amazingly large IR absorption might be just the ticket.

 

Wow, Science Magazine this week has a whole section on forests.

Tears of joy...

 

For those who can't be bothered (to learn) I summarize.

Earth's forests are lesser in extent and much younger than in pre-agricultural times. Back when humans were <10 million. We won this round (in a manner of speaking). Some new forests are built with economically selected tree species. Others develop simply based on what seeds the birds happen to poop. Even such ‘limited’ forests can host a lot of biodiversity.

This collection of articles was less satisfying than I hoped. Converting old forests to new young ones always includes a lot of CO2 release to the atmosphere. That is often deflected by talking about how much faster young trees grow towards open sky. Well, they do, but the total systems lose carbon. I see this as land-use managers’ ‘hey look a squirrel’. Perhaps because forest clearance is going to happen anyway, and they need to get on board.

It is very clear that forest conversion means $$$ in the short term. Selling old, valuable wood into (sorta illegal) markets (furniture, guitars, etc.), and replacing with oil palm, rubber, or soybeans. But as we have not yet decided whether forest biodiversity has $ value, or whether stored forest carbon has $ values, talking about money seems premature.

Old things are useless! Only new things matter! The Cultural Revolution in a large Asian country comes to mind…

High-latitude (boreal) forests are also very interesting. They are growing faster. They are also dying and burning faster, based on studies over too-short timescales. Yet a longer perspective would require more research, and nobody wants to pay for that.

We are stuck with putting a happy face on how forests are going now, until further notice.

Still weeping, tears not joyful.