Putting an Upper Bound on Climate Change: Permafrost

Disclaimer:  I am now retired, and am therefore no longer an expert on anything.  This blog post presents only my opinions, and anything in it should not be relied on.

When trying to figure out the most likely rate of global warming in our “business as usual” society, I always go back to that amusing quote from the movie version of Tolkien’s Fellowship of the Ring:  “Are you scared?  Not scared enough!”  The reason I remember this is that up to now, all of our scientific models of how climate change will play out over the next 100 years or so have consistently underestimated the rate of warming, not to mention the rate at which weather extremes have become the “new abnormal”.  And the reasons for this underestimation in the scientific community, from what I can tell, are (a) conservatism (even though the modeler may know that an effect will add to global warming, until the effect can be bounded with 95% likelihood in a positive direction it is assumed to have neither positive nor negative effect) and (b) lack of knowledge (for example, for a long time, the effect of increased cloudiness on global warming was not clearly understood).

Over time, these certainties and uncertainties in models have tended to be sorted out into the categories of Donald Rumsfeld’s pernicious classification:  knowns, known unknowns, and unknown unknowns:

1.       The knowns are now, effectively, all those direct effects (e.g., the direct effect of CO2 and methane on global warming) and feedback or “knock-on” effects (e.g., the effect of release of black carbon by wildfires on decreasing Arctic albedo, where global warming from CO2 increase causes increased wildfires, which causes black carbon to fall on snow and ice, decreasing Arctic albedo and hence causing more Arctic warming).

2.       The known unknowns are those effects that we know will play a role, but which are not incorporated in models because we don’t know the extent of the role they will play.  Of these, perhaps the largest ones are (i) melting permafrost and (ii) methane (CH4) releases other than from permafrost melting, including methane clathrates, release of methane locked in land and ocean repositories, and release of methane from human action, including cow emissions and natural-gas processing emissions.

3.       The unknown unknowns are, obviously, effects that we probably can’t anticipate until they happen.  We can, however, take a guess at them by looking at the relationship between CO2 atmospheric emissions and global temperature during the last two major rises in CO2 – 250 million years ago (mya) and 55 mya (the Paleocene-Eocene Thermal Maximum, or PETM, also known as “hell and high water”).  If known unknowns turn into knowns, then the difference between what our models tell us will happen and what past experience suggests is probably due to unknown unknowns.
  

If we can turn the known unknowns into knowns, there appears to be a reasonable prospect that the revised models will track with past PETM (and other) experience, which would mean that the unknown unknowns probably don’t have a significant impact on global warming one way or the other.  In fact, the only remaining known unknown upside to be accounted for might be the fact that we are accelerating carbon emissions at a far greater pace than they have ever increased before.  The usual thinking is that this may speed up the process of actual global temperature warming, (e.g., in our case, a doubling of atmospheric carbon since 1850 should lead to a 2-2.8 degree C temperature increase in the next 100 years, and a total 4 degrees C temperature increase over the next 1000 years, rather than a 1200-year gradual doubling leading to an increase of 1.3 degrees C by 100 years from now, but with the same total 4 degrees C increase at the end), although it is possible that our rush to emit carbon will trigger unknown unknowns that will lead to an even greater rise in temperature at the end of each doubling.  In a nutshell:  with permafrost and methane accounted for, we would begin to see a plausible upper bound for the amount of long-term global warming from increased atmospheric CO2 and related greenhouse-gas emissions.

In long-ago posts, I said that research seemed to suggest that increased methane emissions would not deliver a major boost to global warming.  Without going into horrendous detail, I saw the research as suggesting that if even if methane clathrates, sea-floor methane, and permafrost methane suddenly started rising into the atmosphere a very high rates over the next 100 years, it was still unlikely that methane would achieve “saturation” in the atmosphere, which would cause methane to stay in the atmosphere much longer and therefore have a much greater warming effect – perhaps as much as 1 degree F while it lasted.  Nothing in the second edition of Joe Romm’s “Climate Change:  What Everyone Needs to Know” (summarizing findings as of early 2018) suggests that this scientific consensus has changed.

And so, I would argue, getting at the likely effect of melting all the permafrost gives us a reasonable shot at an upper bound for the most likely effects from “business as usual” increases in carbon emissions.  Or, as I like to say, we may finally know how scared is scared enough.

New Findings on Permafrost

Only nine years ago, it wasn’t clear that permafrost melting was happening yet.  Now, it’s not only clear that it’s happening, it seems to be happening faster than anticipated.   So a plausible upper bound for global warming is increasingly seeming more like a “middle bound” – the most likely case – for business-as-usual global warming.

Here’s a back-of-the-envelope SWAG at the effects of full permafrost melt.  According to “Climate Change”, there are 1.5 trillion tons of carbon locked in the world’s permafrost.  Studies cited in CC also suggest that for each 90 tons of permafrost carbon released, atmospheric carbon goes up about 60-80 ppm.  Thus, total melt means about 1000-1333 ppm of added atmospheric carbon.
 
The effect on global warming then depends on how fast it happens and what else is going on.  More specifically, if melt is fast, then most of its effect falls within the first two doublings of atmospheric carbon.  Thus, very loosely, with a 2 degree C direct effect of non-permafrost added atmospheric carbon on temperatures, we are talking about somewhere around a 4 degree C direct effect of total permafrost melt.

But direct effects of carbon are not the only effects.  A significant proportion of the carbon in permafrost will almost certainly be emitted as methane (CH4), not carbon dioxide.  While much of this will eventually turn into CO2 in the atmosphere, the rise in per-decade atmospheric methane during quick permafrost melt can add up to another degree C to warming over centuries-to-millenia time periods, because methane can be up to 86 times as powerful a greenhouse gas as carbon dioxide.  And the lack of snow cover and increased vegetation associated with the peat bogs likely to be a result of permafrost melt mean a shift in albedo that, to my mind, should significantly up global warming as well.  In sum, aggressive total permafrost melt seems to me at first glance to result in an average 4-6 degrees C of global warming for at least the next 1000 years – and, considering the unknown unknowns, that may be conservative.

It should be pointed out that if we are effective in ending business-as-usual global warming in the near future, much less of the permafrost will ultimately melt.   At another SWAG, we may have locked in melt of 5% of permafrost already (the result of non-permafrost feedbacks adding 0.5 degrees C to the temperature henceforward plus the effects of additional heating from initial permafrost melt).  The rest is still in play.

Glimpses of an Upper Bound

What strikes me about this estimate (4-6 degrees C) is that it seems to fit in more nicely both with the experience of past catastrophic global warming and with recent Hansen papers trying to set an upper bound.  In the PETM, carbon ppm started at about 1000 and apparently went up to about 2000, but the temps seem to have gone up 6 degrees C in the process, 4 degrees more than direct atmospheric carbon effects can explain.  One recently raised suggestion is that elimination of stratocumulus clouds, which should thin out as air temps get warmer, can add 8 degrees C to global warming.   But this is not likely to take effect until well beyond the 1000 ppm level, below which aggressive permafrost melt plays its major role.

In trying to square the PETM with the likely direct effects of atmospheric carbon, Hansen conjectured, iirc, that each doubling of atmospheric carbon would lead, without human interference, to a little more than 2 degrees C of direct effects plus a little less than 2 degrees C of feedback effects, for a total of 4 degrees C.  But the feedback effects he identified only seemed applicable to the first doubling (to 550-odd ppm), and the temps in the PETM seemed too high, imho, for a 2000-ppm atmospheric carbon level.  Some combination of permafrost melt and cloud thinning, with permafrost melt playing its major role before 1000 ppm (at the time of the late Cretaceous global warming 11 million years before, with loss of sea ice and therefore probably loss of permafrost) and cloud thinning after, may therefore explain some of the PETM warming (whether it played a role in the global warming/mass extinction 250 mya, which involved a super-continent with no extreme north or south land, is not clear).

This also squares with another Hansen paper (iirc). In it, he argues that using up most of our present fossil fuel reserves will lead ultimately to 16 degrees C/30 degrees F average warming, or 30 degrees C/54 degrees F average warming in the Arctic and Antarctic.

All of the above statements contain large fudge factors, of course, and can be and are argued over.  However, I do now believe it is much more probable now that something like this upper bound is in store for us, if business as usual continues indefinitely. 

Implications for Armageddon

With all of the above in mind, I like to think of the worst as four stages – horrible, catastrophic, apocalyptic, and decimating, the first three corresponding to doublings of atmospheric carbon, and the last comprising only feedback effects.  Aggressive permafrost melt gives the second and third stages, which have yet to arrive, a similar warming effect over time to our first stage.  And that arbitrary classification leads to a couple of assertions:

1.       Each stage is much worse in its effects than the previous one; and

2.       Each stage becomes harder to prevent or ameliorate than the previous one.  In a sense, each stage adds momentum and size to the downward rolling snowball, because (a) new feedback effects are triggered, like permafrost melt and Arctic/Antarctic ice melt, (b) saturation effects start occurring, like inability of the ocean to store oxygen or saturation of atmospheric methane leading to longer stays in the air, and (c) our ability to mitigate is increasingly hindered by having to undo greater  amounts of now-inappropriate fossil-fuel infrastructure and optimized-for-the-wrong-temperature energy-inefficient dwellings.

      And that is why I disagree with both the optimists and pessimists.  Yes, failure to undo business as usual is rife in the air.  Yes, we may well have effectively crossed the boundary into Stage 2, with horrible effects of climate change already locked in.  Yes, the ultimate end of Stage 4 may well be the decimation of the human race and the rest of the natural world.  But until 100 or 200 years from now, we still have the ability to break utterly the cycle of business as usual, harder though it gets as time goes by.  And therefore every setback in our quest demands not despair but a fiercer effort, more confrontation of the guilty, and greater demands for even more to be done.

It’s like a crooked poker game.  Yes, right now it’s the only game in town, and yes, right now you can’t win or fold, just keep on losing.  But the game will end, and your job is to lose as little as possible, as the stakes go up and up, so that when the game is over you may have lost your heart’s desire but you will not be an indebted slave for life, or killed because you couldn’t pay your debt.  Or most of the effects may fall on your great-great-grandchildren; but they’re still the same shattering effects.  On everybody.

Oh, and one extremely small hopeful note:  it seems to me that to avoid business as usual resurfacing at any time over the next 1000 years, we will have to change fundamentally.  To sustainability.  To a method of living that almost certainly will not destroy the remainder of humanity.  Stage 4 will be as bad as it gets.

And so, hopefully, understanding the effects of permafrost and having a likely upper bound means you are scared enough.  Absolutely, totally scared stiff.  With decimation staring you in the face.  And so, said the psychiatrist in Portnoy’s Complaint, now ve may perhaps to begin, yes?

A Methane Scenario

In reading recent posts about the methane “Arc tic time bomb” on the Neven Arctic blog (neven1.typepad.com), I realized that no one was developing a full-fledged scenario for how a serious methane emissions uptake from Arctic deposits could occur.  So here’s my (amateur) stab at it.

2007-2014

When, around 2007, the Northeast Passage opened up, few worried about the implications for methane emissions.  True, there were 50 Gt of methane locked up in methane clathrates (CH4 in a “water cage”), mostly under the shallow waters of the Arctic above Siberia, but it seemed there were several reasons not to worry:

• ·         Methane has a short half-life, unless it attains a concentration well above its concentration as of now;
• ·         It seemed then that even if the permafrost in which the clathrates resided melted, methane would only be released in a “bursty” manner by landslides caused by the loosening of the icy bonds of the underwater permafrosted land – certainly not in a steady stream such as would be needed to overcome the short half-life;
• ·         It also seemed that even if the methane was released from the clathrates, it would “pop” before reaching the surface, which in turn would mix more carbon with the water and hence put it in the atmosphere, or feed “blooms” which when they died each year would likewise release their carbon in the water and thence to the atmosphere – a fraction of the carbon already being emitted;
• ·         At present, the methane released (if any) was no more than a small fraction of the man-made amount of methane emissions – and that was still not near the danger point.

However, the warming water poured in from the North Atlantic along the western part of the Siberian Sea during the summer, and when Soviet researchers checked during the summer of 2012, methane bubbles hundreds of meters in diameter were coming up.  That meant that both the idea of “bursty” methane and the idea that all the methane would “pop” before reaching the surface were not accurate.  And yet, even during summer, the fluctuations detected amounted to less than 1% of methane emissions measured in the Arctic.  Clearly, some scientists argued, the other two factors (short half-life, small fraction of the total) meant that there was no immediate cause for concern.

And then el Nino arrived.

2015-2023

The splashier effects of el Nino distracted attention from its effects on methane emissions.  While it did indeed raise the temperatures down south significantly, its main effect was to warm the air in the Arctic (already in record-breaking territory) by 3 degrees in summer and by 10 degrees in winter.  The initial effect was to extend summer “insolation” (heating of ice and water from above) and above-freezing average air temperatures for 2 weeks on either end, so that the Arctic water was now just about completely ice-free and accumulating a “storage bank” of heat with which to melt the permafrost.

Now, the period of methane bubbles was lasting twice as long, and the pace of melting was four times as great.  Moreover, towards the end of the period, the small but steady warming of the Beafort Sea from the south was beginning to push into the eastern end of the seas above Siberia.  These, too, began to see bubbles and spikes in methane usage.

At the end of this period, another “distraction” arrived:  adjacent permafrost in Siberia began to thaw.  Although it was not clear in the beginning how much of that thaw would be methane and how much carbon, it turned out to be perhaps a 2/3-1/3 ratio.  Still, compared to human-caused methane emissions (which had gone up another 10% since 2007), the emissions from clathrates and the small contribution from Siberian permafrost were still much less.

2024-2032

Soon after 2025, la Nina arrived; but it had surprisingly little effect.  True, the ascent of temperatures in the Arctic slowed; but the warming water from previous years continued to pour into the Arctic.  That, in turn, extended the iceless Arctic period well into November, and the increasing energy in the air likewise extended the melting-out period over the Siberian seas into June.  And so, having quadrupled the last period, methane clathrate emissions tripled over this period, so that by 2033 worldwide methane emissions were up by 25% compared to 2007 – 15% from humans, 6% from methane clathrates, and 3% from land permafrost melt, which was undergoing its own steep climb.

Still, for a little while, the world could still file methane emissions in the Arctic under “lesser concerns”, at least compared to carbon emissions.  And there, as well, the contributions of carbon from permafrost were still minor compared to human emissions – not to mention the almost full effect of the decreased albedo of the Arctic.

2033-2040

These were the years when things got really serious.  El Nino returned, and the Arctic became ice-free year-round by around 2039.  The warm water year-round plus the increased insolation and the increased energy in the air year-round, transmitted to the water via storms, meant a quintupling of methane clathrate emissions – to a 30% increase over 2007.  Add on 10% from land permafrost and the 20% from human emissions, and methane emissions were up 60% -- an effect of much less than one degree F globally, but nonetheless significant.

And still the worst effects held off, until …

2041-2100

Methane clathrate emissions had reached somewhat of a “steady state”, in which melt reached progressively deeper into the permafrost, but the adjacent melted sediment continued to warm faster, as it penetrated to areas of greater pressure.  However, this “steady state” was adding about 50% more methane emissions than in 2007, at a steady pace.  Meanwhile, the permafrost contribution was steadily climbing, as melted permafrost converted to swamps which produced their own methane.  By about 2060, the result was a 100% increase in methane emissions in total – and that’s when the second shoe dropped.

Doubling methane emissions meant that the methane in the air was now saturated – it was far less likely to decompose into water and/or carbon dioxide.  As a result, the half-life of methane shot up, first to 20 years, and then to 40.  Now the other aspect of methane – that it is 70 times as powerful a greenhouse gas as carbon for the same half-life – began to come into play.  Effectively, the effect was 1 degree F of average global warming; but this was equivalent to the effect of the entire increase in carbon ppm in the atmosphere pre-2007.  To put it another way, methane added perhaps 33% to global warming up to 2070.

In the longer run, of course, carbon emissions continued to dominate for the next thousand years.  However, the land permafrost methane now assumed center stage, continuing the saturation for perhaps 300 of those years.  Global warming baked us; methane clathrates in the Arctic were the trigger to ensure that we were truly well done.

Methane Talk-Down: Partial

One of the true joys of learning about science – as opposed to, say, economics – is that eventually you can usually get to a scientific summary that clears up many of the distortions that popular reports create. In the midst of wading through yet another cherry-picked-evidence blog post (this one on methane) by Andrew Revkin of the NY Times, it suddenly occurred to me that I should check out Justin Gillis of the Times, whose posts have been praised iirc by Joe Romm of climateprogress fame. Gillis’ reporting still seemed a little superficial to me, but he had a link to a 2006 scientific summary of the research about methane and climate change, an oldie but goodie where I found the answers to many of my questions. My recent blog post on methane laid out the doomsday scenario that I fear; Chapter 6 of this summary, as Rachel Maddow would say, talked me down – but only partially.

Because the broad scenario that I laid out is not drastically affected by the information in the summary, it is easier to lay out the summary’s picture of methane and then, at the end, note how this may affect my scenario. I will focus on methane clathrates, since the changes to everything else are less substantial. And, of course, I am sure that more misconceptions remain – because a summary article of ongoing research can’t be expected to answer everything. Anyway, let’s begin.

Methane Clathrates, Water Methane

Last time, I presented a very summarized picture of natural-source methane as coming from three sources: methane clathrates under the sea, permafrost on land at high latitudes, and peat bogs next to the permafrost or in the tropics. It turns out that the picture is a bit more complicated, and the complications matter.

To start with, methane clathrates are formed and remain stable in sea-floor sediment in particular combinations of sea temperature and pressure from the sea above that limit them to the sea floor somewhere between 200 meters and 1000 meters below sea level. In other words, the water has to be near zero F, and the clathrate has to be lower than 200 meters below sea level and higher than 1000 meters below sea level. Between those two limits, the deeper the sea floor, the wider the zone in the sediment where it can exist. Guesstimates for a typical clathrate “stability zone depth” might be 250-300 meters. Btw, a confusing part of the scientific lingo apparently refers to Arctic clathrates as “subsea permafrost.”

What happens to melt the clathrates? The water next to the sea floor warms up, or warmer temps further up the sea slope cause the equivalent of a mudslide on the sea floor that basically slices through the clathrate, stirs up everything above the slice as a cloud of sediment, and melts all the clathrate above the new sea floor. That is what they think happened at Storegg, a place near Norway where there is a “crater” 30 km across that may have released a gigaton of carbon, all at once (methane is CH4).

Now here’s an odd part. We are used to thinking of gas coming up to the surface in bubbles and releasing itself into the atmosphere when the bubble pops. Not so with clathrate methane – most bubbles pop long before they rise the 200 meters or more to the surface, according to the models. Instead, one of several things happens: the methane rises to the surface but not as bubbles (it is “buoyant”) and then releases into the atmosphere, or it is eaten by methane-eating bacteria, or it converts (typically to carbon dioxide) en route. Initial indications are that a small percentage of melted clathrate should rise to the surface combined with water and is released into the atmosphere as methane, which happens effectively immediately; a large percentage should be eaten by bacteria, who convert it into carbon dioxide on the surface of the sea, and the carbon dioxide is released into the atmosphere in order to equalize atmospheric and oceanic CO2; and a medium-sized percentage should convert to carbon dioxide without going through the bacteria, to be released into the atmosphere as carbon dioxide in the same way.

The methane clathrates in the Arctic seas contain perhaps 50%-80% of all clathrates. They are also by far the most likely to be affected by global warming, since water temperature variation due to increased sunlight on the water and increased temps of sun-warmed currents from the south are widest there.

Other Methane Sources

The picture of land-based methane sources also needs amendment. It appears that much of the methane stored in permafrost is stored in peat within the permafrost – which can extend as far down as 200 meters or so. Meanwhile, wetlands at whatever latitude are generators of methane, the Amazon as much as Ireland. When the permafrost melts, the water plus peat turns into a bog that (under global warming) is maintained by increased precipitation: that’s what often drives increased methane production.

Here, the translation to the atmosphere is more clear. Melting of permafrost releases any methane locked in the ice (but not in clathrates), and also creates new constantly-emitting sources of methane. Likewise, wetlands inject methane directly into the atmosphere.

Now we come to the tricky part. We are accustomed to thinking of methane in the atmosphere as separate from carbon dioxide. Not so. What often happens to methane in the atmosphere is that it "oxidizes”, which typically means that one of the hydrogen atoms is broken off to help form H2O (water), while the rest forms a methyl group (CH3) which eventually breaks down to carbon dioxide. In other words, much of the methane tossed into the atmosphere actually winds up as the major greenhouse gas, and stays up there for 150-250 years.

What’s the Effect? Um …

OK, so now the scientist wants to figure out what the global-warming effect of unlocking all that methane is going to be. The problem is that we have two sources of comparison, and neither of them is great.

The first is to use what happens over 10-20,000 years immediately after a Milankovitch-cycle minimum (a “glaciation”) as a model. Using that model, scientists have pretty well determined that in such times of rising global temperatures, the amount of methane in the atmosphere probably doesn’t vary by a heck of a lot, and the effects on global temps compared to atmospheric carbon are pretty minimal. Methane melt in general might have a role in things like sea-ice melting near Greenland, which has been shown to have surprisingly wide effects on global climate, but most of the good candidates for that type of melt (subsea, permafrost, wetlands) just don’t make a strong case for themselves.

The problem with this type of analysis is that it looks only at periods when most of the ice remains – because that’s what happens at the peak temps of a Milankovitch cycle. We have almost certainly moved above those peak temps in the last couple of decades, and so we are in much less charted waters. For a period much more comparable, you have to go back to the PETM – 55 million years ago.

OK, in the PETM, temps were 5-10 degrees C warmer than now. Increases in carbon in the atmosphere just don’t seem to be enough to justify those warmer temps. So for a while, there were theories floating around that methane was the complete reason for that kind of warming – no carbon needed. That would have been nice, since figuring out why carbon suddenly spiked in the first place, not to mention why the time period of this rapid warming was around 20,000 years as the latest research suggests, has been a headache. Bad news: there simply doesn’t seem to be a natural source of methane that comes near to explaining the whole temperature rise, not to mention keeping going for 20,000 years. So it looks like we have a choice between carbon emissions plus “unknown”, and carbon plus methane. Tentatively, the scientists are voting for carbon plus methane.

But the PETM isn’t great as a model, either. The problem there is that things happened slowly compared to today. If we say that the carbon atmospheric-concentration rise then happened over the course of 20,000 years, well, our carbon rise appears to be happening over 350 years – and it may very well double the rise of the PETM over the course of those 350 years. In other words, this is happening at least a hundred times faster. And, as we’ve seen in the case of carbon, that can mean that the positive follow-on effects happen well before the negative “stabilizer” effects. So, for example, don’t necessarily expect the magical munching methane sea bacteria to appear in the Arctic and save the day.

OK, so the models we have aren’t great. Can we at least use them for some guesstimates?

Preliminary Guesses

Well, the scientists have done the guessing for me. The key sentences I find in Chapter 6 say, more or less (with the usual caveats about my understanding), that the amount of atmospheric methane from natural sources pre-Industrial Revolution equals the amount of methane added from human sources since then, which equals the likely amount of methane to be added at some point due to all natural sources except subsea methane, which equals the potential amount of methane from subsea methane. In other words, in a worst-case scenario with 2006 models, at some point in the next 300 years, we might expect atmospheric methane four times what it was in 1850.

How much added heating would that translate to? Again, reading between the lines, perhaps 1 degree C from the methane alone. However, if we take the PETM as a model, it might be more like 2 degrees C. And that’s the maximum, so we can all semi-relax, right?

Well, no. You see, there are two problems. First of all there’s the fact that much of that methane is going to convert to carbon dioxide when it’s up there. Second, there’s the fact that the more methane gets into the atmosphere from now on, the longer it sits there. The 2006 estimate was that methane hangs up in the atmosphere an average of 9 years. But at twice the concentration, I think we can count on it sitting up there for 12-18 years on average. So those two things should add another ½-1 degrees C to the “additive effect” of methane in the atmosphere.

And then, of course, there’s the question of methane that converts to carbon dioxide before it gets into the atmosphere. Here, the summary didn’t really have much to add in the long term. Even by their time-frame estimates, all that methane-to-carbon-dioxide, even if it doesn’t get there in the next 100 years, will almost certainly show up in the next 1000 years. So it’s a more extreme version of my “pay me now or pay me later” scenario – except that we can at least hope that by the time the methane-turned-carbon-dioxide shows up, we will have managed to cut down on our human-caused carbon emissions and the amount in the atmosphere will have begun to go downhill significantly.

All in all, not great, but not as bad as my full doomsday scenario. Instead of 6 degrees C from methane-turned-CO2, perhaps 2-3, although that increase will stick around for maybe twice as long; instead of 7-9 degrees C from methane-stayed-methane over the next 160 years, perhaps 1-2 degrees over the next 300-500 years. And it will happen more gradually, so it won’t be really noticeable, probably, for the next 30-40 years. Except …

I’m Not All the Way Down

Read carefully the interview with the head of the survey of methane releases in the Siberian Sea. He states, effectively, that the diameter of the “craters” I referred to earlier had increased by up to 100 times this year, and this methane was “bubbling to the surface.” If you look at the 2006 summary, neither is supposed to happen. Very little methane should arise to the surface in a bubble, as noted above, and the methane hydrates should not suddenly do a big jump in melting: and 5 degrees C increase in water temps (since 1984, a jump of 2.1 degrees C has been observed) should cause perhaps 1 meter’s worth or less of methane hydrates to melt over the next 40-80 years – and it can’t be explained as mudslides, since it has happened in quite a few places.

So why would scientists’ models be wrong? Well, in the first place, they assume that relative sea-water warming will only occur in a short space in the summer, when the ice is melted and the sun warms its top. However, the depth of the surface ice in winter is also less than before, and the water carried by currents from the south is warmer. Clearly, it’s very possible that scientists are underestimating the amount of melting going on the rest of the year. Add this to the known problems with the original model developed in 1995, and you have some, but maybe not all, of the increase in clathrate atmospheric methane release explained.

The second flaw may be the modeled prediction that very little methane melt will rise to the surface as bubbles. Why might this model be wrong? I don’t have a clear answer from the summary – it could be that the turbulence of the water keeps the bubble from popping, although that seems unlikely. One thing seems clear: the magical munching methane bacteria are nowhere to be seen.

And the third flaw, which also affects the land methane emissions rate, is a major underestimate in the models of the rate of global warming. The models implicitly assume that the Arctic sea ice won’t melt entirely in summer before somewhere between 2030 and 2100, and year-round perhaps never – that one seems clearly wrong. Therefore, they underestimate the speed of the follow-on effects, including much faster warming of water within 100 meters of the surface, which would inevitably mean much faster warming at the 200-500 meter level – sorry, that’s not “deep ocean.”

In other words, what the latest information is telling us is that the semi-comforting story I just gave you is almost certainly an underestimate. The “true” effect of methane is somewhere between my doomsday estimate and the one above – except that the roles of methane-stayed-methane and methane-turned-carbon-dioxide have switched, because we now know that much of that atmospheric methane is going to change to carbon dioxide while it’s up there.

I find the logic of the summary convincing as well as semi-comforting; so if I had to guess, I would say that the net effect is somewhere between 3-5 degrees C, mainly in carbon dioxide, and spiking over the next 40-150 years before leveling off. But that’s a complete guess. Until I understand just how the models went wrong, I’m only partially talked down from my panic. So here’s to the New Year: It will be a season of hope, it will be a season of despair, it will be a season of enormous impatience until the first scientific explanations come out.