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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 29701 to 29750:

KR at 00:01 AM on 22 April 2015

Global warming hiatus explained and it's not good news

Joel - Homewood has, not surprisingly, got his picture roughly backwards. From Santer et al 2014:

On the basis of the results presented here, we argue that the divergence of modelled and observed low-frequency TLT changes over the final 15 years of the satellite record is partly due to systematic errors in the post-Pinatubo volcanic forcing in the ALLC8.5 simulations. (emphasis added)

In short, that illustration shows ENSO and two large eruptions removed, but with remaining early 21st century volcanic forcings not included in the model forcings present. And that Homewood is quite wrong - there is an underlying warming trend over the last two decades, masked in part by volcanic variability that wasn't part of the model forcing sets.

In fact, you can see the error in Homewoods insistence on: "Ignore the misdirection about early twenty-first-century volcanic eruptions." In short, ignore the core of the paper so that he can mislead you. Nothing but denial.

One Planet Only Forever at 23:48 PM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

Ranyl @ 8,

"A 50/50 chance at 450ppm of keeping warming to 2C by 2100, so that is akin to Russian Roulette with 3 bullets in the barrel, not sure why our policy makers are such brave gamblers considering the risks?"

The gamblers are gambling with consequences that otehrs will face. And they are able to round up popular support for getting away with damaging but cheaper ways of benefiting today because those unacceptable activities will only affect future generations, or people in other nations, or poeple who are not as fortunate.

Such leaders are not gamblers at all. They are more like criminals since they actually have the ability to better understand what is going on yet they deliberately do not push for the action they can understand is required.

Popularity and profitability fueled by successful deliberately misleading marketing is a fundamental problem that has been massively successful. I am hopeful that humanity can overcome the temptations. But it seems those temptations will not be overcome before massive irreparable damage occurs. The impacts of CO2 accummulation are going to be massive compared to the impacts of the accummulation of junk mortgages in the USA that led to the global economic catastrophe of 2008.

Joel_Huberman at 22:56 PM on 21 April 2015

Global warming hiatus explained and it's not good news

Thanks very much, CBDunkerson. The graph you've posted is the one Homewood is talking about. Homewood is looking at panel c in the figure, the bottom panel, after removal of ENSO, El Chichón and Pinatubo effects. Note that Santer et al. removed those effects not only from the CMIP-5 calculations, but also from the RSS and UAH observations. After removal from the observations, the observations do, indeed, appear flat after 1993. Homewood interprets this to mean that all of the rise in RSS and UAH temperatures after 1993 (panel a) must be due to "natural variability" (ENSO and volcanoes). Santer et al. don't appear to comment on this in their paper (at least I couldn't find a comment), meaning that they're not surprised. I'm upset by it, because the denial crowd appears to be jumping on this as just another "proof" of the "hiatus". I want to be able to debunk denialist claims, and this one's (temporarily, I hope) got me stumped. Thanks for any additional help you can offer.

CBDunkerson at 21:22 PM on 21 April 2015

There's no empirical evidence

Got it. A smaller 'global carbon sink' has resulted in greater atmospheric CO2 from fossil fuel emissions than would have existed otherwise.

However, wouldn't the slowly degrading carbon sink have resulted in atmospheric increases from the natural emissions cycle? That is, assuming natural emissions and sinks were roughly in balance (otherwise atmospheric levels would have been changing) wouldn't human degradation of the natural carbon sinks have resulted in rising atmospheric CO2 levels? The only way I can see to avoid this would be if natural emissions somehow declined at essentially the same rate as natural sinks. That's possible, but would need to be demonstrated.

Meanwhile, the problems with carbon isotope levels and vastly different estimates from other studies remain.

CBDunkerson at 21:06 PM on 21 April 2015

Global warming hiatus explained and it's not good news

Joel, well the first thing which jumps out at me is that his starting principle is simply false;

"After taking out the effect of ENSO and eruptions, it is apparent that temperatures have been flat since the early 1990’s; indeed they have arguably been falling since."

Is he looking at a different graph? Because the one in the study, and copied on his page, clearly shows a rising trend from the early 90s to present;

Figure 1 from Santer et al 2014

Moderator Response:

[RH] Adjusted image size.

ranyl at 20:53 PM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

Thanks Andy intersting but not sure we have a carbon budget really more of a debt and the permafrost melting is akin to interest on it.

http://www.sciencedaily.com/releases/2015/03/150309155521.htm

Ground water methane releases.

http://www.sciencedaily.com/releases/2015/03/150330095359.htm

More methanogensis bugs in the lakes as they warm and the lakes are full carbon for them to eat.

When do the models melt the Arctic summer ice away in the paper by?

Last CMIP5 RCP8.5run I’ve seen still had plenty of summer ice up to 2070, so presume that there might be a type 1 error model underestimation, given the way the arctic sea ice is melting already (can only get faster as we warm further and last 12 months have been the hottest in the temperature record, with an EL Nino just starting to brew), and most experts seem to suggest that an Arctic ice free summer by 2050 is inevitable at current rate of heating, and there is nothing we can do to slow the rate of heating by 2050, apart from geo-engineering and that is unlikely to be a safe bet.

And melting the sea ice has been shown to accelerate Arctic warming.

“We find that rapid sea ice loss forces a strong acceleration of Arctic land warming in CCSM3 (3.5-fold increase, peaking in autumn) which can trigger rapid degradation of currently warm permafrost and may increase the vulnerability of colder permafrost for subsequent degradation under continued warming.”

(Lawrence 2008)

Keep in mind that stopping burning fossil fuels will also stop the emissions of SO2 and that is providing a very significant cooling effect at present and thus when go warming increase markedly, as the CO2 levels wouldn't drop enough to slow warming even if all emissions stopped today for millennia.

Atmospheric CO2 300ppm, sea levels 6-9m higher(LIG).

CO2 350-400ppm, sea levels 20-25m higher (Early Pliocene), Arctic 14-19C hotter.

CO2 400-450ppm, sea levels 30-40m higher (Miocene).

We've emitted 500GtCO2, does anyone really think that the same can be released again and civilization can be safe (Whatever that means)?

Not to mention ocean acidification and considering the changes already being witnessed.

BECCS also needs to take into account the CO2 emissions from the cultivation of the biomass which some incidences can be higher than fossil fuel emissions if done poorly, (like taking tree brash and roots out forcing the soil respiring bugs to feast on old soil carbon), so no negative carbon, and CCS reduces power output significantly therefore you have burn more biomass to get the same output than without CCS.

Scary that RCP2.6 is totally dependent on it!

And can't help feeling climatic changes might make growing food alone, never mind extra biomass, more challenging in many places, like California say?

Do we really have a carbon budget at all?

Don't we need to get CO2 to 350ppm at least and adapt massively at the same time to new climatic systems the earth is heading for?

Do we really have the luxury of being able to gamble anymore carbon emissions?

A 50/50 chance at 450ppm of keeping warming to 2C by 2100, so that is akin to Russian Roulette with 3 bullets in the barrel, not sure why our policy makers are such brave gamblers considering the risks?

Moderator Response:

[JH] Links activated.

[AS] I hot-linked the Lawrence reference. The long URL was breaking the page

RedBaron at 20:17 PM on 21 April 2015

There's no empirical evidence

@CBDunkerson,

Flat when it should be dropping is significant. I have tried to get at the flaw from both angles, the emissions and the mitigation. In simple abstract terms.... moving from -3 to +3 is not moving 3..it is moving 6. The emissions are not the whole story when discussing biome effects. Sure in discussing fossil fuel emissions you can simply measure the CO2 released because FF are so slowly formed that it approaches 0 in our timeframe. But when you talk about emissions from the soil due to ecosystem degradation, you must include both the emissions and the carbon that would have been sequestered if the ecosystem hadn't been degraded and add them together. Essentially what we have done by degrading the terrestrial biomes of the planet is to damage the capabilty for the ecosystems to moderate the excess carbon produced by fossil fuels. In no way am I denying the fossil fuel emissions. Instead I am pointing out the loss of the ecosystem service of carbon sequestration found naturally in healthy ecosystems.

So please don't confuse what I am saying with climate deniers arguments. I am actually saying that AGW is roughly twice as bad as the arguments presented on this forum. Fortunately though that is potentially a good thing because it also means that restoring the ecosystem function will likely have a much greater effect than projected here as well.

Please go back to post #258 and look at reference #5 soil degradation map. That whole area with degraded soils is either currently + emissions sources or has been +emissions sources since distubance by Man. Yet most of that area should have been a carbon sequestration sink over that same period. In the case of grasslands a very large sequestration sink. In the case of forests a smaller sequestration sink, but in both cases a sink not a source. So you must add the two together.

That is my explanation as to why in the Ruddiman (citation on post #251) graphs figure 1 and figure 2 the curve deviates from its downward trend and flattens. Next comes fossil fuels, and lacking the ecosystems ability to sequester carbon, the atmosphere instead begins to become saturated with excess CO2. Thus in reality the hockey stick is actually a result of ecosystem services loss rather than fossil fuel emissions alone, my original premise.

scaddenp at 18:36 PM on 21 April 2015

Human CO2 is a tiny % of CO2 emissions

One other little gotcha is that turning desert/grassland to forest say reduces the albedo of the planet - it doesnt reflect as much radiation to space but I think that would be a minor concern.

scaddenp at 18:34 PM on 21 April 2015

Human CO2 is a tiny % of CO2 emissions

Well mushrumps, I have made a mess of this sort of calculation in past but lets see how I go. The difference between emissions and absorption of land/vege is 11Gt. Land area of earth is 150,000,000 km2. 1/3 is desert, so non-desert is 100,000,000 or .1Gkm2. So land/vege currently is moping up 110 tonne/km2. To mop up an extra 17Gt at current rate, then need 17G/110 = 150,000,000km. That's current area of planet. Cant plant that much forest. Looks like a challenging problem to me.

mushrumps at 16:51 PM on 21 April 2015

Human CO2 is a tiny % of CO2 emissions

The chart at the top tells me that vegetation and land, plus the oceans absorb 17 more gigatons than they emit. Assuming we can't do much about the oceans, all we need to do is increase veg&land absorption by 12 gigatons to balance human production of CO2!

Andy Skuce at 13:53 PM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

jja:

The Hollesen paper was not cited by Schuur et al.

I would imagine that the models cited in this paper do take albedo changes into account since that's a rather basic effect, but I don't know for sure.

Can you provide a reference or more reasoning for the 300% amplification?

jja at 13:23 PM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

Do these models incorporate the microbial heating of Hollesen et. al. (2015)? paper here: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2590.html

Also, are these models including regional forcing feedbacks associated with ice-loss dynamics or do they simply look at radiative forcing parameters from the RCP runs? If they do not include ice-loss albedo functions (as well as a 20% increase in regional temperature due to arctic surface algae growth) (carbon brief today: http://www.carbonbrief.org/blog/2015/04/tiny-marine-plants-could-amplify-arctic-warming-by-20-percent-new-study-finds/ ) Then these models could be underrepresenting frozen soil feedbacks by over 300%

We really need to get a handle on these regional feedback parameters under a potential arctic summer ice free condition within the next 10 years to be safe.

Joel_Huberman at 13:06 PM on 21 April 2015

Global warming hiatus explained and it's not good news

I want to change the topic, back to the content of the original posting. One of the paragraphs in the original posting is:

"Volcanic eruptions generally cool the planet's surface. A study in the journal Nature Geoscience found that some climate models did not properly account for the higher levels of volcanic activity in the early 20th century. This meant that some models had overestimated the amount of atmospheric warming during the so-called slow-down."

A friend of mine alerted me to a contrarian web site (https://notalotofpeopleknowthat.wordpress.com/2015/04/18/no-underlying-global-temperature-increase-for-20-years/) where a blogger, Paul Homewood, has posted Figure 1 from the above paper in Nature Geoscience (the first author of the paper is Benjamin Santer). Homewood points out that Figure 1 appears to show that, after ENSO effects and volcanic effects have been removed from satellite data on lower tropospheric temperatures, there has been no significant change in those temperatures since 1993. Homewood concludes: "What Santer’s study shows is that there has been no underlying upward trend in global temperatures for more than 20 years."

I'm sure that Santer's conclusion must be incorrect, even for the lower troposphere (which, as I understand it, hasn't warmed as much as surface temperatures). But I can't see what's wrong with Homewood's reasoning. Can someone help me? Thanks!

DMarshall at 12:14 PM on 21 April 2015

Global warming hiatus explained and it's not good news

@Peter Carson

A certain well-known, heavily-trafficked "contrarian" site had a lively discussion about 3 years ago regarding undersea volcanos and ENSO.

The overwhelming "consensus" was that it ha zero-to-minimal impact.
When you find yourself putting forward an idea that NEITHER side of a polarized debate finds plausible, you're either about to overturn an entire field of study or - more likely - are treading on razor-thin basalt.

ubrew12 at 06:32 AM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

"Just because the emissions are uncertain does not mean that they should be excluded, after all, projections of fossil-fuel emissions are probably even more uncertain." Another good reason to include these emissions: as a matter of policy they are largely beyond human control. Based on new information (or, more likely, a long-delayed epiphany), the U.S. can always say "Oops, my bad" and cut its emissions dramatically. But the 'permafrost U.S.' is doing no such thing.

Andy Skuce at 05:38 AM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

wili. thank you.

Here's what the paper says, verbatim:

Our expert judgement is that estimates made by independent approaches, including laboratory incubations, dynamic models, and expert assessment, seem to be converging on ~5%–15% of the terrestrial permafrost carbon pool being vulnerable to release in the form of greenhouse gases during this century under the current warming trajectory, with CO2-carbon comprising the majority of the release. There is uncertainty, but the vulnerable fraction does not appear to be twice as high or half as much as 5%–15%, based on this analysis.

I should have added the word "carbon" after "permafrost (which I will now do). From their second sentence, I would expect that, while there is admitted uncertainty, the GHG release is very likely to be bigger than 2.5% in their judgement and likely bigger than 5%. The "current warming trajectory" that this is based on is something close to RCP8.5, so mitigation efforts could defer or cancel some of this, as well.

wili at 05:07 AM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

Thanks for this great update, and especially for the very apropos final 'rant.' One point for now that I would love further clarification on:

The second bullet-point under "The bottom line" section says:

"During this century, 5-15% of the land permafrost is vulnerable to release in the form of carbon dioxide or methane."

That seem rather low to me, given how rapidly the Arctic is warming. Are there uncertainty bars on the upper end that we're not seeing here? Does this assume a particular (perhaps optimistic?) emissions pathway?

There is now a very wide range of possible increases in global temperature by the end of the century. How can the range of potential melt of permafrost be so relatively narrow?

Also, is the low end of 5% pretty solid--that is, have we pretty well by now guaranteed that at least that much will thaw by the end of the century no matter what we do?

Thanks ahead of time for any light you can throw on my (typical state of) bewilderment.

Rob Honeycutt at 02:51 AM on 21 April 2015

Andy Lacis responds to Steve Koonin

Ger @21... You should read this article on the relationship between gravity and glacial melt.

Ger at 02:40 AM on 21 April 2015

Andy Lacis responds to Steve Koonin

@20. Gravity has nothing to do with it. Gravity is an expression of potential energy (water above sea level) No mass is going away by melting ice, nothing will change in the gravity. Water will get some kinetic energy when going down, converted into some heat and extra flow of seawater when it smacks into the fast inertia of the sea.

Moderator Response:

[TD] Actually, gravitational attraction from ice does pull water toward it. Amazing but true. For example, see this post about Jerry Mitrovica's work.

Andy Skuce at 01:58 AM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

"Reserves" definitions always imply commerciality. At today's commodity prices many undeveloped bitumen deposits may not be economically viable. Indeed, some oil sands development projects are currently being shelved.

Here is the Society of Petroleum Engineers definition:

RESERVES are those quantities of petroleum anticipated to be commercially recoverable by application of development projects to known accumulations from a given date forward under defined conditions. Reserves must further satisfy four criteria: they must be discovered, recoverable, commercial, and remaining (as of the evaluation date) based on the development project(s) applied.

Many commentators including Alberta's ERCB do refer to the established number as "reserves" (my emphasis)

Established reserves—those reserves recoverable under current technology and present and anticipated economic conditions, specifically proved by drilling, testing, or production, plus that judgment portion of contiguous recoverable reserves that are interpreted to exist, from geological, geophysical or similar information, with reasonable certainty.

That was written a few years ago, before the oil price crash took many forecasters (especially the Alberta government) by surprise. It will be interesting to see if they downgrade their established reserves numbers in the face of the new reality.

Until then, I will keep using "resource" for any undeveloped deposit that may or may not be commercial.

It's worth noting also that in a recent paper by McGlade and Ekins in Nature, they used much lower numbers for Canada's reserves, although it is not completely clear to me what assumptions they used.

[Comment updated]

bouke at 01:21 AM on 21 April 2015

Permafrost feedback update 2015: is it good or bad news?

The established bitumen resource in the Athabasca oil sands is approximately 169 billion barrels

Small terminology nitpick: 'resource' should be 'reserve'. 'Resource' refers to the total amount of stuff present, 'reserve' is the portion that can potentially be mined. Wikipedia uses the terminology correctly.

One Planet Only Forever at 00:29 AM on 21 April 2015

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