Support the Arctic Sea Ice Forum and Blog

Author Topic: IPCC possible scenario: 9 C over next century or so  (Read 81164 times)

wili

  • ASIF Upper Class
  • Posts: 2039
    • View Profile
IPCC possible scenario: 9 C over next century or so
« on: October 15, 2014, 04:45:38 AM »


Discuss...
« Last Edit: October 15, 2014, 12:41:09 PM by wili »
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

ccgwebmaster

  • ASIF Upper Class
  • Posts: 1085
  • Civilisation collapse - what are you doing?
    • View Profile
    • CCG Website
Re: IPCC possible scenario: 9 C by 2100
« Reply #1 on: October 15, 2014, 09:28:21 AM »


Discuss...

Looks more like 2125 to me?

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #2 on: October 15, 2014, 12:17:10 PM »
That shows around 1.5 degrees of warming by now.  By GISS we have seen more like 1 degree.  So far we are well behind this scenario.  Based on the warming over the last 100 years it seems most likely that if climate sensitivity is at the high end then it involves slow feedbacks and we would be unlikely to see all of it within a 100 year timeframe.

As for the future, this scenario can only happen if climate sensitivity is at the high end, yet we do nothing to slow Co2 emissions growth for the next 100 years.  This seems absurdly unlikely.  We have already been acting on Co2 for several decades - even if many would argue that this action has been too slow etc.  And while so far we have not seen any significant reduction in co2 emissions we have seen a significant improvement in renewable energy technology, and dramatic growth in this industry.  Further growth will soon be enough to make a noticeable difference to Co2 emissions.  At this stage 'business as usual' would be more like RCP 4.5 which shows further steady growth in Co2 emissions for another 30 or 40 years before a gradual reduction.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

jai mitchell

  • ASIF Upper Class
  • Posts: 1762
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #3 on: October 15, 2014, 12:29:42 PM »
Worst case is ECS 6.0, not 4.5

Then include carbon cycle feedbacks (with two sigmas of potential error, not one sigma as in figure 6.24)



THEN include emissions due to permafrost, also not included.

According to RS2014 presentations we are following right along with RCP 8.5 so far.

https://twitter.com/icey_mark/status/514393978150854656/photo/1

RCP 4.5 requires CCS in their scenario.  I hope that you are right in your estimations, however as percent of total energy generation, renewables growth is still growing at a slower rate than coal.



Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

wili

  • ASIF Upper Class
  • Posts: 2039
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #4 on: October 15, 2014, 12:40:14 PM »
ccg: Doh! You're right, of course. I guess I'm so used to all these charts ending (rather absurdly) at 2100. I tried to change the title of the thread--I don't know if it will apply itself to all new posts, though.

MH wrote: "This seems absurdly unlikely"

It seemed absurdly unlikely to many scientists who were pointing out the dangers of climate change decades ago that "we do nothing to slow Co2 emissions growth," but emissions have in fact continue to grow and at an increasing pace pretty much throughout that time. If you think the richest and most powerful industry on earth is just going to lie down quietly to die without putting up further fights as the economics of renewables starts turning against them, well, I would just suggest that this is a rather naive view, and one that flies in the face of realities we have already witnessed.

We do seem to be living right inside of 'absurdly unlikely' times, indeed.

In any case, IPCC certainly is presenting this as a worst case, very high end possibility. But that such a very conservative, chronically understating body would even include it in their scenarios, I found...interesting.
« Last Edit: October 15, 2014, 12:49:56 PM by wili »
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Sigmetnow

  • ASIF Royalty
  • Posts: 9616
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #5 on: October 15, 2014, 03:08:09 PM »
Here's a graph which includes historical performance, as well.  Although so far it fits nicely to the worst-case scenario, I seriously doubt we will continue on that line. 
Simply using "human nature" (is that an oxymoron?) as a guide would suggest we will do worse than that projection for a short while -- until we get our act togther and make sudden rapid, downward progress.  (The ”Oh, sh*t" scenario.  Doesn't have a number.  ::) )
People who say it cannot be done should not interrupt those who are doing it.

S.Pansa

  • ASIF Citizen
  • Posts: 125
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #6 on: October 15, 2014, 04:01:26 PM »
On the short run, I doubt that there will be any significant change.
See for instance one of the most recent short-term emission estimates (til 2019) by Friedlingstein 2014 below (http://dx.doi.org/10.1038/ngeo2248), based in parts on this voluminous paper by Corinne Le Quéré 2014 (http://www.earth-syst-sci-data-discuss.net/7/521/2014/doi:10.5194/essdd-7-521-2014)


jai mitchell

  • ASIF Upper Class
  • Posts: 1762
    • View Profile
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

wili

  • ASIF Upper Class
  • Posts: 2039
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #8 on: October 15, 2014, 07:03:54 PM »
Thanks all for the great graphs and links. Much to ponder.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

ccgwebmaster

  • ASIF Upper Class
  • Posts: 1085
  • Civilisation collapse - what are you doing?
    • View Profile
    • CCG Website
Re: IPCC possible scenario: 9 C over next century or so
« Reply #9 on: October 15, 2014, 09:01:34 PM »
In any case, IPCC certainly is presenting this as a worst case, very high end possibility. But that such a very conservative, chronically understating body would even include it in their scenarios, I found...interesting.

Trouble is, their assumptions are necessarily too far from reality. They assume an indefinite trajectory of industrial emissions - flawed as at some point civilisation starts to collapse and resources deplete. They ignore natural feedbacks for the most part - also flawed - as those can contribute very significant additions to the problem.

Overall, I think we really don't know and the IPCC stuff is not solid enough to risk the future of humanity upon.

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #10 on: October 15, 2014, 11:07:45 PM »

It seemed absurdly unlikely to many scientists who were pointing out the dangers of climate change decades ago that "we do nothing to slow Co2 emissions growth," but emissions have in fact continue to grow and at an increasing pace pretty much throughout that time. If you think the richest and most powerful industry on earth is just going to lie down quietly to die without putting up further fights as the economics of renewables starts turning against them, well, I would just suggest that this is a rather naive view, and one that flies in the face of realities we have already witnessed.

The fossil fuel industry has been fighting long and hard.  The progress of renewables to date has been in the face of this fight.  As temperatures rise this is only going to tilt the playing field further in favour of renewables.

Those who claim or imply that nothing is being done about Co2 are just as much in denial as those who say that Co2 isn't warming our planet.  Now if you want to argue that not enough is being done, then you'd have my agreement.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

ccgwebmaster

  • ASIF Upper Class
  • Posts: 1085
  • Civilisation collapse - what are you doing?
    • View Profile
    • CCG Website
Re: IPCC possible scenario: 9 C over next century or so
« Reply #11 on: October 15, 2014, 11:16:38 PM »
Now if you want to argue that not enough is being done, then you'd have my agreement.

I'd submit that what is being done is considerably closer to the "nothing" end of the spectrum than the "enough" end.

wili

  • ASIF Upper Class
  • Posts: 2039
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #12 on: October 15, 2014, 11:18:59 PM »
What ccg said.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #13 on: October 15, 2014, 11:37:35 PM »
Here's a graph which includes historical performance, as well.  Although so far it fits nicely to the worst-case scenario, I seriously doubt we will continue on that line. 
Simply using "human nature" (is that an oxymoron?) as a guide would suggest we will do worse than that projection for a short while -- until we get our act togther and make sudden rapid, downward progress.  (The ”Oh, sh*t" scenario.  Doesn't have a number.  ::) )

Note that Co2 emissions have grown at the high end - I suspect primarily because we have underestimated economic growth, particularly in developing countries.  But other greenhouse gases have slowed significantly, perhaps because action on these has been easier than Co2.  This means that the greenhouse gas forcing has been lower than the high end.  See this detailed discussion of Hansens 1988 scenarios.  I assume that the IPCC scenarios would follow roughly the same logic.

So overall greenhouse gas forcing is growing slower than expected.  However the Co2 component is growing faster than expected.  And unfortunately the Co2 component is the component that lasts many centuries whereas the other components are much shorter lived in the atmosphere.  So our short to medium term trajectory (ie up to 100 or so years) is definitely not on the high end.  However later on, particularly if carbon cycle feedbacks kick in (and it seems something has to explain those ice ages).... well thats a problem beyond the century time frame.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #14 on: October 16, 2014, 02:05:56 AM »
That shows around 1.5 degrees of warming by now.  By GISS we have seen more like 1 degree.  So far we are well behind this scenario.

Michael,

While your comment that the graph that wili presented shows around 1.5 degrees C of mean global surface temperature warming by now (while the earth surface temperature is well below this temperature), many be in keeping with conventional scientific thought only a few months ago; I would like to point out that such thinking is out-of-date now that Durack et al (2014) have identified a previously unidentified ocean heat content in the Southern Hemispheric oceans that is sufficient to temporarily suppress surface temperature rise, while still allowing Equilibrium Climate Sensitivity, ECS, to be about 4.5 degrees C.  The CMIP5 models average over multi-decadal oceanic cycles such as the IPO/PDO and the AMO, that have recently been sequestering heat into the oceans at a higher than average rate since at least 1999; thus as the IPO/PDO and the AMO move into warming phases we can expect the mean global surface temperatures to catch-up to the average CMIP5 forecasts for ECS = 4.5 oC.

Paul J. Durack, Peter J. Gleckler, Felix W. Landerer and Karl E. Taylor, (2014), "Quantifying Underestimates of Long-term Upper-Ocean Warming", Nature Climate Change, 4 (11), DOI: 10.1038/nclimate2389

http://www-pcmdi.llnl.gov/about/staff/Durack/dump/oceanwarming/140926a_Duracketal_UpperOceanWarming.pdf

Abstract: "The global ocean stores more than 90% of the heat associated with observed greenhouse‐gas‐attributed global warming (Levitus et al., 2005; Church et al., 2011; Otto et al., 2013; Rhein et al., 2013). Using satellite altimetry observations and a large suite of climate models, we conclude that observed estimates of 0‐700 dbar global ocean warming since 1970 are likely biased low. This underestimation is attributed to poor sampling of the Southern Hemisphere, and limitations of the analysis methods that conservatively estimate temperature changes in data‐sparse regions (Gregory et al., 2004; Gouretski & Koltermann, 2007; Gille, 2008). We find that the partitioning of northern and southern hemispheric simulated sea surface height changes are consistent with precise altimeter observations, whereas the hemispheric partitioning of simulated upper‐ocean warming is inconsistent with observed in‐situ‐based ocean heat content estimates. Relying on the close correspondence between hemispheric‐scale ocean heat content and steric changes, we adjust the poorly constrained Southern Hemisphere observed warming estimates so that hemispheric ratios are consistent with the broad range of modelled results. These adjustments yield large increases (2.2‐7.1 x 1022 J 35yrs‐1) to current global upper‐ocean heat content change estimates, and have important implications for sea level, the planetary energy budget and climate sensitivity assessments."

Best,
ASLR
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #15 on: October 16, 2014, 02:20:00 AM »

THEN include emissions due to permafrost, also not included.


As the permafrost emissions are estimated to include about 2% methane (and 98% carbon dioxide), and as methane has a 100-year GWP of about 35, the fact that AR5 projections did not include the permafrost methane emissions is a serious short-coming.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #16 on: October 16, 2014, 02:47:03 AM »
According to the linked article, in order to fight-off encroachment of its market Saudi Arabia has chosen to maintain high crude oil production rates that has caused oil prices to drop 23 percent between June 2014 and Oct 13 2014, and looks likely to drop still further (possibly to around $70 per barrel). This is forecast to promote energy inefficiencies and to reduce the rate of growth of renewable energy.

http://www.washingtonpost.com/business/economy/oil-prices-plunge-as-production-rises-fueling-concern-in-opec/2014/10/14/9bfd877c-53c9-11e4-892e-602188e70e9c_story.html

Extract: "With a weak global economy, the customary swing producer of oil — Saudi Arabia — has cut prices instead of cutting production, setting off a scramble on world markets. Crude oil prices have tumbled more than 23 percent since June, including a more than 4 percent drop Tuesday. Prices fell below four-year lows to wind up at $81.84 a barrel for the benchmark grade, West Texas Intermediate."

Needless to say such a drop in the price of oil will also stimulate the economies of the EU, the USA and China (among others), and serve to keep the world on the RCP 8.5 for at least several more years to come.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #17 on: October 16, 2014, 09:05:09 AM »

I'd submit that what is being done is considerably closer to the "nothing" end of the spectrum than the "enough" end.

According to page 11 of Edgar report on Co2 emissions Europe has been decreasing in Co2 emissions from 1990.  Even famously in denial America rose very slowly up to just after 2000 and has since  dropped to be at about 1990 levels.

The only reason why action to date has not had enough impact to stabilise emissions is the growth in China and to a lesser extent India.  The original Kyoto agreement in 1990 excluded China, and no one expects China to be excluded from the next agreement.

Enough is being done that scenario 8.5 is totally unrealistic - although still worth reporting from the point of view of 'this is why we have been doing something about climate change and must continue to do this and more'
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #18 on: October 16, 2014, 09:16:11 AM »
That shows around 1.5 degrees of warming by now.  By GISS we have seen more like 1 degree.  So far we are well behind this scenario.

Michael,

While your comment that the graph that wili presented shows around 1.5 degrees C of mean global surface temperature warming by now (while the earth surface temperature is well below this temperature), many be in keeping with conventional scientific thought only a few months ago; I would like to point out that such thinking is out-of-date now that Durack et al (2014) have identified a previously unidentified ocean heat content in the Southern Hemispheric oceans that is sufficient to temporarily suppress surface temperature rise, while still allowing Equilibrium Climate Sensitivity, ECS, to be about 4.5 degrees C.  The CMIP5 models average over multi-decadal oceanic cycles such as the IPO/PDO and the AMO, that have recently been sequestering heat into the oceans at a higher than average rate since at least 1999; thus as the IPO/PDO and the AMO move into warming phases we can expect the mean global surface temperatures to catch-up to the average CMIP5 forecasts for ECS = 4.5 oC.

Paul J. Durack, Peter J. Gleckler, Felix W. Landerer and Karl E. Taylor, (2014), "Quantifying Underestimates of Long-term Upper-Ocean Warming", Nature Climate Change, 4 (11), DOI: 10.1038/nclimate2389

http://www-pcmdi.llnl.gov/about/staff/Durack/dump/oceanwarming/140926a_Duracketal_UpperOceanWarming.pdf

Abstract: "The global ocean stores more than 90% of the heat associated with observed greenhouse‐gas‐attributed global warming (Levitus et al., 2005; Church et al., 2011; Otto et al., 2013; Rhein et al., 2013). Using satellite altimetry observations and a large suite of climate models, we conclude that observed estimates of 0‐700 dbar global ocean warming since 1970 are likely biased low. This underestimation is attributed to poor sampling of the Southern Hemisphere, and limitations of the analysis methods that conservatively estimate temperature changes in data‐sparse regions (Gregory et al., 2004; Gouretski & Koltermann, 2007; Gille, 2008). We find that the partitioning of northern and southern hemispheric simulated sea surface height changes are consistent with precise altimeter observations, whereas the hemispheric partitioning of simulated upper‐ocean warming is inconsistent with observed in‐situ‐based ocean heat content estimates. Relying on the close correspondence between hemispheric‐scale ocean heat content and steric changes, we adjust the poorly constrained Southern Hemisphere observed warming estimates so that hemispheric ratios are consistent with the broad range of modelled results. These adjustments yield large increases (2.2‐7.1 x 1022 J 35yrs‐1) to current global upper‐ocean heat content change estimates, and have important implications for sea level, the planetary energy budget and climate sensitivity assessments."

Best,
ASLR

If this result is confirmed by further study.  Then the faster accumulation of heat in the southern oceans may have been slowing down the temperature rise over the last century.  If so it will continue to slow down temperature rise for as long as emissions continue to grow - i.e. for as long as we stay near rcp 8.5. 

It is only when emissions stop growing that any higher than accounted for thermal inertia of the oceans will makes its impact known with more warming than otherwise expected.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

viddaloo

  • ASIF Upper Class
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #19 on: October 16, 2014, 11:41:34 AM »
Needless to say such a drop in the price of oil will also stimulate the economies of the EU, the USA and China (among others), and serve to keep the world on the RCP 8.5 for at least several more years to come.
In a somewhat dark mood, one could say it will keep the world in the OSS(*) for another decade...

*) OSS — the infamous "Oh, Shit! Scenario", according to which we will find out in late 2099 that things are a lot more serious than the Panel told us they were.
[]

crandles

  • ASIF Upper Class
  • Posts: 1793
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #20 on: October 16, 2014, 01:11:22 PM »

I'd submit that what is being done is considerably closer to the "nothing" end of the spectrum than the "enough" end.

According to page 11 of Edgar report on Co2 emissions Europe has been decreasing in Co2 emissions from 1990.  Even famously in denial America rose very slowly up to just after 2000 and has since  dropped to be at about 1990 levels.

The only reason why action to date has not had enough impact to stabilise emissions is the growth in China and to a lesser extent India.  The original Kyoto agreement in 1990 excluded China, and no one expects China to be excluded from the next agreement.

Enough is being done that scenario 8.5 is totally unrealistic - although still worth reporting from the point of view of 'this is why we have been doing something about climate change and must continue to do this and more'

But the reason Europe and America have been slowing or reducing CO2 emissions is surely in part because they increased imports of goods from China, India ... surely this increased the CO2 impact of making those goods. Even if it didn't increase the CO2 impact, moving the source from one place to another isn't a huge success in reducing CO2 emissions is it?

TBH I haven't analysed numbers to see if the effect of this is significant or not.

S.Pansa

  • ASIF Citizen
  • Posts: 125
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #21 on: October 16, 2014, 04:03:42 PM »
@ jai mitchell

Thanks for the correct link to the Le Quéré paper.

@ crandles

I wondered the same and the amount seems to be at least not insignificant, if the IPCC is to be believed. A quote from IPCC WGIII AR5, chapter 5, p. 30 (emphasis mine):

The overall picture shows a substantial gap between territorial and consumption‐based
emissions, due to emissions embedded in trade. For the OECD‐1990 countries, the gap amounts to 2.6 Gt CO2 in 2010.
The data shows that the reduction in territorial emissions that has been achieved in the OECD‐1990
countries has been more than negated by an increase in emissions in other countries but
related with consumption in OECD‐1990 countries. Furthermore, while countries with a
Kyoto Protocol commitment did reduce emissions over the accounting period by 7%, their
share of imported over domestic emissions increased by 14% (Peters et al., 2011a; Aichele
and Felbermayr, 2012). 

See also the following picture from the same chapter

edit: the initially attached paper was about something completely different

« Last Edit: October 16, 2014, 04:15:56 PM by S.Pansa »

oren

  • ASIF Upper Class
  • Posts: 1590
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #22 on: October 16, 2014, 04:22:59 PM »
Great chart

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #23 on: October 16, 2014, 04:50:52 PM »

Note that Co2 emissions have grown at the high end - I suspect primarily because we have underestimated economic growth, particularly in developing countries.  But other greenhouse gases have slowed significantly, perhaps because action on these has been easier than Co2.  This means that the greenhouse gas forcing has been lower than the high end.  See this detailed discussion of Hansens 1988 scenarios.  I assume that the IPCC scenarios would follow roughly the same logic.

So overall greenhouse gas forcing is growing slower than expected.  However the Co2 component is growing faster than expected.  And unfortunately the Co2 component is the component that lasts many centuries whereas the other components are much shorter lived in the atmosphere.  So our short to medium term trajectory (ie up to 100 or so years) is definitely not on the high end.  However later on, particularly if carbon cycle feedbacks kick in (and it seems something has to explain those ice ages).... well thats a problem beyond the century time frame.

Michael,

While the atmospheric CO2 concentration is currently just under 400ppm, per the following Robert Scribbler link & extract the CO2 equivalent concentration is currently about 481ppm.

http://robertscribbler.wordpress.com/2014/10/08/its-worse-than-we-thought-new-study-finds-that-earth-is-warming-far-faster-than-expected/

extract: "In the push and pull between all the various political and scientific interests over setting these goals and limits, the glaring numbers really jump out at the wary analyst. One is the total heat forcing now being applied to the atmosphere by all the greenhouse gasses we’ve dumped into the air over the years and decades. That total, this year, rose to a stunning 481 parts per million CO2 equivalent. And if we look at paleoclimate temperature proxies, the last time the world’s atmosphere contained 481 parts per million CO2 was when temperatures were in the range of 3-4 degrees Celsius hotter than we see today."

I note that the last time the atmosphere contained 481 parts per million CO₂ the aerosol negative feedback was not as high as today; however, China in-particular is determined to clean-up its air pollution as quickly as practicable which would greatly reduce this negative feedback mechanism.

Furthermore, from the current Robert Scribbler post Arctic carbon emissions could account for 35% or more of human emission by 2100 under a BAU scenario (which you say is ridiculous but which you cannot even prove is not the most likely scenario)

http://robertscribbler.wordpress.com/

extract: "In 2011, a group of 41 Arctic researchers projected that Arctic carbon release would equal ten percent of the total human emission if rapid reduction of carbon emissions was undertaken as soon as possible. Under business as usual carbon emissions through 2100, the researchers suggested that the Arctic feedback would amplify to a size equaling 35% or more of the human emission. Enough to set off a runaway to a hothouse state even if all human emissions were to cease."

Best,
ASLR
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

ccgwebmaster

  • ASIF Upper Class
  • Posts: 1085
  • Civilisation collapse - what are you doing?
    • View Profile
    • CCG Website
Re: IPCC possible scenario: 9 C over next century or so
« Reply #24 on: October 16, 2014, 04:59:51 PM »
But the reason Europe and America have been slowing or reducing CO2 emissions is surely in part because they increased imports of goods from China, India ... surely this increased the CO2 impact of making those goods. Even if it didn't increase the CO2 impact, moving the source from one place to another isn't a huge success in reducing CO2 emissions is it?

TBH I haven't analysed numbers to see if the effect of this is significant or not.

That's just the problem. Europe and America jump up and down politically claiming to be reducing carbon emissions but if you take into account the footprint of imported goods, they're actually still responsible for increasing emissions. A little sleight of hand and trickery at work mostly (I guess some countries - eg Germany perhaps - genuinely have improved somewhat though?) with no fundamental change in behaviour or consumption.

All we need to be watching is the global atmospheric concentration of carbon dioxide for the truth, and it sucks. No reductions or slowdowns there.

I don't know if the increased footprint from long range imports vs local manufacturing is significant or not - at face value, you'd assume yes - because you're transporting the items very long distances and probably using lower efficiency manufacturing techniques to make them. On the other hand, given the massive amount of movement of resources required for modern manufacturing I suspect you'd have to check the whole supply change for every resource consumed in such manufacture to get a proper picture - very hard to do properly.

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #25 on: October 16, 2014, 05:21:16 PM »
That shows around 1.5 degrees of warming by now.  By GISS we have seen more like 1 degree.  So far we are well behind this scenario.

Michael,

While your comment that the graph that wili presented shows around 1.5 degrees C of mean global surface temperature warming by now (while the earth surface temperature is well below this temperature), many be in keeping with conventional scientific thought only a few months ago; I would like to point out that such thinking is out-of-date now that Durack et al (2014) have identified a previously unidentified ocean heat content in the Southern Hemispheric oceans that is sufficient to temporarily suppress surface temperature rise, while still allowing Equilibrium Climate Sensitivity, ECS, to be about 4.5 degrees C.  The CMIP5 models average over multi-decadal oceanic cycles such as the IPO/PDO and the AMO, that have recently been sequestering heat into the oceans at a higher than average rate since at least 1999; thus as the IPO/PDO and the AMO move into warming phases we can expect the mean global surface temperatures to catch-up to the average CMIP5 forecasts for ECS = 4.5 oC.

Paul J. Durack, Peter J. Gleckler, Felix W. Landerer and Karl E. Taylor, (2014), "Quantifying Underestimates of Long-term Upper-Ocean Warming", Nature Climate Change, 4 (11), DOI: 10.1038/nclimate2389

http://www-pcmdi.llnl.gov/about/staff/Durack/dump/oceanwarming/140926a_Duracketal_UpperOceanWarming.pdf

Abstract: "The global ocean stores more than 90% of the heat associated with observed greenhouse‐gas‐attributed global warming (Levitus et al., 2005; Church et al., 2011; Otto et al., 2013; Rhein et al., 2013). Using satellite altimetry observations and a large suite of climate models, we conclude that observed estimates of 0‐700 dbar global ocean warming since 1970 are likely biased low. This underestimation is attributed to poor sampling of the Southern Hemisphere, and limitations of the analysis methods that conservatively estimate temperature changes in data‐sparse regions (Gregory et al., 2004; Gouretski & Koltermann, 2007; Gille, 2008). We find that the partitioning of northern and southern hemispheric simulated sea surface height changes are consistent with precise altimeter observations, whereas the hemispheric partitioning of simulated upper‐ocean warming is inconsistent with observed in‐situ‐based ocean heat content estimates. Relying on the close correspondence between hemispheric‐scale ocean heat content and steric changes, we adjust the poorly constrained Southern Hemisphere observed warming estimates so that hemispheric ratios are consistent with the broad range of modelled results. These adjustments yield large increases (2.2‐7.1 x 1022 J 35yrs‐1) to current global upper‐ocean heat content change estimates, and have important implications for sea level, the planetary energy budget and climate sensitivity assessments."

Best,
ASLR

If this result is confirmed by further study.  Then the faster accumulation of heat in the southern oceans may have been slowing down the temperature rise over the last century.  If so it will continue to slow down temperature rise for as long as emissions continue to grow - i.e. for as long as we stay near rcp 8.5. 

It is only when emissions stop growing that any higher than accounted for thermal inertia of the oceans will makes its impact known with more warming than otherwise expected.

Michael,

Your last statements assume that the oceanic cycles will continue to swing from cooling to warming phases; however, the truth of the matter is that if our current high emission rates continue for several more decades, the cooling phases will stop and we will only be left with warming phases, as indicated by the following reference:

Nicola Maher, Alexander Sen Gupta and Matthew H. England, (2014), "Drivers of decadal hiatus periods in the 20th and 21st Centuries", Geophysical Research Letters, DOI: 10.1002/2014GL060527


http://onlinelibrary.wiley.com/doi/10.1002/2014GL060527/abstract


Abstract: "The latest generation of climate model simulations are used to investigate the occurrence of hiatus periods in global surface air temperature in the past and under two future warming scenarios. Hiatus periods are identified in three categories, (i) those due to volcanic eruptions, (ii) those associated with negative phases of the Interdecadal Pacific Oscillation (IPO) and (iii) those affected by anthropogenically released aerosols in the mid 20th Century. The likelihood of future hiatus periods is found to be sensitive to the rate of change of anthropogenic forcing. Under high rates of greenhouse gas emissions there is little chance of a hiatus decade occurring beyond 2030, even in the event of a large volcanic eruption. We further demonstrate that most non-volcanic hiatuses across CMIP5 models are associated with enhanced cooling in the equatorial Pacific linked to the transition to a negative IPO phase."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #26 on: October 16, 2014, 06:01:49 PM »
Worst case is ECS 6.0, not 4.5

First, do not forget that Cowtan & Way (2014) proved that the reported historical values for mean global temperature rise have been under reported (so this accounts for some of the missing heat), but also supports the case for a higher ECS value:

Cowtan, K. and Way, R. G., (2014), "Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends", Q.J.R. Meteorol. Soc., doi: 10.1002/qj.2297

Second, not only does the Durack et al (2014) finding point to a ECS higher than 3.3 degrees C, but I point-out that Sherwood et al (2014) and Fasullo and Trenberth (2012) indicate that ECS is likely between 4 and 4.5 degrees C.  Furthermore, Shindell (2014) indicates that TCR is also likely proportionally higher than the AR5 assumes.

See:
Sherwood, S.C., Bony, S. and Dufresne, J.-L., (2014) "Spread in model climate sensitivity traced to atmospheric convective mixing", Nature; Volume: 505, pp 37–42, doi:10.1038/nature12829

http://www.nature.com/nature/journal/v505/n7481/full/nature12829.html

Fasullo, J.T. and Trenberth, K.E., (2012), "A Less Cloudy Future: The Role of Subtropical Subsidence in Climate Sensitivity", Science, vol. 338, pp. 792-794, 2012. http://dx.doi.org/10.1126/science.1227465.

http://www.sciencemag.org/content/338/6108/792

See also:

Shindell, D.T., (2014), "Inhomogeneous forcing and transient climate sensitivity", Nature Climate Change, Vol.: 4, pp: 274–277, doi:10.1038/nclimate2136.

http://www.nature.com/nclimate/journal/v4/n4/full/nclimate2136.html

Third, as you point-out, as the GHG levels exceed the pre-industrial levels, climate sensitivity will gradually increase from the ECS value to the Earth System Sensitivity, ESS, value, which prior to the Holocene was approximately 7.8 degrees C (as indicated by the first attached image from Shakun et al, 2012).  While it might be reasonable to use an ECS value for a RCP projections through 2050, there is no rational/scientific reason for using an ECS value for a RCP 8.5 projection after 2050 other than the value judgment of desiring to err on the side of least drama, as using a ESS value would just as likely to be correct as using a ECS value for a RCP 8.5 analysis between 2050 and 2100. The second attached image (from Hansen & Sato, 2011), clearly shows that during the warming phase of the Eemian the ESS was essentially linear beyond our current GHG levels, indicating that climate sensitivity should (as a first approximation) converge towards this approximately 7.8 degrees C (plus or minus, see the third attached image and the following extract from Pagani et al 2009 for the early and middle Pliocene, as an example of other ESS values that we might be converging towards) by the end of this century following RCP 8.5, as all of the slower feedback factors are engages including: (a) ocean venting of CO₂, (b) reduction of Arctic Sea Ice Extent and NH snow cover; (c) loss of NH albedo due to shrub growth; (d) decomposition of the permafrost; (e) degradation of the tropical and boreal forests (due to drought, fires, and attack by pests); (f) potential partial collapse of the WAIS, (g) reduction of Greenland albedo; (h) acidification of the oceans (and associated reduction of plankton); (i) slow-down of the AABW (Antarctic Bottom Water); (j) heat stress to plants; etc.  There is no rational reason for calibrating GCMs to the ECS for RCP 8.5 after 2050, rather than calibrating to the ESS, which is clearly the condition that our current non-stationary world is converging to as we continue to follow the BAU.


Mark Pagani, Zhonghui Liu, Jonathan LaRiviere, Ana Christina Ravelo (2009), "High Earth-System Climate Sensitivity determined from Pliocene CO2 Concentrations", Nature geoscience, doi:10.1038/NGEO724

http://people.earth.yale.edu/sites/default/files/files/Pagani/1_2009%20Pagani_NatureGeosci.pdf

Extract from Pagani et al 2009: "Data and modelling for the middle Pliocene (~3–3.3 Myr) indicate that the global mean temperature was 2.4–2.9 "C warmer than preindustrial conditions, and ~4 "C warmer during the early Pliocene (!4–4.2 Myr; ref. 5). If changes in carbon dioxide and associated feedbacks were the primary agents forcing climate over these timescales, and estimates of global temperatures are correct, then our results imply a very high Earth-system climate sensitivity for the middle (3.3 Myr) to early (4.2 Myr) Pliocene ranging between 7.1 ± 1.0 "C and 8.7 ± 1.3 "C per CO2 doubling, and 9.6±1.4 "C per CO2 doubling, respectively."

Caption for the third attached image : "Estimated CO2 trends considering probable oceanographic changes at each site. Each line represents a modified CO2slope for each site and the dashed green line (1012(alt)) represents an alternative nutrient scenario for Site 1012 (Supplementary Information). Vertical grey lines intersect CO2 concentrations at 3.0–3.3 and 4.0–4.2 Myr, the time intervals representing the Earth-system climate sensitivity estimates presented in the text."
« Last Edit: October 16, 2014, 06:07:27 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #27 on: October 16, 2014, 08:31:54 PM »
With a hat tip to Sigmetnow in the "Oil and Gas Issues" thread:

The following linked Bloomberg article indicates that OPEC (and in-particular Saudi Arabia) is currently driving down crude oil prices (thus promoting energy inefficiency and slower development of renewables) in order to test the profitability of US shale oil.  However, the Bloomberg and subsequent links indicate that the price of crude oil may need to drop well below $70 per barrel before this crude oil price war hurts US shale oil sufficient to result in a drop in US production, thus keeping us above the RCP 8.5 forcing for some time to come:

http://www.bloomberg.com/news/2014-10-15/opec-finding-u-s-shale-harder-to-crack-as-rout-deepens.html

Extract: "OPEC is resisting pressure to cut oil production while demand slumps as it tests how low prices must go to make U.S. shale oil unprofitable. As producers become more efficient, that floor is sinking.
...
About 2.6 million barrels of daily production, or 2.8 percent of global output, requires an oil price of $80 a barrel or more to be profitable, the IEA said. Only about 4 percent of U.S. shale output needs prices above that level, it said. Canadian synthetic oil projects are the most dependent on high prices, with about a quarter needing oil to remain above $80, the agency said.
...
Global oil consumption will expand by about 650,000 barrels a day this year to 92.7 million, the lowest growth since 2009 and about half the increase projected in June, the IEA said. OPEC boosted production in September, pumping 30.47 million barrels a day, the most since August 2013, the group said Oct. 10 in its latest monthly oil market report. Its next meeting is scheduled for Nov. 27 in Vienna."

Furthermore, while the following wiki extract is a few years old, it gives an idea that if Saudi Arabia is really serious about testing how low prices must go to make U.S. shale oil unprofitable, the the price of crude oil could drop well be $70 per barrel:

http://en.wikipedia.org/wiki/Oil_shale_economics

extract: "The United States Department of Energy estimates that the ex-situ processing would be economic at sustained average world oil prices above US$$54 per barrel and in-situ processing would be economic at prices above $35 per barrel. These estimates assume a return rate of 15%."

See also:
http://www.marketwatch.com/story/why-cratering-oil-may-not-crush-shale-producers-2014-10-14

“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #28 on: October 16, 2014, 10:55:48 PM »
Further to my Reply #26 about Earth System Sensitivity, I would like to point out that on balance there are many more positive feedbacks than there are negative feedbacks, and that when forced by strong warming scenarios such as RCP 8.5, many of the positive feedbacks become non-linearly positive; which can easily change a slow response feedback into a fast response feedback; just because society continued down a BAU pathway for a few years too long (thereby tipping some of the strong positive feedbacks into the highly non-linear range).
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

jai mitchell

  • ASIF Upper Class
  • Posts: 1762
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #29 on: October 16, 2014, 11:02:05 PM »
ASLR,

You are right of course, ESS is the final value.

In other words, nature bats last.

your post is one of the best I have seen on the subject, I will have to go through those references.

a few points on the use of ECS vs. ESS

1.  ESS is based on a paleoclimate analysis that is not experiencing the perturbations of carbon that humans have imposed on the biosphere.  In other words, the final sum value may be much worse or much better than the paleo runs.  I am talking about the incredible deforestation and loss of bony fish mass (as well as other land and ocean carbon storage/sequestration modes).  When we are gone, these will bounce back instantly (on the ESS scale) 

2.  Magical thinking.  The same kind of magical thinking that makes most people not bother about climate change because they think it will happen 100 years from now and we can't rule out "savior technology" being developed and, hey, I'll be long gone so why should I bother" attitudes.

3.  And, yes, the inherently cowardly nature of scientists to stay within the herd and privately express their concerns but don't ever lead the fray and say right out that we are headed immediately and permanently into oblivion (under BAU emission scenarios-- and possibly even if we do enact best case mitigation scenarios without CO2 extraction technology implementation (returning to 300 ppmv)).

In 2009 MIT stated their own models showed a potential 7.4C by 2100 scenario under BAU.

http://www.edouardstenger.com/2009/05/22/temperatures-could-rise-by-7%C2%B0c-by-2100/
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #30 on: October 17, 2014, 01:28:58 AM »
jai,

Some thoughts about your three points:

1. As I have shown that just before 10.5 kyr ago ESS was about 7.8 degree C, and if we assume now that ECS is 4.5 degrees C but is being temporarily masked by air pollution, cyclic sequesterization of heat into the ocean and a temporary bust of plant growth in the tundra and deserts; to appear to be an ECS of between 3 and 3.3 degrees C; then the real question is how fast might the masking factors come to partially stop masking and how fast can the slow response feedback mechanisms be reactivated to the pre-Holocene level (or above).  It seems to me that the influence of the masking factors could be slowed sufficiently to expose the full ECS value of 4.5 degrees C within 10 to 20 years from now (as people control air pollution, as the IPO and the AMO oscillations move to warm phases, and as plants are stresses by: droughts, floods, insects, and wildfires).  You are correct that anthropogenic forcing is at least 100-times stronger than paleo-forcing, however, almost all of the slow response mechanisms have some inertia to over-coming in order to become fully engaged (such as thermal inertia to degrade the permafrost and to warm key layers of the ocean, or to stress plants sufficiently that they die).  Nevertheless, as during the Younger Dryas period the slow response mechanisms kick-in to full activity with at most 200-years (to give the ESS of 7.8 degrees C); I would guess that under RCP 8.5 we could get to that level of activity within 50-years; and if after that the atmosphere flips to an equable climate then the ESS could continue increasing up to 9.6 degree C value cited by Pagani et al 2009.

2. Human thinking (magic or otherwise) is what it is; however, peoples thinking can be changed and in a democracy we only need 51% of the voters to take appropriate climate change action.  The information just has to be presented to the voters in a manner that they can relate to such as: jobs, patriotism, health, and safety.

3. Scientists are no more cowardly than anyone else, and everyone needs to work together to address the slow moving tsunami of climate change.

Best,
ASLR
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #31 on: October 17, 2014, 04:45:05 AM »

extract: "In 2011, a group of 41 Arctic researchers projected that Arctic carbon release would equal ten percent of the total human emission if rapid reduction of carbon emissions was undertaken as soon as possible. Under business as usual carbon emissions through 2100, the researchers suggested that the Arctic feedback would amplify to a size equaling 35% or more of the human emission. Enough to set off a runaway to a hothouse state even if all human emissions were to cease."

Best,
ASLR

The study Robert links to states 60b tonnes in 2040 and 380b tonnes of Co2 equivleant emissions by 2100 from the Arctic.  320m/60 is just over 5billion tonnes.  That is around 15% of current (2012) emissions of Co2 alone (and not Co2 equivelant) and a much lower proportion of what human emissions would be in 2100 under the imaginary 8.5 scenario.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #32 on: October 17, 2014, 04:48:10 AM »

Michael,

Your last statements assume that the oceanic cycles will continue to swing from cooling to warming phases; however, the truth of the matter is that if our current high emission rates continue for several more decades, the cooling phases will stop and we will only be left with warming phases, as indicated by the following reference:

Nicola Maher, Alexander Sen Gupta and Matthew H. England, (2014), "Drivers of decadal hiatus periods in the 20th and 21st Centuries", Geophysical Research Letters, DOI: 10.1002/2014GL060527


http://onlinelibrary.wiley.com/doi/10.1002/2014GL060527/abstract


Abstract: "The latest generation of climate model simulations are used to investigate the occurrence of hiatus periods in global surface air temperature in the past and under two future warming scenarios. Hiatus periods are identified in three categories, (i) those due to volcanic eruptions, (ii) those associated with negative phases of the Interdecadal Pacific Oscillation (IPO) and (iii) those affected by anthropogenically released aerosols in the mid 20th Century. The likelihood of future hiatus periods is found to be sensitive to the rate of change of anthropogenic forcing. Under high rates of greenhouse gas emissions there is little chance of a hiatus decade occurring beyond 2030, even in the event of a large volcanic eruption. We further demonstrate that most non-volcanic hiatuses across CMIP5 models are associated with enhanced cooling in the equatorial Pacific linked to the transition to a negative IPO phase."

I make no assumptions about ocean cycles.  My point is about ocean inertia - the amount that the ocean tends to slow down changes in temperature due to its large size and the amount of time taken to overcome this inertia.  It would still be valid even if there are no ocean cycles.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #33 on: October 17, 2014, 04:56:54 AM »
  It seems to me that the influence of the masking factors could be slowed sufficiently to expose the full ECS value of 4.5 degrees C within 10 to 20 years from now (as people control air pollution, as the IPO and the AMO oscillations move to warm phases, and as plants are stresses by: droughts, floods, insects, and wildfires).  You are correct that anthropogenic forcing is at least 100-times stronger than paleo-forcing, however, almost all of the slow response mechanisms have some inertia to over-coming in order to become fully engaged (such as thermal inertia to degrade the permafrost and to warm key layers of the ocean, or to stress plants sufficiently that they die).  Nevertheless, as during the Younger Dryas period the slow response mechanisms kick-in to full activity with at most 200-years (to give the ESS of 7.8 degrees C); I would guess that under RCP 8.5 we could get to that level of activity within 50-years; and if after that the atmosphere flips to an equable climate then the ESS could continue increasing up to 9.6 degree C value cited by Pagani et al 2009.

2. Human thinking (magic or otherwise) is what it is; however, peoples thinking can be changed and in a democracy we only need 51% of the voters to take appropriate climate change action.  The information just has to be presented to the voters in a manner that they can relate to such as: jobs, patriotism, health, and safety.

3. Scientists are no more cowardly than anyone else, and everyone needs to work together to address the slow moving tsunami of climate change.

Best,
ASLR

We will be no where near ECS in 20 years.  It will take many decades to centuries for the full effects of ocean inertia to be overcome.  wiki article
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C by 2100
« Reply #34 on: October 17, 2014, 05:09:09 AM »
Worst case is ECS 6.0, not 4.5

First, do not forget that Cowtan & Way (2014) proved that the reported historical values for mean global temperature rise have been under reported (so this accounts for some of the missing heat), but also supports the case for a higher ECS value:

Cowtan, K. and Way, R. G., (2014), "Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends", Q.J.R. Meteorol. Soc., doi: 10.1002/qj.2297

Second, not only does the Durack et al (2014) finding point to a ECS higher than 3.3 degrees C, but I point-out that Sherwood et al (2014) and Fasullo and Trenberth (2012) indicate that ECS is likely between 4 and 4.5 degrees C.  Furthermore, Shindell (2014) indicates that TCR is also likely proportionally higher than the AR5 assumes.

See:
Sherwood, S.C., Bony, S. and Dufresne, J.-L., (2014) "Spread in model climate sensitivity traced to atmospheric convective mixing", Nature; Volume: 505, pp 37–42, doi:10.1038/nature12829

http://www.nature.com/nature/journal/v505/n7481/full/nature12829.html

Fasullo, J.T. and Trenberth, K.E., (2012), "A Less Cloudy Future: The Role of Subtropical Subsidence in Climate Sensitivity", Science, vol. 338, pp. 792-794, 2012. http://dx.doi.org/10.1126/science.1227465.

http://www.sciencemag.org/content/338/6108/792

See also:

Shindell, D.T., (2014), "Inhomogeneous forcing and transient climate sensitivity", Nature Climate Change, Vol.: 4, pp: 274–277, doi:10.1038/nclimate2136.

http://www.nature.com/nclimate/journal/v4/n4/full/nclimate2136.html

Third, as you point-out, as the GHG levels exceed the pre-industrial levels, climate sensitivity will gradually increase from the ECS value to the Earth System Sensitivity, ESS, value, which prior to the Holocene was approximately 7.8 degrees C (as indicated by the first attached image from Shakun et al, 2012).  While it might be reasonable to use an ECS value for a RCP projections through 2050, there is no rational/scientific reason for using an ECS value for a RCP 8.5 projection after 2050 other than the value judgment of desiring to err on the side of least drama, as using a ESS value would just as likely to be correct as using a ECS value for a RCP 8.5 analysis between 2050 and 2100. The second attached image (from Hansen & Sato, 2011), clearly shows that during the warming phase of the Eemian the ESS was essentially linear beyond our current GHG levels, indicating that climate sensitivity should (as a first approximation) converge towards this approximately 7.8 degrees C (plus or minus, see the third attached image and the following extract from Pagani et al 2009 for the early and middle Pliocene, as an example of other ESS values that we might be converging towards) by the end of this century following RCP 8.5, as all of the slower feedback factors are engages including: (a) ocean venting of CO₂, (b) reduction of Arctic Sea Ice Extent and NH snow cover; (c) loss of NH albedo due to shrub growth; (d) decomposition of the permafrost; (e) degradation of the tropical and boreal forests (due to drought, fires, and attack by pests); (f) potential partial collapse of the WAIS, (g) reduction of Greenland albedo; (h) acidification of the oceans (and associated reduction of plankton); (i) slow-down of the AABW (Antarctic Bottom Water); (j) heat stress to plants; etc.  There is no rational reason for calibrating GCMs to the ECS for RCP 8.5 after 2050, rather than calibrating to the ESS, which is clearly the condition that our current non-stationary world is converging to as we continue to follow the BAU.


Mark Pagani, Zhonghui Liu, Jonathan LaRiviere, Ana Christina Ravelo (2009), "High Earth-System Climate Sensitivity determined from Pliocene CO2 Concentrations", Nature geoscience, doi:10.1038/NGEO724

http://people.earth.yale.edu/sites/default/files/files/Pagani/1_2009%20Pagani_NatureGeosci.pdf

Extract from Pagani et al 2009: "Data and modelling for the middle Pliocene (~3–3.3 Myr) indicate that the global mean temperature was 2.4–2.9 "C warmer than preindustrial conditions, and ~4 "C warmer during the early Pliocene (!4–4.2 Myr; ref. 5). If changes in carbon dioxide and associated feedbacks were the primary agents forcing climate over these timescales, and estimates of global temperatures are correct, then our results imply a very high Earth-system climate sensitivity for the middle (3.3 Myr) to early (4.2 Myr) Pliocene ranging between 7.1 ± 1.0 "C and 8.7 ± 1.3 "C per CO2 doubling, and 9.6±1.4 "C per CO2 doubling, respectively."

Caption for the third attached image : "Estimated CO2 trends considering probable oceanographic changes at each site. Each line represents a modified CO2slope for each site and the dashed green line (1012(alt)) represents an alternative nutrient scenario for Site 1012 (Supplementary Information). Vertical grey lines intersect CO2 concentrations at 3.0–3.3 and 4.0–4.2 Myr, the time intervals representing the Earth-system climate sensitivity estimates presented in the text."
From Shindell:

Recent analyses have suggested that transient climate sensitivity is at the low end of the present model range taking into account the reduced warming rates during the past 10–15 years during which forcing has increased markedly. In contrast, comparisons of modelled feedback processes with observations indicate that the most realistic models have higher sensitivities

Models that more accurately match recent temperature history have lower climate sensitivities.  Those that more accurately match observed cloud behaviour have higher climate sensitivities.  Those in denial like to claim that the studies based on recent temperature history are the best and all the rest are rubbish.  Seems like you are doing the same thing, but in reverse.   On estimating climate sensitivity from paleo data there are many studies that do so, and it looks like you've found one that is higher than just about any other study I"ve seen before.

Some more good reasing at Skeptical Science

Climate change:  Prepare for the worst, hope for the best, expect the middle.

jai mitchell

  • ASIF Upper Class
  • Posts: 1762
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #35 on: October 17, 2014, 07:09:42 AM »
from the skeptical science link provided:  http://www.skepticalscience.com/hansen-and-sato-2012-climate-sensitivity.html#81961

On p.14 HS12 says:
 "[T]he mean sensitivity over the entire range from the Holocene to a climate just warm enough to lose the Antarctic ice sheet is almost 6°C for doubled CO2, but most of the surface albedo feedback in that range is caused by loss of the Antarctic ice sheet [...] [T]he sensitivity is smaller as climate warms from the Holocene toward a Pliocene-like climate. Thus the estimate of Lunt et al. (2010), that slow feedbacks (reduced ice and increased vegetation cover) increase the sensitivity by a factor of 1.3-1.5 is not inconsistent with the Hansen et al. (2008) estimated sensitivity."

 On p.15 they say:
 "If non-CO2 trace gases are counted as a fast feedback, the fast-feedback sensitivity becomes 4°C for doubled CO2, and the Earth system sensitivity becomes 8°C for doubled CO2 with the surface albedo feedback included [...] These sensitivities apply for today's initial climate state and negative climate forcings; they are reduced for positive forcings [...]

 The ultimate Earth system sensitivity includes all fast and slow feedbacks, i.e., surface feedbacks and all GHG feedbacks including CO2. Apparently Sff+sf is remarkably large in the Pleistocene for a negative forcing. No doubt that accounts for the substantial cooling of Earth in the past few million years in response to only small changes of CO2., as well as the increasingly violent glacial-to-interglacial oscillations of the late Pleistocene (Fig. 4).
 The Earth system sensitivity relevant to humanity now is the sensitivity of the present climate state to a positive (warming) forcing. That sensitivity is not as great as for a negative forcing, but it is much larger than the 3°C fast-feedback climate sensitivity."

 So do I understand correctly (from these quotes and their figure 7) that H&S think ESS for doubled CO2 over the past million years was more than 8 deg C and more than 6 deg for the current climate until all the ice has melted, after which it is reduced to somewhere between 4.5 and around 5 deg and rising again for even warmer climates?
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #36 on: October 17, 2014, 11:06:09 AM »
From the text of the H&S paper, H&S certainly believe that full ESS sensitivity is 8 degrees for a doubling in ice age conditions.  Note that this figure involves slow feedbacks, so will take much longer than 100 years to achieve.  It also includes feedbacks due to non-co2 GHGs, so this figure should be used with a co2 only value for forcing, and not co2-equivelant including methane etc as these gases are too short lived to be relevant to long term feedbacks.

Also from the paper Hansen believes that the fast feedback climate sensitivity is most like 3, probably less than 3.5 and 95% confident less than 4 degrees.  How fast is fast feedback?  I'm not sure, but he contrasts this with the slow feedback where millenia time frames are discussed.  A 4.5 degree or greater climate sensitivity is simply not relevant to temperature projections over the next century or three.

One thing I hadn't thought about until having a look at this paper is the importance of the ice sheet albedo feedback to slow feedback climate sensitivity figures.  This has implications for recent studies suggesting that Greenland and West Antarctica are more vulnerable to collapse than previously thought.  If these ice sheets are doomed to collapse (which I believe they are, but over a centuries long time period) then we have also locked in a substantial albedo feedback amount as a result.  The one possible comforting factor is that surely the albedo feedback will have more impact on temperatures in the colder parts of the planet, and less relevant to the hotter parts of the globe.  A 5 degree warming becomes immensely scary due to the potential increase of wet bulb temperatures above the values that human beings can survive without access to air conditioning (i.e no amount of shade/ventillation or evaporative cooling will keep humans alive above a wet bulb of 35.  Current highest wet bulb temperatures are just above 30)
Climate change:  Prepare for the worst, hope for the best, expect the middle.

wili

  • ASIF Upper Class
  • Posts: 2039
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #37 on: October 17, 2014, 11:58:50 AM »
Thanks to all for an interesting discussion.

MH, that's just the problem though--some 'slow feedbacks' seem to be not quite as slow as people thought.

Carbon feedbacks are probably the most important of the slow feedbacks, and they seem to be kicking in already, at least for terrestrial permafrost and probably seabed methane hydrates (a topic of much recent discussion/debate).

I don't get as much comfort as you seem to from the fact that albedo shift in the Arctic will ensure that warming happens there faster than elsewhere, since the major potential carbon feedbacks are located there.

Here's one that I hadn't thought of till chris posted it just now at RealClimate:

From a recent ClimateState interview with Bill McGuire:

"Methane hydrate destabilisation is clearly a real worry, particularly in the context of warming ocean waters in the East Siberian Continental Shelf. It is also a concern around Greenland, where uplift as the ice continues to melt seems likely to raise submarine deposits around the margins more rapidly than sea level increases, thus having the potential to cause destabilisation of methane hydrates contained therein as a consequence of reduced pressures."

http://climatestate.com/2014/10/16/methane-hydrate-destabilisation-is-clearly-a-real-worry-particularly-in-the-context-of-warming-ocean-waters-in-the-east-siberian-continental-shelf/

( RC #104 http://www.realclimate.org/?comments_popup=17588 )

The loss of gravity around GIS as it melts will also mean that local sea level will actually decrease more rapidly than in most other places on the globe. We will certainly see enough GIS melt for these effects to kick in within the coming decades--we won't have to wait centuries to millennia for them.

Good point about wet bulb temperatures, though. Remember that global averages hide big differences. Temperature increases over pretty much all land surfaces will be higher than over most of the oceans. And over some land surfaces it will be significantly higher. 
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #38 on: October 17, 2014, 05:01:35 PM »

extract: "In 2011, a group of 41 Arctic researchers projected that Arctic carbon release would equal ten percent of the total human emission if rapid reduction of carbon emissions was undertaken as soon as possible. Under business as usual carbon emissions through 2100, the researchers suggested that the Arctic feedback would amplify to a size equaling 35% or more of the human emission. Enough to set off a runaway to a hothouse state even if all human emissions were to cease."

Best,
ASLR

The study Robert links to states 60b tonnes in 2040 and 380b tonnes of Co2 equivleant emissions by 2100 from the Arctic.  320m/60 is just over 5billion tonnes.  That is around 15% of current (2012) emissions of Co2 alone (and not Co2 equivelant) and a much lower proportion of what human emissions would be in 2100 under the imaginary 8.5 scenario.

First, you are averaging emissions between 2040 and 2100, rather than referring to 2100 emission value.
Second, you neglect that 2% of the emissions are in the form of methane which has a 100-year GWP of 35 so your numbers contain a 2% x 35 = 70% error (on the low side).

Thus the authors of the paper that Robert Scribbler cites are correct.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #39 on: October 17, 2014, 08:42:22 PM »

Here's one that I hadn't thought of till chris posted it just now at RealClimate:

From a recent ClimateState interview with Bill McGuire:

"Methane hydrate destabilisation is clearly a real worry, particularly in the context of warming ocean waters in the East Siberian Continental Shelf. It is also a concern around Greenland, where uplift as the ice continues to melt seems likely to raise submarine deposits around the margins more rapidly than sea level increases, thus having the potential to cause destabilisation of methane hydrates contained therein as a consequence of reduced pressures."

http://climatestate.com/2014/10/16/methane-hydrate-destabilisation-is-clearly-a-real-worry-particularly-in-the-context-of-warming-ocean-waters-in-the-east-siberian-continental-shelf/

( RC #104 http://www.realclimate.org/?comments_popup=17588 )

The loss of gravity around GIS as it melts will also mean that local sea level will actually decrease more rapidly than in most other places on the globe. We will certainly see enough GIS melt for these effects to kick in within the coming decades--we won't have to wait centuries to millennia for them.


wili,

As I have more things to comment on than I have time to comment; I will limit myself to post about Chris Machens' interview with Bill McGuire, in order to point-out that McGuire's responses (while very good for the Northern Hemisphere) totally ignore the more pressing risks and consequences of the pending collapse of the West Antarctic Ice Sheet, WAIS (which I have discussed much more extensively in the Antarctic Folder).
First, I would like to point-out that the National Research Council (of the National Academy of Sciences) has stated that a partial collapse of the WAIS is plausible, can could be initiated in as little as the next few years to the next few decades, and that the US military is currently preparing response plans for just such a possible occurrence (thus the WAIS collapse is a larger risk that SLR contribution from the GIS).
Second, the following UCSC link (and associate extract), shows that the methane hydrate risk from a possible collapse of the WAIS would be high because: (a) the sea bed could rebound over 100-meters, (b) the weight of the marine glacier on the sea bed would be relieved rapidly with a collapse that would relieve the pressure on the hydrates in the sea bed, (c) the Byrd Subglacial Basin is tectonically active (both seismically and volcanically); (d) a subsea landside could release large amounts of methane gas and methane hydrates, in a short period of time which would ensure that a large amount of the methane would reach the surface; and (e) such a collapse of the WAIS would change ocean currents that would redirect ocean heat content into the hydrate zones (as well as to the ice grounding line area).


http://news.ucsc.edu/2012/08/antarctic-methane.html

extract: "The science team estimated that 50 percent of the West Antarctic Ice Sheet (1 million square kilometers) and 25 percent of the East Antarctic Ice Sheet (2.5 million square kilometers) overlies pre-glacial sedimentary basins containing about 21,000 billion metric tons of organic carbon.

They also calculated that the potential amount of methane hydrate and free methane gas beneath the Antarctic Ice Sheet could be up to 4 billion metric tons, a similar order of magnitude to some estimates made for Arctic permafrost. The predicted shallow depth of these potential reserves also makes them more susceptible to climate forcing than other methane hydrate reserves on Earth.
Coauthor Sandra Arndt, a NERC fellow at the University of Bristol, who conducted the numerical modeling, said, "It's not surprising that you might expect to find significant amounts of methane hydrate trapped beneath the ice sheet. Just like in sub-seafloor sediments, it is cold and pressures are high, which are important conditions for methane hydrate formation."
If substantial methane hydrate and gas are present beneath the Antarctic Ice Sheet, methane release during episodes of ice-sheet collapse could act as a positive feedback on global climate change during past and future ice-sheet retreat."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #40 on: October 17, 2014, 10:04:55 PM »
Here is a follow-on to my last post Reply #39:

The linked (open access) reference indicates that changes in North Atlantic ocean current flow patterns led to abrupt changes in climate (Dansgaard-Oeschger [DO] events) during the last ice age.

Mohamed M. Ezat, Tine L. Rasmussen and Jeroen Groeneveld, (2014) "Persistent intermediate water warming during cold stadials in the southeastern Nordic seas during the past 65 k.y", Geology, v. 42 no. 8 p. 663-666, doi: 10.1130/G35579.1

http://geology.geoscienceworld.org/content/42/8/663.full?ijkey=h3AuZZV5q9nwk&keytype=ref&siteid=gsgeology

http://geology.geoscienceworld.org/content/42/8/663.full.pdf+html

Abstract: "In the Nordic seas, conversion of inflowing warm Atlantic surface water to deep cold water through convection is closely linked with climate. During the last glacial period, climate underwent rapid millennial-scale variability known as Dansgaard-Oeschger (DO) events, consisting of warm interstadials and cold stadials. Here we present the first benthic foraminiferal Mg/Ca-δ18O record from the Nordic seas in order to reconstruct the ocean circulation on DO time scales. The record confirms that convection similar to modern took place in the Nordic seas during interstadials with cold bottom water temperatures (BWTs) close to modern temperatures. The results show gradual and pronounced BWT increases of 2–5 °C during stadials, indicating a stop or near stop in convection. The BWT peaks are followed by an abrupt drop in temperature at the onset of interstadials, indicating the abrupt start of convection and renewed generation of cold deep water. The rise in BWT during stadials confirms earlier interpretations of subsurface inflow of warm Atlantic water below a halocline reaching >1.2 km water depth. The results suggest that warm Atlantic water never ceased to flow into the Nordic seas during the glacial period; inflow at the surface during the Holocene and warm interstadials changed to subsurface and intermediate inflow during cold stadials. Our results suggest that it is the vertical shifts in the position of the warm Atlantic water that cause the abrupt surface warmings."

The following extracts from the linked Reporting Climate Science write-up about the Ezat et al (2014) reference, indicate that researchers are concerned that such changes in ocean current circulation patterns might affect Greenland in the future, but more importantly Antarctica.  Regarding the risk of ocean current pattern changes should the West Antarctic Ice Sheet, WAIS, collapse, the first attached image from Vaughan et al (2011) shows several different ocean current circulation pathways from the Weddell, Bellingshausen, Amundsen and Ross, Seas should the WAIS collapse; while the second attached image shows the BedMap2 topology of West Antarctica, indicating how the collapse of the WAIS would marked change the ocean patterns in this area:

http://www.reportingclimatescience.com/news-stories/article/gulf-stream-did-not-stop-in-last-ice-age.html

Extract: "Understanding what happened with our ocean systems during the Ice Age, helps us understand what may happen to them if ice on Greenland and Antarctica melts in the future. Fortunately, the ice sheet over Greenland is much smaller than the ice sheet during the Ice Age and thus with less potential to seriously disturb the system.
"It is however, imperative to consider recent localized changes around Greenland and Antarctica in the light of our results. The basal melting due to subsurface warming represents an important component of the current ice mass loss," Ezat points out
Also, increase of melt water in the East Greenland Current may cause a weakening in the deep convection in the Nordic Seas. This may cause a warm subsurface inflow that may reach bottom on the East Greenland slope. Such a scenario, though very uncertain, has the potential to influence the stability of gas hydrates on the slope.
Gas hydrate is essentially frozen methane gas under the ocean floor. If it melts it has a potential to release huge amounts of this hyper potent green house gas."

edit: While the third attached image shows how low the sea level would drop around West Antarctica for a unit contribution to sea level rise from the WAIS; and I note that any such drop in local sea level around West Antarctica would contribute to destabilize the marine methane hydrates exposed by such a collapse of the WAIS.
« Last Edit: October 17, 2014, 10:20:55 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #41 on: October 17, 2014, 11:19:43 PM »
While some may think that my discussion of some of the climate sensitivity implications of the potential collapse of the WAIS as being too extreme.  I note that in a world with a mean global temperature rise of 9 degrees C, the collapse of the WAIS is inevitable either this century, or next, and regarding the plausibility of a mean global temperature rise of 9 degrees C by 2100, I provide the following points:

A.  The anthropogenic forcing for the RCP scenarios do not come from scientists, they come from economists working together with policy maker.  Thus these RCP scenarios do not follow normal rigorous scientific procedures, and thus are subject to the wishful thinking of politicians (whom the policy makers work for) who do not want to excite their constituents.

B. The IPCC AR5 projections to not use Earth System Model findings, as they felt that Earth System Models, ESMs, were to avant garde.  Therefore, while ESMs try to consider fast, intermediate and slow response feedback mechanisms (that parallel ESS values), the IPCC AR5 reports do not full capture such factors.

C. In addition to the masking factors that I mentioned previously, one very significant masking factor (or temporary negative feedback mechanism) that I have not cited in this thread yet is that as the amount of volatile organic compounds (VOCs) emitted by forests decrease (due to climate change related stress), global warming will accelerate (see the following linked references):

Mikael Ehn, Joel A. Thornton, Einhard Kleist, Mikko Sipilä, Heikki Junninen, Iida Pullinen, Monika Springer, Florian Rubach, Ralf Tillmann, Ben Lee, Felipe Lopez-Hilfiker, Stefanie Andres, Ismail-Hakki Acir, Matti Rissanen, Tuija Jokinen, Siegfried Schobesberger, Juha Kangasluoma, Jenni Kontkanen, Tuomo Nieminen, Theo Kurtén, Lasse B. Nielsen, Solvejg Jørgensen, Henrik G. Kjaergaard, Manjula Canagaratna, Miikka Dal Maso et al (2014), " A large source of low-volatility secondary organic aerosol", Nature, 506, 476–479, doi:10.1038/nature13032


http://www.nature.com/nature/journal/v506/n7489/full/nature13032.html

Also, see:
http://www.bbc.com/news/science-environment-26340038


Abstract: "Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component of atmospheric aerosol, which is known to affect the Earth’s radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere–aerosol–climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally."

Also, see the link to the following related reference (and associated extract):

Paasonen, P., et. al. (2013), "Evidence for negative climate feedback: warming increases aerosol number concentrations,", Nature Geoscience, 6, Pages: 438–442, doi: 10.1038/NGEO1800


http://www.nature.com/ngeo/journal/v6/n6/full/ngeo1800.html


Extract: "The effect of enhanced plant gas emissions on climate is small on a global scale – only countering approximately 1 percent of climate warming, the study suggested. “This does not save us from climate warming,” says Paasonen. However, he says, “Aerosol effects on climate are one of the main uncertainties in climate models. Understanding this mechanism could help us reduce those uncertainties and make the models better.”
The study also showed that the effect was much larger on a regional scale, counteracting possibly up to 30% of warming in more rural, forested areas where anthropogenic emissions of aerosols were much lower in comparison to the natural aerosols. That means that especially in places like Finland, Siberia, and Canada this feedback loop may reduce warming substantially.
The researchers collected data at 11 different sites around the world, measuring the concentrations of aerosol particles in the atmosphere, along with the concentrations of plant gases, the temperature, and reanalysis estimates for the height of the boundary layer, which turned out to be a key variable. The boundary layer refers to the layer of air closest to the Earth, in which gases and particles mix effectively. The height of that layer changes with weather. Paasonen says, “One of the reasons that this phenomenon was not discovered earlier was because these estimates for boundary layer height are very difficult to do. Only recently have the reanalysis estimates been improved to where they can be taken as representative of reality.”

However, is not pointed out in either the references that as currently estimates of "climate sensitivity" do not include this temporary negative feedback (or masking mechanism); in order for Global Circulation Models, GCM's including this negative feedback to match historical records they will need to utilize higher effective "climate sensitivity" values; which should resulting in higher projections of global temperature increase, if plant growth/activity does not keep path with the rate of future greenhouse gas, GHC, emissions.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #42 on: October 18, 2014, 01:56:49 PM »
The following linked Skeptical Science article (and associated extract) states that when Kummer & Dessler (2014) (see reference at bottom of this post) calculate that the best estimate of ECS is 3oC, they conservatively assume that climate is 33% more sensitive to changes in aerosols and ozone than greenhouse gases; however, Shindell (2014) showed that climate is more sensitive to changes in aerosols and ozone than greenhouse gases perhaps by as much as 50%.  Therefore, perhaps Kummer & Dessler are under estimating the best value of ECS by as much as 50%/33%, or by a factor of about 1.5.  If so then based on Shindell (2014) the best estimate of ECS may perhaps be 4.5 oC instead of 3oC.

https://www.skepticalscience.com/sense-and-climate-sensitivity-kummer-dessler-2014.html

Extract: "In short, Shindell showed that according to models, the climate is significantly more sensitive to changes in aerosols and ozone than greenhouse gases, perhaps by as much as 50%. Kummer & Dessler showed that if the climate is 33% more sensitive to changes in aerosols and ozone, then the 'instrumental' estimates are right in line with those derived from historical climate changes and global climate models, with a best estimate of 3°C warming in response to a doubling of atmospheric CO2."

J.R. Kummer and A.E. Dessler, (2014), "The impact of forcing efficacy on the equilibrium climate sensitivity", Geophysical Research Letters, DOI: 10.1002/2014GL06004

http://onlinelibrary.wiley.com/doi/10.1002/2014GL060046/abstract

“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #43 on: October 18, 2014, 02:04:54 PM »
To me the following linked reference, and extract, from a June 11 2014 Skeptical Science article indicates that: (a) The close match of the CESM1-CAM5 Large Ensemble Community Project, LE, mean global surface warming rates (in degrees C per decade) to the observed NOAA record indicates that the 4.1 degrees C ECS value used by the LE ensemble is a very likely value, and that ESS values this century could exceed this value; and (b) finds that"… a relatively unchanged planetary imbalance during the recent hiatus period is entirely consistent with analogous periods in LE simulations."

http://www.skepticalscience.com/challenges-constraining-climate-sensitivity.html

Caption: "Fig. 2: The range of decadal trends in global mean surface temperature from the CESM1-CAM5 Large Ensemble Community Project (LE, black and grey lines, 18) along with an observed estimate based on the NOAA-NCDC Merged Land and Ocean Surface Temperature dataset. Also shown are the mean (circle) and range (lines) of simulated planetary imbalance (right axis) from 2000 through 2010 for the 10 members of the LE with greatest cooling (blue) and warming (red)."
 
Extract: "The NCAR CESM1-CAM5 Large Ensemble Community Project provides a unique framework for understanding the role of internal variability in obscuring forced changes. It currently consists of 28 ensemble members in simulations of the historical record (1920-2005) and future projections (2006-2080) based on RCP8.5 forcing.
At 4.1 C, the ECS of the CESM1-CAM5 is higher than for most GCMs. Nonetheless, decadal trends from the model track quite closely with those derived from NOAA-NCDC observations (red line), with the model mean decadal trend (thick black line) skirting above and below observed trends about evenly since 1920. In several instances, decadal trends in observations have been at or beyond the LE ensemble range including intervals of exceptional observed warming (1945, 1960, 1980) and cooling (1948, 2009). The extent to which these frequent departures from the LE reflect errors in observations, insufficient ensemble size, or biases in model internal variability remains unknown. Nonetheless, there is no clear evidence of the model sensitivity being systematically biased high. Also noteworthy is the fact that the LE suggests that due to forcing, as indicated by the ensemble mean, certain decades including the 2000s are predisposed to a reduced rate of surface warming.

The LE also allows for the evaluation of subsets of ensemble members, such as in Fig 2, where the planetary imbalances for the 10 ensemble members with the greatest global surface warming (red) and cooling (blue) trends from 2000-2010 are compared. It is found that no significant difference exists between the two distributions and the mean imbalance for the cooling members is actually greater than for the warming members. Thus the finding of a relatively unchanged planetary imbalance during the recent hiatus period is entirely consistent with analogous periods in LE simulations. While the LE does suggest that recent trends have been exceptional, this is also suggested by the instrumental record itself, which includes exceptional El Niño (1997-98) and La Niña events (2010-2012) at the bounds of the recent hiatus."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Laurent

  • ASIF Governor
  • Posts: 2525
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #44 on: October 18, 2014, 04:49:18 PM »
Hello Abrupslr,
There is something I don't understand, when you say doubling of CO2, is it from 0 to preindustrial ? or from the last glacial era to the preindustrial ? Do you include CO2 eq or not ?

Thanks to light my lamp.

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #45 on: October 18, 2014, 05:35:22 PM »
Laurent,

Global (General) Circulation Models, GCMs, and Earth System Models, ESMs, do not use equilibrium (or Charney) climate sensitivity (ECS), transient climate response (TCR), or Earth system sensitivity (ESS); instead, they are calibrated to match various forcing history, climate state, GHG absorption, feedback & interaction mechanisms, etc.  Thus ECS, TCR, and ESS are just short-hand for discussion of how sensitivity the climate is to forcing, over different time spans. 

From Wikipedia:
"The equilibrium climate sensitivity (ECS) refers to the equilibrium change in global mean near-surface air temperature that would result from a sustained doubling of the atmospheric (equivalent) carbon dioxide concentration (ΔTx2).

A model estimate of equilibrium sensitivity thus requires a very long model integration; fully equilibrating ocean temperatures requires integrations of thousands of model years. A measure requiring shorter integrations is the transient climate response (TCR) which is defined as the average temperature response over a twenty-year period centered at CO2 doubling in a transient simulation with CO2 increasing at 1% per year.  The transient response is lower than the equilibrium sensitivity, due to the "inertia" of ocean heat uptake.

A less commonly used concept, the Earth system sensitivity (ESS), can be defined which includes the effects of slower feedbacks, such as the albedo change from melting the large ice sheets that covered much of the northern hemisphere during the last glacial maximum. These extra feedbacks make the ESS larger than the ECS — possibly twice as large — but also mean that it may well not apply to current conditions."

Thus to answer your question ECS relates to the temperature increase from any point in time, due to a doubling of CO₂ equivalent only considering fast feedback factors, until temperature stops increasing (which could be more than 1,000 years).  However, I believe that ESS is the more important gauge of climate change; however, the fundamental problem is that no one knows, or can prove what TCR, ECS, or ESS were in the past, are now, and will be in the future, as these rule-of-thumb values are composite indices of multiple different factors that change with time, conditions, starting point and ending point.  Fundamentally, climate forecasting is so complex that we are dependent on GCMs to project the future, but all GCM projections are wrong; and some of these projections are more useful than others.  What is important is to understand what the uncertainties, and risks, are and then make a decision as no model is ever 100% correct.

Best,
ASLR
« Last Edit: October 18, 2014, 05:42:05 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #46 on: October 18, 2014, 06:06:09 PM »
The following linked Skeptical Science article (and associated extract) states that when Kummer & Dessler (2014) (see reference at bottom of this post) calculate that the best estimate of ECS is 3oC, they conservatively assume that climate is 33% more sensitive to changes in aerosols and ozone than greenhouse gases; however, Shindell (2014) showed that climate is more sensitive to changes in aerosols and ozone than greenhouse gases perhaps by as much as 50%.  Therefore, perhaps Kummer & Dessler are under estimating the best value of ECS by as much as 50%/33%, or by a factor of about 1.5.  If so then based on Shindell (2014) the best estimate of ECS may perhaps be 4.5 oC instead of 3oC.

https://www.skepticalscience.com/sense-and-climate-sensitivity-kummer-dessler-2014.html

Extract: "In short, Shindell showed that according to models, the climate is significantly more sensitive to changes in aerosols and ozone than greenhouse gases, perhaps by as much as 50%. Kummer & Dessler showed that if the climate is 33% more sensitive to changes in aerosols and ozone, then the 'instrumental' estimates are right in line with those derived from historical climate changes and global climate models, with a best estimate of 3°C warming in response to a doubling of atmospheric CO2."

J.R. Kummer and A.E. Dessler, (2014), "The impact of forcing efficacy on the equilibrium climate sensitivity", Geophysical Research Letters, DOI: 10.1002/2014GL06004

http://onlinelibrary.wiley.com/doi/10.1002/2014GL060046/abstract

While there are a lot of different factors that influence climate sensitivity (see the "Selected Forcing Factors .." thread in the Antarctic folder); I provide the following discussion related to aerosol masking as I have pointed out that Shindell (2014) indicates that aerosols and ozone mask the effective transient climate response, TCR.  However, there is currently still a relatively high degree of uncertainty above about the effectiveness of aerosols, thus when Shindell (2014) was published in March of 2014 he assigned a high degree of uncertainty on the influence of aerosols; which, resulted in him citing that TCR values below 1.3 degrees C (roughly 2 to 2.5 degrees C for a comparable value of ECS) are unlike.  However since March 2014 published findings (such as the two studies discussed below), have indicated that aerosols (and ozone not discussed below) are more effective at masking TCR than previously understood.  Such findings could lead to an increase in the projected global warming as China (and others) begin(s) to clean-up its (their) air pollution.

The first linked reference found that aerosol-cloud associated changes in the amount of the clouds and changes of their internal properties are both equally important in their contribution to cooling our planet. Moreover, they found that the total impact from the influence of aerosols on this type of cloud is almost double that estimated in the latest report of the United Nations Intergovernmental Panel on Climate Change. 

Yi-Chun Chen, Matthew W. Christensen, Graeme L. Stephens & John H. Seinfeld, (2014), "Satellite-based estimate of global aerosol–cloud radiative forcing by marine warm clouds", Nature Geoscience, doi:10.1038/ngeo2214

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2214.html

Abstract: "Changes in aerosol concentrations affect cloud albedo and Earth’s radiative balance. Aerosol radiative forcing from pre-industrial time to the present due to the effect of atmospheric aerosol levels on the micro- and macrophysics of clouds bears the largest uncertainty among external influences on climate change. Of all cloud forms, low-level marine clouds exert the largest impact on the planet’s albedo. For example, a 6% increase in the albedo of global marine stratiform clouds could offset the warming that would result from a doubling of atmospheric CO2 concentrations. Marine warm cloud properties are thought to depend on aerosol levels and large-scale dynamic or thermodynamic states. Here we present a comprehensive analysis of multiple measurements from the A-Train constellation of Earth-observing satellites, to quantify the radiative forcing exerted by aerosols interacting with marine clouds. Specifically, we analyse observations of co-located aerosols and clouds over the world’s oceans for the period August 2006–April 2011, comprising over 7.3 million CloudSat single-layer marine warm cloud pixels. We find that thermodynamic conditions—that is, tropospheric stability and humidity in the free troposphere—and the state of precipitation act together to govern the cloud liquid water responses to the presence of aerosols and the strength of aerosol–cloud radiative forcing."

Furthermore, the second linked reference discusses key attributes of “brown carbon” from wildfires, airborne atmospheric particles that may have influenced current climate, while models have failed to take the material’s warming effects into account.

Rawad Saleh, Ellis S. Robinson, Daniel S. Tkacik, Adam T. Ahern, Shang Liu, Allison C. Aiken, Ryan C. Sullivan, Albert A. Presto, Manvendra K. Dubey, Robert J. Yokelson, Neil M. Donahue & Allen L. Robinson, (2014), "Brownness of organics in aerosols from biomass burning linked to their black carbon content", Nature Geoscience, doi:10.1038/ngeo2220


http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2220.html


Abstract: "Atmospheric particulate matter plays an important role in the Earth’s radiative balance. Over the past two decades, it has been established that a portion of particulate matter, black carbon, absorbs significant amounts of light and exerts a warming effect rivalling that of anthropogenic carbon dioxide. Most climate models treat black carbon as the sole light-absorbing carbonaceous particulate. However, some organic aerosols, dubbed brown carbon and mainly associated with biomass burning emissions, also absorbs light. Unlike black carbon, whose light absorption properties are well understood, brown carbon comprises a wide range of poorly characterized compounds that exhibit highly variable absorptivities, with reported values spanning two orders of magnitude. Here we present smog chamber experiments to characterize the effective absorptivity of organic aerosol from biomass burning under a range of conditions. We show that brown carbon in emissions from biomass burning is associated mostly with organic compounds of extremely low volatility. In addition, we find that the effective absorptivity of organic aerosol in biomass burning emissions can be parameterized as a function of the ratio of black carbon to organic aerosol, indicating that aerosol absorptivity depends largely on burn conditions, not fuel type. We conclude that brown carbon from biomass burning can be an important factor in aerosol radiative forcing."
« Last Edit: October 18, 2014, 07:32:50 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 13296
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #47 on: October 18, 2014, 08:00:59 PM »
Hello Abrupslr,
There is something I don't understand, when you say doubling of CO2, is it from 0 to preindustrial ? or from the last glacial era to the preindustrial ? Do you include CO2 eq or not ?

Thanks to light my lamp.

My Reply #45 to Laurent focused on ECS, TCR and ESS, and there I said that these factors should be applied to CO2 equivalent.  However, I did not get into to any of the nuances of how CO2 equiv. is calculated; or how though time (ie new findings) the means for calculating effective ECS, TCR, ESS and CO2 equiv. have changed.

The first attached image shows the IPCC (2001) expressions used by NOAA to calculate the Annual Greenhouse Gas Index (AGGI), shown in the second attached image for 2013 (see the website link and the caption for this figure below); which is effectively the commonly reported CO2 equiv. for the indicated GHGs.  However, I note that such a value does not include such masking factors (eg temporay negative feedback factors) as aerosols that must be included to determine total radiative forcing; nor do these two images consider the impact of recent (since 2001) research that can change the constants used in the expressions of the first image, due to such considerations as the distribution of the aerosols and chemical reactions in the atmosphere between the GHGs and radials (which influence the life of the GHG component in the atmosphere)


http://www.esrl.noaa.gov/gmd/aggi/aggi.html

Caption for the second attached image: "Radiative forcing, relative to 1750, of all the long-lived greenhouse gases. The NOAA Annual Greenhouse Gas Index (AGGI), which is indexed to 1 for the year 1990, is shown on the right axis."

Some key points that I would like to make (in this post) on this matter are:
1. As the expression for change in radiative forcing for CO2 is measured in ppm while the expression for the change in radiative forcing for CH4 is measured in ppb; as relatively small change in CH4 has a larger influence on radiative forcing (as compared to that for CO2).  This implies that it is an excellent idea to reduce CH4 emission into the atmosphere immediately, and a bad idea to promote CH4 emissions (such as from: shale-gas developments, tropical rainforest degradation, permafrost degradation, marine hydrate degradation, and emissions from lakes).
2. As radials (such as OH) get consumed the longevity of CH4 in the atmosphere increases, so we need to consider the influence of atmospheric chemistry.
3. We need to quickly get better control of Black Carbon in the atmosphere.
4. Obviously CO2 is still the biggest contributor to changes in radiative forcing, so carbon pricing should be imposed as quickly a practicable.
5. The expressions giving in the first image are non-linear.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Laurent

  • ASIF Governor
  • Posts: 2525
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #48 on: October 18, 2014, 08:24:01 PM »
I am not seeing water vapor, I think it is also one of the main green house gazes ?! Generaly it is not considered because the molecules do not stay long in the atmosphere. If so then it is like the methane considering a 100 year range is purely statistical, if the water vapor is replaced like methane, the immediate effect has to be considered ?!

Michael Hauber

  • ASIF Middle Class
  • Posts: 664
    • View Profile
Re: IPCC possible scenario: 9 C over next century or so
« Reply #49 on: October 18, 2014, 09:38:00 PM »

First, you are averaging emissions between 2040 and 2100, rather than referring to 2100 emission value.
Second, you neglect that 2% of the emissions are in the form of methane which has a 100-year GWP of 35 so your numbers contain a 2% x 35 = 70% error (on the low side).

Thus the authors of the paper that Robert Scribbler cites are correct.

Co2 equivelant means the methane is already taken into account.  Remember I calculated it as 15%  of 2012 Co2, so if I calculated as percent of 2100 human emissions under RCP8.5, and was able to consider that the 2040-2100 Arctic rate would be higher in 2100 than the average - I'm sure the figure would be lower still. 

I do not disagree with what the authors of the paper Robert cites.  Nowhere do they say 35%.  If I calculate on the figures the authors provide it is nowhere near 35%.
Climate change:  Prepare for the worst, hope for the best, expect the middle.