According to a recent report from the International Energy Agency (IEA), world CO2 emissions hit an all-time high last year at 31.6 gigatons. This means that only a 532 gigaton cushion now remains between pushing the world above the dangerous 2 degree Celsius Equilibrium Climate Sensitivity threshold. At the current rate of emissions, we will run headlong into this threshold within a little more than 16 years. So before 2029, without major changes in the world’s energy structure, a civilization-endangering global warming of at least 2 degrees Celsius will be locked in.
In order to attempt to buy time to respond to this growing crisis, the International Energy Agency has published a policy paper containing recommendations for a path forward that is less damaging than the current one. The agency paper noted that the current emission path brings us to 3.6 to 5.3 degrees warming by the end of this century under Equilibrium Climate Sensitivity (Which measures about half of long-term warming). This pace of emissions is well above that needed to reach the safer goal of 2 degrees Celsius equilibrium warming or less by the end of this century. A level that climate scientists say human civilizations are better able to adapt to.
Pace of Emissions Increase Slowed
Pace of emissions increase did, however, back off from 2011’s rapid growth, slowing to 1.4 percent. IEA noted that US switching from coal to natural gas and a Chinese energy policy that included greater focus on renewables were major contributors to this slower pace of emissions growth. US emissions fell by a total of 200 megatons, reaching a level last seen in the 1990s. Europe also saw significant reductions — cutting emissions by 50 megatons. Unfortunately, despite a stronger renewables policy, the Chinese still emitted 300 megatons more carbon than in the previous year, while Japanese carbon emissions also advanced by a total of 70 megatons. The loss of ground in Japan was primarily due to its switching away from nuclear power as a primary energy source and returning to more traditional fossil fuels — natural gas and coal.
The hiatus in US carbon emissions may also be somewhat temporary. Natural gas prices are rising and, traditionally, this has resulted in a whip-lash effect driving utilities back to coal generation. It is worth noting, however, that wind energy is now competitive with coal power, while long-term coal prices are increasing. Solar energy prices are also falling rapidly. So let us hope that the natural gas whip-lash effect is somewhat muted by more adoption of renewable energy sources.
IEA Policy Recommendations Both Modest and Ambitious
Despite a greater overall adoption of renewables and lower carbon energy sources, CO2 dumping into the atmosphere is still tracking along the worst case scenario for climate change projected by the IPCC. In order to meet this challenge of rising emissions, IEA urges a number of policy changes to be put in place immediately.
These policies include:
- A partial phase-out of fossil fuel subsidies
- Limiting construction of the least efficient coal-fired power plants
- Increasing renewable energy’s percentage of total energy generation from 20% to 27%
- Targeting energy efficiency measures for new buildings
- Reduce methane releases from oil and gas industry activities by half
The IEA claims that these policies would reduce projected 2020 emissions by as much as 8%, preventing about 3.1 gigatons of additional carbon from entering the atmosphere. IEA Chief Economist Fatih Birol, the report’s lead author notes:
“We identify a set of proven measures that could stop the growth in global energy-related emissions by the end of this decade at no net economic cost. Rapid and widespread adoption could act as a bridge to further action, buying precious time while international climate negotiations continue.”
This IEA report can be viewed as a plea to slow the damage even as it provides a compromise plan that could be put in place. The plan is both modest and ambitious. Modest, because the initial changes are easy to incorporate into the current energy structure. Ambitious because long-term goals involve a phase-out of the use of fossil fuel assets.
This call for comprehensive policy-based fossil fuel stranding and phase-out is the first of its kind from a major world policy body. In total, about 5-6 percent of undeveloped oil and gas reserves are projected not to be used. Also implicit in the the report is a stranding of a large portion of the world’s coal reserves as a larger transition to renewable energy is constructed through 2035. The IEA recommends that oil, gas and coal companies can shift to carbon capture and storage if they wish to protect their assets.
In the end, though, the numbers provided by the IEA will require more clarity in order to add up. More than 2,800 gigatons of fossil fuel are on the books of the world’s fossil fuel companies and none of those assets are yet slated to be captured in order to prevent atmospheric release. Even worse, millions of tons of carbon are released into the atmosphere every year via the process of oil and natural gas extraction. These emissions are not listed as assets, but they still end up in the atmosphere. Cutting them in half, as the IEA recommends, will still leave half of this addition active.
Costs of Damage to Leap Higher If Action is Delayed Until 2020
The IEA’s recommended plan would, at best, keep world carbon emissions about stable through 2020. The result would be that 256 gigatons of carbon will be emitted by 2020 through fossil fuel burning, putting us about half-way on the path to 2 degrees Celsius (equilibrium warming) by that time. Such a plan would leave the world with only about 276 gigatons of carbon wiggle room, requiring a very rapid draw-down of carbon emissions post 2020.
That said, starting implementation now would reduce the costs of a long-term transition away from fossil fuels by $3.5 trillion dollars, according to IEA estimates. So beginning changes now would lay the ground-work for a smoother, more rapid transition post 2020. Also, failure to implement these policies through 2020 puts the world on a path for 2 degree Celsius warming to be locked in sometime around 2025. So it is doubtful the goal of preventing a 2 degree Celsius warming (equilibrium) could be achieved without taking on the modest policy changes recommended by the IEA now.
For these reasons, the IEA plan should be both applauded and looked at with caution. Applauded, because it begins to put in place the necessary framework for long-term emissions reductions world-wide. Applauded, because it barely keeps alive the goal of meeting a less than 2 degree (equilibrium) temperature increase by the end of this century. And looked at with caution because it sails very close to a dangerous climate change wind.
For more comfort, we should ask for a more ambitious set of policies. But given a major dearth of such, the IEA measures are among the most prudent yet advanced. Not really much cause for comfort during this late hour.
Links:
Four Energy Policies to Keep the 2 Degrees Celsius Goal Alive
Delaying Action Until 2020 Costs the World 3.5 Trillion
robertscribbler 
xraymike79
/ June 11, 2013Reblogged this on Collapse of Industrial Civilization and commented:
The IEA’s “plea to slow the damage” appears to be a call for help postmortem. I would find such stories of America’s omnipotent surveillance state (http://www.guardian.co.uk/world/2013/jun/09/nsa-whistleblower-edward-snowden-why) much more disconcerting if not for the unfolding global ecocide.
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robertscribbler
/ June 11, 2013I’m hoping for action on both. The level of surveillance is excessive and results in severe moral hazard for abuse. As for the IEA’s pleas, they just show how powerful the fossil fuel interests remain. There may well be change in the wind. I just hope it’s not ‘postmortem.’
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xraymike79
/ June 11, 2013Change will come, but not so much on our terms as we delay emergency actions.
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Dan Pangburn
/ June 11, 2013Global warming ended more than a decade ago http://endofgw.blogspot.com/
Real science has discovered that natural climate change has been hiding in plain sight http://climatechange90.blogspot.com/2013/05/natural-climate-change-has-been.html
Possible changes to non condensing ghg levels in the atmosphere have no significant effect on average global temperature.
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robertscribbler
/ June 11, 2013NASA, NOAA, and the World Meteorological Organization all disagree with the above misinformation:
http://climate.nasa.gov/
http://www.ncdc.noaa.gov/cmb-faq/globalwarming.html
http://www.wmo.int/pages/about/wmo50/e/world/climate_pages/global_warming_e.html
For a comprehensive list of common climate change denial misinformation, as seen above, you can refer to the list here:
http://www.skepticalscience.com/argument.php
Dan, sorry buddy, I’m going with NASA, not Joe ‘head in the sand.’
Best
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xraymike79
/ June 11, 2013It’s becoming apparent to me that these “head in the sand” people will carry on with their peculiar and deluded views all the way through every worsening step of climate chaos to the bitter end of a global mass extinction. The only thing “natural” about what is occurring since the industrial revolution is that it follows the trajectory of so many other empires – Growth > Overshoot > Collapse, only this time it is on a planetary scale.
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robertscribbler
/ June 12, 2013I’m pretty sure they suffer from an acute form of insanity particular to us humans. One akin to hubris and generally a result of self inflicted blindness. Sadly, this brand of affliction is harmful not only to those who suffer from it, but to the rest of us as well.
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Sourabh
/ June 14, 2013Dan,
Oh Common, don’t cite blogpost article without any credible sources. You are just an astro-turffer hired by fossil/denier industry. Don’t pollute this blog with all the misinformation.
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robertscribbler
/ June 14, 2013Yes. There’s his ‘scientific evidence.’ The mighty Blogspot.
To block or not to block? That is the question.
Whether ’tis nobler to allow Dan to demonstrate his ignorance here, or to consign him to the slings and arrows of outrageous fortune?
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Sourabh
/ June 14, 2013I support freedom of speech and expression, but not lies. If you can, you should block him. Its just outrageous that these people spread lies without understanding science. I am just tired of seeing these unsupported/cherry-picking types of deniers on every blog post.
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robertscribbler
/ June 14, 2013Noted.
Sorry Dan, time to take the snake-oil elsewhere.
I’m leaving the current posts for context. But all further ones will be listed as spam.
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F.Tnioli
/ June 13, 2013xraymike79, IEA’s thing is indeed in some sense postmortem – those sad folks apparently are unable to publicly admit that 2 degree celcius warming is already guaranteed (as is 3 degree celcius warming, too) – by effects of thermal lag of the oceans and inevitable massive reduction of athmospheric aerosols (a.k.a. “global dimming”).
I’d like to point out, though, that IEA’s thing is not a call for help – merely, it’s a call for anestesia for certain groups of people, and nothing more. Climate situation cannot be helped now, because the only thing which currently (and for next ~10 years max) prevents runaway catastrophic warming – is increasing amount of particulates (aerosols) emitted by coal-burning power plants (is China still puts 2 new coal power plants every week i wonder?). Stop or massively reduce coal burning (or start to capture all that soot) – and in a few years we’ll get over 1 degree celcius additional warming, which will then be further amplified by positive feedbacks such as albedo reduction.
In other words, IEA’s plan is about eventual reduction of fossil fuel burning (coal included) down to zero or almost so? Well, then it means IEA’s plan is also about making sure we get runaway catastrophic climate change, too.
I think that at least some of IEA’s folks are very well aware that situation cannot be helped. Then, why they do the thing they did? Why publish such a plan? I think they do it to give an illusion of possibility; a hope; a goal; something to get busy with – for quite large number of companies and governments and people around the world. Majority of people now alive are doomed (to die unnatural and premature deaths) if what i know about Arctic shallow shelves, methane clathrates, ice cover retreat during Junes/Julies and insolation – is correct. If IEA also know about it, and deems facts correct, – then the only thing they can do is to forge a document which by all possible means would create an illusion that it’s not less than 2 decades left (for global technological civilization to function) – but many decades ahead at least; to create an illusion that in any case, changes will be slow and grtadual (slow in terms of human life span); to create an illusion that mankind can still control much, if not all, of warming process.
Those illusions are painkillers; painkillers for societies, so to say. Created and administered to prevent despair, to prevent radical measures (which may be up to nuclear strikes exchange – i mean, even Pakistan now can do that, eh), – but perhaps most importantly, to prevent rapid increase in competition for space and resources which are of utmost importance if some society / group / class aims to survive far into – or perhaps indeed through, – the rapid, runaway, catastrophic warming we are approaching. Such space might be highland platous, with much cleaner than low-lands’ environment (water, soil etc) and lower temperatures; such resources might be very-long-shelf-life foods (ones which remain edible after decades or even centuries), various high-quality tools and apparatuses, solidly made buildings (able to serve at least several centuries), etc. Matherials and workforce to create such and similar goods are quite limited, as is amount of already produced goods of this nature.
I deeply despise this IEA’s report emotionally… It’s betrayal of billions lives. But, again, only emotionally. Rational, logical me – applauds this report, and indeed confirms that it is what absolutely needs to be done – as long as the highest goal, the ultimate goal, the thing which we all should be most devoted to – is to do all we can to increase chances of homo sapiens survival (as a species) through incoming anthopogenic thermal maximum event of Earth.
So you see, here in comments, being noone and nobody, i can afford to explain both sides; if i’d be in public and with loud name known to many, i’d most likely stick with IEA’s – no matter how bad, how self-despising i’d feel inside.
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robertscribbler
/ June 13, 2013According to Hansen, current warming has been abated by about half due to particulates/aerosols. So we’d be at around 1.6 C warming now without them.
Long-term warming according to paleoclimate at a constant 400 ppm CO2 is about 3-4 degrees C. It’s not yet certain that the current, large and rapid forcing caused by the initial pulse of GHG’s is enough to set off a runaway or a mini runaway. But the risk, at least for a mini runaway, is currently there (and a mini runaway is a mass extinction event).
I completely agree with this sentiment about the IEA. And I honestly think the paper was an attempt to curve-ball some real policy past the usual detractors. Let’s hope it works. We could use some real policy. And the nice thing is that once the ball starts rolling and a precedent for policy is established, we can keep scaling up the response.
But yes, the IEA and other bodies tend to have understated the problem. And this is a big failure on their part, because what we need now is the sense of urgency you so well display.
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F.Tnioli
/ June 14, 2013Long-term warning according to paleoclimate at a constant 400 ppm CO2 – is NOT about 3-4 degrees C; it would be about ~12.8 degrees C, if correlation between CO2 and temperature would remain linear as it was ( http://en.wikipedia.org/wiki/File:Co2-temperature-plot.svg , just draw horizontal line from 400 ppm CO2 on the right all the way to the left, and you’ll have ~12.8 degrees C ). Of course, in reality it’ll be less, because the higher the temperature go, the higher is the difference between constantly near-absolute-zero-cold outer space and warming Earth, – the more energy is radiated out to space per square meter of Earth surface. But this negative feedback is only able to cut some 15%, perhaps 20% of temperature rise of +12C (it’s 4th power, yes, but then it’s calculated in Kelvins: 4th power of 298 divided by 4th power of 286 = 1.1787, i.e. roughly -18%). Recent direct research on subject produced +8C figure for prolonged 400 ppm of CO2: http://www.guardian.co.uk/environment/2013/may/09/meteorite-crater-global-warming . Last but definitely not least is the fact that we are not stopping at 400. I really, really doubt we’d stop at 450 ourselves, too; and then once methane clathrates start to bubble out on gigaton scale every year, it’ll add up (methane decomposes to CO2), and then forest fires, peat fires of hotter world would add more on top of all that. Count on 500 ppm CO2 long-term at VERY least; 700…1100 ppm CO2 by 2100 is in fact possible, especially if global industrial civilization would manage to function more than half of this century somehow (though i deem it very unlikely).
Hansen’s official papers are bound to “official” climate sensivity of +3 plus-minus 0.5 degrees C for doubling of CO2. Which is a major underestimation as far as i can tell. Yet, it is used by many, if not most, authors; and when one paper uses results of other papers, this underestimation can act multiple times affecting very single end result; Hansen’s papers like http://www.columbia.edu/~jeh1/mailings/2011/20110415_EnergyImbalancePaper.pdf end up saying aerosols forcing is some -1.6W/m2 as a result, which indeed would mean less than +1C extra warming once all aerosols are removed. However, if it would be true, then another thing couldn’t be true: namely, the known fact that during 3 days after 9/11, when most of US civilian jet fleet was grounded, – daily average temperatures over US jumped up by 1 degree C ( http://archives.cnn.com/2002/TECH/science/08/07/contrails.climate/ ). Note, this is without US jets ONLY – power plants kept working, cars, ships, tractors etc kept running (emitting aerosols some of which always end up high in the athmosphere), other countries kept flying jets, etc. And only after 3 days, so not all of aerosols of jet exausts yet settled. And still it ALREADY was +1C. Since i find it extremely very hard to doubt this very practical and multiple-time checked result, i end up thinking that with all due respect, Hansen’s -1.6W/m2 for aerosols forcing is massive underestimation. To Hansen’s honor, though, this figure is from his PEER-REVIEWED papers, which may mean he was forced to correct his numbers to make them look not “ridiculous” – which they might be in the eyes of those who make these models for IPCC which use even times lower figures for aerosols forcing, sometimes as low as 0.4W/m2 (which as far as i can tell is complete and utter nonsense and underestimation by an order of magnitude or close to that).
That’s how what i wrote above about magnitude of additional warming once most of man-made aerosols settle down – is true to the last number of it (of course, this is just my opinion, though with my IQ of some 150+, i dare to think it’s not the least meaningful opinion around). If you have any serious reasons to doubt any of my arguments here, then please, let me know. I’d be most happy to find out i am overestimating the magnitude of aerosols trap; it’s my own life at stake as well as most others’, you know. It’s just that i cannot see how may i be overestimating it… What i see is that even numbers given by me in above post are perhaps understatements itself – it’s just that like many good scientists, i tend to be careful, perhaps too careful, when it’s about something new and not widely accepted (yet). Anyhows, we need to know what awaits, and as usual, together we may be able to find out more than if we all would work solo.
Cheers.
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robertscribbler
/ June 14, 2013The Paleoclimate evidence is pretty simple and direct:
Range of CO2 in the mid-Pliocene:
Around 400 ppmv.
(Source: ^ Raymo, M. E.; Grant, B.; Horowitz, M.; Rau, G. H. (1996). “Mid-Pliocene warmth: Stronger greenhouse and stronger conveyor”. Marine Micropaleontology 27 (1–4): 313–326. )
Range of Global temperatures during the mid-Pliocene at 400 ppmv CO2:
3-4 degrees C hotter than the 1880s average and 2-3 degrees C hotter than today.
Source: ^ Robinson, M.; Dowsett, H. J.; Chandler, M. A. (2008). “Pliocene role in assessing future climate impacts”. Eos 89 (49): 501–502.
Now, the +8 C temperature you mention was found at a polar lake. And it is well known that polar temperatures amplify and warm at a faster rate than the global average over time.
From this recent article on the Lake El’gygytgyn study:
“The researchers lead by Julie Brigham-Grette note that for such plants to be established in this region, temperatures would have been about 8 degrees Celsius hotter than today. These temperatures are consistent with a mostly ice-free Arctic environment.
This research, along with a growing body of Paleoclimate science, indicates that climate is much more sensitive to CO2 increase than current climate models may suggest. Overall, Paleoclimate may well be a far better determiner of the end result of human fossil fuel emissions than models which seek to pin down extraordinarily complex processes and are still in the early stages of development. And if past climate indicators do prove to be the best guide, sustained CO2 levels above 400 PPM will push for a long term temperature increase of around 3-4 degrees Celsius globally and 8-10 degrees at the poles. More importantly, these high levels appear to wipe out most ice in the Arctic environment.”
So it’s pretty well established by research that Pliocene temperatures were 3-4 degrees Celsius warmer than the 1880s average and that CO2 levels were around 400 ppmv during the same time. This Paleoclimate Data leads us to believe that a constant 400 ppmv of CO2 in the atmosphere will result in a long-term warming of 3-4 degrees Celsius above 1880 temperatures.
Equilibrium climate sensitivity, established by climate models, shows a long-term warming of about half that. But as the modelers admit, they haven’t included “Slow Feedbacks” like ice sheet melt.
… Provided for your clarification.
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Dan Pangburn
/ June 14, 2013Geocraft at http://www.geocraft.com/WVFossils/Carboniferous_climate.html has a graphic that shows CO2 level and average global temperature for the last 500 million years. It shows that CO2 has been much higher than the current level for most of this time.
About 440 million years ago the planet plunged in to the Andean-Saharan ice age when the CO2 level was about ten times higher than now.
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robertscribbler
/ June 14, 2013Oh, I see Dan has found yet one more out of context cherry to pick.
500 million years ago… when the sun was much cooler.
NASA finds that CO2 is global thermostat in this study here:
http://www.nasa.gov/topics/earth/features/co2-temperature.html
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Dan Pangburn
/ June 14, 2013CO2 increase from 1800 to 2001 was 89.5 ppmv (parts per million by volume). The atmospheric carbon dioxide level has now increased since 2001 by 25.46 ppmv (an amount equal to 28.4% of the increase that took place from 1800 to 2001) (1800, 281.6 ppmv; 2001, 371.13 ppmv; May, 2013, 396.59 ppmv).
The average global temperature trend since 2001 is flat.
That is the observation. No amount of spin can rationalize that the temperature increase to 2001 was caused by a CO2 increase of 89.5 ppmv but that 25.46 ppmv additional CO2 increase had no effect on the average global temperature trend after 2001.
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robertscribbler
/ June 14, 2013Let’s see.
The last record year for global warming was 2010. Before that 2005 was the hottest year on record. Before that, 1998.
So your argument is that unless every year is the hottest, successively on record, then global warming stopped?
The decade of the 2000s was the hottest on record. In your view, this means global warming doesn’t exist?
The temperature during the 1880s was .8 degrees cooler than now. According to you, this means ‘no global warming.’
No major body of science has claimed that global warming ‘stopped’ and, therefore, ‘CO2 doesn’t warm the atmosphere.’ Yet you come out of the woodwork to provide us with an enlightenment science cannot provide?
Sorry, Dan, I’m still sticking with NASA:
http://www.nasa.gov/topics/earth/features/co2-temperature.html
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F.Tnioli
/ June 17, 2013Robert,
Ok, you have a sound point about polar amplification and that lake (although was it really polar, or subpolar)? Anyhows, that +8 they did found is indeed a subject to polar amplification significantly, that’s true. Therefore my argument about that lake dig seems to be irrelevant. However, it’s not. It’s true that +8 on that lake would correspond to something like +3…+5C global back then (probably in this range, or at least close) – the thing is, i really doubt it was exactly 400ppm at the time; it had to be much lower.
And i am not the only one to think that Pliocene could be having way lower than 400 ppm CO2 – perhaps for much of it, it was near or even below 300. See, for example, http://www.aos.princeton.edu/WWWPUBLIC/gphlder/pliopar.pdf , and in particular its very 1st reference, and also references it mentions too (5, 36, 37).
I’d also like to point out that any precise measurement of athmospheric CO2 levels in the past earlier than ~800k years ago – is, to say the least, extremely difficult, if at all possible at current level of technologies and apparatus. At least, that’s what i heard herer and there in various words; wikipedia seems to agree on that, too: http://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere#Past_variation , – i mean 5th paragraph of the “past variation” part in particular.
Cheers.
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robertscribbler
/ June 17, 2013It’s pretty well established that CO2 averaged around 400 ppmv during the middle Pliocene, the time period in which these events were recorded.
Late Pliocene falls in CO2 are also a pretty settled matter. But temperatures also began to fall at that time as glaciation settled in.
The issue is that during the middle Pliocene (when CO2 was around 400 ppmv) , temperatures were 3-4 degrees warmer than the 1880s average globally. Most proxy values in the research support this observation for this time period.
Now, this value is about double that indicated by Equilibrium Climate Sensitivity. And that, I think, should be concerning enough.
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F.Tnioli
/ June 19, 2013It is more than “concerning enough”, yes.
As for “pretty well established that CO2 averaged around 400ppmv during middle Pliocene” – i agree that it WAS pretty well established; but now, at least in my opinion, it’s not “pretty well established” anymore. Let’s take the look at the details.
The paper you give as a reference – Raymo, M. E.; Grant, B.; Horowitz, M.; Rau, G. H. (1996). “Mid-Pliocene warmth: Stronger greenhouse and stronger conveyor”. Marine Micropaleontology 27 (1–4): 313–326. – is available here: http://www.moraymo.us/1996_Raymoetal.pdf . The statement of yours which you think this paper is confirming – is this one (quoting you): “Range of CO2 in the mid-Pliocene: Around 400 ppmv. ”
This is not exactly the case.
In said paper’s abstract, we can read: “3 millions years ago … athmospheric CO2 levels … were on average only 35% higher than … 280 ppm”. 280 * 1.35 = 378ppm. In other words, not 120 ppm above 1880s, but on average (and without any mention of scale of possible error yet) only 100 ppm higher, which is substantial difference.
Furthermore, in the paper itself, we can read about:
– the empiric equation which was at the base of the research, one which was used to calculate aquatic CO2 concentration – is said to have estimation error of 65 ppm on average (p. 318);
– the possibility of contamination of samples by terrestial organic matter exists, and it is said in the paper that if 10% of organic matter is of terrestial origin, then paper’s CO2 estimates would change by 15% (p. 318);
– the possibility of isotopically selective metabolism, which could or could not be existing at the time (~3M years ago), – effects of this, if it was indeed much different from what we know today, are said to be “essentially unquantifiable” (p. 319);
– figures (graphs) 3 and 5e of the paper do NOT display possible contamination nor possible diagenesis errors as a part of presented error bar, and the reader is explicitly asked to keep both those uncertanties (the 2nd being, again, unquantifiable) in mind (p. 320);
– conclusion of the paper being that it is likely that average middle pliocene athmospheric CO2 levels were “about 380 ppm”, but right away adding that that “may be an overestimate due to diagenesis” on one hand, yet in the same time noting that even possibility of 560 ppm of athmospheric CO2 “cannot be conclusively ruled out given uncertainties in our method” (p.323).
Robert, if you think this paper, which you yourself reference as a paper which “establish” that middle pliocene was 400 ppm CO2, would convince me – well, it doesn’t. See, in simple words, it says “we guess it was ~380 ppm, but may be we are overestimating it and it was much lower, or may be we overestimate it and it was much higher”. In my book, this is NOT “establishing” at all.
My numbers in very 1st message in this topic, on the opposite, are based on quite precise measurements based on icecore data – again, http://en.wikipedia.org/wiki/File:Co2-temperature-plot.svg etc. As you can see, long-term (many thousands years), if we start at “0” degrees C and ~280 ppm CO2 and then go back in time on those graphs, then it takes only approx. -60ppm CO2 (i.e. lowering it to 220 ppm) to drop the temperature, long-term, by 5 degrees C, and it takes approx. -100ppm (i.e. lowering it to 180 ppm) to drop the temperature by ~8 degrees C. If this trend is so obviously present in recent (geologically) past (last couple hundreds thousands years), then why exactly shouldn’t we expect it to work the other way – i.e. “up” – long-term, at least for a few degrees C / several dozens more of CO2 ppm? I say we by all means should expect it to work “up” too, both in the future, and in more distant past (like Pliocene). Which means, if Pliocene had average Earth surface temperature only ~3.5 degrees C higher than 1880s, then CO2 would be some 50 ppm higher than 1880s, ONLY – i.e. 330 ppm, not 400.
And the paper which you said is a reason to believe 400 ppm is “established” CO2 concentration during Pliocene is in fact (see above) NOT ruling 330 out.
That’s how and that’s why in my message above i said: “i really doubt it was exactly 400ppm at the time; it had to be much lower”. It’s quite very easy logic as you can see, assuming i am indeed correct to trust icecore data about CO2 and temperature during past few hundred thousands years being quite precise (possible error being +-2% or less).
Thoughts?
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