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Climate Emergency: Time to Slam on the Brakes

Posted on 8 March 2011 by James Wight

Global warming is an increasingly urgent problem. The urgency isn’t obvious because a large amount of warming is being delayed. But some of the latest research says if we want to keep the Earth’s climate within the range humans have experienced, we must leave nearly all the remaining fossil fuels in the ground. If we do not act now we could push the climate beyond tipping points, where the situation spirals out of our control. How do we know this? And what should we do about it? Read on.

James Hansen, NASA’s top climatologist and one of the first to warn greenhouse warming had been detected, set out to define dangerous human interference with climate. In 2008, his team came to the startling conclusion that the current level of atmospheric carbon dioxide (CO2) is already in the danger zone.

Since the Industrial Revolution, atmospheric CO2 has increased from 280 to 390 parts per million (ppm). Don’t be fooled by the small number – 390 ppm is higher than CO2 has been in millions of years. CO2 is rising by 2 ppm per year as we continue to burn fossil fuels. To stabilise the Earth’s climate, we must reduce CO2 to the relatively safe level of 350 ppm. And we must hurry, because the task will soon be an impossible one.

The 350 target is based not on climate modeling, but on past climate change (“paleoclimate”). Hansen looked at the highly accurate ice core record of the last few hundred thousand years, sediment core data going back 65 million years, and the changes currently unfolding. He discovered that, in the long term, climate is twice as sensitive in the real world as it is in the models used by the IPCC.

The key question in climate modeling is how much global warming you get from doubling CO2, once all climate feedbacks are taken into account. A feedback is something that amplifies or cancels out the initial effect (eg. interest is a feedback on a loan). The models include “fast feedbacks” like water vapor, clouds, and sea ice, but exclude longer-term “slow feedbacks” like melting ice sheets (an icy surface reflects more heat than a dark surface).

Both models and paleoclimate studies agree the warming after fast feedbacks is around 3°C per doubling of CO2. Slow feedbacks have received far less attention. Paleoclimate is the only available tool to estimate them. To cut a long story short, Hansen found the slow ice sheet feedback doubles the warming predicted by climate models (ie. 6°C per CO2 doubling).

Long-Term Climate Sensitivity

The global climate has warmed only 0.7°C, but has not yet fully responded to our past emissions. We know this because the Earth is still gaining more heat than it is losing. There is further warming in the pipeline, and Hansen’s results imply there’s a lot more than in the models. If CO2 remains at 390 ppm long enough for the ice sheet feedback to kick in, the delayed warming would eventually reach 2°C. That would result in an Earth unlike the one on which humans evolved and a sea level rise of not one metre, not two metres, but 25 metres. Imagine waves crashing over an eight-storey building.

It’s hard to dispute this would be “dangerous” climate change. But how quickly could it happen? In the past, ice sheets took millennia to respond, though once they got moving sea level rose several metres per century. But maybe ice sheets can melt faster if CO2 rises faster, as it is now doing. The IPCC predicted they would grow by 2100, but instead they are starting to shrink “100 years ahead of schedule”. Once an ice sheet begins to collapse there is no way to stop it sliding into the ocean. We would suffer centuries of encroaching shorelines. The climate change we started would proceed out of our control.

If ice sheets can melt significantly this century, then Hansen’s long-term warming has near-term policy implications. The tragedy we have set in motion can still be prevented, if we get the Earth to stop accumulating heat before slow feedbacks can kick in. To do so we must target the greatest, fastest-growing, and longest-lived climate driver: CO2.

Under business as usual, we are heading for up to 1,000 ppm by 2100, or nearly two doublings (and that’s not including possible carbon feedbacks). This would surely be an unimaginable catastrophe on any timescale. Even the mitigation scenarios governments are quarreling over are based on IPCC assessments now several years out of date. The lowest CO2 target being considered is 450 ppm, which Hansen concluded would eventually melt all ice on the planet, raising sea level by 75 metres. The Earth has not been ice-free since around the time our distant ancestors split off from monkeys.

Instead of stepping on or easing off the accelerator, we need to be slamming on the brakes. We must not only slow the rise of CO2 in the atmosphere, but reverse it. We must reduce CO2 from 390 to 350 ppm as soon as possible. That should stop the planet’s accumulation of heat. Stabilizing the CO2 level will require rapidly reducing CO2 emissions until nature can absorb carbon faster than we emit it – in practical terms, cutting emissions to near zero.

The only realistic way of getting back to 350 ppm is leaving most of the remaining fossil fuels in the ground. We must:

1) phase out coal by 2030. It is not enough to slow down coal-burning by converting it to liquid fuels, because CO2 stays in the atmosphere for a very long time. The fundamental problem is with the coal being burned at all.

2) not burn tar sands or oil shale. Their reserves are virtually untapped but thought to contain even more carbon than coal. Canada cannot keep burning them.

3) not burn the last drops of oil and gas if their reserves are on the high side. If it turns out we have already used about half, then we can safely burn the rest.

4) turn deforestation into reforestation. We’d still be left with the gargantuan task of removing CO2 from the atmosphere. Nature can absorb some carbon, but it has limits.

CO2 Emissions and Atmospheric Concentration with Coal Phaseout by 2030

It won’t be easy, but with these actions CO2 could peak around 400 ppm as early as 2025 and return to 350 ppm by century’s end. I believe we can achieve this; it’s primarily a question of political will. But our window of opportunity is rapidly slamming shut. Even one more decade of business as usual, and CO2 can be expected to remain in the danger zone for a very long time.

I should point out estimating a CO2 target from paleoclimate is fraught with uncertainties. I’ve had to simplify for this short article. I explain in more detail on Skeptical Science, or you can read Hansen’s paper free here. If there is one lesson recent climate research should teach us, it is that it’s a mistake to call uncertainty our friend. Arguably the most important aspect Hansen ignores, carbon feedbacks, is likely to make things even worse. There is more than enough reason to heed Hansen’s warning.

Right now we stand at an intersection. What we do in this decade is crucial. If we choose one path, by the end of the decade the world could be well on its way to phasing out coal. If we choose the other, we face an uncertain future in which the only certainty is a continually shifting climate. I’ll leave the final word to Hansen et al, whose concluding statements were pretty strongly worded coming from a dense, technical, peer-reviewed paper:

Present policies, with continued construction of coal-fired power plants without CO2 capture, suggest that decision-makers do not appreciate the gravity of the situation. We must begin to move now toward the era beyond fossil fuels. […] The most difficult task, phase-out over the next 20-25 years of coal use that does not capture CO2, is Herculean, yet feasible when compared with the efforts that went into World War II. The stakes, for all life on the planet, surpass those of any previous crisis. The greatest danger is continued ignorance and denial, which could make tragic consequences unavoidable.

Editor's Note: Many thanks to James who wrote this blog post which is also the Basic Rebuttal to the argument "It's not urgent" (if you ever encounter this argument, just point people to ). James originally wrote a much longer blog post but I asked him to shorten it (the longer version now acts as the Advanced Rebuttal). So he patiently rewrote a much shorter version which I asked to shorten again (that version now acts as the Intermediate Rebuttal). In this final version, James informed me, "I cannae shorten it no more, captain!"

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Comments 1 to 50 out of 111:

  1. I wonder if SkS should switch entirely to how we move public opinion and therefore the politicians? The scientific case is iron-clad (despite the protestations of a few posters). We need to figure out how to move people, politicians and nations towards action.
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  2. You have touching faith in James Hansen who manages to draw "amazing" conclusions from data that others interpret quite differently.
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  3. galloping camel i've reviewed a lot of those "others" interpretations in following an interest in this for around 7 years some are simply wrong some are cleverly deceitful others are narrow answers to the wrong question so open your mind your touching faith in the 1% or so that deny the large majority of the scientists isn't touching it's downright dangerous and naieve
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  4. Great posting. The " 1) phase out coal by 2030." - is carbon capitulation. Way too late; too much delay. That gives in to economic interests that caused this problem. Coal combustion should be stopped now. Instead, suggest an ASAP/PDQ approach such that ANY carbon energy is used only for the purpose of establishing clean, renewable energy systems. Starting now. No other use of coal energy shall be permitted.
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    Moderator Response: Obviously that's not feasible - we will need power during the transition. But yes, I agree coal combustion should be stopped ASAP. - James
  5. rpauli: Going cold turkey on fossil fuel is nice in theory, but in practice? Economic disaster, is how I'd describe it. Which is really sad, because it's really what needs to be done. The next best thing is the "gradual phase out", which can be achieved by simply saying "no more coal-fired plants may be built or refurbished". That's a big call on it's own, but it'd certainly put the wind up the power generators to develop alternate sources of energy. Of course, in nations like Australia, where the word "nuclear" is immediately associated with "Chernobyl" in the minds of many, the options are limited somewhat. I really hope some of the promising alternate generation techniques get off the ground *fast*. There seems to be great reluctance, however, for investors to back anything other than nice, safe, predictable coal. As per my comments on the Climate Show thread, I think we're going to have to build a lot of rather large, solar and/or nuclear powered CO2 capture plants, to try to reduce atmospheric concentrations faster than natural processes will do so. That truly would be a "World War II" scale effort, but instead of building tanks & planes & bombs, those factories would be producing sequesterable carbon. This may become a requirement for the survival of human civilisation if, for example, we see significant amounts of clathrate or permafrost methane leaking out as the earth continues to warm. Even if we don't see that methane release, we'd still need to take out "extra" CO2, as the oceans would release plenty more as atmospheric concentration dropped. Herculean effort? I'll say... (Somewhat depressing, aint it?)
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  6. always the same strange assumptions, that the life of mankind is very sensitive to the temperature, but very insensitive to the fossil fuel consumption, whereas all objective data and facts show exactly the opposite. Try a simple exercise. Adopt a "wealth indicator" X (it can be GDP but also any fancy indicator you want). By comparing different countries, compute the "sensitivities" dX /dT and dX/dC where T is the local average temperature and C the fossil fuel consumption. Then to compare dimensionnally comparable constants, compute dX/dT and dX/dC. (dC/dT)c where the latter factor is the variation of fossil fuel consumption. Give me the result, and conclude.

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    Moderator Response:

    Climate change isn’t only about temperature. With global warming comes

    • Ice sheet collapse and sea level rise, as discussed in my article.

    • An intensification of the water cycle which paradoxically means both more intense rainfall and more droughts.

    • Expansion of the drought-ridden subtropics.

    • Glacier melt, which will cause water shortages for hundreds of millions of people.

    • Amplifying feedbacks which cause more warming.

    • Also, the unusually rapid rate of global warming we are causing will make it very difficult for ecosystems – not to mention humans – to adapt.

    • In addition to global warming, fossil fuel burning is causing ocean acidification faster than it occurred in the Paleocene-Eocene Thermal Maximum.

    • I could go on.

    And of course wealth is correlated with fossil fuel consumption, because that’s currently where we get most of our energy from. The whole point is we need to change that. - James

  7. sorry a part of sentence is missing. (dC/dT)c is the variation of fossil fuel consumption necessary to get a climate change per unit T.
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  8. Hansen's findings confirm my worst fears. I have long been concerned that the medium-term models are understating long-term climate sensitivity. Have a fresh look at the familiar Vostok ice core data above, which plots the results through four ice ages and five interglacial periods. Notice that both CO2 and temperature spike at the start of the interglacial periods. The pattern is consistent. An increase in CO2 from 180 to 280 ppm is associated with a rise in temperature at the poles of more than 10°C. The increase in CO2 is less than double, yet the increase in temperature is greater than projected for doubled CO2 in medium-term models. I see this as evidence the estimates for climate sensitivity derived from such models are likely to be conservative. If I have misinterpreted this graph, will someone please explain it to me? If I have correctly interpreted it, the long-term challenge is greater than has so far been acknowledged.
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    Moderator Response: [DB] Fixed html issue.
  9. actually thoughtfull at 16:24 PM on 8 March, 2011 said: "I wonder if SkS should switch entirely to how we move public opinion and therefore the politicians? The scientific case is iron-clad (despite the protestations of a few posters). We need to figure out how to move people, politicians and nations towards action." Bob Guercio's response: "Vote Democratic in the United States"
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  10. Alan : If I have misinterpreted this graph, will someone please explain it to me? maybe you could explain why temperatures often decrease BEFORE CO2 (e.g., -280 000 , -215000, -130000) , after the spike ? and also explain how you can disentangle the sensitivity of temperature with respect to CO2, and the sensitivity of CO2 with respect to temperature (there are TWO factors in a feedback system)
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    Moderator Response: This is discussed in the thread "CO2 lags temperature". - James
  11. Actually, Bob, while that may be the fastest response, a better approach would be: "Persuade Republicans (and other conservative groups) that climate change is real & needs to be addressed." Of course, that's likely to be a *lot* harder, particularly with the disinformation being promulgated by special interest groups who are opposed to climate action on (mostly) financial grounds. It's like farriers & stable owners lobbying to have motorcars banned on 'safety' grounds, except in this situation they're getting awfully close to succeeding... (especially as the benefits of climate action are a lot harder to see than the benefits of motor vehicle use!) alan_marshall: don't forget the polar amplification effect - a 10ºC warming at the poles may be much less on a global scale. Having said that, Hansen argues that the interglacial peaks in the proxy records are constrained by non-temperature factors, so the actual temperature may have been higher. He also argues that we might see 5 metre sea level rises by the end of the century, with another 20 metres over the next few centuries. (see here for details) So, yeah, the long-term challenge is great. It's certainly been acknowledge by the climate science side of the debate. The other side has just barely acknowledged that it's even warming...
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  12. Gilles @ 10- Q. maybe you could explain why temperatures often decrease BEFORE CO2 (e.g., -280 000 , -215000, -130000) A. Woolly mammoths and saber-toothed tigers didn't drive SUV's.
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  13. Gilles @ 10: that's what climate models are for, to take into account the many disparate factors that affect climate. And there are a lot more than just two factors in this particular feedback system... In any event, the lead/lag of CO2 w.r.t. Temperature is dealt with by this SKS page. I highly suggest you read the intermediate version, and discuss it there.
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  14. Rob, Bern, thanks, but I still don't understand the answer : why did temperature decrease so much although CO2 remained constant during several centuries? what was the driver then ?
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  15. another remark :" CO2 is rising by 2 ppm per year as we continue to burn fossil fuels.... Under business as usual, we are heading for up to 1,000 ppm by 2100" of course a simple computation shows that 1,000 ppm by 2100 requires an average +15 ppm/yr, more than 7 times the current rate. Obviously this is only possible with an exponential growth throughout the century - exponential growth is a very useful tool to predict a lot of catastrophe since it requires only a small number of doubling times to reach any reasonable threshold. The basic question is however : how long is an exponential growth sustainable ?
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  16. @14 CO2 lags temperature - what does it mean?
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  17. @15 Probabilistic Forecast for 21st Century Climate Based on Uncertainties in Emissions (without Policy) and Climate Parameters maybe read first then comment
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  18. Not sure that paleoclimatic records support CS is 3C...they seem to point to it being somewhat higher! "Together, it is clear that during the Cretaceous and Paleogene climate sensitivity commonly exceeded 3°C per CO2 doubling." "Fossil soils constrain ancient climate sensitivity" Dana L. Royer1, PNAS | January 12, 2010 | vol. 107 | no. 2 | 517–518, Birgit Schneider and ralph Schneider "Global warmth with little extra co2" nature geoscience | VOL 3 | JANUARY 2010 |pg 6, "The conclusion of a high Earth system sensitivity5,13 is particularly worrying if there is a potential for the hitherto slow components of the climate system to respond more quickly in the face of rapidly increasing CO2 emissions." In this paper the CS long term (1000yr say) with all natural variation taken into account is ~8-12C, "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 +/- 1:0C and 8:7 +/-1:3 C per CO2 doubling, and 9:6=+/-1:4 C per CO2 doubling, respectively." "High Earth-system climate sensitivity determined from Pliocene carbon dioxide concentrations" Mark Pagani1*,NATURE GEOSCIENCE j VOL 3 j JANUARY 2010 "The surface in our PE control simulation is on average 297K warm and ice-free, despite a moderate atmospheric CO2 concentration of 560 ppm. Compared to a pre-industrial reference simulation (PR), low latitudes are 5 to 8K warmer, while high latitudes are up to 40K warmer." Warm Paleocene/Eocene climate as simulated in ECHAM5/MPI-OM M. Heinemann, Clim. Past, 5, 785–802, 2009 On average the PE was 9.4C hotter with large polar amplification and a CO2 basically double, so that makes CS 9.4C. It must be remembered that 1000yr CS from Paleo data is higher than the 100CS used in models, the 100CS is about 60% of the 1000yr. So for the long term 9.4C that is 5.64C and so on, "If the temperature reconstructions are correct, then feedbacks and/or forcings other than atmospheric CO2 caused a major portion of the PETM warming." "Carbon dioxide forcing alone insufficient to explain Palaeocene–Eocene Thermal Maximum warming" Richard E. Zeebe1, Nat. Geo. PUBLISHED ONLINE: 13 JULY 2009 | DOI: 10.1038/NGEO578 In this one the CS is about 9-12C again, but as in the quote the authors feel the CO2 CS is a definitive and thus say another factor is necessary rather than CS being higher. There are plenty more of these and the recent article in science again suggesting CS is underestimated and the article last year by Gavin Schmidt saying it was 30-40% down. It does seem to make no sense to me that the CS is going to a standard figure all the time, as it is dependent on multiple none-linear feedbacks the size of which varies depending on the initial conditions. How can Earth with no ice albedo feedback have the same CS to GHG as one with loads of ice? One with no permafrost have the same CS as one with ,lots melting? At present we have a polar ocean melting, and lots of permafrost to melt. It also clear form this paper that temeprature changes can be dramatic and tipping point in nature, ("Another look at climate sensitivity" I. Zaliapin1 and M. Ghil2,3 Nonlinear Processes in Geophysics), so trying to get a statistical CS from paleodata isn't going to easy as the CS is dependent on initial conditions, and many studies suggest it is higher than thought or modelled, it is more likely that the PDF of CS should be a range humps and bumps ranging long twerm from 6-12C. Which hump the world is currently at is hard ot say, but with polar sea ice to go and permaforst etc, it is likely to be on the high side of things probably. "The conclusion from this analysis—resting on data for CO2 levels, paleotemperatures, and radiative transfer knowledge—is that Earth’s sensitivity to CO2 radiative forcing may be much greater than that obtained from climate models ( 12– 14)." "Lessons from Earth’s Past " Jeffrey Kiehl;14 JANUARY 2011 VO 158 L 331 SCIENCE SO yeah things are urgent very very urgent, for a CS as high as suggested from the past means 350ppm gives a 95% probability spread of temperautre rise by 2100 of 1.8-3C. Now how are we going to get 40ppm of CO2 out of the atmopshere, especially considerign that some models suggest that the CO2 that gone into the sinks will be released and there is of course the climate warming CO2 feedback with gives out about 10-20ppm per 1C. How high can CO2 go before the accumulation of heating is too much for 2C not be a definitive, 400ppm peak, even that seems risky buisness considering. Of course the present CO2 is 390ppm, so to peak at 400ppm would mean only adding another 5 year or less carbon into the atmosphere, divide that up fairly arround the world and it means the west has 1 year of emissions to play with for a carbon budget, so not much and considering all the adaptation that will be needed not much at all. Does anyone think that this is in anyway doable? If bold plans like ZeroCarbonBritain by 2030, cause peak CO2 of 434ppm and that isn't counting all the extra carbon needed to replace everything (cars with electric cars, power infra-structure, all white goods for efficient ones, changing the face of farming etc). And also remember the biosphere basically are only hope of drawing CO2 down (carbon cpature is a ruse to keep using fossil fuels and there isn't enough energy in the world to run special CO2 exchange machines and where do we put the carbondioxide for it seems to leaking from the all sites it has been burioed at so far!!). Is a fossil fuel free society even possible anymore? For that would take changing the whole economic system as the current system has to grow and the only way for that to occur is by using fossil fuels. The only way to get CO2 out the atmosphere quickly is to stop putting in quickly and the only way to do that is stop using power.
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  19. "I wonder if SkS should switch entirely to how we move public opinion and therefore the politicians? The scientific case is iron-clad (despite the protestations of a few posters)." I completely disagree with that... Very few sites provide SkS' level of analysis with such accessibility. IMO SkS is about using the scientific method to cut through the rubbish. That's been done very well for the physical science: SkS has clearly pointed out that it's not the Sun causing global warming, but on the other hand that 7 metres of sea level rise isn't going to happen tomorrow. In terms of actions, it's a lot harder. But taking the approach of explaining the effects of different policies based on peer reviewed work so that those with a political bent can make informed decisions is where SkS should be IMO. That's what James' article here is about: explaining the evidence behind claims of climate sensitivity and why this should be factored into any risk analysis for the future.
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  20. @ranyl “... that some models suggest that the CO2 that gone into the sinks will be released and there is of course the climate warming CO2 feedback with gives out about 10-20ppm per 1C.” Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate, Frank et al., 2010.: “But themagnitudeof theclimate sensitivityof theglobal carboncycle (termed c), and thus of its positive feedback strength, is under debate, giving rise to large uncertainties in global warming projections.” “Our results are incompatibly lower (P,0.05) than recent pre-industrial empirical estimates of 40 p.p.m.v. CO2 per 6C (refs 6, 7), and correspondingly suggest 80% less [!!!] potential amplification of ongoing global warming.”
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  21. In response to the prior comments about how politicians need persuasion to pay attention to the scientific data and take action now, I would like to request permission to share this link all over the place, i.e. C-Span. There is a discussion there now inviting comments about whether or not President Obama should open our oil reserves in a hope to reduce the prices at the pump. I would like to share this link there. As you know, I do not have a scientific educational background to be able to offer any intelligent discussion to this link, but I do have common sense and it tells me I should pay attention to the scientific data and open my mind to the discussions among the experts. I know Mother Earth is pretty resiliant, but what I take away from this article, is that even she has her limits and her sustainability for human existence will turn on us eventually if we don't start changing now. Convincing the consumers consumed with consumption will be the tricky part.
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    Moderator Response: [Daniel Bailey] Welcome to Skeptical Science! Feel free to link to any article posted here.

    To get the most out of this educational site, we recommend that Newcomers, Start Here and then learn The Big Picture. I also recommend watching this video on why CO2 is the biggest climate control knob in Earth's history.

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  22. One of the uncertainties I have read as a non scientists is 'climate inertia' or the time it will take for ice and the atmosphere to respond to the 390>PPM CO2 now measured by the NOAA in HI. I read Dr. Hansen's book- he speaks of this inertia- regarding ice melting- it a slow process, but once it starts there is little chance for stopping it. And this melting is going to accelerate at around 400ppm CO2. The OP talks about the urgency we now face- with C02 at such high levels as today- and rising rapidly. Have we passed into the zone of 'Dangerous climate change'- Hansen feels we have- can we stop 'extremely dangerous climate change?' Just my OP- we are in deep deep trouble- and the world seems totally aloof.
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    Moderator Response: [Daniel Bailey] Salient points, all.

    For those paying attention, the demise of Multi-Year (MY) Arctic Sea Ice currently ongoing (expect to see seasonal open water at the pole by 2012 at summer melt maximum, this summer if weather conditions are more conducive). With the albedo-flip kicking in, the energy poured into killing off millennia-old MY ice will then go into the warming of the Arctic Ocean itself, with the result of longer and longer melt seasons each year & a corresponding ramp-up of ice loss from both the Greenland Ice Sheet and the West Antarctic Ice Sheet. More Polar Amplification to come (in the pipeline).

    Is the pot in the red danger zone if the steam is blowing the lid off the pot?

    Not that the world is fiddling while Rome is burning; more like just Wubbling down (since I missed the good doctor's birthday last week).

  23. iana@16 : so do you agree that what alan_marshall said : " The pattern is consistent. An increase in CO2 from 180 to 280 ppm is associated with a rise in temperature at the poles of more than 10°C. The increase in CO2 is less than double, yet the increase in temperature is greater than projected for doubled CO2 in medium-term models. I see this as evidence the estimates for climate sensitivity derived from such models are likely to be conservative." is incorrect, since there must be OTHER forcings ? iana@17 : my comment is the following : you can read here "No judgment is offered in this report as to the preference for any of the scenarios and they are not assigned probabilities of occurrence..." so can you explain me how to compute probabilistic forecast without any a priori probability distribution of scenarios ?
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  24. #23 Gilles, Note what was said, "at the poles", not global. We are already seeing that much increase in the high latitudes.
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  25. RickG, do you mean that the poles can experience a 6°C decrease in temperature (e.g. between -140 000 and -120 000 BP) , without any change in the global temperatures ? Interesting ... but still CO2 hasn't decreased in this period, so what did change in the forcings ? if you look in detail, you will see many periods lasting several centuries during which temperature and CO2 varied in opposite ways; this is obviously contradictory with "Temperature can vary only through a change in forcings AND CO2 is the main driver for these changes AND the relaxation timescale is less than one century".
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  26. The industrialized nations rely on fossil fuels to a large degree. It is a convenient form of portable power. Developing nations are also increasingly become dependent on fossil fuels as they develop infrastructure to improve the quality of life for their citizens. Until (read when and if) solar, wind, wave, or other forms of "clean" energy become reliable and readily available, fossil fuels are going to rule the roost. Nuclear has been maligned to the point that it will take major changes in public perception to put in place.
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  27. Gilles, Have you not been directed to the thread, "CO2 lags temperature"? I suggest reading the Intermediate article and trying to understand its content. CO2 can be both a forcing and an feedback.
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  28. Harry Seaward is quite right. The West in general, and the UK in particular, have enjoyed the benefits of an industrial revolution, which the East now seeks to emulate. It might be interesting to compare the direct evidence, the atmospheric temperature and CO2 records to see if it likely that China and India (or Amrica for that matter) might be persuaded to abandon carbon fuels. The Central England Temperature, measured by thermometers, illuminates the AGW argument. Anyone looking at he overall plot will be struck by the very modest rise in overall temperatures from 1659 to 1979, 320 years. In that time the CO2 concentratiom increased from 280 ppm to 350ppm, with almost no discernible increase in temperature. A linear regression actually gives the rate of increase at 0.19 degrees C per century - per century, not per decade. Between 1980 and 2010 the rate increased very sharply, to almost 3 degrees C per century, while CO2 increased from 350 to 385 ppm. The AGW alarm sounded and has reverberated ever since in blogs like this. Now statistics as a subject is silent about the future, and we cannot project either of these two rates. But if annual temperatures fall back from an average of 10.36 in the decade ending 2009 to the 9.54 average in the decade ending 1979, the AGW alarm will fall silent. Last year the average temperature was 8.83 degrees C, the 90th coldest year in the record, exactly the same as the temperature in the first year of the record, 1659. December, 2010, was the second coldest December.
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  29. So if I read this post correctly, the reason there appears to be no correlation (over the recent past) between atmospheric CO2 concentration and Temperature anomoly when CO2 is above 370ppm is because "there is further warming in the pipeline". The oceans are storing up all this heat and once it is released there will be at least a doubling of the warming that the fast feedbacks are producing. When will this release occur? You state that if the current CO2 level remains at the 390ppm level that we'll experience sea level increases of 25 meters. We will most certainly be at and above that CO2 concentration for the forseeable future so what is the predicted year we'll see that 25 meters of sea level rise? There are many dire predictions in this post but they are all many decades out and very ambiguous on when they will happen. Can you be more specific with regard to time scales of say 5 years out?
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    Moderator Response: We don’t have a good knowledge of the timeframe; that’s one of the scary parts. The question is how fast can the ice sheets respond? On the upside, a 25 meter sea level rise wouldn’t happen overnight; it would probably take at least a few centuries. On the downside, there is a possibility of a few metres of sea level rise this century, and that possibility is looking increasingly likely. Even if Hansen’s ice sheet feedback doesn’t get us, there are still greenhouse gas feedbacks… – James
  30. I dont know were you take your data but those are certainly not global.
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    Moderator Response: Hansen et al accounted for their data not being global by multiplying by the probable ratio. They assumed temperature changes in ice core data were twice the global average. They assumed changes in deep ocean temperature were two-thirds the global average in the late Cenozoic, and allowed for the possibility that it was higher in the early Cenozoic. - James
  31. Hansen feels that by 2100- 5 meters is a reasonable number.
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  32. Gilles at 6 - regarding your differential equation - you are assuming dC is based on cheap fossil fuel. You are incorrect. It is based on cheap energy. And fossil fuels, after you factor in global warming and other pollutions (asthma, the ravages of extraction, particulate matter from burning, etc.) are the most expensive fuels we have. Given renewables are, in reality, cheaper, you don't actually have an argument.
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  33. garyt, CO2 has an annual cycle, so your monthly graph is drowning in this noise. The graph in question should be one of annual temperature and average annual CO2: -- from Grumbine, March 2009 And that's well before 2010 was tied for the hottest year on record, with CO2 in the high 380s. But whatever, its just a correlation and we all know that doesn't mean much these days.
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  34. 32 Actually thoughtful : again, you should explain that carefully to chinese and indian people. They don't seem to get it.
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  35. Harry Seaward wrote : "Until (read when and if) solar, wind, wave, or other forms of "clean" energy become reliable and readily available, fossil fuels are going to rule the roost." I can almost hear a voice from the 19th Century proclaiming : "Until (read when and if) oil becomes reliable and readily available, coal is going to rule the roost." And, before that : "Until (read when and if) coal becomes reliable and readily available, horse-power is going to rule the roost." See how things can change, given enough backing ? Fred Staples wrote : "But if annual temperatures fall back from an average of 10.36 in the decade ending 2009 to the 9.54 average in the decade ending 1979, the AGW alarm will fall silent. Last year the average temperature was 8.83 degrees C, the 90th coldest year in the record, exactly the same as the temperature in the first year of the record, 1659. December, 2010, was the second coldest December." If, if, if. Does that mean anything, when the year so far (Jan and Feb) is showing a higher average anomaly than last year ? Do you believe the anomalies are going to continue to show negative, or are going to be all less than last year ? And why would you think that this decade is going to fall back to the levels seen in the 70s, when every decade since has been higher than the previous ? What are you expecting to cause those cool temperatures ? Will you fall silent if it doesn't ? Also, what do you think you can prove from single years, or even months ?
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  36. For those 'worrying' about India and China - don't : they are well ahead of you and actually doing things while you 'worry' about them : Renewable Energy in China, India To Hit $53.0 Billion, $14.4 Billion Respectively by 2016 The report ‘Renewable Energy Investment in China, India and Brazil’ concludes with a viewpoint on why there is no end to investment in the renewable energy market. India has a flourishing nuclear power program and plans to have 20,000 MWe of nuclear capacity on line by 2020. China has electricity demand growing at 20% per year and a rapidly-expanding nuclear power program. Nuclear capacity of at least 40,000 MWe is planned by 2020. India is already self-sufficient in reactor design and construction and China has become so for second-generation units, but is importing Generation-3 plants. India's uranium resources are limited, so it is focusing on developing the thorium fuel cycle to utilise its extensive reserves of thorium. China's uranium resources are modest and it is starting to rely on imported uranium.
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  37. "Here we quantify the median γ as 7.7 p.p.m.v. CO2 per °C warming, with a likely range of 1.7–21.4 p.p.m.v. CO2 per °C." Arkadiusz Semczyszak From the paper you quoted and therefore my “... that some models suggest that the CO2 that gone into the sinks will be released and there is of course the climate warming CO2 feedback with gives out about 10-20ppm per 1C”; is as per that very same paper although it should have been 5-20ppm as their are very skewed. More from the paper, they constructed a temeprature ensemble of ensembles and found; "The warmest pre-anthropogenic period (1071–1100) was 0.38 uC warmer than 1601–1630, suggesting that recent anthropogenic influences have widened the last-millennium multi-decadal temperature range by ,75% and that late twentieth century warmth exceeds peak temperatures over the past millennium by 0.31 uC." The 80% comment needs to be read carefully as it is saying that as the CO2 rise per 1C is less by at least half and this reduces the amplifiaction of temperature rise due to this feedback by 80% less not that CS is any less at all just not due to CO2 release feedback and 80% seems high as previous CO2 per K feedback estimates were 40ppm. So the 80% isn't is that climate sensitivity to a rise in CO2 is less in any way, just not to accelerating CO2 atmospheric concentrating. In Pliocene temepratures were 3-5C hotter compared to pre-industrial and CO2 was about 350-400ppm, which is a CO2 release/ storage of about 14-40ppm, which is probaly about right considering the values in the papers and the skewed graph in Frank's paper meaning higher CO2 per 1C are more possible. So the Frank paper wasn't looking at CS for temperature it was looking at how sensitive the world is at releasing CO2 per 1C rise in temprature which is a very different thing. It also taken in a time period when temepratures were colder than now and the possibility of large releases of CO2 from frozen ground and sea floor were a lot less. With CO2e hoovering at 450-60ppm (0.7 of a doubling) aren't you just a little concerned that 2C is a distinct possibility even if all CO2 emissions stopped today?
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  38. Fred (#28), Why are you using Central England temperatures to counter global temperatures? Globally, 2010 tied with 2005 as the warmest year on record; 1880 to present. December 2010 was the coolest since 2000 and 1982 & 1994 for 17th warmest on record. State of the Climate | Global Analysis | Annual 2010
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  39. Thanks muoncounter in #33 for the reply. Even when looking at yearly averages instead of monthly averages I still see the period of 'flatness' in the last 11 years and the graph is shown below. I think the reason for this is the heat buildup in the oceans as this post alludes to so my point in posting this comment was to poll the team here and find out when this heat is going to be released.
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  40. Just got through watching the "House Climate Science Committee". I am deeply saddened.
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  41. Why, Bibliovermis, 38? Because it is a long, reasonably self-consistent record. It demonstrates the essential point about AGW very clearly. Which is that, if the temperature record had not increased relatively sharply after the 19seventies, no-one would have taken AGW seriously. You can see the same effect in all the other long-run records. HardCru3, quotes global temperatures over 161 years from 1850 - the period when the globe emerged from the Little Ice Age. The warming trend overall is just 0.45 degrees C per century, with 95% confidence limits between 0.4 and 0.5 degrees C. Most of that warming has appeared in the last 35 years (1.7 degrees per century). From 1850 to 1975 the trend was a very modest 0.25 degrees C per century, with 95% confidence limits between 0.19 and 0.3 degrees per century. Most of the explanations of AGW (and there are many) are not even plausible, but it is difficult to persuade non-physicists of that fact. It it easier to demonstrate that, if the AGW effect exists, it waited until the Western industrial revolution was over before making an appearance.
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  42. It's puzzling that discussions of burning our fossil fuels don't seem to consider a time period going out beyond a couple of centuries. But then given a culture that is captivated by quarterly reports, annual earnings and that can't seem to plan more than a couple of years into the future I suppose that's not too surprising. Unless we see homo sapiens as a flash in the pan, doomed to go down in flames in the next couple thousand years - then the question arises what's our strategy once we start creeping back into an ice age? At that point wouldn't it be helpful to have fossil fuels to burn in a controlled manner to try to cancel out the cooling effects that are coming? If we're concerned about humanity's ultimate future shouldn't we be saving/stockpiling those fossil fuels for the many generations to come who could use them much more beneficially? So aside from the fact that reducing fossil fuel usage through alternative energy production is: 1) economically beneficial (an economy dependent on a depleting energy source is a doomed economy as prices eventually skyrocket with increased demand and reduced supply) and 2)the most reasonable way to mitigate the potentially disasterous effects of AGW - it also makes sense in the long, long run if we're really concerned with the future of our species. But then our track record for thinking rationally about our future is nothing short of abysmal.
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    Moderator Response: (DB) On the bright side, we've probably skipped the next ice age en toto; BAU for another 20-30 years and we skip the next 5.
  43. Do you realize the fallacy of using a regional temperature to counter the global temperature average? if the temperature record had not increased relatively sharply after the 19seventies, no-one would have taken AGW seriously. True. If [physical effect] didn't occur, no would take [scientific theory describing effect] seriously. How is that tautology relevant?
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  44. Alan @ 8, I am afraid your interpretation is probably right. As a civilization we are basically toast. Add in peak oil for sting in the wound. We are in the beginning of a ME event right now and the biosphere is going to take a hit for a long time also. Ocean acidification is going to be nasty too, and theres not much we can do about that now. Its basically 'the end of the world' . Its a reset. We have to keep fighting for the best path through this though. Its all about survival.
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  45. garyt, "I still see the period of 'flatness' in the last 11 years" It's hard to tell what can be seen in a graph with a linear fit yielding r^2=0.07; eleven years of temperature data just aren't enough. Perhaps you should look at a temperature analysis that takes out short-term bumps: --from Tamino's Open Mind, 1/20/2011 A quick eyeball straight line gives 0.2degC/decade, which is convenient because you show ~20ppm increase in CO2 over 10 years. That gives 0.2/20 = 0.01 degrees per ppm increase, which is exactly what the graph from Grumbine showed. You'll no doubt see a stronger correlation coefficient as well. Of course, that's not going to stay a straight line for long, as continued CO2 radiative forcing will result in concave up (accelerating) temperature change.
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    Moderator Response: [DB] Ah, yes, the next great "skeptic" meme: "I see flatness". We'll have to add that one to the rolls.
  46. Muon @ 45, "Of course, that's not going to stay a straight line for long, as continued CO2 radiative forcing will result in concave up (accelerating) temperature change." Do you have a basic timeframe on that statement?
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  47. Fred S "The warming trend overall is just 0.45 degrees C per century, with 95% confidence limits between 0.4 and 0.5 degrees C." A straight line fit over that long a time run may look pretty and sound emotionally satisfying, but it is physically meaningless. You should start by looking at what has changed in the environment over that time period: solar output, aerosols, volcanic events, etc. Try to include all the so-called natural forcings you can find and calculate what they do to temperature. You simply won't be able to recreate the temperature record without adding in anthropogenic CO2 as a positive forcing. That's been demonstrated here time and again; you can find it using Search if you are so inclined. And btw, most graphs show ~0.16C per decade globally. --from Assessing global surface temperatures
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  48. @JMurphy, #36: What your numbers don't tell us is even more important though: it was China and India who sabotaged the Copanhagen talks, refusing to allow enforceable limits, because their use of coal and oils is also growing. Worse yet, they are unwilling to slow that growth for the sake of future benefits. They would rather destroy the chance for a healthy economy for the whole world than give up on their rapid growth now.
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  49. Even if you accept, 47, the AGW theory, you must accept that not much happened while CO2 increased from 280 to 350ppm. I was once responsible for monitoring temperature and humidity in a nuclear power plant. The idea that it could be done with any degree of accuracy in one factory across the seasons was, believe me, absurd. So is the idea that you can not only measure but explain changes in the global average temperature (that's the average temperature across all the lands and oceans, across the globe). The best we can do is to monitor changes at varying points across the globe, at more or less regular times, day and night, and make crude corrections for urban heat island effects. To relate the variations in this data to cause and effect is impossible. I do not know why the medieval warm period happened. I have no idea why the globe then descended into the little ice age, or why it emerged during the 19th and 20th centuries. I can only repeat that there is no sign of any relationship to the increase in CO2 until the late 70's, by which time the CO2 concentration had increased from 280 to 350 ppm. (Climate scientists at that time thought we were heading for another ice age). If you are certain that the increase in temperatures over the past 30 years is permanent and not transient, compare the UAH satellite lower troposphere trend with the mid-troposphere trend (where the action from CO2 is supposed to be). Both sets of data are from 1979 to date: Lower troposphere : 1.4 degrees C per century Mid troposphere : 0.5 degrees C per century If you look at both charts you will see that most of their rather feeble increases depend on the 1998 peak and the subsequent 2008 to 2010 peak. On that set of data over the last 12 years depends the whole AGW edifice. I agree that those modest temperature changes happened, 43. I do not know why they happened. They provide little or no support for CO2 induced AGW theories.
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    Moderator Response: Let's say for the sake of argument that the temperature record is rubbish. How do you explain the rising tropopause, cooling stratosphere, rising humidity, increasing intense rainfall and flooding, rising sea level, shrinking ice sheets and glaciers, expanding subtropics, migrating species, melting permafrost, and disappearing Arctic sea ice? And why isn’t the rising carbon dioxide having any effect?
  50. Harry S, "a basic timeframe on that statement?" Tamino's graph is the satellite temperature period only (since 1979), so it's no surprise it looks linear. Here's the full GISS record (130 years): On this scale, the concave upwards profile can be seen quite clearly. The blue curves are different 'sensitivities,' although its been a while since I generated that particular graphic. So to answer your question, maybe it's already underway. This was also demonstrated in one of the Monckton myth threads (linear warming). The lesson there was that even a constant annual increase in CO2 concentration results in a concave up temperature profile - because the forcing just keeps on forcing.
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