RealClimate logo

Hit the brakes hard

Filed under: — group @ 29 April 2009 - (Español)

There is a climate splash in Nature this week, including a cover showing a tera-tonne weight, presumably meant to be made of carbon (could it be graphite?), dangling by a thread over the planet, and containing two new articles (Allen et al and Meinshausen et al), a “News & Views” piece written by two of us, and a couple commentaries urging us to “prepare to adapt to at least 4° C” and to think about what the worst case scenario (at 1000 ppm CO2) might look like.

At the heart of it are the two papers which calculate the odds of exceeding a predefined threshold of 2°C as a function of CO2 emissions. Both find that the most directly relevant quantity is the total amount of CO2 ultimately released, rather than a target atmospheric CO2 concentration or emission rate. This is an extremely useful result, giving us a clear statement of how our policy goals should be framed. We have a total emission quota; if we keep going now, we will have to cut back more quickly later.

There is uncertainty in the climate sensitivity of the Earth and in the response of the carbon cycle, and the papers are extremely useful in the way that they propagate these uncertainties to the probabilities of different amounts of warming. Just looking at the median model results, many people conclude that a moderately optimistic but not terribly aggressive scenario such as IPCC B1 would avoid 2°C warming relative to pre-industrial. But when you take into account the uncertainty, you find that there is a disturbingly high likelihood (roughly even odds) that it won’t.

Schmidt and Archer N and V figureBoth papers come to the same broad conclusion, summarized in our figure, that unless humankind puts on the brakes very quickly and aggressively (i.e. global reductions of 80% by 2050), we face a high probability of driving climate beyond a 2°C threshold taken by both studies as a “danger limit”. Comparing the two papers is obscured by the different units; mass of carbon versus mass of CO2 (moles, anyone? Is there a chemist in the house?). But chugging through the math, we find the papers to be broadly consistent. Both papers conclude that humankind is already about half-way toward releasing enough carbon to probably reach 2°C, and that most of the fossil fuel carbon (the coal, in particular) will have to remain in the ground.

We feel compelled to note that even a “moderate” warming of 2°C stands a strong chance of provoking drought and storm responses that could challenge civilized society, leading potentially to the conflict and suffering that go with failed states and mass migrations. Global warming of 2°C would leave the Earth warmer than it has been in millions of years, a disruption of climate conditions that have been stable for longer than the history of human agriculture. Given the drought that already afflicts Australia, the crumbling of the sea ice in the Arctic, and the increasing storm damage after only 0.8°C of warming so far, calling 2°C a danger limit seems to us pretty cavalier.

Also, there are dangers to CO2 emission other than the peak, such as the long tail of the CO2 perturbation which will dominate the ultimate sea level response, and the acidification of the ocean. A building may be safe from earthquakes but if it is susceptible to fires it is still considered unsafe.

The sorts of emission cuts that are required are technologically feasible, if we were to build wind farms instead of coal plants, an integrated regional or global electrical power grid, and undertake a crash program in energy efficiency. But getting everybody to agree to this is the discouraging part. The commentary by Parry et al advises us to prepare to adapt to climate changes of at least 4°C, even though they recognize that it may not be possible to buy our way out of most of the damage (to natural systems, for example, including the irreversible loss of many plant and animal species). Anyway, how does one “adapt” to a train wreck? There is also the fairness issue, in that the beneficiaries of fossil energy (rich countries today) are not the ones who pay the costs (less-rich countries decades from now). We wonder why we were not advised to prepare to adapt to crash curtailing CO2 emissions, which sounds to us considerably less frightening.

p.s. For our German-speaking readers: Stefan’s commentary on the KlimaLounge blog.

604 Responses to “Hit the brakes hard”

  1. 401

    Re #67 Anne van der Bom and lots of others,

    I just realized the ultimate problem with wind. It might blow most of the time, but at least occasionally it does not. This has to be true in England, and even in Denmark.

    Therefore there has to be a standby system capable of coming on line at fairly short notice that accompanies every wind power system. A simple solution could be peaking natural gas generators or hydro storage with enough reserve turbine capacity. In any case, the cost is significant. This gets added to the power transmission line costs. All of these things make up a forthright analysis.

    Nothing here is intended to discourage enthusiasm for wind where it is appropriately planned.

    I do not know about the windmills in Holland, but I can tell you with authority that in the 1950s many farms in Iowa had a windmill sitting idle over a well, where its intended water pumping function was left to either manual labor or an electric pump. As a kid that always wanted to know how things worked, I inspected many of these with very little satisfaction. I can also say with authority that one of the windiest places in California, called the Altamont Pass, is densely populated with wind turbines, and of the many dozens of times I have driven over that pass, wind turbines have been mostly sitting idle. Deep and abiding pessimism and distrust comes from being plagued with these memories.

    Now I realize that the farmers in Iowa probably did not care much about their windmills, since even though it would be good when they worked, if they came to rely on them the livestock would sooner or later die of thirst. So it was probably better to just forget about them and curse forever the guy that sold them the junk. There was not a lot of motivation for taking the things down, so they sat silent for many years as a monument to foolishness.

  2. 402
    Rod B says:

    Ray, certainly you can devise a cap-and-trade system that minimizes or mitigates screwing up and that would work better than some undersigned system without proper rules and regulations and enforcement. My point was more… a cap-and-trade that provides the federal government with significantly more revenues than the fuel tax, as one example, just strikes me as 1) not much of a market based system (you know – looks like a tax, feels like a tax, smells like a tax, IS TAX!), and 2) something in a whole other league from sulfates.

  3. 403
    Rod B says:

    Martin Vermeer (379), thanks. I think I can understand that logic.

  4. 404
    Phil Scadden says:

    >Why is only 10m² feasible? What is the average number of people per >house(hold) in NZ? What is the average roof area?

    Good point. Average no. is 2.8. My house has 160m2 but only 40 facing close to north. We have 3 adults, 2 teenagers so more is tricky for us.

    I chose 10m2 because it was what was typically quoted for by sellers. Even crytalline silicone (10% efficienct) is incredibly expense for 10m2 so concentrated more on cheaper renewables. I think solar is way to go for future but maybe when you have concentrating solar or next generation panels. At moment it isnt economic at a rooftop level.

    > I think in the not too distant future solar cells will be so cheap, you >can easily use them on east and west facing roofs too, powering a lot of >the other stuff besides the car.

    I hope so too but finding ways to make them significantly cheaper remains elusive though certainly there is hope.

    >Last december locations were suggested for the realisation of 6 GW >offshore wind in the North Sea

    I hope you are right but were the estimates from people who would build them?

    >Do you have a reference to such an engineering study?

    As I said, see
    References included in there. I am extremely keen for critical inspection of this. I’d love someone to find more energy, though I think the situation is extremely hopeful. I am more than happy for further discussion via email. Are you doing a MacKay type study for Netherlands?
    I have done it for average person not affluent, and for consumer energy figures which exclude energy transform losses in converting to electricity, and exported energy but also exclude imported embodied energy which is important for people bleating about China’s emissions. My energy cost for cars in NZ is based on retail petrol and diesel sales, a very robust data set.

    >If I am not mistaken, total consumption in NZ is 40 TWh/year. 33 kWh/d * >4 million * 365 = 48 TWh/year. So even with those stringent limitations >(sure about the 500 km buffer from urban areas??) that is more than NZ >currently needs.

    Sorry, 500m! (from memory). However, I think you are only looking at electricity consumption. This is 67% renewable with target of 90% by 2025 before the new government came in. Total energy is 94kWh/p/d – much tougher. Our problem is that every windmill and hydro is opposed by NIMBYs who somehow believe that turning appliances off standby and using CFLs is enough. MacKay’s book brings realism that is badly needed.

    >That will very rarely happen with modern turbines.

    Well my experience limited to Wellington where this was listed as main cause of downtime. The point was that it limits generating time.

  5. 405
    Hank Roberts says:

    PS, James, what you’re trying to get at may be what’s explained here:

    But if you’re trying to argue for protecting the desert ecosystem from development — stick with the solid science, not the handwaving hypotheticals. The Endangered Species Act protections are solid, if you look at the sites carefully. Be convincing.

  6. 406
    MikeN says:

    >Much the same goes for China, and I think, India.

    My opinion is that we need to be more clever than to just demand that we stop using coal and other fossil fuels.

    India cancelled an Enron power plant when they didn’t use coal, and instead produced an expensive natural gas plant with fuel from Africa.

  7. 407
    Martin Vermeer says:

    #388 Steve:

    That need not happen for a significant reduction in the positive feedback. That feedback is much less now than during the last ice age.

    But still very much positive. Which was Ray’s point.

  8. 408
    David Murray says:

    Jim Bullis, #330, repying to Anne van der Bom,writes,

    ‘You mention that the plug-in is necessary for transition to electric cars running on renewable energy sources. Please consider the possibility that the process will get stuck with huge inefficient plug-in cars running on coal.’

    He also writes, #376,

    ‘For Europe, including UK, the future is absolutely electric powered cars. There is no other viable long term choice.’
    Plug ins will be transitional because battery improvements will make them obsolete. The four major contending battery technologies (lithium ion, NiMH, zinc air and hybrids) have not yet reached the technical dead end that lead acid batteries seemed to have. And blue sky (Eestor ?) is still out there.

    For Europe, North America and China the future is absolutely electric powered cars. North America has brought us the Tesla, China (and Nebraska) are bringing us BYD.

  9. 409
    Douglas Wise says:

    Nick Gotts,

    It might surprise you to know that quite a lot of erstwhile “dirty little hippies”, having left their studies of Evelyn Waugh behind, have become sufficiently concerned about our long term prospects to feel the need to embrace 4th generation nuclear power.

    You could learn more about this whole subject by visiting Having done so, I would be delighted to hear back from you with an opinion – criticism, if you like – that it more informed.

  10. 410
    Douglas Wise says:

    Wilmot McCutchen #358

    I am no expert on the subject of the S-Prism. However, in my reading of the detailed discussion of the subject at I have, possibly naively, been persuaded by its huge potential. It was for this reason that I invited informed criticism from possible authorities on this site. The lack thereof (to date) tends, possibly wrongly, to reinforce my initial conclusion.

    I am not an appropriate person to answer your specific points in any detail. However, the IFR is , I believe, cooled with liquid sodium, necessitating an extra heat exchange loop for safety. This adds to expense but I understand that other aspects of the design will be significantly less costly than those associated with existing 3rd generation plants. The basic S-Prism unit is small and is designed to be factory built. Units can be grouped together on single sites. I gather that these may include existing obsolescent coal power station sites so that the steam turbines thereon can continue to be used. Obviously, this would imply water cooling. However, I believe salt water to be as acceptable for the purpose as fresh. I also recall that air cooling would be feasible but more expensive.

  11. 411
    David Murray says:

    Doug Bostrom, # 380, gives us a clear picture of the current situation in applied photovoltaics and sees exciting potential for the newer technologies:

    ‘We’re approaching the point where we can discuss “painting” surfaces with amorphous PV compounds on a commercial basis. Seems to me that’s where we might find some real excitement regarding autonomous or semi-autonomous solar vehicles.’

    Silicon cells have reached 20% plus efficiencies at a relatively high cost. Thin films have only recently reached commercial production but have much lower manufacturing costs which make them competitive with higher efficiency silicon cells.

    The next step (Martin A Green, ‘Third Generation Photovoltaics’ discusses this) is to marry the cheap manufacturing cost of thin films with the conversion efficiencies of silicon cells. A thin film with 20% plus efficiencies would change a lot of things.

    Anne van der Bom, #341, puts the same point clearly:

    ‘I think, in the not too distant future solar cells will be so cheap, you can easily use them on east and west facing roofs, powering a lot of other stuff besides cars”

  12. 412
    Allen63 says:

    Question for Climate Scientists here:

    Globally, what is the ratio of human CO2 emission tonnage to natural CO2 emission tonnage annually? I.e. annually, what percent of CO2 emitted into the atmosphere is directly put there by human energy production? I’m not talking concentration in the atmosphere — rather, annual direct emissions from tailpipes, etc vs other sources (e.g. rotting vegetation, animals breathing).

    I’m looking for the current “scientifically accepted” number. I have seen various numbers for this at various sites and wonder which is correct. If there is a link to an authoritative article spelling this out, that would be great. Thanks in advance for a response.

    [Response: It’s a meaningless number – which is precisely why it so beloved of the contrarians. Take a bathtub into which you are pouring an extra bucket of water a minute. Meanwhile the taps are putting a large amount at the same time the drain takes out the same quantity. The bathtub volume increases at a bucket of water a minute regardless of what the natural sink and source is. It could be 0.1 buckets, 1 bucket or 100 bucket, it doesn’t change the math. So if someone tells you this is an important number to know precisely, you know they are trying to fool you. The number that is important is the human contribution to the atmospheric concentration – currently 27% of atmosphere CO2 (~106ppm out of 386 ppm). – gavin]

  13. 413
    Anne van der Bom says:

    Jim Bullis
    2 May 2009 at 2:11 PM

    This realization is secondary to the startling revelation to me that European energy policy is only incidentally connected to global warming concerns.

    Reporting from inside Europe, I can assure you, that is rapidly changing.

  14. 414
    pete best says:

    Re #399, The UK consumes 1.79 million barrels of oil per day. Some of it is probably used for heating homes etc but the vast majority of it is used for transport whatever the kind so when it comes to people its not that important.

    One barrel of oil contains 42 gallons of fuel and a gallon of petrol consists of 43 KWh of energy equivilent (so lets say 40 KWh). The numbers come in at around 3 billion KWh a day. Now here is the major problem, the UK uses 400 TWh of electricity per year but 2.5x that in oil!!

    Now how efficient can an electric car be, in order to offset all that oil energy. Scary!!

  15. 415
    Anne van der Bom says:

    pete best
    2 May 2009 at 2:14 PM

    Re #349, Anne, An electric vehicle is not 5x more efficient than a ICE based one. 26% efficient ultimately.

    Please try harder to understand what I am trying to say: An electric vehicle is 5 x as efficient in converting electricity into kinetic energy than a petrol car is in converting the thermal energy in petrol.

    To all: I am not trying to do a well to wheel comparison of electric cars vs petrol cars. I am merely trying to set the record straight as to how much (carbon free) electricity we are going to need to replace our current fleet of petroleum powered cars.

  16. 416
    pete best says:

    A David Mackay interview with the UK newspaper the Guardian tels us about him and lets us know that its about a honest energy assessment and debate and a lot of peopl out there have to stop saying no to the technologies that are available.

  17. 417
    Anne van der Bom says:

    Phil Scadden
    2 May 2009 at 3:30 PM

    built into your assumptions are passengers per car and fuel efficiency.

    No, I am merely looking at the total number of car-km traveled for Britain and then multiply that with a realistic estimate of how much kWh’s are needed on average for each those km’s. It doesn’t get any simpler than that.

    Since your numbers dont add up to the retail energy sold in fuel, I suspect your numbers of being wrong – you have another explanation?

    Instead of suspecting my numbers are wrong you could try proving them wrong.

    I’m struggling to get an unequivacol number for kWh/km for electric cars too. Can you point one out to me? I want one measures km in to terms of energy going into the car rather than energy going out the battery (so battery efficiency is considered).

    There is no such unequivocal number. Remember, the consumption figures of petrol cars vary wildly between Priuses and Hummers. The Tesla roadster (a high performance sports car) is now sold with an EPA rated range of 244 miles. It has a 55 kWh battery. Look at for more info. There is also a detailed analysis of the Roader’s consumption on the Tesla blog. They measured energy coming out of the battery, so indeed you’ll have to factor in losses for the battery and charger. As far as I know, Li-ion batteries are more than 90% efficient, as are chargers. So do not expect a very different result from factoring that in. Numbers cited for the Mitsubishi MIEV are as high as 10 km/kWh.

  18. 418
    Anne van der Bom says:

    David Murray
    2 May 2009 at 8:32 PM

    Actually it is quite simple. pete’s number is derived from the total end used of petroleum in the UK which, according to BERR data

    There you will find that total petroleum consumption is 70 m.t.o.e per year. Of that, 26.5 million is for passenger vehicles. That is 72,600 per day. 1 m.t.o.e ≈ 45 GJ ≈ 12500 kWh. 72600 * 12500 kWh ≈ 9e8 kWh = 900 GWh. Pretty close, but not exactly. I don’t know where pete’s got his numbers from, so that’s as far as my analysis can go.

  19. 419
    Anne van der Bom says:

    Hit the brakes – how hard?

    How much clean electricity are we going to need? Here is my simple calculation for Britain.

    I got my numbers from these BERR publications

    m.t.o.e. = millions of tonnes oil equivalent ≈ 45 GJ ≈ 12500 kWh.

    End users consume energy mainly in three forms: electricity, natural gas and petroleum. For simplicity I am going to assume that all natural gas is used for space & water heating and not much else (cooking for example).

    The consumption breakdown is as follows:
    – Electricity: 29 mtoe
    – Natural gas: 50 mtoe
    – Petroleum: 70 mtoe

    Leaving the electricity for what it is, the breakdown per type of energy is as follows:

    Natural gas
    – space heating: 38 mtoe
    – hot water: 12 mtoe

    – road transport: 42 mtoe
    – air transport: 14 mtoe
    – other (transport & non-transport): 14

    Now we’re going to have to make an assumption of how much electricity is needed for replacing each of those.

    Space heating

    By more insulation and using heat pumps and storing summer heat under ground for use in the winter, a threefold increase in efficiency does not sound unrealistic. That gives us 13 mtoe of electricity to keep the Brits from freezing in the winter.

    Hot water

    A solar water heater must become sort of mandatory for each house. It can not give you warm water all year round though. We do not need to generate electricity for this, you just use the sun shining on your house. But in the winter it will not generate enough, assume we need 3 mtoe for the luxury of having warm showers in winter.

    Road transport

    As I have argued before, a 4x increase in efficiency (electricity –> motion as compared to heat –> motion) for an electric vehicle is not unrealistic, so we would need 10 mtoe to keep the traffic moving.

    Air transport

    No viable technology exists to replace this with electricity. The planes will remain on a hydrocarbon diet.


    This is a varied collection of all kinds of petroleum use, water transport, fertilizer and plastic production, etc. Let’s keep them on hydrocarbons too.

    The total extra electric energy that emerges from the above assumptions is 13 + 3 + 10 = 26 mtoe. The existing consumption is 29 mtoe, meaning an increase by 90%.

    British electricity consumption is now 380 TWh/year, so that would have to increase to 720 TWh per year. That comes to 33 kWh per person per day.

    How much of the British fossil fuel use will have been replaced then? Total primary use is 230 mtoe, of that only 28 will remain: the air transport & other categories above. That is 88%.

    Number crunchers checking my calculation might notice that 29 mtoe of electricity is only 362 TWh, not 380. I have used those figures from different organisations. The discrepancy is probably due to the in/exclusion of transport losses and energy use by the energy sector itself. It doesn’t change the overall picture though.

  20. 420
    Mark says:

    re #401 rather than have a secondary system (you know there is already one there for peak demand, don’t you???) you could include energy storage.

    And please let me know the next time there is a high pressure the size of continental europe where there is no wind.

    I shall not be holding my breath…

  21. 421
    pete best says:

    Re #416, 1 Tonne of oil equivilent is 41 GJ Anne.

    To think that 1 million tonnes of oil is equivilent to 1.1 billion KWhrs and not 12,500 KWhrs. Thats how much energy oil contains 1680 KWhrs per barrel and one tonne is 7 barrels so a single barrel is around 11,600 KWhrs.

  22. 422
    Anne van der Bom says:

    Correction to my last post.

    In the ‘Other’ of petroleum I mentioned plastics/fertilizer production, but I now realize that the data I based my calculations on only show the energy use of petroleum. Non energy use of petroleum is 10 mtoe.

    That brings total petroleum consumption to 80 mtoe of which 24 mtoe ‘Other’ uses (energy & non-energy). I assume that 10 mtoe of non-energy use will end up in an garbage incinerator and thus will cause CO2 emissions, so that brings the percentage down to 83%.

  23. 423
    Matt says:

    Re Anne 409 (and previous comments)

    Someone reading your comments on this thread might get the impression that Mackay’s book is all about dismissing the idea that a hypothetical massive expansion of renewable energy could ever be capable of supplying a hypothetical UK all-electric vehicle fleet. (I might be wrong, but l’ll speculate that you’re worried that people might therefore conclude that a hypothetical massive expansion of nuclear would be needed instead).

    If you think Mackay’s got some of his numbers wrong on electric vehicles, you may well be right. But if that’s your main issue with the book, I think you’re spectacularly missing the point, and your comments here risk fundamentally misleading people who haven’t read it yet about the nature of the work. That would be a shame, because I believe it’s one of the most important works published on energy and the environment to date, with or without any flaws in its analyses.

    You can quibble about the numbers (and have done so very capably), but this is exactly what he wants- discussion about numbers. It’s about recognising the scale of the energy challenge that faces us.

    The important comparisons are based on the energy consumption of a present-day moderately affluent Briton (not a hypothetical future electric car driving energy efficient Briton) across every aspect of modern living- transport, heating, food and the rest. He relates this to the best estimates of present-day non fossil fuel technologies to deliver this energy. He highlights and clearly explains a convenient unit that helps discussion by making comparisons meaningful- the kWh/day. He concludes that replacing this energy would take a truly massive investment and a widespread, potentially intrusive deployment of alternative technologies, be they renewables, nuclear, or desert solar power. He is very clear about his assumptions. He clearly states that energy efficiency measures are important and will greatly reduce the size of the challenge (and spends some time making comparisons between those that are likely to be helpful, and those that aren’t). He doesn’t explicitly state any preferences. He says you can plug your own numbers into the analyses, but please make meaningful comparisons, use numbers rather than words, and don’t be under any illusions as to the scale of the problem.

    Anne, I’m not qualified to comment on your specific criticisms, and I think it’s great that all this is being discussed. I hope you’re right because I love the idea of more electric vehicles and it would be great if we could supply them with renewables alone. But I’m worried that your comments somewhat mis-characterise Mackay’s book and its intentions.

    If you do have improvements on his figures, he welcomes improved analyses, and has an open-source wiki specifically for this purpose:

  24. 424
    Larry says:

    Allen et al. (2009) in the current issue of Nature say:

    … policy targets based on limiting cumulative emissions of carbon dioxide are likely to be more robust to scientific uncertainty than emission-rate or concentration targets.

    Doug Wise in #331 and I in #159 commented that because the Southern Ocean acidity tipping point is likely to be reached at 450 ppm CO2, at which point a major global carbon sink begins to be affected, that concentration targets still remain important. We cited McNeil and Matear (2008), who believe the tipping point there will be reached between 2030 and 2038. It is unclear whether this tipping point has been considered in the Allen et al. (2009) and Meinshausen et al. (2009) studies. It would seem not – I hope someone here can clarify. Neither of those papers cites McNeil and Matear.

    Furthermore, ocean acidification is happening even more quickly in the Arctic, as shown in Stenacher et al. (2009, April), “Imminent ocean acidification in the Arctic projected with the NCAR global coupled carbon cycle-climate model,” (open access):

    We highlight that the Arctic Ocean surface becomes undersaturated with respect to aragonite at even lower CO2 concentration (than the Southern Ocean). The combination of observation-based estimates … with NCAR CSM1.4-carbon model projection indicates that 10% of the surface water along the investigated Arctic transect will become undersaturated for at least one month of the year when atmospheric CO2 exceeds 409 ppm. This concentration is only 25 ppm higher than today’s value and projected to be reached within the next decade for all SRES scenarios (Plattner et al., 2008; Meehl et al., 2007) and within the next two decades for the recent set of multi-gas mitigation scenarios (Van Vuuren et al., 2008; Strassmann et al., 2008).

    The entire water column in the Arctic is projected to become undersaturated within this century if anthropogenic carbon emissions continue to grow along the SRES A2 business-as-usual trajectory. Even under the relatively low-CO2 scenario B1, more than 50% of the Arctic surface waters are projected to become undersaturated. These results are consistent with the study by (Orr et al., 2008) who analyzed Arctic acidification based on results from different AOGCMS, including the NCAR CSM1.4-carbon.

    Atmospheric CO2 will very likely exceed 400 ppm in the next one or two decades given current carbon emission trends and the inertia of the energy and the whole socio-economic system. The question is thus not whether undersaturation will occur in the Arctic, but how big its magnitude will be, how large an area will be affected by undersaturation, and over how many months of the year undersaturation will be prevalent. Our findings, combined with the emerging evidence on the impacts of aragonite undersaturation on marine organisms imply that not only radiative forcing or temperature, but also atmospheric CO2 concentration should be included as a target in climate policy analyses and in the development of mitigation scenarios with integrated assessment models. Our subjective assessment is that atmospheric CO2 should not exceed 450 ppm in order to avoid the risk of large changes in marine ecosystems.

    … Overall, the volume of water supersaturated with respect to aragonite decreases strongly in the A2 and B1 scenarios considered here, with potentially adverse effect also on species living on the ocean floor and in the deep (Guinotte et al., 2006).

    … In conclusion, human activities are perturbing the ocean and the habitats for marine organisms. The results of this study and of Feely et al. (2008) for the coastal North Pacific and Orr et al. (2008) for the Arctic show that undersaturation of surface waters with respect to aragonite is likely to become reality in a few years only.

    Again, the point is that in both the Arctic and the Southern Oceans this not only will affect significant marine ecosystems, but also major carbon sinks.

    This leads me to believe that we do indeed need to “hit the brakes hard”: that we need to arrest the CO2 concentration well before the trillionth ton is emitted and that many of the technological fixes discussed in this thread will be too little too late. For us in the U.S., Europe, Canada and Australia the necessity of “hitting the brakes hard” also needs to mean constraining our lifestyles — at least until sometime in the future when sufficient technological fixes are reality.

  25. 425
    Ray Ladbury says:

    Steve Reynolds and Martin Vermeer, It is true that once all the snow and ice melt, you do not have the same sort of feedback. However, you do have a whole helluva lot of permafrost exposed to the sun. That ought to worry us as well. Just because feedbacks are not constant in time doesn’t mean feedbacks are decreasing. Note that ocean water has a lower albedo than most coastal terrains–rising sea levels mean more absorption.

  26. 426
    Anne van der Bom says:

    pete best
    3 May 2009 at 9:59 AM

    Thanks for pointing that out, I erroneously stated the value of 1 tonne oil equivalent. Actually, there is no exact value for 1 tonne oil equivalent. My source stated it as 42-45 GJ. I took the high end value of that.

  27. 427
    Forlornehope says:

    A couple of points, from an engineer, rather late than never. Firstly on the optimistic side, it is worth remembering that power generation and transport infrastructure all has a life of less than forty years, and less than twenty for private transport. Even buildings with a life of up to 100 years will receive a major refurbishment in less than forty; though I am writing this in a house built in the sixteenth century! This all means that anything being built now will have to be replaced before 2050 as will all current infrastructure. The cost of zero carbon replacement is only any additional cost compared to the high carbon option. This makes moving to a low carbon economy a much less costly option. The second point is that there is a very good treatment of the real options by Prof David MacKay of the University of Cambridge. It is available online at:

    For anyone interested in the question of what we can do about all this, it is a must read. He is quite a lively writer as well!

  28. 428
    Anne van der Bom says:

    3 May 2009 at 10:15 AM

    Thanks for your opinion. The main gripe I have with prof MacKay’s book is the picture on page 109 in which he shows a 125 kWh consumption stack and compares that to his (mostly opinion-based) estimate of how much renewables (mostly electric) are needed. Mind you, the 125 kWh/d includes conversion losses from fossils to electricity. He waits until page 204 to correct that. By that time, the damage has already been done. That image is burnt into the retina of the reader and no amount of foot notes and extra in-depth information is going to change that first impression. You can not count on people reading every word in his book and digesting it correctly. Most people skim the pages to look at the images and read a caption here and there.

    If you then go over to page 204, where he starts factoring in the efficiency gains, and hey, presto: his estimate of necessary energy shrinks to 56 kWh/d (I am not counting pumped heat since this does not need to be generated anywhere). May I ask you a question Matt? What do you think is the amount of clean electricity that Britain needs? 56 kWh/d or 125 kWh/d? If it is 56, then how do you explain the image on page 109, suggesting it is 125? If it is 125, then how come his suggested plans (renewables & nuclear) only account for 56?

    He highlights and clearly explains a convenient unit that helps discussion by making comparisons meaningful- the kWh/day,

    All I have been trying to do here is to show that that is not a meaningful comparison. It completely ignores the fact that you’re dealing with completely different types of energy. It is as suggesting your car can run on milk, because it is sold by the litre, just as petrol.

    He concludes that replacing this energy would take a truly massive investment and a widespread, potentially intrusive deployment of alternative technologies, be they renewables, nuclear, or desert solar power.

    Talking about desert solar power. The image on page 179 is another example of suggestive imagery that I have a problem with. Why show a big yellow square for all 1 billion people in all of Europe and North Africa? I thought the book was about Britain alone. And why show the square twice? Only one would be enough to represent 125 kWh/d for all those people. There is also a small red square for Britain, but be honest, how much of an impact would that square on its own make? And if you scale it down to the 56 kWh/d that he reckons we actually need, you’d hardly notice it. The same applies to the yellow square: it too should be scaled down to be in accordance with his own energy plans.

    A page before that he quotes someone as having said: “All the world’s power could be provided by a square 100km by 100km in the Sahara”. Who said it? When? He doesn’t say, but in the meantime leaves you with the subtle suggestion that renewables advocates are unrealistic dreamers that do not know what they’re talking about. There are more places where he uses other peoples erroneous claims to reinforce his own.

    I have talked before about the sound bite that made it to The Register: “we need to cover the windiest 10% of Britain in wind turbines to power half our cars”. How on earth are you going to move a car on wind energy, if it is not an electric car? If that is the level of in-depth reading from a site that claims to bring you the ‘Sci and Tech news for the world’, than what do you expect from the general public?

    That sound bite is why I sort of focused on the electric car, and the discussion got carried away into other directions. But don’t forget, road transport is responsible for about a fifth of CO2 emissions, it is a major part of the discussion. He has an extensive and informative chapter on electric cars, that is not my issue. It is that he fails to apply his own information, and when he does, it is already too late and the wrong impression has been given.

  29. 429
    Anne van der Bom says:

    Oops, correction,
    “…how much renewables (mostly electric) are needed. ”

    Should read:
    “…how much renewables (mostly electric) are available. “

  30. 430
    Mark says:

    Matt says :

    “If you think Mackay’s got some of his numbers wrong on electric vehicles, you may well be right. But if that’s your main issue with the book, I think you’re spectacularly missing the point,”

    Spectacularly hitting the point that he’s picked bad numbers and presented them as valid. Even if he later and in obscure fashion says so.

  31. 431
    James says:

    dhogaza Says (2 May 2009 at 8:20 PM):

    “Why should I do this for you?”

    A good question. The fundamental reason is, as I stated, because you’re the one stating a position as fact, and therefore, I think, have some obligation to support your position.

    But to go beyond that, you seem to have gotten the notion that Google is some sort of magic answer machine, that will always supply the correct answer to any question that you ask. This is not the case: it’s a useful tool for some sorts of queries, especially if the query can be pin down by some few keywords. It’s not very good at finding general overviews of some particular subject.

    Then to complicate things, you have the garbage problems – there are several. First is that there’s no way (that I know of – I’d be happy to learn otherwise) to exclude inaccessable sources. For instance, I can’t access material that’s behind scholarly journals’ paywalls, or a second hand reference to a book (“GoogleBooks”), yet maybe 8 or 9 of every 10 results will be something like these. Sure, if it’s something I really need, I can e.g. search on the authors of a paywalled paper to see if they’ve posted a copy, but that all takes time.

    Then there’s GA. You’ve of course heard of the GIGO principle – Garbage In, Garbage Out? On controversial subjects especially, Google is affected by the web’s Garbage Added principle, where “true believers” manage to drown out factual material. Consider some of the denialist websites as examples.

    Now some people do seem to have the knack of formulating queries, but I’m not one of them. Maybe you can formulate a query that will return some reasonable amount of relevant material, and give a considered overview of Chernobyl ecology. (That is, not just a few detailed papers supporting whatever point you want to make.) I simply don’t have that skill.

  32. 432

    Re #411 Anne van der Bom

    Huh? My point was that European heads of state must be very concerned with the fact that their prosperity depends on Russia filling their needs for natural gas. Surely you are not telling me that this is rapidly changing.

    Maybe you just meant that concern for global warming is increasing in Europe. I can understand that, but there must also be a persisting, very strong desire to not be dependent on Russia for energy. Unless something very big has happened that got missed by American news reporting, the Russian power over the flow of natural gas still exists. The last Ukrainian natural gas crisis was not long ago, and it was only temporarily settled then, as I recall.

    A related point I have been trying to make is that there are strong forces for energy independence, or “resiliency” as some say, in the USA that are motivated to promote plug-in cars. The problem is that some of these folks have no concern for global warming, hence a plug-in to them could be a plug-in Hummer or a plug-in Fisker. The effect of a plug-in car is not what many think when it comes to global warming.

  33. 433
    Rod B says:

    Another follow-up question on the main post: One of the referenced articles implies (or at least I infer) that the maximum 1000Gt of our emissions is through 2050 and ends there. Implying (inferring?) that the anthropic emissions need to be zero after 2050. The other article speaks of the 1000Gt max by 2050, and also an emission limit for the year 2050 – but doesn’t say what that is (in the Summary). Does that imply constant but ongoing emissions after 2050?

    sidebar with apologizes to Gavin and David: I’m sure your referenced piece is good and I would like to read it, but in no way will I pay $18 to do it. ;-)

  34. 434
    James says:

    Hank Roberts Says (2 May 2009 at 11:57 PM):

    “PS, James, what you’re trying to get at may be what’s explained here:

    No, not exactly. It’s more like for instance the decline in Yellowstone elk populations after wolves were reintroduced. Simplistically, if humans do not “manage” predators – that is, kill off as many as possible – then there will be more of them, and sp they will kill more prey. If the unmanaged predator range is limited (by fiat rather than natural barriers), this will lead to a prey species deficit and probably inward migration.

    “But if you’re trying to argue for protecting the desert ecosystem from development — stick with the solid science, not the handwaving hypotheticals. The Endangered Species Act protections are solid, if you look at the sites carefully.”

    Which demonstrates that you’ve completely missed the point. I don’t really give a damn whether there are endangered species in those places or not. What I care about is keeping them as living ecosystems, not having them scraped bare, sprayed with herbicides, and covered with mirrors.

  35. 435
    Anne van der Bom says:

    Jim Bullis
    3 May 2009 at 2:25 PM

    I can not talk for each and every european leader, but here in The Netherlands and the countries surrounding us, the main drive for investing in renewable energy is climate change. That is what you hear on television and read in the papers. Perhaps in Romania they have a different opinion, since last winter they suffered the consequences of Russia’s quarrel with the Ukraine, but that has not affected our energy supply nor that of our neighbours. I can however imagine that there is a(n unspoken) desire to be independent from Russia, but the talk is all about the climate.

    I am truly surprised by the seriousness and (relative) speed with which offshore wind on the North Sea is now being developed, mainly by Britain, The Netherlands and Germany. Britain now has 600 MW in operation and another 1500 MW under construction and another 5 GW in various planning stages. Same story for The Netherlands, but then properly scaled for the size of our country.

  36. 436
    MikeN says:

    >By more insulation and using heat pumps and storing summer heat under ground for use in the winter, a threefold increase in efficiency does not sound unrealistic.

    It sounds unrealistic to me that you will store heat generated in summer all the way till winter. Could you give us some more detail of how this works?

  37. 437
    Hank Roberts says:

    James, you complain that you can’t get Google to work.

    Try this approach
    — use your own words as the search string:

    If you don’t like the results, try this:
    — talk to a reference librarian. They’re professionals. Their job is to listen to you and figure out how to help you find good information, and how to borrow it if they don’t have it in the library.

    Google is improving its natural language search — you can take your words, paste them in, and get a fair idea what’s available. You will get far more and much more help from a reference librarian.

    Meanwhile, though, from searching Google using exactly your words:

    That’s a review of the science, at the time it was put on the website it was in press for the journal TRENDS in Ecology and Evolution 2006.
    Look it up in Scholar to find the publication date and check citing papers to see who’s used it in later work.

    This isn’t brain surgery.

  38. 438

    Under the heading of “Mostly Likely to Completely Miss the Point”:

    To make these three power sources work well together, you need smart grid concepts, such energy storage and distribution systems. For example, if nuclear is providing 20% of electric generation, it can be run at steady baseline, maximizing fuel efficiency, while all the other variable demand can be met with solar and wind based power that has been fed into storage systems during the peak periods.

    The only difference between “peak demand” and “baseline demand” are their names. Both are “demands”. Once the storage problem has been solved (it has — compressed air, gyroscopes, pumped hydro, storage batteries, thermal salt storage, etc, ad alphabetum), it makes not one whit whether a KWH is “base” or “peak”. If it’s being produced, deliver that, it it isn’t being produced, draw from storage, if it isn’t being used, store it. “Base” and “peak” exist to describe problems with THERMAL generating systems that function most efficiently at thermal equilibrium — fuel in equals electricity out, minus efficiency losses. Changing the throttle setting, as it were, is costly or impractical, so the term “base” exists to describe those generators.

    reCaptcha is suggesting “phonying through” and that is what I see with the debates about “renewable energy” — the problem isn’t the technology, it’s the deployment of the technology (no massive deployment of power storage) that is the concern. Deployment of storage will happen when incentives exist. They do in some areas of the country — I’d love to get on time-of-day billing, I know some solar people who pay nothing for electricity because they time-shift their usage from the grid, and I have the software to do precisely that, just don’t have the incentive because TXU Energy ain’t paying. Likewise, demand-side responsive products (see Carrier ComfortChoice) will fill the market as more utilities offer those incentives. But it is absolutely NOT the case that wind and solar and … can’t do it all.

    Will it be more expensive? The answer to that is “When?” because right now, we have cheap fuel that just so happens to be creating all these problems. When I bought my electric bike, gasoline was $4/gallon and I figured out how much I needed to drive it in order to pay for it with fuel savings — 3 tanks of gas a month. And then gasoline prices dropped and I’d have to ride it a LOT MORE to pay for it. Will gasoline go back to $4/gallon? Sure — so the answer isn’t “No, it isn’t cost effective” it is “It will certainly be cost effective in the future.” And the same holds true for managed renewable energy as the sole source of power in the developed world.

  39. 439
    J.S. McIntyre says:

    re 419 “No viable technology exists to replace this with electricity. The planes will remain on a hydrocarbon diet.”

    But the real question is: Do we need planes? If the argument is we need planes because they save time, then the answer is yes. But if you factor in telecoferencing and so forth, and realize that any change in energy use is probably going to need a serious eveluation of the pace at which we live our lives and do business, than the possibilities of alternatives are worth considering – like dirigibles instead of planes.

    Just a thought … but it seems, ultimately, most airplane travel as it exists needs to go away – and that this can happen.

  40. 440
    Mark says:

    “It sounds unrealistic to me that you will store heat generated in summer all the way till winter. Could you give us some more detail of how this works?”

    Certainly, you generate energy in the summer and quite a bit of that isn’t needed.

    So you store it until Winter.

    That’s how it works.

    Now, this isn’t an answer you want, but you didn’t ask a question that could be answered. Try asking the question you want answered.

  41. 441
    Phil Scadden says:

    Okay Anne, I was working on 24kWh/p/d for real fuel use. You numbers did not square this. Uncharacteristically, MacKay does not source this no. The best I can find from retail fuel figures is more like 14-16 kWh/p/d of fuel. This DOES square with your numbers. Makes the NZ 30kWh/p/d for retail fuel look even worse. Brits are way better than us.

    Thanks for the electric car no.s. So long as battery efficiency over full life of a battery in normal use is around 90% then no issue though that data isnt easy to come by either.

  42. 442
    dhogaza says:

    It’s more like for instance the decline in Yellowstone elk populations after wolves were reintroduced.

    There was no decline for the first several years.

    Simplistically, if humans do not “manage” predators – that is, kill off as many as possible – then there will be more of them, and sp they will kill more prey. If the unmanaged predator range is limited (by fiat rather than natural barriers), this will lead to a prey species deficit and probably inward migration.

    Yellowstone probably had an overpopulation of elk before wolves were reintroduced. (“probably” == “biologists largely but don’t universally agree”). The reduction has led to a “prey species deficit” only if you think that, say, depopulating manhattan would lead to a “human species deficit” compared to the natural carrying capacity of the island.

    Yellowstone had “inward migration” of elk every year before wolves were introduced, and “outward migration” as well. One of each in fall and spring. Still does. “Migration” isn’t the word you want for the concept you’re trying to describe, but is the proper word to use for the seasonal movements of elk in the Greater Yellowstone Ecosystem.

    And it’s not clear that declines that have been seen are due to wolves. Late last century, elk numbers rose dramatically. For the first several years post-reintroduction, the elk population had remained stable. More recently, it’s declined.

    However, biologists are not certain as to how much wolves have impacted the population. There’s been several years of drought (the rise came about during a string of wet years). Human harvest of elk still targets bulls thus has a greater impact on reproductive output per kill than wolves (who kill whatever they can catch).

    Here’s a reference.

    In general, predator populations tend to track prey populations, not the other way around. For instance, jackrabbits have a ten year boom-and-bust cycle. Golden eagle reproductive success tracks this cycle.

  43. 443
    BJ_Chippindale says:

    There is a technical method of mitigating this problem that is far less expensive than “hitting the brakes” as hard as would be required to keep the CO2 from breaking the budget.

    It requires two things. Cheap Access To Space, which has been blocked IMHO, by the interests of companies that are profiting handsomely from the Expensive access we now enjoy. The second of course, is willingness to build the climate controls we need to allow us NOT to be at the mercy of:

    A. The CO2 budget
    B. The Solar Cycle
    C. Cosmic rays

    A set of big and dead simple mirrors in space would do the trick. More complicated controls are possible. Energy collection is possible.

    It doesn’t solve ALL the problems (acid oceans for instance) but it beats by a wide margin the various proposals to alter the atmospheric chemistry still further. It also beats by several rows of apple-trees, the “we’re all doomed” philosophical approach.

    I wish that this would be kept in the forefront of everyone’s arguments about “what to do”… because there’s a different between a feasible and reversible solution and what comes from people who focus is SOLELY on atmospheric chemistry and exclude the Engineers.


  44. 444

    MikeN writes:

    Well switching to these other technologies makes electricity cost more,

    You’re just going to keep on repeating this no matter how many times it’s corrected, aren’t you?

    For the last time: wind power is CHEAPER than nuclear. And DROPPING. Solar is more expensive but is also DROPPING. A solar-wind future will create CHEAPER electricity, not MORE EXPENSIVE electricity.

  45. 445
    MikeN says:

    >the necessity of “hitting the brakes hard” also needs to mean constraining our lifestyles
    >Do we need planes?

    And people think I’m making stuff up about a loss of comfort.

    >Once the storage problem has been solved (it has

    It has? Then why do you write ‘once it has been solved?’
    Perhaps you should inform the wind energy operators of this breakthrough.

  46. 446
    Steve Reynolds says:

    FurryCatHerder: “Once the storage problem has been solved (it has — compressed air, gyroscopes, pumped hydro, storage batteries, thermal salt storage, etc, ad alphabetum), it makes not one whit whether a KWH is “base” or “peak”.

    Except for the issue you are overlooking – cost. Kind of important in the real world…

  47. 447
    Ray Ladbury says:

    BJ Chippindale,

    You’ve got to be kidding, right? Tell me you don’t really think there’s a massive conspiracy to keep launch costs high. Pray, who would benefit from such a conspiracy? Satellite builders? Nope. Launch vehicle builders? Nope, one of their biggest problems is that their volume is too small. The government? Wrong again.

    Do you have even the first notion what is involved in building a launch vehicle that allows a satellite to reach Earth orbit? Do you have any idea what kind of environment your satellites would have to survive in orbit? Have you considered that fuel for attitude control would probably limit the life of your mirrors? Do you have any understanding of the difficulty of deploying large structures in space? Have you given any thought to what happens if your system fails? Where would you put your system? GEO, L1? How many mirrors would be needed and of what size?

    I commend to you the counsel of H. L. Mencken: “Explanations exist; they have existed for all time; there is always a well-known solution to every human problem — neat, plausible, and wrong.”

  48. 448

    #435 Anne van der Bom

    Thanks for the discussion. I think we are making progress.

    I think you probably describe accurately what people are saying in Europe.

    But you also acknowledge, “I can however imagine that there is a(n unspoken) desire to be independent from Russia, but the talk is all about the climate.

    I am truly surprised by the seriousness and (relative) speed with which offshore wind on the North Sea is now being developed, mainly by Britain, The Netherlands and Germany.”

    Perhaps you would not be surprised at all if you were looking at things more from the military-economic historical perspective. In this field of knowledge, Britain, The Netherlands, and Germany, as well as Russia, have long lasting national memories. Russia is as full of bitter memories as any country. In the depths of the cold war we became immersed in the idea that an “evil empire” was being established; while there were some troubling signs of Soviet international ambitions, there were also signs that they remembered how it was to be invaded. That ingrained thinking goes back through history to days of Napoleon, and maybe long before.

    Many are convinced that Germany might have won WWII if they had not run out of oil. Public announcements do not always convey the real motivation of governments.

    In the USA the situation is dramatically different from that in Europe due to past oil abundance, and present coal abundance. In 1924 we began paying oil companies from government funds to pump oil out of the ground as fast as possible. We call it the oil depletion allowance. That took away any lingering motivation to be efficient. Now that oil is drying up, we must shift to coal to keep our inefficient ways in full swing.

    We can continue to drive as big and dumb as we like simply by shifting to electric power. We will call it “green” and “sustainable” and such, but efforts at real efficiency will be tolerated as long as they leave the basic systems in place. Maybe a little wind will power will get built but it seems highly unlikely that it will significantly impact the coal fired system. Thus, the “unspoken” objectives will very possibly not be aligned with the spoken ones.

    And the “smart grid” might help couple in the wind farms, but it will also perpetuate the USA system of central power plants, where much more energy is thrown away than is made into electricity.

    Your reference on Denmark’s energy system showed a very different sort of electricity generation. Clearly, attitudes are different in Europe.

    I wouldn’t be surprised if wind and solar do not develop as rapidly in the USA as they have in the European world.

  49. 449

    #420 Mark,

    Sure, an existing secondary system can be used as long as it is maintained in stand-by readiness. If such are natural gas peaking plants, great, it is just an added cost. I think I did include energy storage with similar stipulations.

    If wind fails over a large area, it does not have to be very often to be a problem if it is depended on exclusively. Rather large European weather systems are well fixed in my fairly recent memory. Usually these are reported as a heat wave but low wind is usually part of it.

  50. 450
    James says:

    Hank Roberts Says:
    3 May 2009 at 3:27 PM

    “James, you complain that you can’t get Google to work.

    Try this approach
    — use your own words as the search string:

    OK, I did that. Using your linked search string, I got about 301K hits. The first 20 break down as follows:

    4 – link to paywalls or book reviews
    4 – links to news articles
    5 – are dated pre-2000, hence not recent research
    5 – are political opinion of one sort or another
    1 – appears to be notes for a course
    1 – is a page of links, lots in Russian or Ukranian, neither of which I read.

    For the sake of argument, I’ll grant that there may be quite a bit of useful information buried in the remaining 300,980 hits, but I just don’t have the time or patience to scan more than the first few pages of returns.

    “If you don’t like the results, try this:
    — talk to a reference librarian. They’re professionals.”

    Err… And on a Friday evening, I’m supposed to hop in the car, drive ~20 miles to the university library (which may or may not be open & have a reference librarian on duty), get the material, and come back & post here on Saturday? When I’ve got a Border Collie poking her head under my typing hand, insisting that it’s time for her walk? You seriously overestimate my capacity :-)