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Ozone impacts on climate change

Filed under: — gavin @ 27 July 2007

In a nice example of how complicated climate feedbacks and interactions can be, Sitch and colleagues report in Nature advance publication on a newly modelled effect of ground level (or tropospheric) ozone on carbon uptake on land (BBC). The ozone they are talking about is the ‘bad’ ozone (compared to ‘good’ stratospheric ozone) and is both a public health hazard and a greenhouse gas. Tropospheric ozone isn’t directly emitted by human activity, but is formed in the atmosphere as a result of photolytic reactions related to CH4, CO, NOx and VOCs (Volatile Organic Compounds like isoprene, benzene etc.) – the so-called ozone precursors.

It’s well known that increased ozone levels – particularly downwind of cities – can be harmful to plants, and in this new study with a carbon-climate model, they quantify how by how much increasing ozone levels make it more difficult for carbon to be sequestered by the land biosphere. This leads to larger CO2 levels in the atmosphere than before. Hence the ozone has, as well as its direct effect as a greenhouse gas, an indirect effect on CO2, which in this model at least appears to be almost as large.

Actually it’s even more complicated. Methane emissions are one of the principal causes of the rise of ozone, and the greenhouse effect of ozone can be thought of as an indirect effect of CH4 (and CO and VOCs). But while NOx is an ozone precursor, it actually has an indirect effect that reduces CH4, so that the net impact of NOx has been thought to be negative (i.e. the reduction in CH4 outweighs the increase of ozone in radiative forcing – see this paper for more details). This new result might prompt a re-adjustment of that balance – i.e. if the ozone produced by NOx has a stronger effect than previously thought (through this new indirect mechanism), than it might outweigh the reduction in CH4, and lead to NOx emissions themselves being a (slightly) positive forcing.

In a bizarre way this is actually good news. There are plenty of reasons to reduce NOx emissions already because of it’s impact on air pollution and smog, but this new result might mean that reductions wouldn’t make climate change any worse. It also, once again, highlights the role of CH4 (the second biggest GHG forcing), and points out a further reason (if that was required) why further methane reductions could be particularly welcome in moderating future changes in climate and air quality.

243 Responses to “Ozone impacts on climate change”

  1. 201
    Lynn Vincentnathan says:

    #189, I think my response in #82 was a bit rude, so I apologize for that. However, I will stick to my guns about reducing GHGs in the U.S. cost-effectively….up to a 2/3 reduction. This, however, means that in addition to the many many “no cost” solutions (as per #109), in order to make such drastic cuts we will need to put up some money on energy/resource efficient/conservative measures, many of which will eventually pay for themselves in savings, and many of which will go on to save even more (like SunFrost refrigerators, ).

    If the government puts more tax on oil/coal (or better yet, reduces their tax-breaks and subsidies — which I think they just decided to do, but Bush promises to veto), this will cause gasoline & coal-based energy to increase in price, which hopefully will cause people and businesses to implement measures to reduce consumption cost-effectively. I suppose those who still refuse to do so then would be losing money. But I don’t have tons of sympathy for them. We’ve known about global warming for 20 years, and we’ve known about the cost-effective measures, and they really should have started reducing much sooner (for economic reason, if not for the sake of their kids’ future).

    My grandmother (born 1887) used to save string and do many many conservative things; in just a few generations we have become a very liberal (with Earth’s goods), profligate society.

    RE “truth may lie somewhere between, hence my Q2:
    “how do we apportion this [1970.0-2000.0 warming] between CO2, the Sun, and other causes…”

    The way I approach that issue (as a non-scientist) is to look at the component I can change, then make changes (reducing my GHGs). Can’t do much about the sun or volcanoes. However, my thinking is that if the sun or volcanoes were to start contributing to even greater warming, then it would behoove us all to reduce our GHGs even further — maybe even sacrifice drastically to do so — because we’d not only need to reduce our own contributions to the warming, but try to off-set those of the sun/volcanos. So the idea that the sun may start increasing in its irradiance (which seems it could…all the skeptics keep bringing it up), then we need to reduced our GHGs all the more.

  2. 202
    Alan K says:

    sorry to prolong this thread (maybe I’m the only one left on it now) but given the length of forecasts we are dealing with, the supposed huge difference in effect on humanity of a matter of tenths of a degree temperature change and the magnitude in 100yrs time of a very small lessaccuracy today, I think inaccurate and less accurate can be used interchangeably.

  3. 203
    Lynn Vincentnathan says:

    RE my recent comment re #189, I had another idea.

    One of the reasons (I guess) why businesses don’t implement energy/resource conservation/efficiency measures is that the costs are artificially low bec of the subsidies and tax-breaks on fossil fuels. So they focus on labor to increase profits — less raises, layoffs, less benefits, disappearing pension funds, out-sourcing, etc.

    Now if the government were to take some of the money it saves from reducing the tax-breaks and subsidies to fossil fuels, it could redirect that to labor costs in some way….providing, say, some medical insurance (reducing the amount employers have to pay) or tax-breaks to businesses for employing people. Jobs would not have to go overseas as much.

    Meanwhile, with the money businesses save, they would more easily have up-front money for energy/resource conservation/efficiency measures, that would go on to save them even more.

  4. 204
    Lynn Vincentnathan says:

    RE #189, & Null hypothesis (H0) = no global warming from anthropogenic CO2 since 1970
    Alternative hypothesis (H1) = all global warming since 1970 is from anthropogenic CO2. Then #82’s 1-4 become:
    1. False Positive = decide H1 but H0 is true = Type I error, with probability alpha
    4. False Negative = decide H0 but H1 is true = Type II error, with probability beta
    2. True Positive = decide H1 and H1 is true, with probability 1-beta
    3. True Negative = decide H0 and H0 is true, with probability 1-alpha

    Another thing I sometimes bring up here is the enivornmental victims’ perspective, which would be opposite the scientists’. The idea that we need .05 or .01 significance (95% confidence) that AGW is happening (or that poison will kill us, or the lump is cancerous) to accept that it is happening is an unwise approach….albeit scientists have to follow this path to maintain their reputations & not become “the boy crying wolf.” We as lay persons living in the world do not.

    I propose that for us the null hypothesis should be that AGW IS happening & is harming (will harm) people, and we only stop mitigating if we become 95% confident or reach less than .05 probability that the null hypothesis (AGW is happening) is wrong, before we reject it for the alternative hypothesis (that AGW is NOT happening). I call this the “medical model” as opposed to the “scientific model” above.

    OTOH, we may not want to stop mitigating even if we reach 95% confidence AGW is not happening, due to all the money we save & all the other problems we off-set from mitigating. But we can at least celebrate.

  5. 205
    Jim Eager says:

    Re 171 Alan K: “If they are constantly updated then the moment before they are updated they were presumably inaccurate.”

    Change the wording to “less accurate” and you change the meaning of what you wrote to more accurately reflect reality.

  6. 206
    Alan K says:

    ho hum and back we are at the beginning. GCMs, it transpires, are “updated” to reflect the real world once they have been checked and found to be less accurate.

    I am near begging now for the moderator to ban me from this thread.

  7. 207
    Jim Eager says:

    Re 206 Alan K: “I am near begging now for the moderator to ban me from this thread.”

    Why, you’re harmless?

  8. 208
    Nick Gotts says:

    Re #206 [ho hum and back we are at the beginning. GCMs, it transpires, are “updated” to reflect the real world once they have been checked and found to be less accurate.]

    I could be wrong here, but it seems likely from your wording in #198: “Imagine a climate model was “updated” to correct, say, a 0.5% inaccuracy today. Imagine that error hadn’t been corrected. What would the magnitude of that inaccuracy be after 100 years?”
    that you misunderstand the kind of updating that is going on. GCMs are not updated to fit a new estimate of climate sensitivity, or what’s happened to the weather or climate since the last updating, i.e the modellers are not saying anything like “Oh, we predicted a .02 rise in global mean temperature over the last year, and we got .01 [or .03], we’d better change the model”. The updating is to reflect changes in the understanding of specific processes such as cloud formation or glacier flow. As such changes have been made, the ability of models to reproduce past conditions has generally improved – but this is not a foregone conclusion, it has to be tested in each case. Improved ability to reproduce past conditions increases confidence in models’ ability to make conditional predictions about the future, i.e. predictions assuming that greenhouse gas emissions and other relevant factors follow certain trajectories. However, modellers do not rely on a single run of their model, or a single set of parameters; and the conclusions drawn from GCMs do not rely on a single model. The broad agreement between models indicates that the kind of instability in the face of small changes to initial conditions or model parameters which you seem to assume, isn’t a real problem. Of course there may be important processes that are not included or are misrepresented in current models – for example, related to ice sheet stability, as explicitly noted in the IPCC’s AR4. It would be most unwise to assume that any such processes will reduce rather than increase the dangers we face. In any case, what’s the alternative to acting on the basis of the best models we have? Stick our heads in the sand and hope the problem goes away?

  9. 209
    James says:

    Re #194: [It is odd why business leaders allow so much waste. Even more odd why Chief Financial Officers do not insist on a monthly waste account…]

    Apropos of which, this factoid from the current employer’s company newsletter: “XXX’s energy conservation programs from 1990 – 2006 also saved 4.5 billion kilowatt hours of electricity and $291.1M in energy costs”. It is a pretty large company, but adding an extra $17 million per year to the bottom line is still appreciated :-)

  10. 210
    Hank Roberts says:

    Alan, you’re misreading what’s written. GCMs are updated to reflect the _physics_ as our understanding of the real world improves.

    Nothing in the deep past happened as fast as current climate change is happening, except the one big asteroid impact event; see the current Scientific American article and Peter Ward’s current book.

  11. 211
    Chuck Booth says:

    Re Alan K and his repeated posts about GCMs (207, 198, etc)

    Funny thing about human knowledge – it just keeps increasing. As much as we think we know now, we can be certain that we will know more tomorrow, and still more the day after that, and so ad infinitum.

    No one ever said current GCMs are perfect – nothing in the natural world ever is perfect – there is always room for improvement. Sure, the potential for erroneous forecasts increases the further you extrapolate. But, it’s safe to assume that models will improve with time long before we find out if last year’s long-range predictions we accurate, or not. Modelling is an iterative process, so as they keep improving, the long-range forecasts keep getting pushed further and further into the future. But, surely you know this?

  12. 212
    Lynn Vincentnathan says:

    RE #211, of course we could follow a business-as-usual path and see how much damage AGW does over the centuries — which is our current national strategy here in the U.S. Then we wouldn’t need models or other predictive tools. We’d be 100% certain.

    Of course, there might not be any scientists left to document it, since people may have been reduced to scrounging around for survival & all institutions of higher learning long since closed.

    But if 100% certainty about AGW & its harms is required, which many seem to want, that’s the way to go. Though I’d never suggest doing that.

  13. 213
    Rod B says:

    re O3: Well, I guess. I don’t quite understand how other analyses (the effect of CO2 vs. H2O on GW, e.g.) rely on water vapor not getting into the stratosphere, but now it’s up there in spades to destroy ozone. Doesn’t the photodissociation of H2O take higher UV energy than for O3? (Or is the OH-1 made some other way.) I’m confused. But then I understand little here… just sounds strange and a little convenient.

  14. 214
    Rod B says:

    Lynn, so now your going to throw a couple of “null hypotheses” and a few alphas and such to convince me the economy will be better off if we fully mitigated AGW even though we would find out that it wasn’t real… [;-}

    How much beyond the ~$100 billion of (all) taxes Exxon-Mobil paid in 2006 would they pay if we cut their subsidies?

  15. 215
    Hank Roberts says:

    What’s your source for what you believe, Rod?

  16. 216
    J.C.H says:

    That would be their applicable tax rate times the subsidy cut.

  17. 217
    Tim McDermott says:

    Imagine a climate model was “updated” to correct, say, a 0.5% inaccuracy today. Imagine that error hadn’t been corrected. What would the magnitude of that inaccuracy be after 100 years?

    This is really interesting. Alan K, do you suppose that the climate models are spreadsheets doing compound interest?

    If, in fact, the models reacted in an accelerating way to any small change, they would be telling us that we are about to go over a tipping point. The typical behavior of an interated systems is to have relatively small change for relatively small changes. But as the system approaches the edge of a basin of attraction, it starts responding much more dramaticly to small changes.

    I have occasionally had the odd of esxperience of discovering that the person I’m talking to doesn’t define the words we are using the same way I do. (especially distressing when I took a job based on that conversation) It may well be that many of our drive-by scolders just don’t grok science.

  18. 218
    Hank Roberts says:

    No, serioiusly, Rod, where do you get the belief Exxon-Mobil paid a hundred million dollars in taxes?
    Just made the number up?

  19. 219
    Tim McDermott says:


    The link you provided to Exxon (XON) financial data shows that for ’06, XON had revenue of 377.6 billion, profit before taxes of 67.4 billion, and profit after taxes of 39.5 billion. That means they paid 27.9 billion in taxes. Of course this likely includes the gasoline tax, their portion of employees’ social security, real estate taxes, etc.

    That’s a lot of money, but they made, after tax, almost 32 million an hour in ’06.

  20. 220
    Chuck Booth says:

    Re 219 Exxon taxes

    U.S. Energy Bill Showers Tax Breaks on Oil Drillers, Utilities
    By Jim Efstathiou Jr.

    July 29, 2005 (Bloomberg) — The energy bill Congress is set to pass today will spread $14.5 billion in tax breaks among hundreds of U.S. companies.

    Exxon Mobil Corp., ConocoPhillips and other oil and gas producers get incentives to drill wells in the deepest waters of the Gulf of Mexico. Utilities including Southern Co. and American Electric Power Co. gain support for building coal and nuclear plants, and power-line owners such as American Transmission Co. benefit from tax changes. A mandate to boost the amount of corn- based ethanol in gasoline aids Archer Daniels Midland Co.

    “There are a lot of pigs at the trough and the pigs got fat,” said Philip Verleger, a senior fellow at the Institute for International Economics in Washington. “It’s the way politics works in the United States.”

    Environmental and consumer groups say the package is a giveaway with oil prices near $60 a barrel are generating record oil company profits. Exxon Mobil earned $7.64 billion in the second quarter, the company said yesterday. The past three quarters were the most profitable ever for the company.

    The U.S. House passed the bill by a vote of 275 to 156 yesterday afternoon. The Senate is scheduled to vote on the measure today after debating it last night.

    President George W. Bush, who has been seeking an energy bill since he took office in 2001, said last month he favored a less expensive package. He still plans to sign the bill. Energy Secretary Samuel Bodman this week called it a “common sense” measure to help meet the country’s energy needs.

    Oil companies such as Exxon Mobil and utility owners such as Southern spent $367 million over the past two years lobbying Congress on energy legislation, according to data from PoliticalMoneyLine and the Center for Responsive Politics. The legislation contains tax breaks of $1.6 billion for oil and gas producers and refiners and $3.1 billion for utilities….

  21. 221
    Rod B says:

    Hank,it’s 100billion, which I got from their annual report. Remember Income taxes (State and Federal, etc.) are less than half of the total taxes paid. Tim’s $28B is only income taxes.

  22. 222
    Tim McDermott says:

    XON’s 2006 summary annual report (page 40) says that they paid 30.4 billion in sales-based taxes, 39.2 billion in other taxes and duties, and 27.9 billion in income taxes. Grand total is 97.5 billion. That’s a lot. I wonder how much of that was paid in the US?

  23. 223
    J.C.H says:

    Just curious, does that 100 billion include the gasoline tax that consumers pay at the pump?

    Or the royalties paid to the government for the extraction of product from land the government owns?

    Or the sales tax people pay on their coffee?

    I have all my annual reports. What year, what page?

  24. 224
    Tim McDermott says:

    OK, I screwed up the link (why don’t we have a preview button any more?) It is

  25. 225
    J.C.H says:


    So they remit the tax I pay them at the pump to the appropriate government entity. So what? I’m the one who pays that tax, not ExxMob. What ExxMob pays is the expense of collecting that money from me – like any other business.

  26. 226
    Rod B says:

    JCH, I don’t know for certain, but a really good guess is that the gas tax paid at the pump is included (as (as is the comparable revenue), sales tax not — it’s paid by the retailer, not by XON-MOB and not included in gross revenue, and royalties not — that’s not a tax but a cost of production like the royalties they pay to everybody else. There are also numerous other taxes that they pay.

    I’m not in favor of the subsidies either, though I might support them for smaller upstart enterprises on an ICB. Nor do I support giving subsidies then taking it back with the demagogic excess profits tax which Congress imposes every few years, usually close to elections, then later usually retracts as being stupid. It’s ignorant to demonize them to the furthest extreme.

  27. 227
    Hank Roberts says:

    Million, billion …

    My point being — cites, please, gentlement.
    It’s the assertions of belief without a reference that amount to asking for help with homework; checking before posting gives one a chance to accumulate some credibility.

    I don’t care if your number is big or small. I care if it’s based on facts I can look up.

  28. 228
    J.C.H says:

    ExxMob owns a substantial number of retail outlets, so they do transfer the sales tax from the consumer to the applicable government, and that would be in those numbers.

    Claiming that ExxMob pays 100 billion in taxes is fuzzy math. As a longterm investor in ExxMob, which I am, I am only concerned with the demand side of a flow-through number on a transaction tax. If an excise tax is high enough to thwart demand, then it could significantly reduce ExxMob’s federal income tax liability, and that would be horrible.

    All ratios remaining the same, as a shareholder I would love it if that 100 billion you’re talking about was 500 billion as I would be 5 around times as rich.

  29. 229
    Ike Solem says:

    What are the sources of surface ozone? Emissions from vehicles, industrial processes, and vegetation fires. here is a good discussion of tropospheric ozone formation from NOx and VOC precursors, and Here is a good, non-technical educational video on ozone formation.

    Coal-fired power plants account for 25% of the emissions in the US. There are two ways to form NOx from burning fossil fuels in air – one is to add oxygen to N atoms present in the coal, and the other is to split the very stable N=N bond of atmospheric N2. Not only that, there’s the sulfur oxides, arsenic and mercury.

    There really is no way to use coal safely. The sequestration schemes are highly energy-intensive, meaning that if 90% CO2 capture at coal fired plants was put in place, an ~40% reduction in power output would result.

    Nevertheless, DOE is spending several billion dollars on their FutureGen project, a collaboration with coal companies and electric utilities that aims to build an emission-free coal-fired power plant that will sequester millions of tons of CO2 in a geological formation. In contrast, their budgets for similar-sized solar and wind projects are non-existent. Not only that, but they are taking a restrictive approach to intellectual property that is keeping China and India from being very interested.

    The fact of the matter is that most of the coal reserves will have to be left in the ground, unburned. However, politicians and the coal industry (dirty and dangerous, as the latest coal cave-in demonstrates) still refuse to acknowledge this basic fact. In fact, the owner of the mine used the accident as an opportunity to lobby against global warming action.

  30. 230
    Lynn Vincentnathan says:

    #214 RE doubts about the economy will be better off if we fully mitigated AGW even though we would find out that it wasn’t real… “

    I didn’t say “fully” mitigate AGW, only reducing here in the U.S. up to, say, 2/3 our GHGs, perhaps more. However, for those who doubt even this, I would suggest we start by reducing 10% of our GHG cost-effectively. Then once we get our feet wet, try for another 10%.

    OTOH, Amory Lovins suggests in some instances of how “tunneling through” can get us more drastic reductions cost-effectively, for instance, by designing the building in the first place so it doesn’t even need air conditioning (you’ve got to read NATURAL CAPITALISM to see what I mean).

    And you’ve got to keep in mind all the other problems the measures will off-set….a more thorough cost/benefit analysis, holding the GW factor a constant (= 0) to analytically tease out the cost/benefits beyond the GW factor. Of course, when you add in the GW factor, then we should have done all these things 20 years ago…..We’ve been completely remiss on this.

  31. 231
    Rod B says:

    Hank, the annual report isn’t “cite” enough for you??

  32. 232
    Nick Gotts says:

    Re #229 [The sequestration schemes are highly energy-intensive, meaning that if 90% CO2 capture at coal fired plants was put in place, an ~40% reduction in power output would result.]

    That’s too pessimistic, at least according to the IPCC’s “Special Report on Carbon Dioxide Capture and Storage” of September 2005. In the SPM, p.4, the Working Group say:
    “Available technology captures about 85–95% of the CO2
    processed in a capture plant. A power plant equipped with
    a CCS system (with access to geological or ocean storage)
    would need roughly 10–40% more energy than a plant of
    equivalent output without CCS, of which most is for capture
    and compression. For secure storage, the net result is that a
    power plant with CCS could reduce CO2 emissions to the
    atmosphere by approximately 80–90% compared to a plant
    without CCS…”

    In a footnote, they say:
    “The [10-40%] range reflects three types of power plants: for Natural Gas Combined Cycle plants, the range is 11–22%, for Pulverized Coal plants, 24–40% and for
    Integrated Gasification Combined Cycle plants, 14–25%.”

    (For clarification, IGCG plants use coal.) Even if we take the higher figure for pulverized coal plants, that’s 40% more fuel for the same output, which is slightly under 30% reduction in efficiency. The lower figure for IGCG plants gives less than a 13% reduction in efficiency.

    The AR4 WGIII SPM, p.18 says “CCS in underground geological formations is a new technology with the potential to make an important contribution to mitigation by 2030.” Since India and China in particular are going to be burning a lot of coal, we’d better hope they’re right – and that the US DOE abandon the restrictive attitude to intellectual property you rightly censure. I’m not saying CCS is the answer – as I’ve said before, I don’t believe any combination of technologies is going to allow the rich to continue their current lifestyles, particularly with respect to air and auto transport, meat every day, and ever more power-hungry electronic gadgets, in a way compatible with avoiding dangerous climate change. But for China and India particularly, I don’t see a feasible alternative any likely government would adopt voluntarily, and they’re too well-armed and economically important to be forced to do so.

  33. 233

    [[OK, I screwed up the link (why don’t we have a preview button any more?) ]]

    Thanks to Tim for bringing this up. The lack of preview makes it much easier to incorporate unseen mistakes in posts now. Why did RealClimate fix something that wasn’t broken? Please bring back preview.

  34. 234
    Hank Roberts says:

    They’re working on it, Barton; the blog software changed recently, and tweaking is still being worked out. Remember back when all the comments loaded along with the original post instead of separately as a popup window, killing people with slow connections by forcing everything to come at once? It’s incremental fixes.

    I gather it’s how they spend their weekends, when others are out looking for barbeque grills (grin).

  35. 235
    David B. Benson says:

    Re #232: Nick Gotts — If you would follow

    you would read, for example, that China recently announced they will invest $US 2 billion to build 100 biomass fired power plants in the interior, eventually displacing 10% of their use of coal.

    Similar news reports from India, Southeast Asian countries, Africa and South America, although all of those projects are much smaller…

  36. 236
    alvinwriter says:

    Nature has always had a way to offset excess greenhouse gases like carbon dioxide from the atmosphere. Not only does algae in the Arctic do the job quite well, but also melted ice, which also absorb it.

    Melted Sea Ice Absorbs Carbon Dioxide:

    I’m writing in from TheScienceDesk at TheNewsRoom. We have a group of users interested in global warming who have found great content they have used online. You can also do the same. Email for details. We’ll be glad to hear from you!

  37. 237

    [[Nature has always had a way to offset excess greenhouse gases like carbon dioxide from the atmosphere. Not only does algae in the Arctic do the job quite well, but also melted ice, which also absorb it.]]

    The natural sinks are not enough to absorb all the carbon dioxide human technology puts out, which is why the carbon dioxide content of the air around us continues to rise.

  38. 238
    alvinwriter says:

    Here’s an interesting contest that has a $100,000 prize money to whoever proves that global warming is anthropogenic:

    What entry would you give?

    – Alvin from TheScienceDesk at

  39. 239
    alvinwriter says:

    There are plenty of natural carbon sinks and most of these already contain tons of carbon dioxide, especially volcanic lakes. Sometimes, these sinks release carbon dioxide at a brisk pace. It happened in Africa before when a lake there suddenly released a cloud of carbon dioxide which killed all those within the vicinity, it being a heavy gas that kept close to the ground.

    The carbon dioxide released into the atmosphere by people come from natural reserves of fossil fuels. These fuels will soon be exhausted since their volume is finite. When that happens, I think this issue of global warming will subside. Frankly, I would want artificial carbon dioxide emissions minimized, I would want a clean atmosphere with a suitable balance of gases just right for people and all the other organisms that they share the Earth with.

    Otherwise, if global warming activists are right about possible disasters due to global warming, maybe we should prepare. The construction of a seed depository in a mountain is one way of ensuring food supplies in the future. Read about it in this link to TheNewsRoom:

    – Alvin from TheScienceDesk at

  40. 240
    Nick Gotts says:

    Re #235 [If you would follow

    you would read, for example, that China recently announced they will invest $US 2 billion to build 100 biomass fired power plants in the interior, eventually displacing 10% of their use of coal.]

    The story itself is at
    Potentially good news, but the article seemed to be based on unnamed “sources”. And the writer apparently thinks sweet potatoes are a non-food crop! (Mentioned in the context that the Chinese government has, according to the article, banned corn-to-ethanol conversion). And of course one would need to know what the land devoted to biomass was used for previously, what the inputs are, etc.

  41. 241
    Nick Gotts says:

    re #239 [These fuels will soon be exhausted since their volume is finite. When that happens, I think this issue of global warming will subside.]

    If this is the level of argument found on “TheScienceDesk at”, I won’t be visiting any time soon. Just because something is finite, doesn’t mean it will be exhausted “soon”. The sun’s supply of hydrogen is finite, but is going to last a couple of billion years. There’s certainly more than enough accessible fossil fuel to cause disastrous climate change if we keep burning it at anything approaching the current rate.

  42. 242
    alvinwriter says:

    re #241
    Hi, Nick! Of course. The fossil fuels we’re using came from forests like those which dominated Devonian times 350 million years ago. That time, a cooling trend was happening. It’s likely due to the rate at which carbon dioxide was used by the fern forests which were then quick to spread. Volcanic activity was what was releasing carbon dioxide then. When the forests subsided and died off, these became the fossil fuel reserves we now use today, with carbon doioxide which was once already in the atmosphere courtesy of ancient volcanos. If the reduction of carbon dioxide in the atmosphere was responsible for the cooling then, it is possible that by releasing the CO2 back into the atmosphere, a warming trend will be experienced again. Will more carbon dioxide cause more trees to grow again, like what happened in Devonian times? Studies show that trees do grow faster if the air is more saturated with carbon dioxide. But it would take a lot of trees to effect a change in the atmosphere. There are just too few of them left, sadly.

    Drilling could unearth global forecast:

    Scientists test trees’ ability to combat more carbon dioxide:

    Oldest tree fossil found, scientists say:

    TheNewsRoom is all about news. You may want to see how it can work for you. I invite you to email if you want to partner with it for licensed news you can use. We’ll be glad to hear from you.

    – Alvin from TheScienceDesk at

  43. 243
    ClimateCriminal says:

    There is an interesting interview with interview with Dr Chris Rapley, former Director of the British Antarctic Survey, now Director of the Science Museum in London.