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By Robert Rapier on Mar 5, 2012 with 32 responses

Study: Eliminating Coal-Fired Power is Worth 0.2 Degrees in 100 Years

Who could have dreamed solving climate change would be so easy? A new paper in Environmental Research Letters called “Greenhouse gases, climate change and the transition from coal to low-carbon electricity” concludes that replacement of all of the world’s currently operating coal-fired power plants — which produce about 40% of the world’s electricity — and replacing them with renewable energy would have an impact of 0.2 degrees Celsius 100 years from now.

Cherry-Picking Conclusions According to One’s Viewpoint

However, a number of climate change websites took away a very different message than I took away from the paper. Here is Joe Romm’s view:

Bombshell: You Can’t Slow Projected Warming With Gas, You Need ‘Rapid and Massive Deployment’ of Zero-Carbon Power

I seem to recall another “bombshell” that he recently reported upon on the same theme: Natural Gas Bombshell: Switching From Coal to Gas Increases Warming for Decades, Has Minimal Benefit Even in 2100. I debunked that by showing that in that particular study, every possible alternative — including wind power, solar power, and even simply shutting down all of the coal plants — was projected to increase global warming in the short term: BOMBSHELL: Solar and Wind Power Would Speed Up, Not Reduce, Global Warming.

But Joe is back with the hyperbolic titles and exaggerations (which I get into below), and he missed the biggest story in the paper.

Coal and Sunlight-Reflecting Pollutants

The subject of Romm’s earlier “natural gas bombshell” was a paper written by Tom Wigley that concluded that shutting down coal-fired power plants would cause the global temperature to increase in the short term because of the loss of sunlight-reflecting pollutants.

In that particular paper, Dr. Wigley modeled what would happen if coal-fired power was replaced with natural gas. He did indeed project short-term warming in that scenario, yet it was a result of the air becoming cleaner and allowing sunlight through as the coal was phased out. Thus, the media really got that story wrong, which was not about a deficiency of natural gas, but rather about the peculiarity of burning coal — that the particulate emissions reflect sunlight. Those who fixated on natural gas as the culprit could have written the same story about solar power — which the study’s author confirmed for me. Hence, I made that my “Bombshell” to illustrate the point.

However, that particular study didn’t actually model the temperature impact of shutting down coal plants and replacing them with anything other than natural gas. So, I posed the following question to Dr. Wigley:

What does the graph look like in 2100 if all coal-fired plants were replaced with zero emission sources (as the idealized study)? I am just wondering what the potential actually is. Are we talking about 1 or 2 degrees lower? I just have no idea of the relative context.

We had several email exchanges over his paper, and he said that my questions were intriguing and he would look into them. I never heard back from him on that, but this new paper answers the question.

Shuttering All the World’s Coal Plants Wouldn’t Do Much

The authors of this newest study modeled the replacement of coal-fired power plants with either natural gas, coal with carbon capture and storage, hydropower, solar PV, solar thermal, wind power, or nuclear power.  You can see from Joe Romm’s headline how the story is being spun, but let’s break it down in a more objective fashion.

The following graphic from the paper tells the story. Pay particular attention to the temperature scale.

The graphic indicates — as Tom Wigley’s previous paper indicated but which was only reported relative to natural gas — that in every single case, it doesn’t matter what coal-fired power plants are replaced with, the temperature is projected to increase for almost the next 40 years. This is true even in the baseline “Conservation” case, which involves merely idling the coal-fired plants and not replacing them with anything.

The paper projects that if coal-fired power plants continue to operate, the expected temperature rise relative to the baseline (i.e., relative to the expected temperature increase from other sources) in 50 years is 0.15 degrees C, and in 100 years is about 0.33 degrees C. If coal is phased out and replaced with natural gas, the relative 50 and 100 year temperature rise is projected to be 0.14 degrees C and 0.24 degrees C, respectively. So the paper shows slightly less warming when natural gas is used, which Climate Progress Tweeted as “Switch from coal to natural gas would have zero effect on global temperatures by 2100” and included a link to Joe’s “bombshell.” That is obviously an exaggeration, as the graphic clearly shows that the effect is not zero. If it was, the natural gas line would overlay the coal line.

Shocking Implications

One shocking implication from the paper was the projection that hydropower would be worse than coal for the next 60 years. The study’s authors cited methane emissions from organic matter buried under water as the reason for this apparent anomaly. But that’s not the really shocking thing about the study for me.

The most shocking conclusion was the magnitude of the numbers we are talking about. Even if you could in theory shut down all of the coal-fired power plants in the world and replace them with wind, solar, and hydropower — in 50 years the projected temperature is only one-twentieth of a degree C cooler than the base case of continuing to use coal. In 100 years, if I could replace all global coal-fired power plants with firm, renewable power — the temperature is only projected to be about 0.2 degrees cooler than under the coal base case. And the way this is being spun is that the 0.09 degree reduction from switching to natural gas is equivalent to an effect of “zero”, but the 0.2 degree reduction in hypothetically replacing everything with wind and solar power 100 years from now is significant. About the natural gas case, Romm literally said the 0.09 degree lower temperature in switching to natural gas means that “natural gas is a bridge fuel to nowhere”, but the 0.2 degree lower temperature in switching to renewables is “the world’s only plausible hope to avert catastrophic temperature rise.”

I saw comments from some climate change advocates who expressed shock at how small the numbers were, but then they were reassured that this was for only a small portion of the world’s coal usage. So let’s debunk that argument in a crystal clear fashion. From the paper:

To illustrate the consequences of rapid deployments of new energy systems, we considered emissions from a variety of linear energy system transitions, each of which replaces 1 TWe of coal-based electricity by bringing new LGE power plants online at a constant rate over a 40 yr period. (1 TWe is the order of magnitude of the global electrical output currently generated from coal.)

So the paper is suggesting that their projections are if all of the presently running coal-fired power plants were shut down and replaced. In fact, I doubled checked this. Per the BP Statistical Review of World Energy 2011, global electricity production in 2010 was 21,325 terawatt-hours (TWh). About 40% of global electricity production comes from coal power, so that makes 8530 TWh from coal. There are 8760 hours in a year, so it will require (8530 TWh/8760 hours) = 0.97 terawatts of power (TWe) to replace all of the world’s coal production. Thus, the 1 TWe used in the paper is consistent with a total replacement of current (but not planned) coal power. Even if this were possible, the study projects a mere 0.2 degree C lower temperature in 100 years relative to producing electricity from coal at current rates.

Nuclear & Natural Gas to the Rescue — But Most Environmentalists Hate Them

A big irony here is that there are only two power sources that are today capable of achieving the study’s conclusion that we must rapidly replace coal-fired power plants: Nuclear power and natural gas. If people really believe that we must urgently address this issue — and they don’t believe that the change from going to natural gas is enough — that leaves nuclear power as the only option capable of achieving a rapid replacement.

Bear in mind that this is for a global replacement of coal — most of which is used in Asia. Good luck trying to sell China and India on a 0.2 degree temperature difference in 100 years if they quickly abandon their coal-fired power plants and replace them with wind power.

Conclusion: Study is a Major Downer for Activists Battling Climate Change

To be honest, if I was devoting my life to fighting against the threat of climate change, this would be one of the most depressing papers I have ever read. If we could convince everyone in the world to shut down their coal-fired power plants — which we can’t — and replace them with renewable power — which isn’t available in quantities sufficient to replace coal-fired power — then by the end of my life there would still be no statistically significant temperature change to even be able to tell if my life’s work was successful.

But let’s be realistic, shall we? The people who are concerned about global warming have dug in their heels over natural gas, and they are generally opposed to nuclear power. Because of the sheer impossibility that we will rapidly replace coal with wind and solar power (especially since “we” is the world), then we will in all likelihood be left with the status quo. As I have said before, emissions are much higher in Asia Pacific than they are in the U.S. and Europe combined, and they are rising rapidly. Unless we can figure out a way to convince them to develop without fossil fuels — something no country has done — then global carbon emissions will continue to rise. This is why — even though I accept the science behind climate change — it isn’ t my focus. I just don’t see how the West can possibly do anything about it.

One final note about the temperature change reported upon here. I am honestly shocked at the very small difference between the coal status quo and a replacement with renewables. However, one thing to keep in mind is that this is based on current production of coal-based power (and is relative to some underlying projected level of temperature increase that is larger than the 0.2 degrees discussed here). So this temperature difference is reflective of a baseline of keeping coal-based electricity production at the current level for 100 years. If Asia Pacific continues to ramp up their production of power from coal, this will obviously have a larger impact on the expected temperature rise in 100 years. But this ramp-up is likely to run head-on into resource shortages before it gets too far along.

  1. By Raindog on March 5, 2012 at 8:06 am

    Robert – I read that  paper and was confused. The  y-axis on those graphs is the temperature change per 1 TWe.  Coal  currently produces 8 TWe. So multiply by 8.

    Your point about Romm is correct though.  Anything to make gas look bad.  He is more driven by hatred of oil companies than he is by wanting to stop global warming.  This is true for many.  And I agree that the real bombshell is hydropower – something that is classed with renewables – is worse that coal over a 60 year period according to this paper.


    • By Robert Rapier on March 5, 2012 at 11:35 am

      The  y-axis on those graphs is the temperature change per 1 TWe.  Coal  currently produces 8 TWe. So multiply by 8.

      No, I addressed that. That paper said that the world’s current coal power is 1 TWe. I cross-checked that myself with the BP statistical review and got the same number. Where are you getting 8 TWe?


  2. By Raindog on March 5, 2012 at 8:30 am

    I should clarify – to get the predicted warming saved by replacing coal with a different energy source, multiply the y-axis value by 8.  Many have been confused by this.  I am not sure why they didn’t just do it for all coal. 1.8C warming would be saved by switching all coal to wind and solar while only 0.4C would be saved by switching to gas.

    Romm and some others don’t seem to get the meaning  of “bridge fuel.” A bridge fuel means that you use it as a bridge from one form of energy to another.  You use gas as a bridge while you build up wind and solar and whatever else comes along.  And these graphs show that would be a good idea. 

    You can tell Romm’s real motivating force is a hatred of oil companies by the kinds of posts he puts up.  Some are about climate change, but more than a few are about gas prices being too high.  Nothing will lead to conservation and lower emissions in the transportation sector than high gas prices. He should be cheering high gas prices if climate change is his main concern. The fact that he is apparently against high gas prices tells the true story – he is more motivated by hatred of oil companies than anything  else.  This is also true for McKibben and many so-called “environmentalists.”



  3. By Raindog on March 5, 2012 at 8:36 am

    Wow – I need to proofread before I post.  About 1.6C warming would be saved  by switching from all coal to all wind and  solar (assuming the energy storage problem can be solved).


    • By Robert Rapier on March 5, 2012 at 11:47 am

      How are you coming up with these numbers? Where do you get 0.4 C from natural gas? Once more, from the paper, in two different locations they write:

      1 TWe is the order of magnitude of the global electrical output currently generated from coal.


      Here, we have examined energy system transitions on the scale of the existing electricity sector, which generates 1 TWe primarily from approximately 3 TW thermal energy from fossil fuels.

      I think that’s pretty clear, and as I showed in the article I double-checked it.



      • By Clee on March 6, 2012 at 5:44 pm


        Multiply by 1.66.   According to


        Coal is used in a wide range of different areas. The largest consumer is the power generation sector, which uses almost 60% of the produced coal. Metallurgy (iron and steel making) uses 16%, mainly superior quality bituminous coal type, called coking coal.


        The residential & agricultural sector use 14% of the coal, for domestic heating and small-scale heat generation. Cement and other industries, primarily different chemical processes, use the remaining 12%.



        I wouldn’t call 60% “only a small portion of the world’s coal usage.”  However, it is not 100%.  So if you want to replace all coal use, not just electricity generation by coal, that might increase the 0.20C to 0.33C, which still seems pretty small.


  4. By ben on March 5, 2012 at 10:52 am

    Well, 0.2 degrees C. — stop the press!   Hmm, I dare say that may have some of the Enviro-Sophists squirming in their chairs.   Merely some, however, since most of the zealous proponents of a “none of the above” school of  anti-development ideology could really care less what objective analysis may yield about the inevitable trade-offs that continue to require tough choices.       

    I’m pleased to hear some of the reader’s and others expressing interest in the immient publication of Power Play.  One hopes the book’s “no free lunch” theme will encourage the wishful thinking crowd to further expose themselves and an increasingly not-so-subtle ideological agenda that they’ve been prodding for a generation.   Mr. Carson’s “Silent Spring” has, regrettably, devolved into some pretty shrill advocacy , as we muddle toward what seems a frugality of logic and an absence of substantive discourse on issues of great consequence impacting America’s competitiveness in the years ahead.

    Thanks for calling out the Wizard even as his defender’s jump to offer their ”pay no attention to that man behind the curtain.”   Some of these folks need to just get in the baloon.  Lord knows they’ve got more than enough hot air to get then back to Kansas:)








  5. By ben on March 5, 2012 at 10:57 am

    Edit:  Ms. Carson, one of my favorite vsitors to the grogeous Coast of Maine– if not scientists.


  6. By Raindog on March 5, 2012 at 1:08 pm

    Robert  – I may have made a mistake.  I thought that 0.2 could not be right so I went to this Wikipedia page

    And I looked at the table at the bottom and it says that in 2008 8.2 TWh/year came from coal.  I assumed that must be the number for coal.  But I am not sure how TWe and TWh/yr relate to each other



    Source of Electricity (World total year 2008)


    Electricity (TWh/year)




  7. By Raindog on March 5, 2012 at 1:10 pm

    The table got screwed up when I hit post

    Coal – 8,263

    Oil – 1,111

    Gas – 4,301

    Nuclear – 2,731

    Hydro – 3,288

    • By Robert Rapier on March 5, 2012 at 1:13 pm

      That’s not 8 TWh from coal, that’s 8,263 TWh from coal. Divide that by the number of hours in the year and that’s the relationship between TWh per year and TWe. That number is just under 1 TWe, which was the reported number for the paper. So it is fact modeling the impact of removing all of the world’s coal plants.


      • By Raindog on March 5, 2012 at 1:32 pm

        My fault then Robert – Sorry! You can delete the posts above if you want. They confuse the matter. 

        I just couldn’t believe that it was only 0.2C.   I am still having trouble believing that.


        • By Raindog on March 5, 2012 at 1:43 pm

          I’m embarrassed! I really misunderstood that. I just couldn’t believe that it was only 0.2C. 

          • By Robert Rapier on March 5, 2012 at 2:29 pm

            Your response though is very typical of many of the responses I have seen from people who could not believe the number was so small. They said “Oh, but that is only a portion of the world’s coal power.” So I thought it was important to specifically address that.

            On the other hand, it is clear that if the world keeps expanding coal consumption that the number will be larger. But 0.2 C? I would think that would be lost in the noise, and Romm’s characterization of 0.09 C for natural gas as “nothing” and 0.2C for solar and wind just shows that he is being driven by an agenda.


  8. By GeoJeffers on March 5, 2012 at 1:59 pm

    We always need to look at a complete picture, so how does the avoidance of acidifying the oceans (via carbon energy) play into our world’s health?  The new testament phrase of “the meek shall inherit the earth” seems to indicate that the jellyfish will be the winners in ocean pH change if carbon burning continues.

    But decreasing particulate and thereby decreasing lung damage and the release of radioactive substances (mixed in with carbon sources) by solar (see ) seems like a good benefit that might weigh against higher world temperatures if we transfer to non-carbon energy sources.

    If reflecting excess heat can be done with some other inert chemical sent into the upper atmosphere (chem trails?) we might get some relief from global heating.  I think humans will be able to play god as well as the gods.

    • By Robert Rapier on March 5, 2012 at 3:41 pm

      We always need to look at a complete picture, so how does the avoidance of acidifying the oceans (via carbon energy) play into our world’s health?

      To be clear, this article is not about whether it is a good idea to keep dumping CO2 into the air and oceans. It is about the bias shown in the reporting of the results of this paper.


  9. By Stephen on March 5, 2012 at 2:32 pm

    Hello Robert-

    Another excellent post.  But I read the following to mean they modeled a transition from current coal power to the various alternatives over 40 years time, not overnight:

    “we considered emissions from a variety of linear energy system transitions, each of which replaces 1 TWe of coal-based electricity by bringing new LGE power plants online at a constant rate over a 40 yr period.

    I can’t say that the a theoretical overnight switch would make the temperature differences any more dramatic, but I read your article to imply the model was for an instantaneous (“magic wand”) shift in energy sources.

    • By Robert Rapier on March 5, 2012 at 2:44 pm

      Hi Stephen,

      Maybe I should clarify that, but from the paper:

      Although we focus here on 40 yr, linear transitions of a 1 TWe energy system, we examined a far broader range of cases; none of these cases altered our central conclusions. Figure 4, for example, illustrates the HGE warming caused by transitions to several LGE energy technologies that range in duration from 1 to 100 yr.

    • By Robert Rapier on March 5, 2012 at 2:48 pm

      I read your article to imply the model was for an instantaneous (“magic wand”) shift in energy sources.

      I fixed that. Thanks.


  10. By Jim Takchess on March 5, 2012 at 3:14 pm


    Perhaps a future post on these technologies. I seem to recall you were a fan of biobutanol.



  11. By Ed Reid on March 5, 2012 at 4:08 pm

    Arguably, we do not know what the current global average temperature is to within +/- 0.2oC. To suggest that we can know what it will be 100 years from now to +/-0.2oC is laughable. I am not sure that the anomalies we believe we are tracking are known that accurately, regardless of the fact that they are reported to two significant figures.

    Methinks that, as usual, Dr. Romm “doth protest too much”. His is “a tale, full of sound and fury, signifying nothing”. (HT: William Shakespeare)

  12. By Ben on March 5, 2012 at 5:55 pm

    The Wizard of Oz, the New Testament and William Shakespeare in the first 20 responses sets some kind of new standard for elevated discourse on an energy blog!   I say in at least semi- seriousness that we put this publication up for an award of some sort.   It certainly eclipses by a long shot the quality of the policy exchanges that we’ve been hearing out on the political hustings.   I can hardly wait for more protestations as to why we don’t release from the SPRO to relieve an end-of-winter transition to summer blends and incrementally higher gas prices.  Do I like price increases?  Hardly.  Do I think Uncle Sam can/should mitigate these discomforting adjustments in the marketplace?  Nyet, lest the remedy worsen the disease.   Like it or not, we are experiencing a long, slow and not all that pleasant adjustment to global pricing against the backdrop of a fundamental imbalance between available global supply and unyielding increases in (largely Asian) demand.  Absolutley none of this comes as a surprise.  It has been addressed in this space for several years and in other credible sources for a couple of decades.  Yet, we somehow resist the inevitable and, with the witch’s broom in hand, we petition the great and powerful Oz for his beneficence.  Guess it’s about time to start looking around for another balloon. 




    • By Ed Reid on March 5, 2012 at 9:24 pm

      We are an erudite and thoughtful, though rather skeptical,  group. We appear not to be particularly prone to hyperbole. We choose, at least, not to be the lead lemmings in the march to the sea.

      The more ancient among us have seen the results of the forced introduction to the market of technologies which were “not ready for prime time”. Some of the younger among us may be witnessing that phenomenon for the first time. I suspect it will be no prettier in the current instance than it has been in the past. One need only drive past the vast fields of wind turbines mounted on “erector set” towers, standing motionless in the breeze, to be reminded of this particular folly.

      While we realize that the global climate has changed in the past, is changing now and will change in the future, we also realize that the concern regarding CAGW is built on data that aren’t and models that don’t. We have much to learn about the operation of our climate, assuming that we can accept that we do not currently “know it all”. We appear to know enough to get ourselves in trouble, but perhaps not enough to get ourselves out of trouble. Hopefully, we know enough not to cut ourselves off from what works before we have an acceptable substitute.

  13. By Garth Coghlan on March 5, 2012 at 8:30 pm


    This paper has modelled that 1TWe of coal-fired electricity generation will increase temps by 0.33C over 100 years.  But the IPCC predicts increases of between 1.1 to 2.9C by 2100 for a low-emissions scenario.  So what explains the difference between these two predictions?  My guess is: warming that is already locked-in, emissions from other sources (oil, deforestation), growth in emissions generally (due to increased economic activity).

    In the conclusion of the study, the authors state:

    It has been estimated, however, that 10–30 TW of carbon-neutral thermal energy must be provisioned by mid-century to meet global demand on a trajectory that stabilizes the climate with continued economic growth.

    10-30TW!  That’s an order greater than the current level of coal generation.

     If we produce 10 times as much energy from coal, then the temperature increase will be a great deal more than 0.33degC – perhaps 3.3deg C (not that this is a linear system).  If I had to choose between 3.3 degrees, and 1.3 degrees (solar/wind/nuclear?), I’d take the latter.

    So perhaps it doesn’t make a lot of sense to replace the existing coal base, but it sure as hell makes sense not to be building any new ones.

    • By Robert Rapier on March 5, 2012 at 8:41 pm

      If we produce 10 times as much energy from coal, then the temperature increase will be a great deal more than 0.33degC – perhaps 3.3deg C (not that this is a linear system).

      Bingo! But I don’t think there is enough coal to produce 10 times as much energy from coal. I agree that we should do what we can to limit increased coal consumption, but if we tried to expand it by a factor of 10 it would be depleted fairly quickly. 


    • By Garth Coghlan on March 5, 2012 at 11:41 pm

      This study also highlights how little of our emissions come from electricity.  According to this chart, electricity & heat are responsible for about 25% of total greenhouse emissions.  We now have an idea of how difficult it will be to replace coal with clean sources, and how long it will take effect.  Perhaps the other 75% of emissions might be easier to change, and have a faster response time.  I’m thinking transportation, energy efficiency, re/deforestation, livestock.

      But really, they will all be difficult, and we need to try them all.

      • By Ed Reid on March 6, 2012 at 8:04 am

        UN FAO estimates livestock related GHG emissions at ~18% of total GHG emissions; and, states that they exceed transportation globally.

        Energy efficiency reduces emissions from electricity, heat and transportation.

        QUESTION: If the population of the globe were reduced to the “sustainable” level of ~1 billion, living in a vegan commune, using only renewable energy, would that “solve” the “problem”?

  14. By Douglas Hvistendahl on March 5, 2012 at 9:12 pm

    I read that one winter in the 1200s was so warm that people in England were wearing summer clothes all winter. Does anyone know enough history to check this for us?

    I know that there was a warm spell for a century or three roughly 1000 years ago.

    • By Rick Jefferys on March 6, 2012 at 4:12 am

      One interesting spot check on historic temperatures is provided by Otzi, the 5300 year old body who melted out of snowfield in the Italian Alps in 1991, now preserved in a museum in Bolzano. If it had been significantly warmer than 1991 for a significant period any time in the last 5300 years, he would have been exposed to the elements and decayed in a matter of days. Admittedly only one data point, but quite an important one in my view.

  15. By Tom G. on March 6, 2012 at 10:44 am

    And this news just in from another site regarding coal power.

    “Last Wednesday was a big milestone for people who care about public health and a livable climate. Two utilities announced the planned closure of nine coal plants in Illinois, Ohio, Pennsylvania and New Jersey, bringing total retirements (executed and planned) since January 2010 past the 100 mark to 106.”.

    The full story is available here.


  16. By Russ Finley on March 6, 2012 at 11:20 pm

    My depressing moment came a few years ago when the WWF commissioned a study to see what it would take with nuclear held constant.

     To figure out when we need to get started they looked at the history of free market industrial growth. By assuming industries like wind turbine manufacturing and efficient technology growth will grow at maximum known historical rates for industry, they could back off roughly when it will be too late to do anything. In other words, if we don’t hit the ground running in the next four years, industries like wind turbine manufacturing will be incapable of growing fast enough to avert this coming train wreck.

    We are not going to get there using conventional wisdom and today’s technology.

  17. By Ed on March 8, 2012 at 11:29 am


    Arguing with David Lewis, as you are currently doing at TEC regarding this post, is a lot like beating your head against a wall – it feels really good when you stop. His arguments from authority and ad hominem attacks are easy, but rarely persuasive.

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