The causes of the recent decrease in US greenhouse gas emissions

Since their peak in 2007 GHG emissions in the USA have decreased more in absolute terms than in any other country. The results of this review suggest that approximately 40% of this decrease was caused by the replacement of coal with gas in generating plants, 30% by improvements in the efficiency of internal combustion engines and 30% by growth in low-carbon renewables. Another major contributor was the 2008-9 global recession, although its impact can’t reliably be quantified. Had economic growth continued at historic rates between 2007 and the present US GHG emissions would now be substantially higher than they are.

This review was prompted by an article in Time Magazine written by Michael Bloomberg, one of the world’s richest men and also one of its leading contributors to green causes, entitled “Where Washington Fails to Drive Progress, Cities Will Act”. Bloomberg’s conclusion that the decrease in US emissions was “driven by cities, businesses and citizens”struck me as complete nonsense, and I was going to write more about it but decided it wasn’t worth the effort. But his article did get me thinking about what really did cause US emissions to fall, and in this post I document the results of my efforts to find out.

We begin with emissions. Figure 1 shows total US greenhouse gas emissions by sector between 1990 and 2014 (2015 emissions are not available but would probably be slightly lower than 2014 emissions. The data are from the EPA’s US Greenhouse Gas Inventory Report):

Figure 1: Total US greenhouse gas emissions by sector expressed as CO2 equivalents, 1990-2014. Emissions from land use changes and from US territories are not included.

Note that Figure 1 shows total greenhouse gas emissions, which include CO2 along with methane, nitrous oxide and minor GHGs expressed as CO2 equivalents, from all sectors of the economy, not just the CO2 emissions from electricity generation that we usually get to see. According to these results the US electricity sector is in fact responsible for only about 30% of total US GHG emissions – a good illustration of the futility of concentrating on cutting electricity sector emissions while ignoring emissions from other sectors.

Between 2007 and 2014 total US annual GHG emissions fell from a peak of 7,370 to 6,826 million tonnes. This 544 million-tonne decrease is in the same range as the UK’s total annual GHG emissions – i.e. not peanuts. Figure 2, which plots emissions by sector, shows how the different sectors contributed to the decrease (data again from EPA).

Figure 2: Contributions to emissions decreases by sector, 1990-2014.

We see the following absolute changes in CO2 equivalent emissions between 2007, the peak emissions year, and 2014:

  • Electricity: down 373 million tonnes
  • Transportation: down 184 million tonnes
  • Industry: down 48 million tonnes
  • Agriculture: down 6 million tonnes
  • Commercial & Residential: up 67 million tonnes

The emissions reductions were achieved almost entirely in the electricity sector with an assist from transportation. What caused them? Figure 3 shows generation from the electricity sector from 2007 through 2015 (data from EIA annual electricity reports ).

Figure 3: US Electricity sector generation by source, 2007-2015.

Hydro and nuclear have not changed significantly but coal and gas have, and there is a clear antiphase relationship between the two. Between 2007 and 2014 coal generation fell by 400TWh and gas generation rose by 250TWh, largely a result of a surplus of fracked gas displacing more expensive coal. Between 2007 and 2015 coal generation fell by 600TWh and gas generation rose by 500TWh. In terms of its impact on emissions this is roughly equivalent to replacing 250-300TWh of coal generation with low-carbon generation, which is sufficient to cut annual CO2 emissions by up to 300 million tonnes. However, generation from low-carbon renewable sources (dominantly wind) increased by 200TWh over the same period, indicating that the contribution of renewables to the emissions decrease was not that much lower than the coal-to-gas transition.

The cause of the decrease in emissions from the transportation sector is not immediately obvious. Transportation emissions are over 90% dependent on the consumption of gasoline and diesel fuel, and as shown in Figure 4 these fell during the 2008-9 recession. But along with total miles traveled they had recovered to around 2007 levels by 2015, so the emissions decrease can’t be attributed to lower fuel use or less driving. (Data from the 2017 EIA Petroleum & Other Liquids report and the Federal Highway Administration):

Figure 4: US deliveries of gasoline and diesel fuel and total miles traveled, 1984-2015

But after a little searching I came across Figure 5, reproduced from the EPA’s Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends 1975 Through 2016:

Figure 5: CO2 emissions/mile and fuel economy for US cars and trucks, 1975-2016

The left-hand graph shows how CO2 car and truck emissions, expressed in grams/mile, have decreased steadily since 2005. Between 2007 and 2016 combined car and truck emissions fell by almost 20%, from 430 to 350gm/mile, largely as a result of improvements in engine technology. This is more than enough to explain the approximate 10% decrease in transportation sector emissions, but the 20% number will be too high because the data are for vehicles purchased new and don’t allow for emissions from vehicles already on the road at the time (the average age of a car in the US is now estimated to be 11.5 years.)

Based on the results discussed above I came up with the following approximate distribution of percentage contributions to the US emissions decrease since 2007:

  • Gas replacing coal in electricity generation:     40%
  • Decrease in gm/mile vehicle CO2 emissions:   30%
  • Growth in low-carbon renewables generation: 30%

The US government can take credit for roughly a third of the decrease. The 30% contribution from renewables is of course entirely a result of lavish government subsidies, and we can further assume that the anti-coal policies of the Obama administration would have had at least some impact on the decrease in coal usage and that the US Corporate Average Fuel Economy standards might have had a minor impact on gm/mile CO2 emissions, although there was no change in the standards that might explain the post-2005 decrease. The government also provided support to George Mitchell during the 1970s but despite claims to the contrary wasn’t responsible for the fracking boom. As one of Mitchell’s geologists put it: “George probably could have done it without the government. The government would not have done it without George.”

The wild card here, however, is the 2008-9 global recession. Figure 6 reproduces Figure 1 with a trend line drawn through the 1996-2007 data. Had this trend continued annual US GHG emissions would now be about 1 billion tonnes higher than they are. Does this mean that the 2008-9 recession was the basic cause of the emissions decrease?

Figure 6: Total US GHG emissions from Figure 2 with 1996-2007 trend line superimposed

Let’s look at a few more indicators. First US GDP since 1950 (Figure 7, data from the St. Louis fed). We see that previous recessions, such as the 1970, 1974-5 and even the 1981-82 “double dip” recession, had no lasting impact on the overall upward trend in GDP. The  2008-9 recession, however, did. Since 2009 US GDP has run $1-2 trillion/year below the projection of the trend line (which may explain the election of Donald Trump, but I digress):

Figure 7: US GDP, constant 2010 dollars, 1950-2014

Second is US primary energy consumption (Figure 8, data from the 2016 BP Statistical Review). The trend here is convex upwards, indicating a gradual decrease in the growth rate of total energy use with time. But like the GDP graph it shows a sustained decrease, in this case of about 150 million MTOE/year, relative to the trend line from 2009 onwards.

Figure 8: US primary energy consumption, 1985-2015

Third is US total electricity consumption. Since 2007 electricity consumption has flattened out and in 2015 was running over 500TWh/year below the projection of the trend line (Figure 9, data from the EIA electricity browser):

Figure 9: US total electricity consumption, 2001-15

Figures 6, 7, 8 and 9 demonstrate once again the close linkage between GDP, energy and emissions.

So did the 2008-9 recession cause the decrease in US emissions? If economic growth had continued at historic rates between 2007 and the present there’s no doubt that US emissions would now be higher than they are – according to Figure 6 about a billion tonnes higher. Accepting this number as a meaningful estimate is, however, difficult because it involves speculation. No one can be certain what would have happened if economic growth had continued unchecked during 2008-9. The world might, for example, have suffered an even deeper recession in 2009-10. The only thing we can be certain of is that if the goal is to reduce emissions an economic downturn is the best way to achieve it.

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59 Responses to The causes of the recent decrease in US greenhouse gas emissions

  1. David B. Benson says:

    For just the utility company for this service area, Avista Utilities, the actual decline in electricity consumption is puzzling. The population is slowly growing, the economy is doing well and yet electricity use is dropping enough to impact Avista Utilities revenue. The only change I notice is the use of LED lighting, especially street lights.

    • Grant says:

      I suspect in the area of lighting the move from incandescent to LED – almost skipping over 2 technologies in the process – is likely not insignificant BUT surely not anywhere near great enough to produce those numbers without some other effects or inducements.

      I also suspect that measurement methods may need to be inspected – if there are any measurements as opposed to estimates.

      It may be just base economics – or even something like more efficient TVs/Screens in general given how many there are and that they would have a been a significant growth area for electricity consumption since the advent of mass computing.

      And of course a reduction in estimated emissions in no way should lead to an assumption about greater efficiency and effectiveness of production and consumption.

      Watching France for the next couple of decades as it transitions from Nuclear to renewables in an economy mainly run on electricity based on abundant Nuclear capacity should be interesting.

      No real gas penetration and so electricity consumption is about twice the UK for approximately the same level of industrialisation and population.

      Gas in the UK used to be cheap but prices were driven up, making electric look competitive. Now things are swinging the other way with significant price increase being suggested for electric power.

      If one ends up with with a European Electricity market based on notable amount of shared capacity, Brexit or not, France, with a high demand that probably cannot be switched to anything else in a hurry due to lack of infrastructure, could end up in a very interesting and perhaps awkward position. But that will be for the next generation of politicians to grapple with.

      • jfon says:

        France is unlikely to abandon nuclear. President Hollande had promised to close the Fessenheim reactors, the country’s oldest and near the German border, by the end of his term of office. That now looks improbable – Electricite de France is stalling closure till after the election, and all the front-running candidates appear to be pro-nuclear. The Greens are polling below three percent.

        • Grant says:

          I have to agree that I cannot see France electing to dump nuclear in the way the Merkel seems to he jumped.

          However the domestic nuclear industry seems to be in a poor position both financially and technically at the moment – unless this is a situation of the the management and the political owners both playing politics with the tax payers and their “colleagues” in the EU.

          If they are not careful they may find themselves forced to undertake quick action to cover a shortfall – and that would likely involve wind and solar bought from China unless something else appears over the horizon in the next decade.

          • jfon says:

            ‘..they may find themselves forced to undertake quick action to cover a shortfall – and that would likely involve wind and solar bought from China ‘
            As this blog has often demonstrated, the only shortfall wind and solar can guarantee to cover is being down on EU mandated renewables percentages, and that has much less electoral effect than an actual blackout.

          • robertok06 says:

            “If they are not careful they may find themselves forced to undertake quick action to cover a shortfall – and that would likely involve wind and solar bought from China unless something else appears over the horizon in the next decade.”


            The 410 TWh/year that the 58 reactors of EdF generate today are more than TWICE the amount of electricity generated by all of the PV installed on the planet.
            Even 50% replacement of nuclear with PV is out of question, that would entail on a Wh-per-Wh basis (i.e. without considering the intermittence and seasonality of PV) something like the need to install 180 GWp… which would generate sometimes 120 or more GWe at times of low consumption (like weekends or summer holidays in July/Aug, with many factories closed)… and there would be NO WAY to store the excess electricity, there’s simply not enough pumped hydro (let alone other technologies) to do it.
            Similar considerations for wind, I don’t spend any time re-doing the calculation.

            It’s either nuclear and 45 gCO2/kWhe, and no PM2.5, PM10, arsenic, heave metals, NOx, SO2, etc… or else it i 300-500 gCO2/kWhe and plenty of the rest I’ve listed above via gas/coal and a small fraction of wind/PV… and the cost of the MWh hitting the roof, of course… like everywhere else they have tried to do that… Denmark, Germany, Italy, Spain…


          • Grant says:


            I agree that the Renewables route seems unlikely to work well even if it works at all.

            But politically, especially if we assume the procrastination that we have seen in the UK for 20 or 30 years repeated in France a few years from now, what COULD they choose to do IF they needed to do it quickly?

            If one needed to be seen to be doing something AND no one was prepared to bury the national success story that was “The Paris Agreement”, what are the options in the absence of a Nuclear option under pressure from Germany, et al.?

            Coal …. nope and limited local scope for sourcing fuel supply anyway.

            Oil? Unlikely.

            Gas for electricity generation? That would be an option perhaps. Relatively manageable costs and limited development of infrastructure required only to some key locations not every street in every city.

            Gas direct use? Possible if the pipelines exist and can be expanded … but is there a working delivery infrastructure with the scale to undertake countrywide distribution for industry and could that be expanded for domestic use? Is domestic gas to replace electric and relieve the pressure on electricity generation something that people would accept?

            What else?


            More Hydro? (Maybe annex Switzerland and turn it into a huge hydro based energy storage system?)

            Or maybe some wonderful and magical super energy generation system that is unknown to us today?

            What are the options that the political classes might consider and could implement, with any degree of success at all, quickly?

    • meliorismnow says:

      My guess is that its mostly a result of the real estate bubble. Lots of new construction was built (which is more energy efficient than old stock) and people are more house-poor than ever, making them afraid of their thermostat/energy bill. Could also be mild weather assuming you’re looking at a short duration.

      • David B. Benson says:

        No serious housing speculation in the Avista Utilities service area. Also, heating is via natural gas, not electricity.

        • Thinkstoomuch says:

          This is a set of articles from the EIA. Even the charts are good.

          My limited take on the situation follows. I am only going to address residential.

          Trying to figure it for an individual utility area is … difficult. Especially one like Avista. I remember driving through its areas. Spokane, the surrounding areas (especially east of there), Coeur d’Lene, ID, Grangeville, ID. I have driven thru the whole coverage area, not really one thing. All of them have significant differences in economic activity’s and so forth. Spokane and its environs are driving things, most likely but how much?

          Several things come to mind. To light your home what you using in 2007? What did your TV use for a display? Your neighbors. The “Luddite” down the street. Compare what was on the shelves in 2007 and compare it to today. That Luddite is … challenged. They want their CRT TV back none of this fancy flat screen stuff. And the like (what is this CFL stuff any way, “Where’s my incandescent?”). 🙂


  2. Thinkstoomuch says:


    Another wonderful post.

    I saw a similar one recently but didn’t save will search for it.

    One of the things that article attributed the CO2 reduction to was the loss of manfacturing. That article broke things out differently.

    As far as the transportation numbers another factor “may” be the biofuels. And how exactly they get counted. I think they are around 30% reduction (EPA) if as almost all gasoline is a 10% blend that should be another 3%. Also another government study came out last month about the number being 50% reduction for ethanol.

    Which gets us to another interesting number. The agriculture, if we are now producing around a million barrels a day of ethanol …plus more food. Though most is probably due higher yields. Maybe.


  3. Willem Post says:


    It is amazing Bloomberg is writing such nonsense and is so rich, whereas you write with such clarity and likely are a pauper compared to him.

    I think, part of the GDP not increasing as before is due to wastefulness of the RE route, and the money being thrown away on wars, and folks being in some sort of rehab mode, staying home more, eating out less, making do with less, trying to pay outrageous healthcare and education costs, and save for retirement.

    May be Trump can shake up the system out of its torpor. That system surely screwed the US working class these past 50 years, its American Dream totally shattered. He said the carnage has to stop.

    A similar situation has developed in Europe already for at least 20 years, with sub par economic growth, high unemployment and millions of refugees as well.


    • Willem: You’re right. Michael Bloomberg is indeed a wee bit richer than I am.

    • Rob says:

      Has anyone noticed that Bloomberg New Energy Finance seem to be source for every green energy journalists bullshit.

      Energy Matters never quoted at all.

      For example Energy Matters the site which made a in depth look at Tidal Lagoons but
      absolutely no interest from the papers

  4. Dave Rutledge says:

    Hi Roger,

    I must be missing something with respect to transportation emissions. Couldn’t the emissions be calculated directly from the gasoline and diesel consumption, which appear to be very close to 2007 levels?


    • Hi Dave:

      I don’t know exactly how they calculate it, but if you base the estimates on miles driven times CO2/mile then you get lower emissions for the 3 trillion miles driven in 2015 than for the 3 trillion miles driven in 2008. I also don’t know how they tweak engine combustion to get lower carbon emissions for the same amount of gasoline and diesel burned, but maybe someone else does.

      • Dave Rutledge says:

        Hi Roger,

        No one is sequestering the carbon dioxide emitted from gasoline and diesel engines, and no one is storing the gasoline and diesel.

        I do not think you can get transportation emissions by multiplying miles traveled by car/light truck fuel mileage. There are also heavy trucks, aircraft, trains, aircraft, ships. I believe pipelines are also counted as transportation.


        • Dave:

          You have a point about the gasoline. I don’t believe we’ve invented low-carbon gasoline and diesel yet, so if gasoline and diesel consumption was the same in 2014 as it was in 2007 then we should get the same CO2 emissions, not lower CO2 emissions. I’ve been searching for a solution to this problem but so far without success. The EPA shows a decrease in emissions in all transportation sectors, which should be reflected in lower fuel consumption but isn’t:

          • Thinkstoomuch says:

            Roger from the 2014 Fuel Consumption table in your link.

            MOTOR GASOLINE
            129.5 Billion Gallons
            16,073.7 Energy (Tbtu)
            1,146.5 CO2 (Tg)

            12.9 Billion Gallons
            1,092.8 Energy (Tbtu)
            0.0 CO2 (Tg)

            10% of the pumped gallons no CO2. According to the “US EPA” it IS carbon capture or carbonless fuel or something, apparently.

            Less energy per gallon. Probably figures in as well.

            Still contemplating but wanted to get this off hopefully it answers some of what is bothering you.


          • Euan Mearns says:

            There are multiple peer reviewed studies that show the ERoEI of corn ethanol is little above 1. When you add up the CH4 used to make the fertiliser, the diesel used to plant, harvest and transport the corn to the refinery, the electricity in the refinery and the eventual distribution costs of ethanol that is much less energy dense than gasoline, then you find that all those sources consume just about as much energy (mainly FF) than the ethanol provides.

            All these energy inputs should be showing up in the CO2 of agriculture, electricity consumption and in diesel consumption. If whoever compiled the stats did a good job, if they are in there, then the data shows that the economy minus ethanol is doing even worse than it seems because The State invented a system of wasting energy and making people rich doing so.

            Ethanol, like solar in Scotland, is a folly, like The Pyramids and McCaig’s Tower in Oban. Vanity projects celebrating our success before the fall.

            T2M go think a bit more about our obsession with wasting precious energy on energy projects that try to defy the laws of thermodynamics and economics and what the consequences might be.

          • T2M; Thanks, that’s helpful. After checking a few more numbers I find that US gasoline contained 10% ethanol in 2014 and 5% in 2007. With the EPA treating ethanol as a zero-carbon fuel (!) this would explain maybe 3% of the decrease in transportation emissions between 2007 and 2014. Not enough to get us all the way there, but a start.

          • Thinkstoomuch says:


            I was in a hurry and commented before I should. My apologies.

            I was just trying to explain the fuel volume and CO2 accounting that was bothering Roger.

            I should have included a SMILEY or something. Along with the “US EPA”. I THOUGHT my statement meant it obvious that I was being funny/sarcastic. Did I mention one of these days I will figure out this communication thing. 🙂 People are probably better off wishing for telepathy it will happen first, I am pretty sure.

            This is the text for the footnote on biofuels at the bottom of the table in Roger’s link.

            “Biofuels are presented as line items below the total for informational purposes only, in line with IPCC ethodological guidance and UNFCCC reporting obligations. CO2 emissions from the combustion of biofuels are not directly included in the energy
            sector contribution (which includes the contribution of transportation and non-transportation mobile sources) to U.S. totals in the Inventory; instead, net carbon fluxes from changes in biogenic carbon reservoirs are accounted in the estimates for Land Use, Land-Use Change, and Forestry in the Inventory. See page 4 for more information on the Inventory.”

            I SHOULD have included it. 🙁

            If you want the actual carbon numbers for up to 2014 are contained in Table 3-12 of the EPA’s Greenhouse Gas Inventory link in the third paragraph.

            Works the same way as Drax wood pelllets are carbon neutral. But a little better according to some. 😉

            I agree with your comments for current ethanol production. Mostly. There are other environmental dangers. Give a farmer a “cash crop” that can make money on marginal land is dangerous. Just like one of my biggest problems with solar in FL, it displaces carbon sinks. And is not really environmentally friendly. Oh did I mention now you have to mow the area that used to have trees on it. Lets make the mower battery powered. 🙂

            Much like solar and wind is zero carbon. Except for the energy to manufacturing and constructing of them requires fossil fuels. That are accounted for in those sectors. NOT in electrical generation. Same with Battery Vehicles.

            Again apologies for making your day worse,

            PS As I posted earlier there is a January report saying that Corn Ethanol is all the way up to a 50% reduction in CO2. 🙂


            185 page document. I haven’t actually read anything but the reporting and a few comments that were fairly scathing.

            Which I would “assume” gets the EROI all the way up to that point. “Maybe” (see scathing comments). At least it is a “jobs program” that generates more energy than it uses, hopefully. With my politicians I consider that a win. Low bar but with what I got …

            PPS None of which really makes me a proponent of Ethanol

          • Euan Mearns says:


            T2M go think a bit more about our obsession with wasting precious energy on energy projects that try to defy the laws of thermodynamics and economics and what the consequences might be.

            I’m being totally straight here. I look at Roger’s charts, and history, and feel as though I should be able to quantify what is going on, but can’t.

            The mixing pot of resource scarcity / abundance, economics, time lags, ignorance, green thinking, UN et al policy, I can’t work it out.

            And so I’m serious when I ask you to go think a bit more and to try and toss out some answers. Philosophy is perhaps best delivered one bit at a time. And not in a hurry.

          • Thinkstoomuch says:

            For Euan,

            “I’m being totally straight here. I look at Roger’s charts, and history, and feel as though I should be able to quantify what is going on, but can’t.

            The mixing pot of resource scarcity / abundance, economics, time lags, ignorance, green thinking, UN et al policy, I can’t work it out.

            And so I’m serious when I ask you to go think a bit more and to try and toss out some answers. Philosophy is perhaps best delivered one bit at a time. And not in a hurry.”

            First thing remember I am really not all that “smart”. Decent enough shade tree mechanic and electronics technician. Fairly good at understanding data and such. Maybe even applying known things to new problems. I am quite definitely not a well organized thinker or communicator. Which is what I admire most of the posters on your blog.

            I have spent many hundreds if not thousands of hours contemplating those questions. My cost/benefit analysis varies for all of them, on my mood more times than not. 🙁 Lately my mood has not been good watching people defecate in their own well does that to me.

            For energy it all boils down to horses for courses, IMO.

            I had thought past posts made it obvious. I am very pro fission nuclear (almost always a very decent solution). Not that I think it is the be all and end all.

            Do I think Ethanol can have a place? Yes, cellulosic would be great if they can get to an EROI of even 3 (though I hope for much more) it would keep our transport system running, in the near future. Lots of problems with making that happen. On the supply, storage, usage and other areas.

            EROI is not a be all and end all, in my opinion, though it should be weighted heavily.

            I am also for waste to energy(and biofuels in general when intelligently/correctly applied). $160 million dollar plant operational less than 2 years ago generated 473,000 MW is its last year of available operation data. About half of that out of plain garbage, yard clippings and such. Material that was already being collected anyway (oh look it is right next to with said landfill). Saves landfill space (is that a good thing for carbon capture? CH4? N2O? …)

            It really is a very complicated situation that always seems just on the edge of understanding to my view. But in this case we are talking about currently well over 300 million people that grew 27% over the whole period covered (1990-2014).

            As far as policy in the UN, (and the Washington, DC to a lesser extent) more “a stopped clock is right twice a day.” Maybe once depending on how it is displayed. 🙂

            That is probably the kindest thing I can say about the UN.

            But then again all politics is about the art of the possible. If an ex-governor can be vilified (despite his former state generating the most verifiable “renewable energy” by the CO2 brigade) while a governor who has killed 8 nuclear plants and working on 9 is applauded by the same CO2 brigade (despite starting with an enormous lead is now in second in the RE is now second). Which one is saving more CO2 emissions? (lots of reasons and the governor is not responsible for all of it but …)

            Chicken Little crossed with Rube Goldberg is running the place, not rational thought, IMO. Something is fundamentally wrong with the politicians AND the people that voted for them as THEIR representatives.

            So in the end anytime politicians get energy even slightly right as per ethanol in the US (with all its warts) is a good thing. IMO. Especially in the era of 24 hour news and the sound byte.

            Last thought on the CO2 front. Why don’t we have CO2 costs labeled on the products on the shelves? Some products get labeled for energy savings why not costs.

            This is actually the shortest version of three attempts and about 9+ hours of thought.

            For what little it is worth,

            PS Remember “best” is the enemy of “good enough”.

          • Euan Mearns says:

            T2M, modesty is a virtue. The core issue here is that most of those who want to reduce CO2 emissions to save the climate want to do so not using nuclear power which is the proven way of achieving their objective.

            This information illuminates the integrity of the whole debate and those involved in it.

            To be clear, your thoughtful 2 much comments here are valued and I’m sure many folks read them!


      • Grant says:


        I would guess that these days it might be possible to get a reasonably accurate measurement of distance travelled and fuel consumed across many categories of transportation based on tracking and monitoring systems.

        Applying the results and comparing them to notional fuels delivered (and assumed consumed?) might take a bit of working out but would be no more complex than, say, gridded-cell global temperature estimates and so presumably share the same level of accuracy.

        If shipping has been included somehow recent lower activity levels might suggest a measurable and so potentially notable effect on the numbers.

        Ditto and notably for the US the swing over the past decade to a significant increase in acceptance of smaller cars with more efficient engines. The older stuff may now be dropping out of the pre-owned market/mileage estimates.

        Trucking usage and consumption models may also be changing due to prior year influences. It should in theory be possible to check the likely veracity of one set of numbers with another before the responsible department publishes an authoritative set of numbers.

        However, absent error bars it is difficult to be sure of efficacy.

        If, for example, a Government through their official reporting body wishes to “review and improve” the way their stats are calculated and presented it would quite easy to subtly change the basis of the measurements and the assumptions made and come up with alternative answers. Or, indeed, just not spot an error – especially if it worked for the results one wished to report. After all, who else is going to be in a position to check them with any degree of credibility and the funding to do so?

        Is it possible that the official numbers are based on manufacturer’s official emission test figures somehow?

        As we know those numbers have been tending to improve significantly in recent years by fine tuning engine management to specific driving situations. Fine when those driving conditions prevail but clearly not so pertinent for most users across the range of their usage activities no matter what the ICE class and usage cycle might be. One might expect significant variance between estimate and reality on that basis but could one identify and quantify it?

      • robertok06 says:

        The emissions in the USA are calculated using the “CAFE” data, which assume an average amount of CO2 (and other chemicals/particulate) per mile travelled for each type of car of each manufacturer (which, in fact must go through some sort of “certification” prior to being able to sell a particular model… this is what has put VW in big trouble… they’ve cheated on these declared values, as far as I understand it).



  5. “We see that previous recessions, such as the 1970, 1974-5 and even the 1981-82 “double dip” recession, had no lasting impact on the overall upward trend in GDP. ”

    These statistics are as fake as can be. Please refer to


    There are 94 million working-age Americans not in labour force and we are supposed to believe that unemployment is 4.8% ? Give us a break!

    94,366,000 Americans Not in Labor Force as Participation Rate Ticks Up in January

    Here is as good an indicator of the real state of the US economy at present as any:

    Goldman Stunned By Collapse In Gasoline Demand: “This Would Require A US Recession”

    Obama got out in time – leaving a gigantic mess behind.

  6. Thinkstoomuch says:

    They are labeled CO2 Equivalent values.

    Tweaked, better emissions control to get rid of other exhaust gases. Other hydrocarbons mostly. I think. Maybe.


  7. Euan Mearns says:

    Roger, great post. Figs 6, 7, 8 and 9 are eye popping. Part of the backdrop is high energy prices 2006-2014 acting as a drag on the economy and discouraging energy use. Of course the finance crash of 2008-09. Unsustainable levels of debt. And globalisation. Ithink all these things do combine to produce Donald.

    Figure 2, panel 3 shows declining emissions from industry. Has American industry become very energy efficient? I don’t think so. It re-located to Mexico and China. Missing from the analysis is the CO2 embedded in imports. I’d be interested to see a chart of US exports and imports and the balance over this period.

    Picking up on DaveR’s point, the transport data are a bit puzzling. Perhaps the simplest explanation is that vehicles have become more efficient – not hard to achieve in the USA. This can happen simply by folks buying smaller, more fuel efficient cars – its a natural response to high gas prices.

    • Willem Post says:


      Regarding the US, not just high gas prices (largely offset by more efficient cars), but also:

      – increasing local real estate and sales taxes, fees and surcharges,
      – increasing healthcare premiums,
      – increasing education costs.

      It is harder to offset these three items, other than by life style changes.

      They all combine to reduce living standards, i.e., eat out less, stay home more, go on fewer vacations, and being unable to save for retirement, etc.

      They all combine to produce Donald, and Le Pen, and Wilders, and Brexit.

      Stay tuned.

    • Euan: I agree that the oil price had something to do with the 2008-9 recession. The only factor common to all depressions since 1970 has been a leading spike in the price of oil.

      As I noted in a response to Dave Rutledge above the decrease in transportation emissions remains a puzzle. If it was caused by smaller, more efficient vehicles we should see a corresponding decrease in fuel consumption, but we don’t.

      I think the decrease in industry emissions was more a result of a depressed economy than anything else. It’s possible that some of it was caused by carbon leakage, but we’re talking about only 48 million tonnes, i.e. less than 10% of the combined decrease in the electricity and transportation sectors.

      And the 67 million tonne increase in residential and commercial sector emissions puts Michael Bloomberg’s claim that the US’s emissions reduction was “driven by cities, businesses and citizens” in its true perspective.

      • Dave Rutledge says:

        Roger, T2M, Euan,

        Thanks for all the thoughtful comments. They are helping me understand that calculating sector emissions may have similar accounting problems to the land temperature series. There are bureaucratic incentives that favor reduced emissions and rising temperatures and the long-term result is the corruption of the series.


        • Thinkstoomuch says:

          Dave, I may have been unduly negative in my tone yesterday.

          The overall emissions data is something that I mostly believe. Especially with the fossil fuels. X amount gets burned produces Y, Z, … outputs. US EIA tracks sales of fossil fuels to the destination and sales of electricity. Total gasoline sales by volume and so forth. Which is also, I believe Roger was getting frustrated trying to make sense of it.

          Simple math which is why I tend to focus there, I think I understand it. Where it gets complicated is land use. Factors get complicated. Understanding footnotes and higher math is required. The higher math is generally beyond me.

          When you get to the calculated net CO2 (carbon sinks and such) it isn’t worth toilet paper, IMO. For the reasons you specify. As well as people not understanding the forest for the sage brush (literally, there is a story involved but just anecdotal) Understanding my limitations to evaluate it.

          Oh and one thing I forgot to add about ethanol. It is used is as octane booster as well replacing past chemicals that were not good for the environment or people.


        • Dave:

          It may be a self-fulfilling prophecy, but the EPA’s electricity sector CO emissions are easily replicated. I made a crude estimate by taking the EIA’s estimates of lbs CO2 emitted per kWh for coal and natural gas, which are the only fuels that emit CO2 in EPA’s book:

          and by factoring them using the EIA generation numbers shown in Figure 3 to get CO2 emissions. Then I plotted the results against the EPA electricity sector emissions shown in Figure 1, and here’s what I got:

          Good enough for government work, I think.

        • I might also add that the emissions data don’t have the same problems as the temperature data. As shown above, I can replicate the emissions results from the raw data, which I have to assume are correct. However, because of numerous (and in my opinion mostly bogus) “adjustments” the temperature series that are used to track the progress of climate change don’t look much like the raw GHCN and ICOADS data they are based on.

          • Dave Rutledge says:

            Hi Roger,

            I think that you have a fair comment for the temperature in that people are trying to read a lot into small fluctuations and this makes them more vulnerable to manipulation.

            For emissions, people claim they want an 80% reduction, and the data makes it clear that we are not currently on a path to achieve that, regardless of the accounting conventions for biofuels.


  8. meliorismnow says:

    The 2008-2009 financial crisis was really just the slight deflation of a massive credit bubble (starting with tech in the mid 90’s, then converting to real estate to avoid reversion/deflation). So GDP (and CO2) were amplified (pulled forward). In the late 90’s most people in the US felt wealthy so they spent accordingly. The same happened during the real estate bubble. Ever since 2007 most people haven’t felt that way (even with recent stock performance because most Americans don’t have significant stock holdings). As others have said, they feel financially insecure and/or underemployed and certainly less wealthy than they are accustomed to (in the bubble).

    And yes, blowing another bubble and keeping financial zombies alive (as the Fed is indeed doing with 0% rates) is only going to increase the pain (whether in duration or depth).

    Significant emissions weren’t moved offshore in the 2009-17 period because almost all of them had already moved over the previous 25 years (major emitters tend to favor lax pollution controls and cheap energy even more than cheap labor).

  9. jacobress says:

    Increase in TWh electricity produced by renewables does not automatically mean a proportional decrease in CO2 emissions. One should measure emissions from the electricity sector by the amount of fuels burnt in power plants, not the amount of electricity produced. I don’t know how the figures for electricity sector were calculated.

    • One should measure emissions from the electricity sector by the amount of fuels burnt in power plants, not the amount of electricity produced. I believe that’s the way the EPA does it.

      On the question of how much renewables have reduced emissions by, this depends on what generation sources they replaced. Figure 3 shows that only coal generation has decreased significantly since 2007, so it’s reasonable to suppose that they replaced coal, and 200TWh of renewables generation replacing 200TWh of coal generation would lower emissions by about 200 million tonnes of CO2/year.

      • jacobress says:

        You can’t assume that 1GWh of renewable electricity replaced 1GWh of coal or gas. Renewable electricity has preference – it’s electricity must be bought and used. But some FF power plants were and are in stand-by for the hour the sun sets or the wind stops. You can’t turn on and off thermal plants every few hours, so they keep burning fuel and maintain their boilers hot, even when in stand-by, without selling electricity. And they spend additional fuel in the ramp-up phase.
        You cannot know how much FF plants emitted from the electricity they sold to the net. You have to check the quantities of fuel burnt.

        • Well, if it didn’t replace coal and gas, what did it replace?

          • jacobress says:

            Renewable electricity did replace coal and gas electricity, but not emissions. Emissions per GWh electricity supplied to the grid, by the FF sector probably increased somewhat because of the intermittent nature of this supply, caused by the intermittent supply of renewable electricity.
            You pay in emissions for ramping up and down FF plants to follow renewables.

  10. steve says:

    Re. Fuel economy figures, I was considering buying a new picasso,as my 2006 one has excellent performance often doing 65mpg. Over 10 years the manufacturers have found ways of keeping claimed figures the same. Unfortunately, real consumption has dropped from 98% to 74% for the same sized up dated model. The same is happening with most manufacturers. They may have used the same methods to claim CO2 reduction in the US.

    • Grant says:


      While I think collective fuel consumption results, like self reporting what on claims to eat and drink, may have a place in the world they should only ever live with enormous error bars and health warnings.

      If you get 65mpg from your diesel travelling on flowing motorway I would think that is probably about right. Claim that attmptingvto drive to shopping or in commute time through a town or city and I will assume you have had a failure and at being towed to a repair centre!

      • steve says:

        I drive long distance commuting and, providing there is no high wind in the wrong direction,it isn’t wet or dark it does 65mpg. In town 56mpg.It has never conked out and has travelled 140k miles. My wifes new 3 cylinder Ford Focus petrol is supposed to do 50-60+. It never does more than 40. This model is also sold in the US.

        • Grant says:


          Long distance commuting is usually rather viable – so long as you are moving along all the time!

          I found that even running relatively large cars with relatively large engines (Petrol) from abut 20 years ago I could get over 30mpg without trying on long distance commutes. My current car – now very close to 15 years old and owned for the past 12.5 years, will return close to 35mpg on a good run – nearer 40 if I deliberately take it easy or the journey consists of almost entirely speed restricted roadworks as seems so common in the UK.

          Around town – 20 or less for previous cars. The current one sees mostly short run local work these days and low 20s overall seems to be the average.

          However … it’s worth almost nothing so no depreciation. Maintenance costs are not as high, so far, as depreciation would be on a newer vehicle. I think after 15 years (and counting) the CO2 cost, were it important, at time of manufacture would have been considered reasonable if written off over the period.

          Apparently the air coming out of the exhaust has less noxious pollutants in it than went in through the air intake. (By weight/volume I assume.)

          These days my annual mileage is quite low so a relatively high assessed CO2 output (it is from a time before the numbers were pre-assigned for taxation purposes – I think yours is too?) attracts a disproportionately high vehicle tax – gouged another £10 this year at the end of the month by the Government – but I would guess that for estimated purposes of Government Stats any usage numbers it may count as attached to by category are likely to be entirely wrong.

          Whether all the misalignment work out over a large sample to give much the same number, as is often claimed, I have no idea.

          I would guess that, all in all, a 1 or 2 % difference between real and estimate would be no big deal in real terms – though others may make political capital out of such a difference.

          However, if seeing 10 or 20% or more as the apparent discrepancy it seems reasonable to start asking questions.

          As for your wife’s car … the detail of the assessments and the requirements for emission regulations on the one hand and safety on the other (i.e. bigger and heavier at least plus other factors) will almost certainly mean that there is a perfect “performance curve” that would apply to testing and the model of “journey” against which the test is run and it might produce the claimed results or very close to them depending one which tyres are fitted and what pressures they are running at, etc.

          But anything outside that perfect objective will likely be a long way off whereas in the days past it would make less difference.

          I used to regularly run mine for months with roof bars and a roof box and kit inside with weight probably the equivalent of at least 2 adults. I did not notice a difference unless there was a very strong headwind or tailwind in which case the fuel consumption over a long journey could clearly be seen to be different. (No problem though if it was blowing the same way upon return!)

          It occurs to me that there are so many variables across the categories when attempting this sort of self-reported mete analysis that the error bar tolerances, should they happen to head in different directions from one year to the next, could account for huge apparent changes where none really exist.

          However, I’m guessing … and trying to be even handed about it in relation to the report’s authors.

  11. Energy Consumption vs. Core Populations – Trending Down Together

    This looks at several countries – USA, EU, Japan, China, India etc.

  12. Ryan Paulsmeyer says:


    Just popping in to say excellent article and analysis. Likely USA will continue these trends into the early 2020s.

    A very similar article and conclusions over at TEC from John Miller:

  13. Grant says:

    I’m not sure if comparison with the UK might prove enlightening or confusing. Perhaps both?

    However for anyone with a deep need to assess Government produced numbers (or a bad case of insomnia?) here is a 2015 report from the erstwhile UK Department of Energy and Climate Change

    Digest of United Kingdom Energy Statistics 2015.

    In the pdf are some links that provide portals to ever more detailed analysis.

    I have started to have a look but it would take someone with much greater skills (not difficult) and and understanding of the subject to make sense of them.

  14. brianrlcatt says:

    I have spent much time on DUKES, am quaified to do so, and they, unsurprisingly corroborate the basic physics of energy generation in the facts on the ground. As they must. Replacing coal with gas is a clean solution that has 60% less CO2 emissions per unit enrgy than coal and is 50% more thermally efficient , as DUKES confirms, and reduces the toxic dangerous toxic emissions of coal to zero. This approach can reduce overall UK fossil emisionsfrom the grid by 40% on 2014 levels, without subsidy, replacing coal on mainly existing sites and grid connections. No renewables required. We have a lot of gas under the ground, perfectly safe to extract, a lot safer than coal was.

    Nuclear replacing both over the next few decades will reduce CO2 emissions from generation to zero, and provide the electricity surpluses to power our vehicles and heating after fossil, again unsubsidised, the safest of all, and ultimately sustainable. We have the technology. Problem solved.

    What do we plan?

    60 GW or so of Renewables, duplicating their essential 100% fossil backup that produces 70% on the enrgy, an amount that would cover the country and coastline in renewables at huge expense, and can only reduce all fossil emissions by 33% at most by offsetiing all fossil generation on the grid the 33% of the time it is working, at the very best, maybe not when needed. And VERY expensively ar 2 or 3 times the price by law, wasting £Billions pa on pointless subsidies for a lesser result. Illogical. Malfeasance. nb: Duty cycles are also in DUKES Chapter 5 and 6

    Renewables and their subsidies add no value on the technical facts of this mix, they make each of the measurements of energy policy worse versus better alternative. Do the arthmetic.

    POINT: The massive waste of resources on weak/diffuse and intermittent energy collectors is wholly unnecessary to best deliver the supposed objectives of energy supply, and of minimising climate change. Renewable subsidies fraudulently waste £Billions of our money by wholly regressive law that must make climate change worse in fact, jeupardising supply for a fast buck for government lobbyists, and a slower more discrete one (mostly) for polticians and officials.

    It appears few in government are interested in understanding the best way to save us from climate change, if caused by our CO2 emissions, or to deliver a sustainable, adequate, affordable or secure electrical enrgy supply.

    They are overtly promoting regressive renewable subsidies for easy profit of their lobbyists at public expense, the most blatant renewable promoters for financial rewards during and after office I know of being Yeo, Deben, Huhne, Davey, Hendry, at least one while they were in power. Davey promoted bio fuels on the basis they reduced climate change, while in fact they produce more CO2 per unit enrgy that coal, at twice the price, and are unsustainable in quantity (why we stopped burning wood to deliver the industrial revolution). etc.

    For a last word from Sir David MacKay FRS, the DECC’s Chief SCientist from 2008-2014, watch this. It is all you need to establish the principles of the basic physics and research you can do for yourself, to understand thes blatant fraud on the physics and the public that is “renewable energy”, exploiting fear of climate change for easy profit by subsidies for what jeopardises energy supply and makes our net CO2 emissions expensively worse by law.An “appalling delusion”….

    You can’t make it up, that’s the job of government. For crony profit.

    Brian Catt CEng, CPhys, MBA

    • Euan Mearns says:

      Brian, this is priceless commentary.


    • Dave Rutledge says:

      Hi Brian,

      “We have a lot of gas under the ground, perfectly safe to extract, a lot safer than coal was.”

      I am a fan of natural gas, but who is the “we” and where is the “ground”? British gas production is down 63% from its peak in 2000.


  15. Pingback: The causes of the recent decrease in US greenhouse gas emissions –

  16. jacobress says:

    It looks from the graphs that the whole reduction of CO2 emissions happened between 2007 and 2009, and from 2009 on the emissions trend is upwards.

  17. Pingback: US GDP, Energy Consumption and CO2 Emissions | Energy Matters

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