In recent years, as developed economies have seen downturns in their economic growth due to the global financial crisis, an inevitable consequence has been a corresponding decrease in carbon dioxide emissions. It would be tempting to conclude that based on the decrease in emissions, the 2020 UK Climate Change Act target is now easier to reach. However the lesson that should be drawn is the folly of relying solely on carbon dioxide emissions as a policy metric, since emissions are so tightly coupled to economic growth.
The metric that we should be paying attention to is the rate of decarbonization of the economy, measured in carbon dioxide emissions per unit of GDP, as this integrates two metrics that we want to see go in different directions -- GDP up and emissions down. When we look at the decarbonization of the UK economy, we see that while the UK economy has continued to decarbonize in recent years -- significantly so in 2009 -- the overall challenge of decarbonizing the UK economy has changed very little.
I illustrate this with the following graph which provides an update to Figure 2 in my 2009 paper on the UK Climate Change Act.
The four red dots connected with the red line show actual decarbonization of the UK economy from 2006 to 2009. This data is encouraging as it shows a significant rate of decarbonization during the economic crisis. It is not directly comparable to the dim lines underneath since GDP growth (contraction) fell outside the bounds of my 2009 analysis. The dashed black line shows the rate of decarbonization implied by a 2.0% GDP growth 2010 to 2022, based on the updated data. There is some reason to believe that 2010 actually saw a recarbonization of the UK economy, which would imply that the next red dot would be higher than the one for 2009 -- we shall see when official data is released.
Regardless what happened in 2010, the implication of the updated graph is virtually identical to the conclusions that I reached in the 2009 paper and in The Climate Fix: To be on target to meet its 2020 emissions reduction target the UK needs to become as carbon efficient as France by no later than 2015, under any positive future GDP growth. The reduction in emissions in 2009 do not alter that conclusion. The overall sense I get from media reports is that this reality is generally, if not universally, understood.
Now for something interesting that I cannot explain [UPDATE: See the comments for a valuable exchange with the ever-helpful Harrywr2.]. I routinely use the US EIA data on carbon dioxide emissions, because it is authoritative and they use an apples-to-apples approach for all countries around the world, enabling comparative and aggregated analysis. But when comparing the US EIA data with the official data from the UK (here in PDF) there is a distinct bias -- the UK has its emissions growing at a considerably slower rate than does EIA, as shown in the following figure.
The UK doesn't report aviation and bunker fuel for international transport. Aviation fuel accounts for 35 million MT of the difference.
ReplyDeleteThe EIA includes aviation and bunker fuel based on where the fuel was dispensed.
The EIA method is a unfair to locations with major aviation and shipping hubs.
The Kyoto method creates a black hole.
Roger,
ReplyDeleteIs it possible that there is a consistent positive bias in the US EIA emissions. I seem to remember when checking 2035 world emissions from US EIA and IEA last year the US EIA figures were considerably higher: 42.4 billion metric tons in 2035 v 35.4 billion tonnes in 2035 (2010 World Energy Outlook). Different assumptions on energy mix???
The sources are http://www.eia.doe.gov/oiaf/ieo/emissions.html and http://www.worldenergyoutlook.org/docs/weo2010/factsheets.pdf (p6)
-1-Harrywr2
ReplyDeleteThanks ... the Kyoto accounting is indeed itself interesting, but I'd be surprised if it accounts for the divergence in data from 1990 to 2009 between US EIA and UK.
-2-David Palmer
co2scorecard.org recently discussed these issues in a report, see:
http://rogerpielkejr.blogspot.com/2010/09/discrepancies-in-co2-reporting.html
and the IEA response:
http://rogerpielkejr.blogspot.com/2010/09/exchange-between-co2scorecardorg-and.html
Roger,
ReplyDeletefrom you UK CO2 emissions link page 8
In 2009, emissions from international aviation fuel use were estimated to be 33.0 million tonnes carbon dioxide equivalent. This was 4.3 per cent lower than the 2008 figure of 34.5 million tonnes. However, between 1990 and 2009 the level of these emissions has more than doubled.
Bunker fuel(boat fuel) accounts for 10 Million tonnes, Aviation Fuel Accounts for 33 Million tonnes.
UK says 474 Million for CO2, EIA says 519 million.
519-43= 476.
Close enough for government work:)
-4-Harrywr2
ReplyDeleteThanks, this makes sense mathematically. My sense has always been that aviation is included, based not on the Act but the guidance of the CCC, but a closer look just now shows that it is at least ambiguous (if not plain old confusing).
Here is what the Climate Change Committee has said in a recent report on the inclusion of aviation emissions:
"In the context of providing advice on the level and scope of the first three carbon budgets, the Committee was required to consider whether international aviation should be formally included. The Committee’s position was that international aviation should be part of climate strategy and would ideally be included in carbon budgets...
The Committee therefore concluded that international aviation emissions should not for the time being be included in carbon budgets. They were reflected, however, in the Committee’s advice, which proposed carbon budgets that, together with the EU ETS cap on aviation emissions, would be an appropriate contribution to required global emissions reductions over the first three budgets...
Given that the approach for allocating auction revenues from aviation inclusion in the EU ETS to Member States may be consistent with suitable methodologies for allocating aviation emissions (thereby reducing the potential for confusion), it is appropriate to reconsider inclusion of international aviation emissions in the UK carbon budgets."
http://downloads.theccc.org.uk/Aviation%20Report%2009/21667B%20CCC%20Aviation%20AW%20COMP%20v8.pdf
So after this flip and flop, it seems that aviation is going to be a part of the targets eventually, which has been my understanding.
Given that these emissions do not make up a constant fraction of the total, leaving them out at present provides a misleading picture as to performance of the CCA. Consider that when they are eventually added back in, emissions will then jump. I can think of a number of ways to finesse this ;-)
At a minimum DECC should give the numbers with and without aviation:
http://www.decc.gov.uk/assets/decc/Statistics/climate_change/1214-stat-rel-uk-ghg-emissions-2009-final.pdf
In any case, to compute decarbonization rates using the emissions-minus-aviation would also require subtracting out that part of GDP attributable to aviation and shipping, which would be pretty huge (and probably nonsensical). Calculating decarbonization without aviation and shipping but with total GDP would misleading.
Thanks for your help in clarifying these issues!
Roger,
ReplyDeleteThis brings up a related question I had when reading The Climate Fix. In your de-carbonisation analysis, you consistently assume an exponential decay model for carbon efficiency, but you never justify that assumption. Indeed, your plots of historical de-carbonisation seem never to conform to this model (though they don't consistently conform to any other model, either).
The only data I have to hand is for the energy efficiency of the UK economy (not carbon efficiency) for the past 40 years. The data looks to me to be a linear trend, not exponential decay. There was a brief pause around 1990 (two or three years) but otherwise the trend is remarkably consistent. This data comes from the UK Dept of Business, Energy and Regulatory Reform report, Energy Consumption in the United Kingdom.
If the de-carbonisation trend follows the energy efficiency trend and is linear rather than exponential, then of course we can achieve later targets with much lower initial rates than you derive in your analysis, and we avoid the rather odd feature of your analysis that relatively heavy cuts by 2020 require less initial effort than very heavy cuts by 2050.
So: Is your exponential decay justifiable, or is it just assumed?
-6-Tom
ReplyDeleteThanks for this question. It has come up a few times from others.
The historical dearbonization data is (in many countries) linear. Going forward to illustrate the challenge, I present decarbonization as occurring at a constant rate (rather than constant amount) per year. The choice is of course arbitrary to some degree. One could of load all of the reduction into the last year, or any other distribution. Obviously, the linear rates of the past won't do the trick going forward.
My analysis of the magnitude of the effort begins with a conditional, if the rate of decarbonization is constant over the period ... This is both for intuitive purposes, but also because what I am presenting is neither a recommendation nor a prediction, simply a straightforward way to illustrate the size of the challenge. If I had presented straight lines in the book I'm sure that I'd be asked why they weren't exponential ;-) But to be clear -- if you'd prefer a straight line (rather than exponential) to illustrate the challenge, I wouldn't quibble as the overall implications won't change.
That said, the integrated magnitude of the challenge is of course the same, however you decide to distribute it across the period. So when I say -- in round numbers, "a nuclear power plant per day of carbon free energy" -- that is a metric of scale. It is the mathematical equivalent of saying "two nuclear power plants per day during the second half of the period."
There is of course a policy debate about when cuts should occur, sooner or later, and the balance of view is sooner. Tom Wigley and colleagues (Richels, Edmonds) caused a stir a while back when they suggested that it might be better to put those cuts off into the future when technologies have advanced. Based on my analysis in The Climate Fix, you could make a case that we really don't have much choice in any case.
Roger Pielke, Jr. said... 5
ReplyDelete....Calculating decarbonization without aviation and shipping but with total GDP would misleading.
Aviation is the hardest piece of CO2 emissions to address.
Dumping cement and steel production offshore as a 'quick fix' for CO2 reduction wouldn't be such a great fix if the CO2 emissions from the shipping get allocated to the consuming country.
Politico's always leave themselves an 'out'.