Unpacking the DECC Inventory… Part 2: Carbon Dioxide

My previous post on the UK emissions statistics was about non-CO2 greenhouses gases. This one is about carbon dioxide itself.  As I discussed in that post, the UK’s non-CO2 greenhouses gas emissions have fallen by 49 per cent since 1990 while CO2 emissions have fallen by only 19 per cent over the same period. This post looks at CO2 emissions by economic sector and particularly at the reduction between 2008 and 2009.


[Update: Feb 2013 In early 2013, DECC’s website moved to http://www.gov.uk, and many of the links in this post now don’t work. Some of the documents are now here:
https://www.gov.uk/government/publications/final-uk-emissions-estimates]

As in Part 1, I am using the DECC greenhouse gas inventory (data tables from 2010 (excel – backup link here)), and as in that post I calculate percentage changes from 1990 to 2009 as these were the dates used in the Carbon Plan 2011. Over this time, annual greenhouse gas emissions fell 26 per cent (a reduction of 200 MtCO2e). Of this 200 Mt, 113 Mt was due to a reduction in carbon dioxide emissions.

The following graph shows the emissions by economic sector from Table 4 of the DECC spreadsheet. In that spreadsheet these emissions are given by ‘source’, ‘fuel’ and ‘final user’, Here I am following the Carbon Plan’s use of ‘emissions by final user’ where all power station emissions are attributed to the sector that uses them.  The main sectors emitting carbon dioxide are ‘business’, ‘residential’, and ‘transport’. Annual business CO2 emissions fell by 70 Mt between 1990 and 2009; residential emissions fell by 19 Mt while transport emissions rose very slightly (1 Mt). Other sectors showed significant falls as well, contributing 24 Mt to the overall reduction. Exports emissions showed an increase (of 6.5 Mt CO2).

Fig7 CO2 emissions by final user

I was intrigued by the sudden drop between 2008 and 2009. If the Carbon Plan 2011 had reported the fall to 2008 and not 2009, the overall fall in annual CO2 emissions since 1990 would have been only 10 per cent, rather than 19 per cent. That is, over 45% of the total reduction in annual emissions occurred in that final year. This ‘jump’ is most pronounced for the business, residential, transport and industrial process sectors. Indeed transport would have recorded an increase of 7 Mt CO2 since 1990 were it not for the fall of 6 Mt from 2008 to 2009.

This ‘jump’ can be seen more clearly in the following graphs. The first shows annual CO2 emissions in each of the years, 1990, 2008 and 2009. We can see that for several sectors the fall between 1990 and 2008 (i.e. over 18 years) is comparable to the fall in the single year from 2008 to 2009.

Fig8 Annual CO2 emissions 1990 2008 2009The next graph shows just the changes (1990 to 2008) and (2008 to 2009) to highlight the differences:

Fig9 change in annual CO2 emissionsThe fall was not limited to one fuel, but was seen in emissions from coal, oil and gas:

Fig10 CO2 emissions by fuel

So why did emissions fall so steeply in 2009?  A change in accounting methods? The global recession?  An increase in renewable energy?

The fact that the fall in emissions was not limited to the UK alone but was seen across the industrialised world, though not in China or India suggests that it was not due to some change in accounting or reporting methods by DECC. Discussion about the reduction in emissions in 2009 can be found online in various places.  The US Energy Information Administration attributed the sudden drop in US emissions to mild weather as well as the weak economy.

The Earth Policy Institute attributed the fall to the global recession and also mentioned a possible contribution from renewable energy. The article noted that emissions from China and India continued to rise, while those from the US, Japan and EU fell.

“In 2009, carbon dioxide (CO2) emissions in China—the world’s leading emitter—grew by nearly 9 percent. At the same time, emissions in most industrial countries dropped, bringing global CO2 emissions from fossil fuel use down from a high of 8.5 billion tons of carbon in 2008 to 8.4 billion tons in 2009.
[…]
In the United States, CO2 emissions shrank by nearly 10 percent from 2007 to 2009 […] The United Kingdom’s CO2 emissions fell by over 10 percent from 2007 to 2009. German emissions dropped by 8 percent, and French emissions dropped by 5 percent. Japan saw its emissions decline nearly 12 percent over the two-year period.
[…]
While much of the global emissions drop in 2009 was due to declining fossil fuel use associated with the recession, the past year also saw strong growth in the use of renewable energy. Installed wind capacity alone grew by over 30 percent worldwide. In the United States, where coal use dropped by more than 13 percent from 2007 to 2009, over 200 new wind farms came online during the same period, adding more than 18,000 megawatts of capacity.”

Wind energy could in fact have made only little contribution to the fall in emissions in 2009 despite significant growth in installed capacity. Wind energy contributed less than 1 per cent of total US electricity generation in 2009. Overall, wind contributed just 2 % of total global electricity demand in 2009 according to the World Wind Energy Report. Even a 32 per cent increase in wind generation in 2009 could not have accounted for more than a small fraction (less than 5 per cent) of the fall in CO2 emissions in 2009.

As Roger Pielke jr, among others, points out, emissions are strongly coupled to economic growth. Targets that are only met because of a recession or by importing goods from other countries, will not lead to global long-term reductions in carbon dioxide emissions. Although our elected representatives insist that ‘decarbonisation does not mean deindustrialisation’ (see my post on MPs’ views on meeting the Climate Change Act targets), that is in fact how the fall in CO2 emissions from 2008 to 2009 was achieved.

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3 thoughts on “Unpacking the DECC Inventory… Part 2: Carbon Dioxide

  1. Ah yes, the Original Sin of the 1990 baseline. Why, after all these years, is 1990 still serving as the reference point for greenhouse gas emissions? As i recall, the reason why it was first accepted was that the UK negotiators for the Kyoto wanted to take advantage of coal fired power plants that were already being taken off-line for other reasons, and the German negotiators wanted to be able to count old factories and power plants in the former East Germany that were already slated for the same fate. Other countries didn’t particularly care, so 1990 it was. If the baseline had been set at the time the treaty was adopted, the UK would have had about 40-45 more mt of CO2 (eyeballed from your graph) to cut. Instead, Hey, Presto! the cut was written in for them.

    • That’s very true. The Kyoto treaty could have been ‘designed to make the EU look good’ as Dieter Helm puts it.

      Deindustrialisation in the EU also made cutting (EU) carbon dioxide emissions relatively easier, but if consumption (imports) is taken into account, the EU’s ‘carbon footprint’ can be shown to have risen considerably.

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