Tracking year to year changes in greenhouse gas emissions can be problematic. It is incredibly easy to read too much into what happens in a single year. And this can go in two directions.
Consider coal in China. Last year, China’s coal use declined (officially that is, but we can’t trust China’s coal statistics that much). If you are naive, you would believe that China has reached peak coal. This view is somewhat delusional given that China has over 100 gigawatts of coal power plants under construction.
So, what are we to make of the fact that Britain’s GHG emissions declined by 8.4% last year? Two things are notable. First, this is a record one year drop for Britain (depending on how far back you go), and it is also probably a record drop for any country with an economy that is growing.
But, the numbers deserve a closer look. A big influence on year to year changes in energy consumption, and thus emissions, is temperature. Put simply, if it is warmer, people are less likely to turn up their gas boilers.
For example, Germany’s early estimates indicate that its energy consumption fell last year by 5%. But, if you adjust for temperature the fall was only 2% or so. In other words, the majority of the decline in energy consumption was due to the weather.
So, what about Britain’s GHG emissions last year? The British government produces temperature adjusted emissions estimates. There are some uncertainties in these estimates, but they are the best way to measure the real changes in the energy system and emissions.
Unfortunately, they aren’t yet available for the entire year. But they are available for the first three quarters. And they tell a similar story to Germany. More than half of the emissions cuts seem to come from changes in temperatures.
Here are the basic numbers (available here). Total GHG emissions were down 9% in the first three quarters. However, after temperature adjustments the decline was only 3.7%.
The chart below shows the changes in each quarter compared with the year before. The two bars show the actual decrease and the temperature adjusted decrease. Temperature had the effect of exaggerating the fall in emissions in each quarter.
The first quarter sees the biggest adjustment. Britain’s actual emissions fell 10% in the first quarter compared with the previous year. But, after temperature adjustments they only fell by 0.7%. It was clearly a warm winter.
We will have to wait until next month for the official temperature figures for the entire year. But, based on these numbers it looks as if Britain’s GHG emissions fell by less than 4%, not 8.4%, once you take account of the weather.