Central England Temperature
Following requests, I am planning to start running a monthly update of the Central England Temperature series.
First, let’s have a look at the monthly numbers for this year.
It is important to note that the anomalies are based on the 1961-90 period, which was about 0.5C colder than the 1981-2010 baseline, and also cooler than the 1931-60 period, which preceded it.
The CET for 2012 is going to finish at around 9.6, which will leave the year as comfortably the second coldest since 1996, when the temperature reached only 9.2C. The coldest year for many years, of course, was 2010, when we shivered through one of the coldest winters for decades.
Standing back a bit though, we can look at the annual numbers since 1980.
The red line is the mean for 1980-2011. The step up in temperatures from around 1990 is clear, but, in the last five years (including this year), only one has been significantly above the mean.
Figure 2 shows the running 12 month average, with the mean line this time covering the period from 2000 to date. Since the start of 2008, apart from a few months, the CET has been consistently and significantly below the mean. Assuming my estimate for this year is correct, the average for 2008-12 will come in at 9.8C, which compares with 9.97C for the 1981-2010 baseline.
How long does it take for a trend to become a trend?