Monday, 26 June 2017

Climate change in Cambridge

We know global temperatures have been increasing - it is happening here in England too. Here are some charts based on MET office monthly average data since 1910 [1]. The clearest changes are in minimum temperature. I see no trends in rainfall, which surprised me.

These are for East Anglia (which includes Cambridge where I live). The blue lines are the 10 year running average. The first chart is for August. There is considerable variation even in the running average and the increase is not linear but is more marked since about 1995.
(max - min) for the running 10 year mean is 2.1C. In my lifetime the change is 1.3C.

Now the summer as a whole - this is the average of monthly minimums from June to October. There is less change overall but the trend is clearer because there is less variability.

(max - min) for the running 10 year mean is 1.9 C. In my lifetime the change is 0.9C.

If you look at England as a whole, the trend is similar.
(max - min) for the running 10 year mean is 1.7 °C. In my lifetime the change is 0.8C.
However the pattern is less clear in winter. If there is a trend, it starts in about 1990.

(max - min) for the running 10 year mean is 2.0 C. In my lifetime the change is 1.3 C.

When it comes to rainfall, there are no clear trends at all: neither in overall trends nor in severity.

There last two charts are temperature again but for the whole year: East Anglian mean temperature  for comparison with global temperature.
Mean temperature b year. (max - min) for the running 10 year mean is 1.5C. In my lifetime the change is 1.1C

The global temperature chart is from the NOAA. The scale is the difference in temperature from the average between 1901 and 2000 and it goes back further to 1880. Our peaks and troughs are not exactly aligned with the global weather fluctuations. Our minimum is  a little later than the global dip in 1910 and we don't see the global mini peaks in 1942 and 1960. However both datasets show a strong upwards trend and are significantly higher since 1990 than at any time before.

Global mean temperature changes [2]

We expect climate change to bring more frequent droughts but this is not obvious so far in the weather for England since 1910, which I found surprising. We do see increase in temperature, especially summer minimum temperatures. This means more hot, sweaty nights (as we have endured recently). There seem to be significant changes within my lifetime, an increase of 1.3C in East Anglia and 0.9 C in England as a whole so when I complain I am not being unreasonable :-). However there will be worse to come. These trends are broadly consistent with global trends, albeit with local fluctuations as you would expect.

Perhaps we will become accustomed to the 'new normal' and forget what it used to be like - as illustrated in this XKCD cartoon.

[1] MET office UK and regional series
[2] Global Climate Report Annual 2013 (NOAA)

1 comment:

  1. It's not as simple as 'we expect more frequent droughts'. Some areas get dryer, some get wetter (higher temps support higher humidity). It's very hard to predict these trends at the moment, but one of the surest predictions is that the Mediterranean will get significantly drier. What happens in the UK/Northern Europe is less clear although most work I've seen suggests that it will get somewhat wetter, although if the AMOC reduces significantly then who knows what we'll get.