1
00:00:00,780 --> 00:00:04,530
Well, I'm going to take a slightly different perspective.

2
00:00:05,220 --> 00:00:13,590
My background is very much as well as instrumental data and datasets as in climate variability and climate change.

3
00:00:14,100 --> 00:00:23,310
So what I'm going to talk about, first of all, is the contribution of the Ratcliff dataset to Central England temperature.

4
00:00:24,550 --> 00:00:32,410
And centrally in temperature is the longest instrumental data in the world, but it's a composite dataset.

5
00:00:32,800 --> 00:00:35,950
So the Ratcliff is from one station.

6
00:00:36,160 --> 00:00:40,930
Central England is too many stations. It starts in 1659.

7
00:00:40,930 --> 00:00:46,510
And as you heard Tim say, there are no instrumental observations in 1659.

8
00:00:46,810 --> 00:00:54,220
So some of the early data, although it's nominally quantitative, is actually reconstructed from diaries and things like that.

9
00:00:54,490 --> 00:00:58,420
And I won't mention a lot about that, but that's the work of Gordon Manley.

10
00:00:58,840 --> 00:01:05,559
And then finally, I'm going to show you how we can use the Ratcliffe Observatory data even though it's in one station.

11
00:01:05,560 --> 00:01:12,010
This actually slightly surprised me to cause quite a lot of light on the relationship between synoptic

12
00:01:12,010 --> 00:01:18,819
variability in the North Atlantic and temperature and some other parameters at Oxford itself.

13
00:01:18,820 --> 00:01:22,120
So it's so it's more useful than I thought.

14
00:01:22,510 --> 00:01:32,800
So there's the observatory, there is the site which, as Tim said, is a fairly constricted site.

15
00:01:33,070 --> 00:01:36,700
That's probably actually changed quite a lot over time.

16
00:01:39,130 --> 00:01:47,950
And here, just to overlap with Tim's talk is a book of observations from The Observer in March 1773.

17
00:01:48,730 --> 00:01:51,820
The world temperature data in those days, but they're incomplete.

18
00:01:52,150 --> 00:02:00,730
And so the complete data only starts, as Tim says, in 1814, though I daresay some use actually could be made of that earlier data.

19
00:02:01,840 --> 00:02:08,770
That's Gordon Manley. Gordon Manley is very famous in meteorology for the Central England temperature dataset.

20
00:02:09,190 --> 00:02:12,400
This was a tremendous effort over decades.

21
00:02:12,860 --> 00:02:21,340
And in those days, it was before global climate change existed as a viable study.

22
00:02:21,610 --> 00:02:30,700
People many people thought the climate was constant. So Gordon actually pioneered this work as a time when this sort of work wasn't very fashionable.

23
00:02:30,970 --> 00:02:37,270
And we are now very grateful in the days of climate change that he actually did this all those years ago.

24
00:02:37,510 --> 00:02:48,080
He was also president of the World Meteorological Society, and he wrote papers, as you can see on that slide from 1946 up to 1974 on this topic.

25
00:02:49,990 --> 00:02:55,840
The first paper in 1946 didn't include the Radcliffe data,

26
00:02:56,230 --> 00:03:05,020
but Central England temperature tries to represent something like the Midlands, but there aren't enough data in the true Midlands.

27
00:03:05,050 --> 00:03:14,840
So what he did, he took data from the Lancashire region and from the Oxford region and averaged them together to represent the Midlands.

28
00:03:14,860 --> 00:03:23,650
So that's what it is, Central England temperature, but it covers everything from the Lancashire Plains down to down to the Radcliffe Observatory.

29
00:03:24,850 --> 00:03:36,190
Then in 1953, this was the first monthly Central England temperature paper which combined the Lancashire data with the Radcliffe data.

30
00:03:37,430 --> 00:03:46,820
And you can see on that graph, Lancashire and lots of stations there, those, those places are just to give you a geographical perspective.

31
00:03:47,150 --> 00:03:57,620
It's basically the area was to the west of Halifax and Salford between there and the coast, and you can see Oxford.

32
00:03:57,980 --> 00:04:01,280
And so that's the sort of range of Central England temperature.

33
00:04:03,800 --> 00:04:15,620
And this is his most famous paper in 1974, which published the full Central England temperature data from 6959 to 1973,

34
00:04:16,070 --> 00:04:21,710
and the central inland temperature data is quoted and used throughout the whole world.

35
00:04:22,250 --> 00:04:26,310
And I'll show you some very surprising reasons why that might be so light.

36
00:04:26,330 --> 00:04:34,640
At the end of the lecture, it's not only the longest temperature dataset, it's also surprisingly useful in a much wider context.

37
00:04:35,510 --> 00:04:47,840
And thanks to Tim, these are Gordon Manly's original manuscript diagrams showing up summarising what he achieved.

38
00:04:48,590 --> 00:04:54,650
I think these are different seasonal. This is the winter top, spring, summer, autumn and the year.

39
00:04:54,770 --> 00:04:58,340
So don't worry about that because you can see things much more clearly afterwards.

40
00:04:58,640 --> 00:05:05,360
But that is itself a historical document is quite as much as some of the Ratcliff data themselves.

41
00:05:06,740 --> 00:05:14,059
Now one of the problems with the Ratcliff data is that it is subject to urbanisation.

42
00:05:14,060 --> 00:05:17,720
The city has grown. The site has also changed somewhat.

43
00:05:18,230 --> 00:05:28,129
So when the work was done to try and update the Ratcliff work and its application to Central England temperature,

44
00:05:28,130 --> 00:05:32,930
which we did in the Met office, we had to take a very close look at this problem.

45
00:05:33,830 --> 00:05:41,780
We also wanted, if we could, to create a daily central temperature dataset back as far as possible.

46
00:05:41,780 --> 00:05:50,089
This is very valuable for looking at synoptic variability, remembering that the Central England temperature is actually monthly,

47
00:05:50,090 --> 00:05:56,360
even though the Ratcliff Observatory itself has and daily data going back quite a long way.

48
00:05:56,930 --> 00:06:04,639
So we had a lot of difficulty because we couldn't really find the only data back

49
00:06:04,640 --> 00:06:11,780
as far as you want it to go in the Lancashire area and in the Oxford region.

50
00:06:12,230 --> 00:06:14,570
So we use a whole variety of other stations.

51
00:06:14,570 --> 00:06:24,680
You can see some of them in Black Linden, I think that's in Rutland, Cambridge and more recently, more recent years, more Vernon Squires Gate.

52
00:06:25,550 --> 00:06:30,980
And we managed to extend the daily Central England temperature record back to 1772.

53
00:06:33,650 --> 00:06:40,430
But we could only use the Ratcliffe recalled in up to 1973.

54
00:06:42,850 --> 00:06:49,490
So this is the daily central England temperature record from 1772 to 1991.

55
00:06:49,510 --> 00:06:55,600
It's kept up to date. Although Hadley Centre on a daily basis, actually, it's actually updated in real time.

56
00:06:55,600 --> 00:06:59,630
So you can see what's happening. The Central England temperature today.

57
00:07:00,070 --> 00:07:13,180
What happened yesterday, which is very valuable for lots of applications, but we cannot include the Radcliffe data after 1973 and in the later paper,

58
00:07:13,570 --> 00:07:20,830
this is the last paper that was written on Central England temperature in 2005 by David Parker and Brian Holton.

59
00:07:21,280 --> 00:07:30,280
They compared the Ratcliffe Observatory minimum temperatures to the daily Central England temperature minimum temperatures.

60
00:07:30,640 --> 00:07:37,600
Now, when urbanisation takes place, you guys, the heat actually comes partly from the buildings,

61
00:07:37,780 --> 00:07:43,480
but quite a lot of it actually comes from the concrete surfaces, the roads, etc.

62
00:07:43,960 --> 00:07:49,150
And it's the heat released night that actually causes the major problem.

63
00:07:49,600 --> 00:07:56,950
So it's the the night time temperature, the suffers from urbanisation much more than the daytime temperature.

64
00:07:57,340 --> 00:08:06,280
So if you want to detect urbanisation, you should look at the Night-Time temperatures and you can see that the graph is the

65
00:08:06,290 --> 00:08:11,919
reactive observatory relative to the minimum daily central England temperature,

66
00:08:11,920 --> 00:08:14,470
which itself is corrected for some urbanisation.

67
00:08:14,920 --> 00:08:26,840
And you can see a rise of about half a degree since the beginning of the 19th, 20th century, and most of that's taken place since about 1960.

68
00:08:27,220 --> 00:08:32,470
I don't think we fully understand the cause of the shape of that curve.

69
00:08:32,710 --> 00:08:39,550
I think it is quite complicated. Oxford is grown, but I suspect slight changes may contribute.

70
00:08:39,940 --> 00:08:43,360
And so you can see even up to 1973,

71
00:08:43,720 --> 00:08:50,830
Central England temperature probably might have a small amount of uncollected urbanisation, but they tend to be small.

72
00:08:52,860 --> 00:09:01,800
Now what we've done, what I've done next is to look at what these Central England temperature and the Ratcliffe Observatory

73
00:09:02,040 --> 00:09:09,420
temperature records can tell us about climate change actually in central England and at Oxford.

74
00:09:09,750 --> 00:09:19,920
So on the left hand side sky, we will see temperature anomalies, temperature differences from an average over the last 30 years, 1981 to 2010.

75
00:09:20,340 --> 00:09:27,540
And the Central England temperature record is a red and the Ratcliffe Observatory record is is blue.

76
00:09:27,810 --> 00:09:30,960
And these are the annual means of the day and the nights.

77
00:09:31,230 --> 00:09:34,320
And the first thing you can see, if you look at the blue records,

78
00:09:35,130 --> 00:09:44,100
it parallels Central England temperature up to about 1960, and then it overtake and then it catches up with it.

79
00:09:44,100 --> 00:09:52,860
And that's a sign that the Ratcliffe Observatory temperatures have warmed more than the central England temperature, which has little urbanisation.

80
00:09:53,190 --> 00:09:58,140
So and you can see that the amount is several tenths of a degree.

81
00:09:58,170 --> 00:10:02,010
So when you average the minimum and the maximum is probably about.

82
00:10:02,960 --> 00:10:08,300
0.3 degrees. Which shows you that you the maximum temperatures are probably okay.

83
00:10:08,540 --> 00:10:12,340
They probably don't suffer from urbanisation. It's the minimum temperatures.

84
00:10:12,500 --> 00:10:24,740
And you can see the sharp rise in temperature in the last 40 years or so from minus point five relative to 1981 to 2010,

85
00:10:25,130 --> 00:10:27,740
up to about 2.3 degrees above.

86
00:10:27,770 --> 00:10:37,969
So it's been a rise of about 0.8 degrees centigrade in central England, temperature one degree in the Ratcliffe in the last 50 years or so.

87
00:10:37,970 --> 00:10:41,330
And that really is quite strong warming on this 10%.

88
00:10:41,480 --> 00:10:46,490
It's actually had quite a big effect on what people can grow, not only vines.

89
00:10:46,760 --> 00:10:53,210
And there's a magnificent vineyard near where I used to live in the South Chilterns, which produces excellent white wine.

90
00:10:53,540 --> 00:10:57,740
I don't fully recommend some of the red wines produced in Devon.

91
00:10:58,370 --> 00:11:07,460
We had a party one day and it was a bit of a disaster when we bought a very expensive bottle of red wine from a vineyard north of Exeter.

92
00:11:07,880 --> 00:11:11,360
But something else you can grow very well nowadays is maize.

93
00:11:11,780 --> 00:11:23,269
And maize wasn't viable in England till about 30 or 40 years ago because you need most summers to get a good crop to make it financially viable.

94
00:11:23,270 --> 00:11:30,710
And there are papers in that the Met Office have written about this. And so maize is now very much commercially viable, even on the high chilterns.

95
00:11:30,980 --> 00:11:34,920
It was a field literally next to our house, 600 feet above sea level.

96
00:11:34,940 --> 00:11:39,110
Growing maize quite successfully in the 1990s.

97
00:11:41,250 --> 00:11:47,910
2014. Go back. The last point on that graph is 2014, the warmest year.

98
00:11:48,210 --> 00:11:53,220
You can see the Ratcliff just point pokes up as blue above the red slight, slightly warmer.

99
00:11:54,030 --> 00:12:02,970
And there's one of the Ratcliffe observers on the telephone to Radio Oxford on 9:15 a.m.

100
00:12:03,240 --> 00:12:08,880
on the 1st of January 2015 to tell the world what had happened of this great event.

101
00:12:09,390 --> 00:12:14,850
And indeed it was. So we have just had the warmest year on record.

102
00:12:15,090 --> 00:12:21,480
And one of the surprising things about 2014, there were no there were no extreme temperatures.

103
00:12:21,510 --> 00:12:29,610
It was just uniformly warm all the time for a whole variety of reasons, which I haven't got time to go into, but you could ask.

104
00:12:30,180 --> 00:12:32,850
So it's a sign of what might happen in the future.

105
00:12:33,000 --> 00:12:40,410
We don't have to have great extremes that the whole record can just lift up the whole statistical distribution of temperatures.

106
00:12:40,710 --> 00:12:49,410
Countries rise as a whole. You don't need a big change in the extremes, though that may happen as well, but it didn't happen in 2014.

107
00:12:50,160 --> 00:13:02,940
In the top diagram, I show you in blue the rise of minimum temperatures and Ratcliffe and the rise in Central England minimum temperatures.

108
00:13:03,210 --> 00:13:11,320
And again you can see the problem that there is a they were relative to 1981 to

109
00:13:11,320 --> 00:13:17,460
2010 they were pretty well parallel until 1960 and then they join together.

110
00:13:17,700 --> 00:13:22,620
And so we've had a rise in the minimum temperatures and below is the maximum temperatures.

111
00:13:22,860 --> 00:13:26,640
And there you can see Central England and Ratcliffe.

112
00:13:26,670 --> 00:13:30,870
I mean, there's slight differences in detail, but they've gone together essentially.

113
00:13:30,870 --> 00:13:36,360
So the Ratcliffe is a pretty good measure of the way that maximum temperatures have risen in central England.

114
00:13:36,660 --> 00:13:39,239
So it's a very vulnerable record. And in fact,

115
00:13:39,240 --> 00:13:49,650
it's worth pointing out that temperatures in one place are actually very highly correlated with temperatures in another place of the United Kingdom.

116
00:13:50,160 --> 00:13:57,270
So you have to go a long way away from that, from the Ratcliffe Observatory before the temperature changes that you get,

117
00:13:57,270 --> 00:14:02,100
rather than the mean temperatures which vary across the country actually very, very much.

118
00:14:02,370 --> 00:14:05,190
It's not the case. Rainfall is much more complicated.

119
00:14:05,580 --> 00:14:13,950
So the Ratcliffe Observatory record on its own can be surprisingly useful on its own, even though it's one side.

120
00:14:15,780 --> 00:14:24,000
The last thing I want to point out, if I go on to climate variability, is although the Radcliffe Observatory suffers from urban warming.

121
00:14:25,220 --> 00:14:30,500
This could be quite valuable in future because the climate change that the majority

122
00:14:30,500 --> 00:14:36,200
of our population will suffer is the general climate change plus the urban warming.

123
00:14:36,530 --> 00:14:41,840
And there's no work going on in the Met Office to model these effects in detail.

124
00:14:42,140 --> 00:14:46,380
And this will become a big topic, I'm sure, over the next 20 or 30 years.

125
00:14:46,910 --> 00:14:54,799
So if you can correct for very local site changes, the Radcliffe Observatory together with London,

126
00:14:54,800 --> 00:15:02,060
various London records, various other records in big cities, could become especially valuable in its own right.

127
00:15:02,330 --> 00:15:06,530
And the fact it suffers some urbanisation could be a positive advantage.

128
00:15:06,890 --> 00:15:11,810
And that's often not pointed out when these sorts of talks are done.

129
00:15:12,440 --> 00:15:22,580
So there is of the winter and central England is in red, the active observatory is in blue and this is the mean temperature.

130
00:15:22,590 --> 00:15:30,050
So there's a bit of urban warming at the end. First of all, the straight red line is the trend in central England temperature.

131
00:15:30,380 --> 00:15:38,450
And you can see over the last two centuries taking the simplistic view of a straight line, there's been a rise of one degree centigrade.

132
00:15:38,780 --> 00:15:47,030
But what's much more interesting are the wobbles in that curve, and they really their major wobbles over a century.

133
00:15:47,270 --> 00:15:56,210
So if you look at the dip around about 1899, both together, there was a rise up to about 1920.

134
00:15:57,080 --> 00:16:05,270
Then there was a fall until the 1970s and then a rise since then and a bit of a flattening.

135
00:16:05,810 --> 00:16:09,500
So is that chance or is it due to something?

136
00:16:09,920 --> 00:16:18,890
And you can notice at the bottom of that fall is the great winter of 1962, 63, after which the warming restarted.

137
00:16:18,920 --> 00:16:27,290
Why was that? Well, a lot of the cause of that, as I was showing the minute, is weather variability.

138
00:16:27,800 --> 00:16:35,390
Now, the most important weather pattern that exists that affects the United Kingdom in the winter is the North Atlantic oscillation.

139
00:16:36,410 --> 00:16:44,120
The North Atlantic oscillation measures the strength and frequency of the westerly winds that flow from the Atlantic,

140
00:16:45,260 --> 00:16:55,670
from the Atlantic to Western Europe. And in the positive phase, the storms tend to go over into the north of the UK, bringing in westerly winds.

141
00:16:55,700 --> 00:16:59,510
Warmth from the Atlantic over the observatory.

142
00:16:59,780 --> 00:17:03,590
In the negative phase, the storms tend to go into the Mediterranean much more.

143
00:17:03,800 --> 00:17:09,950
We get an increased frequency of easterly winds and this is accounts for about half

144
00:17:10,280 --> 00:17:15,200
of the weather variability that affects Oxford or Wallingford for that matter.

145
00:17:16,370 --> 00:17:20,840
And you can measure it in a very simple way. And this is almost unbelievable.

146
00:17:20,870 --> 00:17:28,010
But if you just take the pressure difference between Iceland and the Azores, that measures it perfectly, almost perfectly.

147
00:17:28,070 --> 00:17:35,900
There are other ways of doing it. So this is a major fluctuation in the atmosphere, and it could be measured very simply.

148
00:17:36,230 --> 00:17:43,160
And we've got data from of these areas going back to the early 19th century.

149
00:17:43,760 --> 00:17:50,090
So how does the Ratcliffe Observatory record compare with the winter North Atlantic Oscillation?

150
00:17:50,510 --> 00:17:58,700
So the winter North Atlantic oscillation strength is measured in red and the Ratcliffe Observatory temperatures are measured in blue.

151
00:17:58,700 --> 00:18:04,790
And what I've done so this is a little trick we do in climatology because they're very different measures of different things.

152
00:18:05,270 --> 00:18:10,309
We've brought them to the same scale. So the variability of both is the same.

153
00:18:10,310 --> 00:18:15,950
This is in the standardisation for the guests here. So we can plot the graphs on the same scale.

154
00:18:16,100 --> 00:18:26,270
And you can see that although towards the end of the curve, the red the blue curve doesn't quite follow the red curve because of global warming.

155
00:18:26,870 --> 00:18:32,510
This is substantial similarity. In fact, the correlation of the winter values, not the smooth curve.

156
00:18:32,550 --> 00:18:35,960
Winter values is 0.71. That's half the variance.

157
00:18:36,410 --> 00:18:43,520
So the North Atlantic oscillation explains half the variance of the Ratcliffe the temperatures in the winter.

158
00:18:44,030 --> 00:18:53,720
And not only that, you'll notice that in fact the warming in the last few decades is not been very great in Central England temperature in the winter.

159
00:18:54,140 --> 00:19:01,940
So the winter actually winter shows the least warming of all the seasons and it's dominated by synoptic variability.

160
00:19:02,270 --> 00:19:08,600
So if you look towards the end of the record, you'll see in central in the winter, North Atlantic Oscillation,

161
00:19:08,870 --> 00:19:15,920
a big, huge negative blob and you'll see in the blue curve a smaller negative blob.

162
00:19:16,160 --> 00:19:21,739
That was the winter of 2010 11.

163
00:19:21,740 --> 00:19:24,740
We had the coldest December since 1890.

164
00:19:24,860 --> 00:19:31,239
Five caused by a negative North Atlantic oscillation almost entirely.

165
00:19:31,240 --> 00:19:38,630
The easterly winds from Russia and Siberia caused that winter, and that's the North Atlantic oscillation.

166
00:19:38,930 --> 00:19:43,460
Then the bottom is a it's a parameter we haven't discussed so far as the wind speed.

167
00:19:43,880 --> 00:19:50,640
This is the relative wind speed. It turns out that in the westerly phase from the Atlantic.

168
00:19:50,660 --> 00:19:57,020
The winds tend to be strong in the easterly phases. When you get high pressure and winds from the east, they tend to be weak.

169
00:19:57,230 --> 00:20:02,780
And you can see the wind through the winds. At the Ratcliffe Observatory, though, it's an open site.

170
00:20:02,780 --> 00:20:06,920
You might think it's not very reliable and we know there may be some problems right at the end.

171
00:20:08,330 --> 00:20:13,250
Follow each other very well. And by the way, these smooth curves are all 22 year running mates.

172
00:20:13,550 --> 00:20:24,560
So that is another indication that the North Atlantic Oscillation actually controls Ratcliffe Observatory winds.

173
00:20:25,130 --> 00:20:29,630
Something that perhaps is not often discussed is of great interest to the

174
00:20:29,630 --> 00:20:34,100
energy industry because as I'm going to show you some new results in a minute,

175
00:20:34,400 --> 00:20:38,930
that they are very much affected by the winds around the British Isles in the winter.

176
00:20:39,710 --> 00:20:45,920
If the turbines don't don't turn, they don't generate much electricity.

177
00:20:45,920 --> 00:20:52,090
So wind turbines are highly sensitive to the winter North Atlantic oscillation when

178
00:20:52,100 --> 00:20:56,450
a lot of electricity is generated because the winds are strongest in the winter.

179
00:20:57,620 --> 00:21:06,290
Now, we've had a very big breakthrough in the last two years in forecasting the winter North Atlantic oscillation.

180
00:21:07,100 --> 00:21:15,740
Until recently, this was thought to be impossible, the winter North Atlantic Oscillation, because it's something in the stormy North Atlantic,

181
00:21:16,010 --> 00:21:22,520
fantastic variability was thought to be completely unpredictable beyond the timescale of weather forecasting.

182
00:21:22,520 --> 00:21:28,090
So we had but that turns out not actually to be true and so on.

183
00:21:28,100 --> 00:21:40,880
On that graph in black is the winter North Atlantic oscillation in this standardised scale and in the in blue that the solid blue line

184
00:21:41,510 --> 00:21:50,360
high costs from the latest climate model of the winter North Atlantic oscillation and all the little blobs are individual members.

185
00:21:50,360 --> 00:21:58,190
We have to run the middle many, many times. And so the the blue is the average and the correlation is is over point six.

186
00:21:58,700 --> 00:22:06,229
And when you get the correlation of over point six, all the all the users start to get interested because such a rough measure of,

187
00:22:06,230 --> 00:22:11,630
of, of the threshold of usefulness to society of a forecast.

188
00:22:11,990 --> 00:22:20,540
So these forecasts are now regarded as useful and this is developing new commercial opportunities for the Met Office.

189
00:22:21,710 --> 00:22:27,620
And this is all published in Geophysical Research Letters in April 2014.

190
00:22:30,220 --> 00:22:35,830
So congrats to the Radcliffe Observatory. Extreme cold months was December 2010.

191
00:22:36,580 --> 00:22:40,030
You can see the scale there. The darker the blue, the colder it was.

192
00:22:40,480 --> 00:22:48,370
And you can see Oxford on the Thames there was just outside the coldest area relative to normal.

193
00:22:48,370 --> 00:22:54,550
These are relative to normal, but it was quite close and the lowest temperature that she was -10.9.

194
00:22:54,880 --> 00:22:59,560
But no, that was nothing like as low as in the great winter of 1947.

195
00:23:01,600 --> 00:23:06,760
The reason for that probably is not so much global warming as a little component of that.

196
00:23:07,090 --> 00:23:14,880
But 1947 had continuous deep snow for a much longer period than December 2010.

197
00:23:14,890 --> 00:23:19,090
Nevertheless, it was the lowest temperature for a long time.

198
00:23:19,090 --> 00:23:26,830
I think for several decades has been record. Ratcliffe And this urbanisation, of course, and this is December 2010.

199
00:23:27,160 --> 00:23:33,670
On the right hand side, there's the snow cover. And you can see Ratcliffe is right in the middle of that snow covered area.

200
00:23:34,060 --> 00:23:40,330
And Cornwall wasn't it wasn't snow covered that might that top picture might have me in that plane.

201
00:23:40,600 --> 00:23:47,170
I was that was a British Airways plane. I think that's the one the last one that landed from San Francisco to London.

202
00:23:47,470 --> 00:23:53,650
And we landed in the blinding snowstorm and the airport was closed 3 minutes later for the next five days.

203
00:23:53,980 --> 00:23:58,420
So those are pretty dramatic introduction to the winter of 2010 for me.

204
00:23:58,690 --> 00:24:06,970
And there's a a Waitrose fan who went a bit too fast in in Devon for the conditions.

205
00:24:08,950 --> 00:24:13,450
And coming on the summer now, this is the Radcliffe Observatory.

206
00:24:13,460 --> 00:24:23,020
June to August temperatures, the mean temperature is in black, the minimum temperatures in blue and the maximum in red.

207
00:24:23,290 --> 00:24:29,710
And you see, again, not as much warming perhaps as you see in the annual mean.

208
00:24:30,760 --> 00:24:38,710
The minimum temperatures and the maximum temperatures have not followed exactly the same course.

209
00:24:38,920 --> 00:24:46,810
This is almost certainly due to atmospheric circulation. I haven't actually looked in great detail so that would bear some some looking at.

210
00:24:47,080 --> 00:24:53,170
Well, we can relate to some extent these values to atmospheric circulation.

211
00:24:53,470 --> 00:24:57,880
Now, in the winter I mentioned the winter North Atlantic oscillation.

212
00:24:58,180 --> 00:25:02,620
In the summer there was a summer North Atlantic oscillation, but it's somewhat different.

213
00:25:03,400 --> 00:25:11,050
In the winter, you can measure the North Atlantic oscillation by the difference in pressure between Iceland and the Azores.

214
00:25:11,800 --> 00:25:22,300
If it's positive, the Azores is high pressure and the Iceland is low pressure in the summer is very much more the UK versus Greenland.

215
00:25:22,600 --> 00:25:27,940
So in the positive phase of the summer, North Atlantic oscillation, all those solid lines,

216
00:25:28,690 --> 00:25:39,370
that's high pressure and cyclonic conditions over the UK to Scandinavia and low pressure over Greenland and it's very strongly

217
00:25:39,370 --> 00:25:47,469
related to rainfall below and you can see the correlation scale on the bottom and you see the colours and the correlations,

218
00:25:47,470 --> 00:25:54,250
that's the negative correlations. So when these anti cyclonic positive, some of those Atlantic oscillation is dry.

219
00:25:54,490 --> 00:26:03,910
So this is a drought pattern and the correlations, negative correlations exceed point six over reasonable sized areas.

220
00:26:04,150 --> 00:26:06,010
Now over the Ratcliff Observatory,

221
00:26:06,010 --> 00:26:15,040
you wouldn't expect the correlations to be so high because at one position you're much more in the hands of individual thunderstorms,

222
00:26:15,250 --> 00:26:21,310
whereas if you average over a region, you know, you average having lots of storms and it it smooth things out.

223
00:26:21,610 --> 00:26:25,030
Nevertheless, we do get quite a good relationship.

224
00:26:26,380 --> 00:26:32,320
This is July and August where we at the moment define the summer North Atlantic oscillation.

225
00:26:32,940 --> 00:26:41,589
The temperature correlation is 0.49, and that is caused by the fact that when the summer North Atlantic isolation is in,

226
00:26:41,590 --> 00:26:45,910
it's positive and it's cyclonic mode, there's lots of sunshine and it's warm.

227
00:26:46,690 --> 00:26:53,620
The rainfall I plotted is as negative of the rainfall just to show how it goes with the some of those to Arctic oscillation.

228
00:26:53,890 --> 00:26:58,060
And the correlation is almost the same, but negative but minus .48.

229
00:26:58,390 --> 00:27:01,840
And the similar situation circles is in in black.

230
00:27:02,200 --> 00:27:08,080
So we can explain rather less of the Ratcliff record by the sum of those, the Atlantic oscillation.

231
00:27:08,320 --> 00:27:14,260
But nevertheless, that's about 25% of the variance rather than 50% of the variance.

232
00:27:14,560 --> 00:27:20,350
This is because summer weather patterns are much more variable than the winter weather patterns.

233
00:27:20,350 --> 00:27:22,870
That may surprise you, but that is the case.

234
00:27:23,080 --> 00:27:29,110
So very recent work that I've done suggests that we can do a better job of the summer North Atlantic Oscillation,

235
00:27:29,320 --> 00:27:34,000
and it might explain a bit more of the variance, but not as much as in the winter.

236
00:27:34,900 --> 00:27:42,370
So extreme warm months, which was a positive phase of the summer, North Atlantic Oscillation and some other weather patterns as well.

237
00:27:43,000 --> 00:27:46,030
You'll probably remember August 2003.

238
00:27:46,890 --> 00:27:55,390
That's when the highest temperature ever recorded in Britain, 38.5 degrees centigrade, when old man it's over 101 degrees Fahrenheit.

239
00:27:56,230 --> 00:28:06,610
So that so that was in Kent and the Ratcliffe didn't get quite to those temperatures where you got to 35.6, which is 96 degrees Fahrenheit.

240
00:28:06,940 --> 00:28:16,390
And you can see the the red blobs are the warmest areas, which were which were over two and a half degrees above normal for that month,

241
00:28:16,840 --> 00:28:22,600
were mainly to the southeast of the Ratcliffe Observatory, the London area, and towards Kent.

242
00:28:24,180 --> 00:28:27,810
And just to. I live on Dartmoor. It was a drought.

243
00:28:27,930 --> 00:28:32,730
Summer and autumn. And there's the fern, the reservoir.

244
00:28:32,970 --> 00:28:40,230
And what's exposed is the old bridge in fern where the village which was drowned by the reservoir in 1942.

245
00:28:40,500 --> 00:28:51,370
The Clapper Bridge and the road bridge. And that's not been seen since I had the look in the drought of 2010 12, and that did not appear.

246
00:28:51,390 --> 00:28:56,940
So that shows you how much that wasn't a very long period, I don't think.

247
00:28:57,150 --> 00:29:03,750
But the temperatures made the effect of the decreased rainfall that much more severe because it was so warm.

248
00:29:06,570 --> 00:29:09,570
Spring in autumn. Now these have shown the most warming.

249
00:29:10,410 --> 00:29:11,670
This is the pattern.

250
00:29:11,670 --> 00:29:20,430
Right back for 18, 15, 20 year one remains and the annual values in spring and autumn, the three months, autumn, September to November.

251
00:29:20,700 --> 00:29:24,300
Spring is March two to May. And you can see a lot.

252
00:29:24,330 --> 00:29:33,750
Lots of interannual variability, but lots and lots of warming in the last of 30 years or so over one degree.

253
00:29:33,780 --> 00:29:42,390
So the lion's share really of the warming of Central England temperature and the Radcliffe Observatory really has come from spring and autumn.

254
00:29:43,880 --> 00:29:46,620
And the reason for that is not utterly clear.

255
00:29:47,370 --> 00:29:54,660
But as I pointed out, too, in the other seasons, the weather patterns have a very large effect on the temperatures.

256
00:29:55,680 --> 00:29:57,870
So this has not happened in the autumn.

257
00:29:58,890 --> 00:30:06,030
What's tended to happen, I think, is the weather patterns in the autumn and spring have tended to be warm weather patterns.

258
00:30:06,360 --> 00:30:13,870
And that's probably slightly added to the background effect of global warming, though there is no paper actually yet written on that subject.

259
00:30:13,890 --> 00:30:22,230
So, you know, you could use the fact of observatory record with Central England temperature to write a nice paper on that that topic.

260
00:30:23,820 --> 00:30:29,250
Finally, global warming. And this is quite surprising.

261
00:30:31,320 --> 00:30:40,350
In the dotted line is the classical global warming record is a ten year running means, by the way, of land and ocean.

262
00:30:40,440 --> 00:30:44,579
The ocean warmed slower than the land. So in the black,

263
00:30:44,580 --> 00:30:50,130
the black solid line is the global land that's everywhere over land that we can measure

264
00:30:50,520 --> 00:30:56,940
temperature back to the mid-19th century and we can make estimates of uncertainty.

265
00:30:56,940 --> 00:31:06,060
But that's too much to put on there. Superimposed on that is Central England temperature with the ten year running main and the Ratcliffe Observatory.

266
00:31:06,690 --> 00:31:11,060
Now we know the Ratcliffe Observatory has got a bit more warming due to urbanisation.

267
00:31:11,460 --> 00:31:16,860
So just concentrate on Central England temperature and although it fluctuates more because

268
00:31:16,860 --> 00:31:21,540
of weather patterns locally and there were some local effects in the Atlantic as well,

269
00:31:21,540 --> 00:31:25,110
the Atlantic temperatures don't always vary in the same way as the globe.

270
00:31:25,560 --> 00:31:30,360
Nevertheless, if you take out this sort of multidecadal variability,

271
00:31:30,600 --> 00:31:41,160
you'll see that Central England and Ratcliffe Observatory taking out the urbanisation has fluctuated very much the same as the global mean.

272
00:31:41,430 --> 00:31:47,640
So those sceptics that don't believe in global mean temperature can't really believe in the Ratcliffe record either.

273
00:31:51,720 --> 00:32:04,050
On my last slide, I want to congratulate the Richard and his predecessors, Tim, on maintaining this unique long record.

274
00:32:04,410 --> 00:32:11,700
Unfortunately, that some of the other records have not been maintained like Q Observatory and the Met Office slows down.

275
00:32:12,720 --> 00:32:18,420
And then we have 200 years of continuous meteorological observations, and that's Myles Allen,

276
00:32:18,420 --> 00:32:22,290
who's well-known climatologist, and he's got a bottle of something in his hand.

277
00:32:22,830 --> 00:32:25,920
So I imagine he celebrating something, whatever it is.

278
00:32:26,040 --> 00:32:26,970
Thank you very much.