Bluebell wood Copyrighted image Credit: Michael Jobling

“Every spring is the only spring - a perpetual astonishment.” - Ellis Peters

The arrival of spring seems to have a special meaning for us. The days get longer and warmer and the colours of the world around us change from drab to bright. But the phenomenon of spring is linked closely to our place on the globe. At the equator the differences between the seasons are not marked in the same way – there are only two: wet and dry. The experience that Ellis Peters refers to of each spring having a unique feel to it chimes with our own experience; but short-term differences from year to year mask worrying, longer term trends.

Tracking Spring

In the 18th century two people started to record the events of spring and link them to the calendar. They both also established the idea of continuing their studies year on year to begin to document how much the timing and events of spring varied over long periods of time. Gilbert White published his records in a book, The Natural History and Antiquities of Selborne, in 1789. Robert Marsham kept records over 62 years from 1736. He identified 27 indicators of spring, which were published by the Royal Society. Robert is regarded as the founding father of a new area of science, Phenology, which is the study of the first observation of a biological event in the annual cycle of the seasons.
A burst of oak leaves in spring Copyrighted image Credit: BBC
An oak bud burst.
Although Robert died in 1797, his descendants continued the records until 1958. One of the indicators that particularly interested Robert, who managed large woodland estates, was the date at which oak leaves first appeared. This varied from year to year as some springs were cold and others warmer, but the true value of his work can be seen by examining a period of 100 years from 1850 to 1950. There is an underlying trend of oak leaves appearing earlier while, over that same period, there is a trend of warmer temperatures. Here, then, is the rationale for making a link between watching and recording spring and our current concerns about climate change.

The late Richard Fitter, an economist by training, kept records of the first flowering date of 557 species in the Chilterns for 50 years. With his son, Alastair Fitter, he published a paper in the journal Science in May 2002, entitled ‘Rapid changes in flowering time in British plants’. In this paper they showed that 16% of the species they studied flowered significantly earlier in the 1990s than previously and that the flowering date in these species had advanced on average by 15 days in 10 years. They also showed that the date of first flowering was very sensitive to temperature. In their paper they conclude,

‘These data reveal the strongest biological signal yet of climate change.’

Kate Humble met Richard Fitter in 2005 and talked to him about his work.

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Kate Humble: When I was six, my best friend lived just down there, and we spent huge amounts of our childhood, up here, chasing about with the family dog. We used to build camps in the woods over there, climb trees and have the really most terrifying races down this slope. You’d end up screaming at the bottom and piling into a hedge. And the wonderful thing about this area is that it’s only about fifty minutes from where I now live in London. And when I’m feeling a little bit over-citied and I haven’t got very long and I need to come somewhere close by to get my, kind of, ‘countryside fix’, this is where I come. This is my respite. It’s a really special place, it’s the Chiltern Hills.

And of course, one of the best times to come here when I’m feeling down is the spring because it just brings back so many memories.

The beech woods are particularly beautiful around here, and this is one of my favourite signs that spring is definitely on its way, these new, really soft, vivid green beech leaves just beginning to emerge.

I love the contrast between the still pretty leafless trees, that still look very grey and skeletal, but the unbelievably rich, alive, green of the woodland floor that seems to just happen overnight like a miracle.

And isn’t it weird how smells can just make memories flood back? I’m sitting here and I feel like a ten-year-old again. This lovely, earthy, mulchy smell of dead leaves and there’s the astringent, fresh smell of pine, and then - I don’t know quite how to describe it - but it’s the smell of green; if you were sitting here right now you would know exactly what I mean, it’s like the smell of things growing. That very fresh subtlety of primroses in the early spring, then cuckoo flowers a little bit later.

And I can remember being so excited every year the first time I saw a butterfly or a ladybird.

But of course, the big topic of conversation at the moment is whether spring is actually coming earlier in the year. And coming back here now, I mean, I can remember all these little details, all these things are sort of triggering off in my head, but what I can’t really put my hand on my heart and say is that it is happening earlier in the year than it was thirty years ago when I first started coming here. And so, really, to be sure whether spring is changing, I kind of needed somebody to, well, notice all those little details for a start and then note them down over a very long period of time.

Well, amazingly, somebody did. He worked right here in the Chilterns and every single natural event that he noticed, he made a note of it, for fifty years, and his name is Richard Fitter.

Kate Humble: Richard, this is an extraordinary record, an amazing record, why did you do it? Why did you start?

Richard Fitter: Because I’m an inveterate maker of lists of all kinds.

Kate: But are you a scientist?

Richard: No, no, I was an economist by training but I’ve been interested in nature and wildlife ever since I can remember.

Kate: So how did you go about keeping these very comprehensive lists of species?

Richard: Well, I noticed the wildflowers, the dates they came into flower, but I kept records of birds' nests, birds singing, of… and of butterflies when they appeared - as I say, almost anything I could make a list of. I mean, this is how I did it for plants for the year 1975 and it was made when I was living at Chinnor and I believe you were there at the same time?

Kate: I was almost certainly running around, probably getting under your feet, how amazing! And when did you realise that this data was actually important to science and not just a fun list?

Richard: Well that was due to my son, Alistair, who is a biologist at the University of York, and he knew that I was keeping these records and he realised that these might be of importance in climate change studies.

Kate: And would you say, once Alistair had alerted you to the fact, would you say that, looking back over this time, that spring has changed over the time that you’ve been keeping these records?

Richard:
Oh, absolutely, no doubt. I mean, flowers are flowering earlier, birds are arriving earlier in the spring and some of them are nesting earlier. You know, there’s a general advance of a week or ten days over what it was, say, fifty years ago.

Kate: And do you think this has had a knock-on effect not just on spring but for the rest of the year and the other seasons?

Richard: Oh yes, I mean autumns are getting later. In some cases winter seems almost to be eliminated because the white dead nettle, for instance, now flowers regularly through a winter unless there’s a very severe frost.

Kate: Well, Richard, it’s been a huge pleasure to meet you, thank you very, very much, and thank you too for this very important collection of data which has added so much to our understanding of climate change and how it’s affecting our wildlife. Thank you.

Nature's Calendar

There are a number of people who kept records of spring events over long periods and the Woodland Trust is collecting them to add to their Nature’s Calendar project. Other amateur recorders are at work and one of the most well known is Jean Combes, who started her records in 1947. She has contributed her data to the annual State of the Countryside report which uses them as an indicator of climate change in the UK.

You don’t have to embark on a life-time project in order to contribute to tracking spring events. Nature’s Calendar has records of 2 million observations going back to the 1600s and you can add data yourself. For example, you can look in local ponds and record the first date on which you see frogspawn or tadpoles.

tadpoles Copyrighted image Credit: The Open University
Tadpoles in a pond

Start a diary

You can also visit the iSpot website and get help in identifying plants and animals that you record. The users of this website make up a substantial community who help each other with identifications.

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Also you can start a diary of the human side of the environmental change story. Over the next ten years the Creative Climate website will be collecting pieces of writing, audio, video and pictures from people all over the world. Every six months we will be asking you to help to document the unfolding story of how humanity is understanding and acting on environmental challenges such as biodiversity loss and climate change.

These may seem like small actions, but it is only with large numbers of observations over longer periods of time that underlying trends become apparent and we can be sure that we can both identify climate change using natural indicators and also document the effects those changes will produce in the natural world around us.