How the blurring of the seasons is a harbinger of climate calamity
Martin Warren
A red admiral, normally seen in Britain in summer, was photographed in February among snowdrops
Spring, which officially starts today, is starting to dissolve as a distinct season as climate change takes hold.
According to documented observations throughout 2007 and 2008, events in the natural world that used to be key spring indicators, from the blooming of flowers to the appearance of insects, are now increasingly happening in what used to be thought of as mid-winter, as Britain's temperatures steadily rise.
Although many people may see the changes as quaint or charming – butterflies certainly brighten up a January day – they are actually among the first concrete signs that the world is indeed set on a global warming course which is likely to prove disastrous if not checked.
In fact, the blurring of the seasons in Britain is now as serious a piece of evidence of climate change as the rapidly increasing melting of ice across the globe, in glaciers and in the land-based and marine ice sheets of the Arctic and the Antarctic.
The phenomenon shows that a whole range of organisms is already responding actively to the greatest environmental change in human history, in a way that people – and especially politicians – are not.
Last month, that shift produced its most remarkable image yet – a photograph, taken in Dorset, of a red admiral, an archetypal British summer butterfly, feeding on a snowdrop, an archetypal British winter flower.
Although that is not an event likely to cause alarm among the public, it was quite inconceivable until very recently. It is undeniable confirmation that a profound alteration in the environment, the consequences of which are likely to prove catastrophic, is already under way.
It is happening so quickly, and without people realising its true significance, because, in Britain, the major effects of climate change are initially being felt as less cold winters, rather than as hotter summers.
That has produced a startling rise in winter temperatures in recent years, clearly visible when current monthly means are compared to the average for 1961 to 1990.
To take the figures for last winter from the Central England Temperature Record, the world's oldest, which dates back to 1659: January 2007 was 3.2C warmer than the 1961-90 average, February was 2.0C warmer, March was 1.5C warmer, and April was 3.3C warmer. So far this year, January has been 2.8C above the 1961-90 average for the month, and February, 1.6C
Those are substantial rises. Although there is always natural variation in temperatures, recent winters taken together show a remarkable warming trend.
It has meant that many of what used to be thought of as the traditional signs of spring are happening very much earlier, causing primroses, for example, spring flowers par excellence, to bloom in some parts of the country as early as November. Other traditional spring plants, such as dog's mercury and the lesser celandine (a favourite of Wordsworth's) can be seen in January rather than March.
And in what is perhaps an even more vivid change, dandelions and daisies, which used to come into flower in spring on lawns (where they were permitted), now flower in many places all winter long.
