It's cherry blossom time in our topsy-turvy weather

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A branch on a cherry tree told the story of this topsy-turvy autumn. In early December, in a side street near Kew Gardens in west London, this year's leaves and next year's blossom sat side by side on the ornamental tree.

A branch on a cherry tree told the story of this topsy-turvy autumn. In early December, in a side street near Kew Gardens in west London, this year's leaves and next year's blossom sat side by side on the ornamental tree.

Such was the warmth of the autumn of 2001 that the natural world turned upside down. Last summer determinedly lingered and spring 2002 was making an early beginning. That is a small illustration of just part of a remarkable year of weather, which may be the shape of things to come. Many scientists suspect these phenomena are the first and most obvious signs of widespread global climate change.

It was the warmest October in Britain since records began in 1659, and the warm autumn followed another record: the wettest winter and spring since at least the 18th century, and possibly for 500 years or more. They combined to produce attractive surprises, not least the biggest harvest of wild fruit, and the most spectacular display of autumn foliage, that most people could remember.

October's average temperature was 13.3C, which is 2.7 degrees above the 1961-1990 average. (October 2000 was chilly and damp with an average of only 10.6C.) At the end of the month there were 21C (70F) temperatures and the heat in mid-October was an astonishing 25C (77F) across much of the South-east.

The natural world responded. Butterflies, moths, dragonflies and bees were all on the wing astonishingly late. The meadow brown butterfly, and the holly blues and speckled woods could be seen at the end of October, as were spectacular monarch butterflies from North America, blown by storm winds across the Atlantic when they should have been migrating to Mexico. More than 100 of them were recorded along the south coast.

Flowers flourished. Not only did many last much longer but, in some places in October, next spring's daffodils started to push through and spring flowers such as cow parsley and blue fleabane were in bloom. Birds that should have been migrating south from southern Europe, such as pallid swifts and Sardinian warblers, migrated north and ended up in Britain.

But wild fruit outperformed everything else. It was the best year for blackberries in the countryside that most of us have seen, and bramble branches everywhere were bent and laden with fat berries. Other hedgerow fruits, such as elderberries, sloes and bullaces (relatives of the damson) grew in extraordinary profusion. So did the largely inedible berries, such as hips and haws (the fruits of wild roses and hawthorns), holly berries and rowan berries.

Commercially grown fruit was not far behind: this has been one of the best harvests of English apples, with Cox's orange pippins doing particularly well. It was also an extraordinarily plentiful year for wild mushrooms and toadstools, and enthusiasts on woodland "fungal forays" were finding up to 100 species.

But the most vivid countryside sight of 2001, will, for many people, have been the autumn leaves. No one can remember a more vivid or a longer-lasting display of glorious reds and russets, yellows and golds. At times, England looked like New England in the fall. The unusually warm weather meant the leaves hung on for much longer, giving them the chance to store more sugar and starch than normal, which resulted in colours of an almost fiery brightness.

The trees were at their astonishing best in the third week of November, but even in the first week of December, in southern counties including Hampshire, Wiltshire and Dorset, up to a quarter of the trees still held their leaves, something no one can remember.

No scientist will say these changes are proof of global warming; but they are certainly consistent with scientific predictions of what climate change is likely to bring.

Another global warming prediction come true was last winter's astonishing rainfall (the 12 months up to the end of March 2001 being the wettest such period on record). Wetter winters are a prominent expected feature of global warming, as are droughts, hurricanes, crop failure and disease in much of the world. If all we are suffering in Britain so far is an abundance of blackberries and autumn leaves, let us give thanks.

How we're warming up and drying out

Several rainfall and temperature records were broken over the past 12 months. The year 2001 was the second warmest one for the world since the instrumental records started nearly 150 years ago. Only 1998 was hotter. The global mean temperature last year is likely to have been more than 0.4C higher than the average.

October 2001 was the warmest October recorded in Britain, with an average central England temperature of 13.3C, which is 2.7 degrees above average. Autumn 2001 in Britain (September, October and November) was very warm, with an average temperature of 11.4C, ranking with 1995 and 1999, although not quite as warm as autumn 1978. There were no hard air-frosts before mid-December.

The heavy rain of 2000 continued into 2001, making the 12 months up to the end of March 2001 the wettest in the England and Wales precipitation series that began in 1766, and perhaps for much longer. Although October 2001 was wet, with flooding in eastern England, November and December were generally drier than the average.

Up to mid-December, the 2001 rainfall total averaged across England and Wales, was 938mm, nearly 10 per cent above average.

The total for Scotland is about 10 per cent below average, and Northern Ireland has had a very dry year, with a rainfall total more than 20 per cent below average.