London -- Scientists have produced the clearest evidence yet that global warming is affecting the natural world. Three separate studies in the journal **** Science **** show that plants and animals are adjusting their lifestyles and habitats in response to climate change, DPA reported.

A father-and-son team has uncovered some of the most dramatic evidence after analyzing 47 years of data on the flowering times of more than 350 British plants.

They found that flowers bloomed in the spring significantly earlier in the 1990s than they had during the previous four decades.

First flowering had advanced by four-and-a-half days on average over the past 10 years compared with the previous 40, according to Alastair Fitter, from the University of York, and his father, Cambridge naturalist and author, R.S.R. Fitter.

In 16 per cent of species -- between 150 and 200 types of plant -- flowering time had shifted by 15 days in the 1990s.

The greatest change was for the white dead nettle, the researchers reported. From 1954 to 1990, its average first flowering date was March 18. But from 1991 to 2000, the plant bloomed at around January 23 -- an advance of 55 days.

Another wild flower, sun spurge, shifted its first flowering date by about 32 days.

The Fitters wrote: "These data reveal the strongest biological signal yet of climatic change. Flowering is especially sensitive to the temperature in the previous month, and spring-flowering species are most responsive." A British and French study has found evidence of large scale changes in the ranges of tiny shrimp-like plankton creatures called Copepods.

Survey data showed that warm-water copepod species had shifted northward by more than 10 degrees latitude.

Meanwhile, northerly cold-water species had decreased in diversity.

The researchers, led by Gregory Beugrand from the Sir Alister Hardy Foundation for Ocean Science in Plymouth, wrote: "The observed bio-geographical shifts may have serious consequences for exploited resources in the North Sea." The third study, from a team of U.S., German, French and Swedish scientists, compared satellite measurements with a climate model.

It linked the increasing length of the growing season in northern high-altitude forests with climate change.

Climate data recorded over the past two decades were fed into a computer model of vegetation growth. The results matched the forest-greening trend revealed by the satellite observations.