Global warming is already directly affecting the lives of animals and plants living in a variety of habitats across the world, according to one of the most detailed ecological studies of climate change.
An international team of scientists working across a range of disciplines has found that the relatively small increase of 0.6C in the global average temperature seen over the past 100 years has left a major imprint on wildlife.
The scientists, from nine research institutes in five countries, found an array of seemingly random changes in wildlife have one thing in common a warmer world.
The scientists, writing in the journal, Nature, said: "Although we are only at an early stage in the projected trends of global warming, ecological responses to recent climate change are already clearly visible."
Gian-Reto Walther, an ecologist at the University of Hanover in Germany, and the lead author of the study, said climate change has begun to bite.
"We want to emphasize that climate change impacts are not something we expect for the future but something that is already happening. We are convinced of that," Dr Walther said yesterday.
"If you have so many studies from so many regions with so many different species involved and all pointing to the same direction of warmer temperatures, then to me it's quite convincing," he said.
The study involved British specialists in amphibian breeding cycles and Antarctic ecology, German experts on bird migration and Australian marine biologists studying changes to coral reefs in tropical oceans.
DR Walther said: "It's the first time that researchers from various disciplines have come together to compare their own work. We made comparisons between and across various ecosystems and we compared different species to look for common traits and their all point to the same direction of warmer temperatures."
"We know that the global average temperature has increased by 0.6C and for many people this may sound very minor but we are quite surprised that this minor change has had so many impacts already on natural ecosystems," he added.
The scientists all found that typical springtime activities, such as arrival and breeding of migrant birds or the first appearance of butterflies and plants, have occurred progressively earlier during the past 40 years.
Meanwhile, some warm-weather species and diseases have extended their range. "There is much evidence that a steady rise in annual temperatures has been associated with expanding mosquito-borne disease in the highlands of Asia, East Africa and Latin America," the scientists say.
Mosses and other plants have appeared in areas of the Antarctic that were previously considered too cold and coral reefs have undergone mass "bleaching" on at least six occasions since 1979 linked with warmer sea temperatures.
Variations in the atmospheric wind patterns over the Bering Sea and their interaction with local patterns of ocean circulation has affected the distribution of walleye pollock, an important "forage species" for other fish and sea mammals.
A similar change in the ocean circulation around the Antarctic peninsula has affected the breeding grounds of the krill, an important shrimp-like animal which constitutes the base of the Antarctic food chain.
In Britain, warmer winters have led to newts breeding earlier, bringing them into contact with the eggs and young of the common frog at a point when they are most vulnerable to predation, said Trevor Beebee, professor of molecular biology at the University of Sussex and a co-author of the study.
"Newts and other amphibians with a protracted breeding season are responding to climate change whereas frogs and toads which usually breed earlier are not," Professor Beebee said. "You can relate these changes to temperature changes observed over the same period," he said.
With temperatures expected to increase by a further 1.4C during the coming century, more changes are expected, DR Walther said. "We see the process of adaptation has started but it's difficult to extrapolate to a warming process that is double the size of what we have already seen," he said.
© 2002 lndependent Digital (UK) Ltd