"They've finally established at the global level that there is a manmade climate signal coming through on plants, animals, water and ice," said Martin Parry, co-chair of working group II. "This is the first time at the international level, and for the IPCC, that this signal has been confirmed. We're no longer arm-waving with models, this is empirical information - we can measure it on the ground."

The IPCC team looked at 29,000 observational data series from 75 studies that showed significant change in many physical and biological systems since 1970. Of these, more than 89% of the data series were consistent with the change expected as a response to warming.

"This time we have far greater regional detail than the third assessment [in 2001]," said Raj Pachauri, chair of the IPCC. "These details cover things like the melting of glaciers in different parts of the world and projections on what the implications of that melting are going to be; sea level rise, which clearly threatens a large number of countries, the small island states in particular; and ... impacts on agriculture...with important implications for food security."

But there is a lack of observational data for developing countries, which could well suffer more from the effects of climate change.

"It's the poorest of the poor in the world - this includes poor people even in prosperous societies - who are going to be the worst hit and who are the most vulnerable to climate change," said Pachauri. "This certainly requires attention because people who are poor are least equipped to adapt to the impacts of climate change. This does become a global responsibility in my view."

With regards to snow and ice, Working Group II has a high confidence that glacial lakes are getting larger and increasing in number, that there is increasing ground instability in permafrost regions and more rock avalanches in mountain regions, and that changes are occurring in Arctic and Antarctic ecosystems. Many glacier- and snow-fed rivers are experiencing increased run-off and earlier spring peak discharge while lakes and rivers in many regions are warming.

Terrestrial biological systems have also seen changes, with spring events such as leaf-unfolding, bird migration and egg-laying occurring earlier and the ranges of plant and animal species shifting towards the poles and higher altitudes.

High-latitude oceans are experiencing shifts in ranges and abundance of algae, plankton and fish, while high-latitude and high-altitude lakes are seeing increases in abundance of algae and zooplankton, and rivers are undergoing range changes and earlier migrations of fish.

The report details potential future impacts of climate change on fresh water resources, ecosystems, food, fibre and forest products, coastal systems, industry, and health, as well as looking at effects by region. According to the authors, the impacts of climate change are very likely to impose net annual costs that will increase over time as global temperatures rise.

The IPCC's working group III will present its fourth assessment report on mitigation of climate change on May 4th.