THE evidence for global warming is "unequivocal", and it is "extremely likely" that human activity has been the dominant cause of the phenomenon since the mid-20th century, a new UN report concludes.

The fifth assessment of the Intergovernmental Panel on Climate Change (IPCC) is based on about 9000 peer-reviewed scientific papers and 50,000 comments from expert reviewers.

Published on Friday, the summary of the report, Climate Change 2013: the Physical Science Basis, states that "Warming in the climate system is unequivocal and since 1950 many changes have been observed throughout the climate system that are unprecedented over decades to millennia.

"Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850."

It is "extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century", the report states. "Extremely likely" refers to a 95-100-per-cent probability.

Dr Thomas Stocker, Professor of Climate and Environmental Physics at the University of Berlin, who co-chairs the working group that produced the report, said: "Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse-gas emissions."

The group has predicted that the earth will warm by more than 1.5°C by the end of the 21st century, relative to 1850-1900, possibly by more than 2°C. Sea levels are expected to rise at a faster rate than that seen in the past 40 years, by between 26 and 81cm, as the ocean warms and glaciers reduce. In the Copenhagen Accord in 2009, governments promised to prevent the rise of global temperature by 2°C above pre-industrial levels.

Professor Stocker said: "Heatwaves are very likely to occur  more frequently and last longer. As the earth warms, we expect to see currently wet regions receiving more rainfall, and dry regions receiving less, although there will be exceptions."

He warned that the effects of climate change would persist "for many centuries", even if emissions of carbon dioxide, were to stop.

On Friday, the chairman of the Mission and Public Affairs Council, Philip Fletcher, said that the report made it "clearer than ever that climate change is happening, that we, the human race, are largely or completely responsible for that, and that we really ought to proceed on that basis, rather than just hoping that it will all turn out to be wrong".

The Church of England is committed to reducing its carbon footprint by 80 per cent by 2050, with an interim target of 42 per cent by 2020. St Michael and All Angels', Withington, Gloucester, is claimed to be the first zero-carbon church in the UK since the PCC took measures that included installing a biomass boiler and solar panels.

"There are things we do well and things we do badly but we have been seeking to work at shriking our own footprint for some time," Mr Fletcher said. "We know that we should be doing more, and we shall be thinking hard about the implications of that. We are taking it seriously, and we know we are part of the problem."

On Friday, Christian Aid's senior climate change adviser, Dr Alison Doig, said: "We need to support countries and communities most at risk in preparing to cope with disaster, to lessen the impacts of extreme weather events, and help communities recover more rapidly when they do occur.

"As a developed, industrialised country, the UK has to lead the way by ending our dependence on fossil fuels, and investing in clean, renewable sources of energy, which we are fortunate enough to be blessed with in the UK."

The advocacy director at Tearfund, Paul Cook, said: "This report gives further scientific backing to what our partner organisations around the world have been telling us: the climate is changing, and not in a good way. Droughts, floods, and erratic weather are ruining crops and damaging communities."

The IPCC was established by the  UN and the World Meteorological Organization in 1988 "to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts". It does not conduct research, but assesses the most recent relevant material. Thousands of scientists from across the world contribute to its work. Currently, 195 countries are members of the IPCC. Governments endorse its reports, and it describes itself as "policy-relevant and yet policy-neutral, never policy-prescriptive".

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