The press conference has concluded and we're ending our live coverage.
BBC Science Editor, David Shukman, says:
"The last big climate gathering, in New York in September, saw leader after leader talk up the need for action on global warming. But events in Copenhagen back in 2009, when a disastrous and dysfunctional summit failed to agree anything substantial, showed how easily rhetoric crumbles in the face of economic pressures or domestic realities.
"The talk today is that attitudes have somehow changed, that next year's summit in Paris really does have a chance to reach a global agreement. Let's see."
EPACopyright: EPA
Post update
Peruvian minister Manuel Pulgar Vidal told the conference that upcoming climate summits in Lima and Paris will be successful.
The IPCC says that the cost of taking action to keep the rise in temperature under 2 degrees C over the next 76 years will cost about 0.06% of GDP every year.
Over the same period, world GDP is expected to grow at least 300%
Post update
Speaking to the BBC earlier, Dr Pachaudri said today's announcement was, categorically, the "strongest, most robust and most comprehensive" document that the IPCC has produced.
He said: "It gives you a very clear global view with that unless we start doing something about this seriously, with adequate adaptation and mitigation measures, then everyone on this planet is going to be affected, there is no part of the globe that is going to be untouched."
Kalee Kreider, former adviser to US vice president Al Gore
@kaleekreider
tweets: From Secretary of State Kerry, "This report is another canary in the coal mine." #IPCC #Climate2014
Post update
BBCCopyright: BBC
Ban Ki-moon, in response to questions, says world leaders were "not fully ready" for a climate agreement in 2009. "Since then," he adds, "we have been building up."
Post update
David Shukman
Science editor, BBC News
"Each IPCC report offers slightly tougher language than the last. But the authors also try to suggest hope too."
Matt McGrath, BBC environment correspondent
@mattmcgrathbbc
tweets: "Dr Pachauri showing some complicated charts at #ipcc press conference - brows start to furrow!"
UK chief scientist reacts
Sir Mark Walport, the government's chief scientific adviser, says:
"The IPCC Synthesis Report is clear: climate change is happening and it poses widespread and serious risks.
"We can still avoid the most serious impacts. We need to transform the way we power our lives.
"The longer global emissions are allowed to continue to increase year on year the more difficult, and expensive, the transition to a low carbon future will become."
Post update
Dr Rajendra Pachauri, IPCC chair, is now presenting a summary of the report.
The White House
@whitehouseostp
The White House tweets a statement by John P. Holdren, senior advisor to President Obama on science and technology: http://www.wh.gov/icwwV
Post update
Mr Ban says he has travelled the world in his eight years as secretary-general, to see the impact of climate change in person.
"I have seen for myself, those rapidly melting glaciers."
He says he wanted to be able to add his voice to those of scientists, "as a common man".
Post update
Ban Ki-moon describes how "hundreds of thousands of people" recently marched in New York City demanding firm action on climate change.
He says today's IPCC report is the most comprehensive appraisal of climate change ever taken.
Post update
Post update
The press conference in Copenhagen has just commenced. Watch using the "live coverage" tab above.
UNEP chief: risks "increasing exponentially"
Speaking to the BBC, the executive director of UNEP Achim Steiner said the synthesis report delivered more region-specific detail and "greater granularity".
"Much of climate science has had to resort to a planetary set of data and scenarios. We now have a greater amount of data that you can interpret at regional level and that is critical for policymakers and for action to happen."
He also said there had been a "quantum leap" since 2009 in terms of action being taken.
"There is plenty of evidence that countries are acting - the challenge that remains is that the scale of action is incremental and we need transformational approaches.
"Risks are increasing, opportunities to act are diminishing, and the IPCC gives us a lot of confidence that the response isn't one of sitting back in paralysis."
Post update
Welcome to our live coverage of the launch of the IPCC's "Synthesis Report".
Live Reporting
Matt McGrath and Jonathan Webb
All times stated are UK
EPACopyright: EPA 
BBCCopyright: BBC 
Latest PostThank you and goodbye
The press conference has concluded and we're ending our live coverage.
BBC Science Editor, David Shukman, says:
"The last big climate gathering, in New York in September, saw leader after leader talk up the need for action on global warming. But events in Copenhagen back in 2009, when a disastrous and dysfunctional summit failed to agree anything substantial, showed how easily rhetoric crumbles in the face of economic pressures or domestic realities.
"The talk today is that attitudes have somehow changed, that next year's summit in Paris really does have a chance to reach a global agreement. Let's see."
Post update
Peruvian minister Manuel Pulgar Vidal told the conference that upcoming climate summits in Lima and Paris will be successful.
"I am sure we will get an agreement," he said.
Post update
Matt McGrath
Environment correspondent, BBC News
The IPCC says that the cost of taking action to keep the rise in temperature under 2 degrees C over the next 76 years will cost about 0.06% of GDP every year.
Over the same period, world GDP is expected to grow at least 300%
Post update
Speaking to the BBC earlier, Dr Pachaudri said today's announcement was, categorically, the "strongest, most robust and most comprehensive" document that the IPCC has produced.
He said: "It gives you a very clear global view with that unless we start doing something about this seriously, with adequate adaptation and mitigation measures, then everyone on this planet is going to be affected, there is no part of the globe that is going to be untouched."
Kalee Kreider, former adviser to US vice president Al Gore
@kaleekreider
tweets: From Secretary of State Kerry, "This report is another canary in the coal mine." #IPCC #Climate2014
Post update
Ban Ki-moon, in response to questions, says world leaders were "not fully ready" for a climate agreement in 2009. "Since then," he adds, "we have been building up."
Post update
David Shukman
Science editor, BBC News
"Each IPCC report offers slightly tougher language than the last. But the authors also try to suggest hope too."
Matt McGrath, BBC environment correspondent
@mattmcgrathbbc
tweets: "Dr Pachauri showing some complicated charts at #ipcc press conference - brows start to furrow!"
UK chief scientist reacts
Sir Mark Walport, the government's chief scientific adviser, says:
"The IPCC Synthesis Report is clear: climate change is happening and it poses widespread and serious risks.
"We can still avoid the most serious impacts. We need to transform the way we power our lives.
"The longer global emissions are allowed to continue to increase year on year the more difficult, and expensive, the transition to a low carbon future will become."
Post update
Dr Rajendra Pachauri, IPCC chair, is now presenting a summary of the report.
The White House
@whitehouseostp
The White House tweets a statement by John P. Holdren, senior advisor to President Obama on science and technology: http://www.wh.gov/icwwV
Post update
Mr Ban says he has travelled the world in his eight years as secretary-general, to see the impact of climate change in person.
"I have seen for myself, those rapidly melting glaciers."
He says he wanted to be able to add his voice to those of scientists, "as a common man".
Post update
Ban Ki-moon describes how "hundreds of thousands of people" recently marched in New York City demanding firm action on climate change.
He says today's IPCC report is the most comprehensive appraisal of climate change ever taken.
Post update
Post update
The press conference in Copenhagen has just commenced. Watch using the "live coverage" tab above.
UNEP chief: risks "increasing exponentially"
Speaking to the BBC, the executive director of UNEP Achim Steiner said the synthesis report delivered more region-specific detail and "greater granularity".
"Much of climate science has had to resort to a planetary set of data and scenarios. We now have a greater amount of data that you can interpret at regional level and that is critical for policymakers and for action to happen."
He also said there had been a "quantum leap" since 2009 in terms of action being taken.
"There is plenty of evidence that countries are acting - the challenge that remains is that the scale of action is incremental and we need transformational approaches.
"Risks are increasing, opportunities to act are diminishing, and the IPCC gives us a lot of confidence that the response isn't one of sitting back in paralysis."
Post update
Welcome to our live coverage of the launch of the IPCC's "Synthesis Report".