In response to the UN's intergovernmental panel on climate change (IPCC) findings, climate action commissioner Connie Hedegaard said, "If your doctor was 95 per cent sure you had a serious disease, you would immediately start looking for the cure. Why should we take bigger risks when it's the health of our planet at stake?
''The issue is not whether to believe in climate change or not. The issue is whether to follow science or not. The day when all scientists with 100 per cent certainty warn you against climate change, it will be too late", she warned.
According to Qin Dahe, a co-chair of the working group responsible for the report, "Observations of changes in the climate system are based on multiple lines of independent evidence. Our assessment of the science finds that the atmosphere and ocean have warmed, the amount of snow and ice has diminished, the global mean sea level has risen and the concentrations of greenhouse gases have increased
"As the ocean warms, and glaciers and ice sheets reduce, global mean sea level will continue to rise, but at a faster rate than we have experienced over the past 40 years."
His working group colleague Thomas Stocker 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.
"As a result of our past, present and expected future emissions of CO2, we are committed to climate change, and effects will persist for many centuries even if emissions of CO2 stop."
Satu Hassi, parliament's Greens group climate spokesperson, said, "Today's report confirms the increasing global scientific conviction about the impact of human activities on climate change and the implications this will have if left unchecked.
"The window of opportunity for taking action to reduce our emissions and preventing runaway climate change is closing, yet the EU response to climate change is slowing, rather than strengthening.
"The EU needs to make climate change a policy priority again and end its climate prevarication.
"This means repairing its malfunctioning existing climate policy measures, notably increasing the outdated 2020 greenhouse gas reduction target and fixing the emissions trading scheme. It also means setting longer term targets for greenhouse gas emissions reductions."
Her fellow Greens spokesperson Bas Eickhout emphasised the need for the EU to "adopt ambitious climate and energy targets", adding that "the next crucial milestone for the EU is 2030".
"The EU must take swift steps to adopt ambitious climate and energy targets for this timeframe, notably a target of reducing greenhouse gas emissions 60 per cent by 2030 from their 1990 levels.
"This is essential for investor certainty and to ensure those EU businesses that have invested in good faith on the basis of EU climate policy are not punished, as well as to ensure the EU stays on track as part of global efforts to tackle climate change.
"The IPCC report makes clear that we cannot continue burning fossil fuels if we are to prevent extreme climate change. For the EU, this means moving to a fossil-fuel free and 100 per cent renewable energy-powered economy by 2050," he continued.
The report has also received widespread reaction from environmental NGOs, with Stephan Singer, WWF's director of global energy policy, saying, "It's CO2, mainly from burning fossil fuels, that dissolves in oceans and may destroy an already fragile ecosystem in an almost irreversible way if mankind does not shift from fossil fuels to renewables as soon as possible
"Warmer and much more acid oceans are detrimental for fish, coral reefs and most other parts of marine ecosystems.
"It is incumbent on all sectors of society, including governments, to now act on the facts and science presented in this report which has gone through an unprecedented process of review," he urged.
Nicolas Fournier, policy advisor at Oceana in Europe, also weighed in, saying, "This 5th IPCC assessment report sadly confirms that climate change is probably the biggest threat to our oceans and marine ecosystems.
"Scientists now recognise not only that changes, such as sea level rise or ocean acidification are profoundly modifying our environment, but they will accelerate and last for centuries.
"Until now acting as shield against those impacts, oceans are getting closer to a tipping point: they have absorbed more than 90 per of the warming so far," he added.
Further comment came from Friends of the Earth's executive director Andy Atkins, who said that "scientists are now as convinced that humans are causing climate disruption as they are that smoking causes cancer," before adding, "politicians can't continue to stand idly by while the world goes spinning towards climate catastrophe".
"Tough action is urgently needed to end the planet's dangerous fossil fuel fixation and to develop the huge job-creating potential of renewable power."
Meanwhile, Tim Gore of Oxfam said, "The latest climate science affirms what small scale farmers around the world are telling us, seasons are changing, weather is increasingly extreme and unpredictable making it tougher to feed their families.
"This report also tells us it is possible to avoid the very worst impacts of climate change and the goal of ensuring everyone has enough to eat is still attainable. Governments should learn from the mistakes of the global financial crisis where warning signs were ignored and listen to the experts before it is too late.
"They must take actions immediately to slash emissions, as well as investing in building the resilience of people in poverty so we can move from the current path facing disaster to higher safer ground."
Commissioner Hedegaard highlighted the efforts of the EU saying that "Europe will continue to lead the fight against climate change".
"We have ambitious legislation in place. We are reducing our emissions considerably, expanding renewables and saving energy. And we are getting ready for the next step: climate and energy targets for 2030 that the commission will present before the end of the year.
"The reality is that others are now following suit. Europe will continue to demand more action from all the emitters,' she concluded.