Geneva, Switzerland — A new report from the UN Intergovernmental Panel on Climate Change (IPCC) concludes that human impact on the climate system is clear and evident in most regions of the globe.
It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century, the analysis states, adding that the evidence for this warming is unequivocal.
“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,” said Qin Dahe, Co-Chair of IPCC Working Group I, which developed the report titled Climate Change 2013: the Physical Science Basis.
Thomas Stocker, the other Co-Chair, added: “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.”
Stocker concluded: “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.”
The assessment comprises some 2,500 pages of text and draws on millions of observations and over 2 million gigabytes of numerical data from climate model simulations. Over 9,200 scientific publications are cited, more than three quarters of which have been published since the last IPCC assessment in 2007.
According to the IPCC, global surface temperature change for the end of the 21st century is projected to be likely to exceed 1.5°C relative to 1850 to 1900 in all but the lowest scenario considered, and likely to exceed 2°C for the two high scenarios.
“There are few surprises in this report but the increase in the confidence around many observations just validates what we are seeing happening around us. Since the IPCC issued its last big report in 2007, terrestrial glacier loss and sea-level rise has dramatically accelerated; the Arctic summer sea ice losses are higher than originally projected and the last decade was the warmest since 1850,” concluded Samantha Smith, leader of WWF’s Global Climate & Energy Initiative.
Indeed, in response to the report, six of the world’s largest environmental and development non-government organisations have made a unified call to governments to act on the findings and introduce strong climate pollution controls.
“We already know that the energy sector is the main culprit – but also the main solution – for global climate change. We already know that a large source of climate-changing pollution comes from burning fossil fuels. Extraction of fossil fuels is also increasingly a driver for the displacement of people, local pollution, and the direct loss of biodiversity.
“At the same time, renewable energy provides a straightforward, proven and increasingly affordable solution (with far fewer direct impacts) that can also bring energy access to the 1.2 billion people currently without. If we are to follow what the science says, then we have to stop investing in fossil fuels and increase investment in sustainable renewable energy,” a joint statement reads from groups including WWF, Friends of the Earth, Oxfam and Greenpeace. Stephanie Tunmore, Senior Climate and Energy Campaigner, Greenpeace International, said: “What the IPCC has set out are projections not prophecies. Alongside the warnings of unimaginable levels of warming and the chaos that would follow, the report shows us the potential pathway to a very different tomorrow. We can still limit global warming by ramping up renewable energy and making faster and deeper emissions cuts but the longer we wait the more the prospects diminish and the costs increase. A bleak and hopeless future is not a foregone conclusion, it’s a choice.”
Commenting, Carmen Becerril, Chief International Officer at Acciona, said: “This warning from the science must provide a trigger for action. A comprehensive, effective and ambitious global response must be agreed at the UN climate change meeting in Paris in 2015, which means we need to start working now to greatly enhance global cooperation and build the foundations for a workable deal and investment in low carbon solutions.”
Meanwhile, Maf Smith, Deputy Chief Executive of RenewableUK, said: “The scientific community is sending a clear and unequivocal message to policymakers that urgent action is needed to reduce our carbon emissions and set in place paths to create a future of clean, carbon reducing sources of energy if we are to reduce our negative impacts on our environment.”
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