Nick Miller and Tom Arup
, Published: September 27, 2013
It is more certain than ever that human civilisation is the main cause of global warming, putting the world on track for dangerous temperature rises, the latest major UN assessment of climate change science has found. The Intergovernmental Panel on Climate Change says it is "extremely likely" that humans are the dominant cause of observed warming since the mid-20th century, with carbon dioxide emissions the main factor. If emissions remain high, by 2100 temperatures are likely to rise by more than 2 degrees - and up to 4.8 degrees - breaching a threshold agreed by governments as limiting the worst impacts of climate change. Heatwaves will be more frequent and last longer, the report found. Most wet regions will get more rainfall, and most dry regions less. Glaciers and ice sheets will continue to shrink, and the sea level will rise more quickly. On Friday in Stockholm the UN's Intergovernmental Panel on Climate Change released a summary of its fifth major assessment of climate science after a week of debate, and years of work. "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 the IPCC working group that compiled the report. These findings were based on multiple lines of independent evidence, he said, much of it new since the IPCC's previous report in 2007. Co-chair Thomas Stocker said "substantial and sustained" reductions of greenhouse gas emissions would be necessary to prevent further warming and climate change. The report found that:
Evidence for human influence in climate change has grown in the last five years, the report found. The IPCC report has been six years in the making and has involved more than 800 scientists from around the world to pull it together. The panel was established by the UN to provide scientific assessments of climate change to governments, who get the final sign off on its reports. The working group went right down to the wire, finishing the substantive parts of the report only hours ahead of its planned release after an all-night debate. The group has been wrestling with figures that showed a slower rise in global temperatures than expected in the past decade. The report concludes "with high confidence" that more than 90 per cent of the extra heat generated in between 1971 and 2010 has been stored in the world's oceans. Environment Minister Greg Hunt said: "The report's findings reinforce the government's bi-partisan support for the science and the targets set for emissions reductions. UN secretary-general Ban Ki-moon said the IPCC had used the world's best science to address the world's biggest challenge. He said political commitment was needed to keep global temperature rise below the 2 degrees threshold. "The heat is on, now we must act," he said. United States Secretary of State John Kerry said: "This is yet another wake up call. Those who deny the science or choose excuses over action are playing with fire. This is science, these are facts, and action is our only option." Australian Academy of Science president Suzanne Cory said the world could be more certain than ever that human-induced climate change was real and a serious threat to the planet. "Overwhelmingly, the scientific evidence suggests the world should take action to limit the dangers posed by climate change for societies and ecosystems and to adapt to the changes that are already inevitable," Professor Cory said. The 36-page 'summary for policymakers' released on Friday covers the first part of its assessment looking at the physical science, with the full version to be released on Monday. It is based on 9200 scientific studies, more than three quarters of which were published since 2007. Two more reports – looking at impacts and mitigation of climate change – will be released next year. ABOUT THE INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Source: smh.com.au Related articles:
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