The U.N. climate panel sounded a dire warning Monday, saying the world is dangerously close to runaway warming – and that humans are "unequivocally" to blame.
"Today’s report by the IPCC is a stark reminder that we have limited time in which to act to prevent more devastating impacts from climate change. The report, based on the latest climate science, has observed unprecedented changes in the climate system. Every region of the world, across the entire climate system, has already been impacted by extreme event. There is ever greater certainty about climate change and ever greater urgency about the need to tackle it - Minister Eamon Ryan
Already, greenhouse gas levels in the atmosphere are high enough to guarantee climate disruption for decades if not centuries, scientists warn in a report from the Intergovernmental Panel on Climate Change (IPCC).
That’s on top of the deadly heat waves, powerful hurricanes and other weather extremes that are happening now and are likely to become more severe.
Describing the report as a "code red for humanity," U.N. Secretary-General António Guterres urged an immediate end to coal energy and other high-polluting fossil fuels. read more
The IPCC report comes just three months before a major U.N. climate conference in Glasgow, Scotland, where nations will be under pressure to pledge ambitious climate action and substantial financing.
Drawing on more than 14,000 scientific studies, the report gives the most comprehensive and detailed picture yet of how climate change is altering the natural world -- and what still could be ahead.
Unless immediate, rapid and large-scale action is taken to reduce emissions, the report says, the average global temperature will likely cross the 1.5-degree Celsius warming threshold within the next 20 years.
Reacting to the findings, governments and campaigners expressed alarm.
“The IPCC report underscores the overwhelming urgency of this moment,” U.S. climate envoy John Kerry said in a statement. “The world must come together before the ability to limit global warming to 1.5 degrees Celsius is out of reach.”
That means that, as societies transition away from fossil fuels, much of the aerosols in the air would vanish -- and temperatures could spike.
Scientists warn that warming more than 1.5C above the preindustrial average could trigger runaway climate change with catastrophic impacts, such as heat so intense that crops fail or people die just from being outdoors.
Every additional 0.5C of warming will also boost the intensity and frequency of heat extremes and heavy rainfall, as well as droughts in some regions. Because temperatures fluctuate from year to year, scientists measure climate warming in terms of 20-year averages.
"Today’s report makes it clear that failure to act will have devastating consequences, but it also offers hope. Strong and sustained reductions in emissions of C02 and other greenhouse gases would limit climate change. We know what we have to do. We now need to harness a national and global effort to do it - Minister Eamon Ryan
The 1.1C warming already recorded has been enough to unleash disastrous weather. This year, heat waves killed hundreds in the Pacific Northwest and smashed records around the world. Wildfires fueled by heat and drought are sweeping away entire towns in the U.S. West, releasing record emissions from Siberian forests, and driving Greeks to flee their lands by ferry. (Graphic on warming planet)
"Every bit of warming matters," said IPCC co-author Ed Hawkins, a climate scientist at the University of Reading in Britain. "The consequences get worse and worse as we get warmer."
Greenland’s ice sheet is "virtually certain" to continue melting. Oceans will keep warming, with surface levels rising for centuries to come. (Graphic on Greenland)
“We are now committed to some aspects of climate change, some of which are irreversible for hundreds to thousands of years,” said IPCC co-author Tamsin Edwards, a climate scientist at King’s College London. “But the more we limit warming, the more we can avoid or slow down those changes.”
‘WE STILL HAVE CHOICES TO MAKE’
But even to slow climate change, the report says, the world is running out of time.
If the world does not cut emissions dramatically and instead continues the current trajectory, the planet could see 2.0C warming by 2060 and 2.7C by the century’s end.
The earth has not been that warm since the Pliocene Epoch roughly 3 million years ago -- when the first ancestors to humans were appearing and oceans were 25 meters (82 feet) higher than today.
It could get even worse, if warming triggers feedback loops that release even more climate-warming carbon emissions -- such as the melting of Arctic permafrost or the dieback of global forests. Under these high-emissions scenarios, Earth could broil at temperatures 4.4C above the preindustrial average by 2081-2100.
The question now, he said, is how many more irreversible changes we avoid: "We still have choices to make."