The report is the work of the Intergovernmental Panel on Climate Change (IPCC), an international body established in 1988 by the United Nations and the World Meteorological Organization. It synthesizes the findings of three earlier documents released earlier this year by the organization, though its tone is much franker and more forceful than what has come before.
The report speaks of man-made climate change in no uncertain terms: “Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reduction in snow and ice, and in global mean-sea-level rise; and it is extremely likely to have been the dominant cause of the observed warming since the mid-20th century,” the authors write. “The risk of abrupt and irreversible change increases as the magnitude of the warming increases.”
At this stage, sea level rise, extreme heat waves and wild variations in climate are already being experienced throughout the world. These changes in weather patterns are in large part the symptoms of rising greenhouse gas emissions, the report states.
At a time when the western Antarctic ice sheets are already at a stage of “irreversible retreat,” Greenland’s ice sheet may soon follow. The melt would take centuries, but the result would be a sea level rise of 23 feet, drowning many of the world’s coastal cities.
The starker tone of the report has much to do with the accelerating pace of atmospheric pollution. From 1970 to 2000, greenhouse gas emissions grew an average 1.3 percent per year. From 2000 to 2010, that almost doubled to 2.2 percent per year. The report traces this acceleration to China, which is now the world’s leading emitter of carbon dioxide.
Today, the Earth’s temperature is about 1.5 degrees Fahrenheit warmer than it was before the Industrial Revolution. According to the IPCC report, if emission trends continue, the Earth could warm an additional 8 degrees in the decades to come.
“Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems,” the report says.
The final version of the report will be released in November.