Doyle Rice, USA TODAY
The world's top group of climate scientists is preparing to report that man-made global warming is "extremely likely," putting the odds that humanity is the main reason for the warming at 95%.
The findings are from a draft of the 5th Intergovernmental Panel on Climate Change (IPCC) report obtained by USA TODAY.
The IPCC is a United Nations group that is the planet's pre-eminent climate organization, which issues reports every few years about the effects of global warming. The next official report is due out in September. This draft copy of the report is not the final version.
The previous report, released in 2007, pegged the likelihood that humans were the prime explanation for climate change at about 90%.
"Emissions at or above current rates would induce changes in all components in the climate system, some of which would very likely be unprecedented in hundreds to thousands of years," the report states.
Carbon dioxide emissions from the burning of the fossil fuels that power the world are the main cause of global warming.
"Changes are projected to occur in all regions of the globe" and will impact sea level, the world's icy and snowy regions, and ocean acidification, the report says.
"Many of these changes would persist for many centuries," it notes.
There was one slight change for the better in this draft report: While the prior summary from 2007 dismissed a warming of less than 3.6 degrees Fahrenheit if atmospheric CO2 levels doubled, this report says that a warming of only 2.7 degrees is still "possible."
Some of the report's other findings include:
• Each of the past three decades has been warmer than all preceding decades since 1850. The first decade of the 21st century has been the warmest. In the Northern Hemisphere, the period 1983-2012 was likely the warmest 30-year period of the past 1,400 years.
• There is stronger evidence that the ice sheets and glaciers worldwide are losing mass and sea ice cover is decreasing in the Arctic.
• It is virtually certain that the rate of sea level rise has accelerated during the past two centuries. Global sea level will rise during the 21st century, potentially by over 3 feet.
• It is extremely likely that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951-2010.
• It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere snow cover will decrease during the 21st century as global temperature rises.