1. Opinion

Editorial: We have been warned
Published Aug. 21, 2013

The climate is changing, the seas are rising and we're at fault.

The Intergovernmental Panel on Climate Change has drafted its latest report, and the United Nations' panel of experts is more certain than in its prior reports about the main cause of climate change and its future impact. It's us, and it's not pretty. The consequences of denying the obvious and refusing to act are clear.

1990 "Emissions resulting from human activities are substantially increasing atmospheric concentrations of the greenhouse gases..." "These increases will enhance the greenhouse effect, resulting on average in an additional warming of the Earth's surface."

1995 "The balance of evidence, from changes in global mean surface air temperature and from changes in geographical, seasonal and vertical patterns of atmospheric temperature, suggests a discernible human influence on global climate..." "Significant reductions in net greenhouse gas emissions are technically possible and can be economically feasible."

2001 "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."

2007 "Warming (caused by humans) over the last three decades has likely had a discernible influence at the global scale on observed changes in many physical and biological systems..." "There is very high confidence that the net effect of human activities since 1750 has been one of warming ..."

2013 "It is extremely likely that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951 to 2010..." "There is high confidence that this has warmed the ocean, melted snow and ice, raised global mean sea level and changed some climate extremes in the second half of the 20th century."

Here is how the United Nations' panel of experts over the years has calculated the likelihood that human activities are the main cause of global warming since the 1950s:

1995: 50 percent

2001: 66 percent

2007: 90 percent

2013: 95 percent