Referring to Russia in a radio broadcast in October 1939, Winston Churchill stated, "Russia is a riddle wrapped in a mystery inside an enigma." The same may have been true several decades ago in terms of our understanding of Earth's climate system, but no longer.
When putting together a puzzle, a lot of pieces may be in place, but some are still missing. But there is no doubt about the image that is emerging. The Intergovernmental Panel on Climate Change published its report, "Climate Change 2007: The Physical Science Basis," and it took 998 pages to summarize and interpret all of the data then available. This was not a sound bite.
An updated report is due in 2013, and it will fill in many of the missing pieces, giving us all an ever-clearer picture of what is happening to the Earth's weather and climate system.
As research continues, and questions generated by earlier research findings are answered, the data continues to make it clear that climate change is occurring. Note the chart, courtesy of Capital Climate, "2011—12 Ratio of Heat to Cold Records."
In a stable climate, one would expect that the number of high temperature records divided by low temperature records for a given month or year would be about one. That is not the case anymore.
The heat records in March 2012 were unmatched in recorded history for the United States and Canada. The ratio of 35.3 to 1, of highs to lows, is almost off the charts.
In the Midwest, Great Lakes and Northeast, monthly average temperatures were 15 degrees or more above normal. According to Bloomberg (April 9, 2012), more than 15,000 daily temperature records were broken or tied in the United States in March, and the average temperature in the contiguous United States was 8.6 degrees above the 20th-century average.