U.S. Experiences Warmest 12-Month Period Since 1895m,
May 11, 2012
Average atmospheric temperatures in the United States for the period from April 2011 to May 2012 were the highest for any consecutive 12-month period in 117 years, the National Climatic Data Center (NCDC) has reported. Average running temperatures were 2.6 °F (1.45 °C) above those for the 1900′s and 0.1 °F (0.06 °C) above those for the second-warmest 12-month period–November 1999 to October 2000. All of the top-10 warmest 12-month periods in the United States have occurred since June 1999. The record-breaking period also included the warmest March, the third-warmest April, the second-hottest summer, and the fourth-warmest winter on record. Twenty-two states reported record warmth during this 12-month period. The NCDC, a part of the National Oceanic and Atmospheric Administration, maintains the official weather records for the continental United States (not including Alaska and Hawaii) dating back to 1895.
Higher-than-normal temperatures (shown in red) severely damaged crops and livestock in the lower Great Plains states in the summer of 2011 and triggered massive wildfires in the Southwest. (NASA's Earth Observatory)
Many U.S. cities also broke temperature records for the first four months of 2012, according to preliminary data from the NCDC. Among them were Atlanta; Bismarck, North Dakota; Boston; Chicago; Detroit; Indianapolis; Oklahoma City; New Orleans; St. Paul, Minnesota; and Tampa, Florida. Overall, a record 42 percent of the country experienced extreme weather, chiefly extreme heat, during this period.
NCDC scientists said the record-breaking warm weather over the continental United States in 2012 “is related to a jet stream pattern which has locked up cold air in the high latitudes and favored sprawling heat domes over the mid-section of the country which have meandered east and west at times.” They also reported “the intensity and persistence of the warmth compared to the past is very likely related to the elevated greenhouse concentrations in the atmosphere from human activities.”
Additional World Book articles:
- Climate
- Global warming
- The Great Meltdown (A Special Report)
- Global warming 2011 (A Back in Time article)
- Global warming 2010 (A Back in Time article)
