July Heat is a Record!

Econintersect:  It is official – July 2012 was the hottest month on record for the “lower 48” states.  Econintersect has been following the drought that has been devastating crops through the nation’s midsection.  As of July 31 the area of the country in moderate drought or worse declined from 63.86% to slightly less than 63%.  At the end of July there was some actually some small relief for some areas.  Whereas the area of exceptional drought increased from the week before from 1.99% to 2.52%, and the extreme drought area expanded from 17.2% to 18.63%, the areas in moderate drought declined to bring the overall total down.  (Note:  The extreme and exceptional drought figures include all 50 states and Puerto Rico.)

Click on photo for larger picture of a Kansas corn field.

In addition, the NBC News report says that the month of July is part of a longer period of record warmth:

The hot July contributed to a record-warm first seven months of the year and the warmest 12-month period the nation has experienced since accurate record keeping started in 1895.

However, weather is like real estate: It’s all about location, location, location. Globally July 2012 was not a record. According to data reported by John Christy (professor of atmospheric science and director of the Earth System Science Center (ESSC) at The University of Alabama in Huntsville) via Fabius Maximus, the heat waves in the U.S. were not representative of the entire globe. Here is a summary from Fabius Maximus:

• Global composite temperature: +0.28 C (about 0.50 degrees F) above 30-year average for July.

• Northern Hemisphere: +0.44 C (about 0.79 degrees F) above 30-year average for July.

• Southern Hemisphere: +0.11 C (about 0.20 degrees F) above 30-year average for July.

• Tropics: +0.33 C (about 0.59 degrees F) above 30-year average for July.

• Global climate trend since 16 November 1978: +0.14 degrees C per decade.

• Compared to global seasonal norms, July 2012 was the coolest July since 2008.

So the higher temperatures were disproportionately in the northern hemisphere and over that entire half globe were only modestly above normal. This compares to the 48 contiguous states which experienced temperatures 3.3 degrees F (Fahrenheit) above the 20^th century average. (That’s 1.8 degrees Celsius higher.) The average temperature of 77.7 degrees F easily beat the old record of 77.3 degrees set in July 1936. Thus the temperature extreme for the U.S. (and much of Canada as well) was more than four times the average for the entire northern hemisphere.

Also from Fabius Maximus, the following global temperature map was provided by the National Space Science & Technology Center at the University Of Alabama at Huntsville:

Click on map for much larger image.

The British Isles and western France were cooler than normal, as were several other locales in the northern hemisphere. However, the big outlier on the cold side was the entire Antarctic region. The average temperature during July for the South Pole was 8.1 degrees F below normal.

What is the weather?  Depends on where you are.

John Lounsbury

Sources:

• July is hottest month on record; drought expands to 63 percent of United States (Jeff Black, NBC News, 08 August 2012)

• U.S. Drought Intensifies (GEI News, 27 July 2012)

• Drought Intensifies over the middle of the country (Drought Monitor, University of Nebraska Lincoln, 02 August 2012)

• How warm was the world in July, amidst the historic heat waves? (Fabius Maximus, 08 August 2012)