Global Analysis of Land And Sea Temperatures July, 2015: Not Just The Hottest July — The Hottest Month Ever

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Home / Global Analysis of Land And Sea Temperatures July, 2015: Not Just The Hottest July — The Hottest Month Ever
The graphic shows the July temperatures in percentiles. Large areas reported the warmest July ever. The global average was the warmest single month since the beginning of reliable record-keeping, and probably the warmest in thousands of years.. Graphic courtesy of NOAA.

The graphic shows the July temperatures in percentiles. Large areas reported the warmest July ever. The global average was the warmest single month since the beginning of reliable record-keeping, and probably the warmest in thousands of years.. Graphic courtesy of NOAA.

If it felt hot this July, it’s because it was.

As global land and sea temperatures continue their inexorable increase, July, 2015 has now gone into the record books as the hottest single month of the 1,627 months since meteorologists began keeping track in 1880.

Virtually all authorities cite this July as the warmest in at least 11,000 years, and according to some, the hottest month in over a hundred thousand years.

July 2015 By The Numbers

According to NOAA’s National Centers for Environmental Information (NCEI), global land and sea temperatures in July averaged 61.86 degrees Fahrenheit, 1.46 degrees above the 20th century average and 0.14 degree above the previous record set in the El Niño year of 1998.

NCEI calculates that this represents an increase of 1.17 degrees per century, but this is very conservative as it begins with the first year of reliable observations, 1880. Using more recent starting points, we can calculate the following rates of combined land and sea temperature rise, which are more representative of the current rate:

  • For the century from 1915 to 2015, the temperature rose about one and one-half degrees Fahrenheit.
  • From 1965 to 2015, the temperature rose at a rate of 3.2 degrees per century.
  • From 2005 to 2015 the temperature rose at a rate of 1.5 degrees per century.
  • From 2010 to 2015, the temperature rose at a rate of 2.9 degrees per century.
  • It should be noted that both 2005 and 2010 were anomalously warm years,  warmer than any of the next four or preceding four. So the calculated rise per century is less than that calculated starting from any other year in the past fifteen.
  • From 2014 to 2015, the temperature rose at a rate of 19.8 degrees per century. (You read that right: Nearly TWENTY degrees per hundred years.)
  • To get a more balanced view of recent temperature rise, we can average the July temperatures for 1996-2005 and compare that with the average rise from 2006-2015. This computation yields an average July to July rise of 1.19 degrees per decade, or 11.9 degrees per century.
The roller coaster of Earth's temperatures normally has modest undulations. The recent rapid rise makes July, 2015 the hottest month in over 11,000 years. Graphic courtesy of NOAA.

The roller coaster of Earth’s temperatures normally has modest undulations. The recent rapid rise makes July, 2015 the hottest month in over 11,000 years. Graphic courtesy of NOAA.

Temperature rise has accelerated and subsided in the past, but it should be noted that the current rate of rise, whether measured year to year, decade to decade, or century to century, is unprecedented by any historical standard.

Furthermore, this is the combined land and sea temperature. The rise of land temperature is considerably greater than that of the ocean.

Where Was It Hot?

Increasing temperatures have not been distributed evenly over the globe.

In fact, some places were colder than normal in July, and one location set a record for cold.

Here are some of the highlights:

  • Austria had its hottest July in the long record that dates from 1767. July of 2015 was a full five degrees above the 1981 to 2010 average. Innsbruck recorded its hottest day ever on July 7 (101 degrees), and many stations reported record July temperatures.
  • Bandar Mahshahr, Iran reported a heat index of 165 when the temperature of 115 combined with a dew point of 90 to make a most unpleasant day.
  • The North Atlantic Ocean south and east of Greenland was far below normal for July, and one buoy reported a record cold month. This cold water anomaly induced low pressure over the ocean, which pushed warm air into most of southern Europe.
  • Water temperatures in the Gulf of Alaska, thought to be a major contributor to the California drought, continued to be above normal.
  •  The tropical Pacific was much warmer than normal as El Niño Eggplant continues to build. This anomaly is now competing with the Alaskan waters to control the weather over the United States. Southern California has received some rain, and more is expected in the winter.

    Temperature Year-To-Date

    The temperature percentiles for January through July, 2015 show warmth in most places. Parts of Canada and the US were below normal, and the northeast North Atlantic Ocean set a record for coldest July ever. Graphic courtesy of NOAA.

    The temperature percentiles for January through July, 2015 show warmth in most places. Parts of Canada and the US were below normal, and the northeast North Atlantic Ocean set a record for coldest July ever. Graphic courtesy of NOAA.

    For the first seven months of 2015, temperatures averaged hottest ever in eight of nine categories covering northern, southern, and combined northern and southern hemispheres.

    Southern hemisphere land temperature was only the third highest since 1880.

    Since five of the first seven months of 2015 have been the warmest ever, and with El Niño Eggplant continuing to build, it seems likely that 2015 as a whole will be the warmest year in many millennia.

    July 2015 Precipitation

    The precipitation pattern for July, 2015 shows dry and wet areas in close proximity in South America and Europe. Graphic courtesy of NOAA.

    The precipitation pattern for July, 2015 shows dry and wet areas in close proximity in South America and Europe. Graphic courtesy of NOAA.

    In general, El Niño Eggplant has started to affect weather worldwide.

One example is the below average July precipitation in India; the monsoon is often subdued by El Niño. But elsewhere, there were extremes of both drought and deluge, often quite closely juxtaposed.Southern South America had rainy and dry areas. England was wet, while much of southern Europe was dry and the Middle East was very wet. The northwest Gulf Coast of the United Sates was especially interesting, with a very dry July following a record wet June.

Extremes of both temperature and precipitation are forecast to accompany global warming, and July could be just a taste of what’s to come.

Global Warming And El Niño

1998 was the last year with a powerful El Niño. If the projections are correct, El Niño Eggplant will rival the 1998 El Niño in potency. Whether the current acceleration of the increase in global land and sea temperatures is just a spike caused by the warm Pacific waters or a permanent trend is unknown.

One thing the current series of ever higher monthly temperatures, culminating in the warmest month ever in July, 2015, shows is that the temperature has not leveled off since 1998. Measured from El Niño to El Niño, the temperature is unquestionably rising.

Signs Of A New Normal Atmospheric Circulation

The atmosphere’s adjustment to climate change appears to be a much warmer pole and a southwardly-displaced jet stream. This leaves the northern mid-latitudes in a zone where colder than normal temperatures are possible, even likely. Recent cold trends in the northern North Atlantic Ocean and the northern US and Europe are evidence for this.

Do you see anything to support or refute this hypothesis where you live?

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