Feeling the heat: Earth in July was hottest month on record

By Seth Borenstein
20 August 2015 WASHINGTON (AP) — Earth just keeps getting hotter. July was the planet’s warmest month on record, smashing old marks, U.S. weather officials said. And it’s almost a dead certain lock that this year will beat last year as the warmest year on record, they said. July’s average temperature was 61.86 degrees Fahrenheit, beating the previous global mark set in 1998 and 2010 by about one-seventh of a degree, according to figures released Thursday by the National Oceanic and Atmospheric Administration. That’s a large margin for weather records, with previous monthly heat records broken by a 20th of a degree or less. “It just reaffirms what we already know: that the Earth is warming,” said NOAA climate scientist Jake Crouch. “The warming is accelerating and we’re really seeing it this year.” NOAA records go back to 1880. Separate calculations by NASA and the Japanese weather agency also found July 2015 to be a record. The first seven months of 2015 were the hottest January-to-July span on record, according to NOAA. The seven-month average temperature of 58.43 degrees is 1.53 degrees warmer than the 20th-century average and a sixth of a degree warmer than the old record set in 2010. […] The heat hit hard in much of Europe and the Middle East. It was the hottest July on record in Austria, where records go back to 1767. Parts of France had temperatures that were on average 7 degrees above normal and temperatures broke 100 in the Netherlands, which is a rarity. And an Iranian city had a heat index (the “feels like” temperature) of 165 degrees, which was still not quite record. Nine of the 10 hottest months on record have happened since 2005, according to NOAA. Twenty-two of the 25 hottest months on record have occurred after the year 2000. The other three were in 1998 and 1997. [more]

The July average temperature across global land and ocean surfaces was 1.46°F (0.81°C) above the 20th century average. As July is climatologically the warmest month for the year, this was also the all-time highest monthly temperature in the 1880–2015 record, at 61.86°F (16.61°C), surpassing the previous record set in 1998 by 0.14°F (0.08°C).
Separately, the July globally-averaged land surface temperature was 1.73°F (0.96°C) above the 20th century average. This was the sixth highest for July in the 1880–2015 record.
The July globally-averaged sea surface temperature was 1.35°F (0.75°C) above the 20th century average. This was the highest temperature for any month in the 1880–2015 record, surpassing the previous record set in July 2014 by 0.13°F (0.07°C). The global value was driven by record warmth across large expanses of the Pacific and Indian Oceans.
The average Arctic sea ice extent for July was 350,000 square miles (9.5 percent) below the 1981–2010 average. This was the eighth smallest July extent since records began in 1979 and largest since 2009, according to analysis by the National Snow and Ice Data Center using data from NOAA and NASA.
Antarctic sea ice during July was 240,000 square miles (3.8 percent) above the 1981–2010 average. This was the fourth largest July Antarctic sea ice extent on record and 140,000 square miles smaller than the record-large July extent of 2014.

Global highlights: Year-to-date (January–July 2015)

The year-to-date temperature combined across global land and ocean surfaces was 1.53°F (0.85°C) above the 20th century average. This was the highest for January–July in the 1880–2015 record, surpassing the previous record set in 2010 by 0.16°F (0.09°C).
The year-to-date globally-averaged land surface temperature was 2.41°F (1.34°C) above the 20th century average. This was the highest for January–July in the 1880–2015 record, surpassing the previous record of 2007 by 0.27°F (0.15°C).
The year-to-date globally-averaged sea surface temperature was 1.21°F (0.67°C) above the 20th century average. This was also the highest for January–July in the 1880–2015 record, surpassing the previous record of 2010 by 0.11°F (0.06°C). Every major ocean basin observed record warmth in some areas. For extended analysis of global temperature and precipitation patterns, please see our full July report.

Global Summary Information – July 2015

Introduction

Temperature anomalies and percentiles are shown on the gridded maps below. The anomaly map on the left is a product of a merged land surface temperature (Global Historical Climatology Network, GHCN) and sea surface temperature (ERSST.v4) anomaly analysis as described in Huang et al. (2015). Temperature anomalies for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCDC’s Global Surface Temperature Anomalies page. The percentile map on the right provides additional information by placing the temperature anomaly observed for a specific place and time period into historical perspective, showing how the most current month, season or year compares with the past. The most current data may be accessed via the Global Surface Temperature Anomalies page.

Temperatures

In the atmosphere, 500-millibar height pressure anomalies correlate well with temperatures at the Earth’s surface. The average position of the upper-level ridges of high pressure and troughs of low pressure—depicted by positive and negative 500-millibar height anomalies on the July 2015 and May–July 2015 maps—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. The combined average temperature over global land and ocean surfaces for July 2015 was the highest for July in the 136-year period of record, at 0.81°C (1.46°F) above the 20th century average of 15.8°C (60.4°F), surpassing the previous record set in 1998 by 0.08°C (0.14°F). As July is climatologically the warmest month of the year globally, this monthly global temperature of 16.61°C (61.86°F) was also the highest among all 1627 months in the record that began in January 1880. The July temperature is currently increasing at an average rate of 0.65°C (1.17°F) per century. [more]