Wunderground - Sept. Global Temperatures Largest Departure From Monthly Averages On Record

September 2015 had the largest departure of temperature from average of any month among all 1629 months in the record that began in January 1880, said NOAA's National Centers for Environmental Information (NCEI) on Wednesday. (Note that since July and August are typically the warmest months globally in absolute terms, September was not Earth's warmest month in that regard.) NASA rated September 2015 slightly cooler, as the 2nd warmest September on record, falling below September 2014's mark. September 2015's warmth makes the year-to-date period (January - September) the warmest such period on record, according to both NOAA and NASA. September 2015 was the fifth consecutive month a monthly high temperature record has been set in NOAA's database, and the seventh month of the nine months so far in 2015. A potent El Niño event in the Eastern Pacific that crossed the threshold into the "strong" category in early July continues to intensify, and strong El Niño events release a large amount of heat to the atmosphere, typically boosting global temperatures by at least 0.1°C. This extra bump in temperature, when combined with the long-term warming of the planet due to human-caused emissions of heat-trapping gases like carbon dioxide, makes it virtually assured that 2015 will be Earth's second consecutive warmest year on record--with 2016 a good bet to exceed even 2015's warmth.

NOAA's top ten warmest global monthly departures from average
1) 0.90°C, Sep 2015
2) 0.89°C, Aug 2015
2) 0.89°C, Mar 2015
2) 0.89°C, Feb 2015
2) 0.89°C, Jan 2007
6) 0.87°C, Jun 2015
7) 0.86°C, Feb 1998
8) 0.85°C, May 2015
8) 0.85°C, Mar 2010
10) 0.84°C, Dec 2014



Figure 1. Departure of temperature from average for September 2015, the warmest September for the globe since record keeping began in 1880. Record warmth was observed across northeastern Africa stretching into the Middle East, part of southeastern Asia, most of the northern half of South America, and parts of central and eastern North America. Record warmth was also over much of the world's oceans, including the Eastern Mediterranean Sea, most of the Arabian Sea, and the waters surrounding Hawaii, where the warm waters are expected to cause a significant coral bleaching episode resulting in a large-scale die-off of coral. Record warm waters were also observed between the Bahama Islands and Bermuda, which helped fuel Hurricane Joaquin's rapid intensification into a Category 4 storm in mid-September. A loss of 10 - 20% of all coral worldwide over the next few months is expected due to the record warm ocean temperatures causing a global bleaching event. Image credit: National Centers for Environmental Information (NCEI) .

Global satellite-measured temperatures in September 2015 for the lowest 8 km of the atmosphere were tied for 3rd warmest in the 37-year record, according to the University of Alabama Huntsville (UAH), and were the 5th warmest on record, according to RSS. The lowest 8 km of the atmosphere heats up dramatically in response to moderate to strong El Niño events, with a time lag of several months. The two warmest Septembers occurred during the El Niño events of 1998 and 2010.

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