By Jeff Masters and Bob Henson From Weather Underground

The Atlantic and Pacific tropics were buzzing with activity on Thursday, but Thursday brought other big news as well: July 2015 was the warmest single month in 1627 months of global records that go back to January 1880, said NOAA’s National Centers for Environmental Information (NCEI). The globally averaged temperature above both land and ocean surfaces was 1.46°F (0.81°C) ahead of the 20th-century average. This trumps the record for any month that was set in July 1998, surpassing that value by 0.08°F (0.14°C). On average, July is the warmest month of the year globally, tpyically driven by midsummer conditions across the Northern Hemisphere’s extensive land areas. However, according to NOAA, record warmth across much of the Pacific and Indian oceans played a major role in July’s new global record. NASA also rated July 2015 as the warmest July on record. July 2015’s warmth makes the year-to-date period (January – July) the warmest such period on record, according to both NOAA and NASA. 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 extremely likely that 2015 will be Earth’s second consecutive warmest year on record.

 

Figure 1. Departure of temperature from average for July 2015, the warmest single month for the globe since record keeping began in 1880. Large areas of record warmth were analyzed across many parts of the Indian and Pacific oceans, as well as in northern South America, southeast Africa, and parts of southern Europe. Image credit: National Centers for Environmental Information (NCEI) .

Global satellite-measured temperatures in July 2015 for the lowest 8 km of the atmosphere were the 10th warmest in the 37-year record, according to the University of Alabama Huntsville (UAH). 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–as occurred during the El Niño events of 1998 and 2010. Thus, we should see Earth’s lower atmosphere temperature hit record levels late this year and/or early in 2016.