Hotter than ever? 2015 saw the warmest June on record

2015 is now on its way to becoming the hottest year on record, and June the hottest month, scientists say.

NASA, the National Oceanic and Atmospheric Administration (NOAA), and the Japan Meteorological Agency (JMA) have each reported that June 2015 has matched or topped every other June temperature in historical records. The last 12-month period leading up to July has also been the warmest ever, according to NOAA, in a report that comes as discussion over global warming and public policy heats up in the approach to December’s Paris conference on climate change.

"It was the hottest June on record. From January through June, it was the hottest first half for any year," NOAA climate scientist Jessica Blunden says. It was also the highest June temperatures over both land and sea, she adds.

"Everything was the hottest," Dr. Blunden says. "We don’t usually see that."

The combined average global temperature for June was 61.5 degrees Fahrenheit, about 1.6 °F above the 20th-century average and 0.22 °F higher than the previous record, set last year, NOAA’s latest calculations show. NASA’s analysis puts the figure at 1.4 °F above average, with 2015 tying 1998 for the warmest June on record. JMA’s estimates have June 2015 temperatures at 0.74 °F warmer than average, besting 2014 for the hottest on record.

In other words, the exact figures vary, but the conclusions coincide: Earth is experiencing the hottest temperatures recorded in the last 136 years, Blunden says.

While June was warm all over the world, Spain, Austria, parts of Asia, and Australia saw exceptional heat, the Associated Press reported. A heat wave that struck Pakistan that month killed more than 1,200 people, making it the eighth deadliest since 1900.

Rising temperatures are not the only markers showing warning signs: "Sea ice is melting, glaciers are continuing to melt, snow packs are low… that has a real impact on people," says Blunden.

"You can look at [this data] as another beat on the drum: 'Please, pay attention to what’s happening,' " she adds.

Part of the reason behind the record heat has to do with a particularly strong El Niño for this year. The phenomenon results in unusually warm temperatures in the tropical Pacific Ocean, which tends to boost air and sea temperatures worldwide.

"Climate change is a long-term driver, so that’s like standing on an escalator as it goes up," Deke Arndt, head of climate monitoring at NOAA’s National Centers for Environmental Information (NCEI), told Mashable. El Niño/La Niña cycles, on the other hand, are "like jumping up and down while you’re on that escalator."

When they happen at the same time – as is the case for 2015 – the two "play together to produce outcomes like what is likely the warmest year on record," Mr. Arndt said.

The latest data seems dissonant with recent reports of an upcoming "mini Ice Age" – a claim that comes from Valentina Zharkova, a professor of mathematics at Northumbria University in the United Kingdom, who used a new model of the sun’s solar cycle to predict that waning solar activity in the next 15 years will trigger lower temperatures.

But many scientists are unconvinced. In studying the effect a solar minimum might have on the Earth’s climate, Georg Feulner, the deputy chair of the Earth system analysis research domain at the Potsdam Institute on Climate Change Research, found that temperature drops correlated to a less intense sun would be insignificant compared with anthropogenic global warming.

"The expected decrease in global temperature would be 0.1°C at most, compared to about 1.3°C warming since pre-industrial times by the year 2030," Dr. Feulner told the Washington Post.

Others have also argued that global warming peaked in the late 1990s. But while Earth has broken monthly heat records 26 times since the start of the 21st century, it hasn’t broken a monthly cold record since December 1916, according to NOAA’s Blunden. 

"There is a definite warming trend over time," she says. "There is a natural variability [to global temperatures], but that doesn’t change global warming."