July was the Hottest Month Ever Recorded; 2016 Set to Make 1998 Look Cold by Comparison

July 2016 was the warmest July in 136 years of modern record-keeping, according to a monthly analysis of global temperatures by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York. NASA GISS.

2016 — 99 Percent Likely to be the Hottest Year on Record by a Big Margin

In 1998, the world went through a big heat wave. In just one year, global temperatures jumped by about 0.15 degrees Celsius above previous record highs. Riding on the wave of an extraordinarily powerful El Nino, atmospheric CO2 that was then in the range of about 365 parts per million (and CO2e — CO2-equivalent greenhouse gasses — in the range of 415 ppm) pushed global temperatures to around 0.9 C above 1880s averages by year-end.

This extreme heat set off a rash of weather and climate disasters around the world. A global coral bleaching event sparked off. At that time it was only one of a few ever recorded and was seen by scientists as one of the early warning signs of global warming. Droughts, floods, and fires occurred with a then-unprecedented frequency. Some began to wonder if the bad effects of climate change were starting to take hold.

But 1998 was just a mild foretaste of what was to come. In the years that followed, new global temperature records were breached time and time again. 1998 was swiftly surpassed by 2005 which was again beaten out by 2010, then 2014 and finally 2015. Now, 2016 looks like it will end around 1.2 C hotter than 1880s averages. It appears that in just three years, the world will have warmed by more than 0.2 C. In the 18-year period since 1998 the world’s long and worsening hot spell will have increased its top range by as much as 0.3 degrees C, or more than 30 percent.

Gavin Schmidt, NASA GISS head, tells this tale far more succinctly, stating:

July data are out, and what do you know, still 99% chance of a new annual record in 2016.

2016 Hottest Year on Record

(Can you pick out 1998 on this graph? Look hard. You might find it… Driven on by record levels of atmospheric greenhouse gasses in the range of 490 ppm CO2e, global temperatures are in the process of spiking to around 1.2 C above 1880s averages in 2016. Climate scientists like Gavin Schmidt indicate that there’s a 99 percent chance that this year will be the hottest ever recorded. Image source: Gavin Schmidt.)

Another way to sum up how much the world has warmed since 1998 is the observation that the coolest months and years going forward are likely to be hotter than 1998 average temperatures. In other words, if we saw 1998 global temperatures now, it would be anomalously cold. The Earth’s natural cycling between La Nina and El Nino is, at this time, highly unlikely to produce a year as cool as 1998.

Hitting a New High Mark for Global Heat

As for 2016, the unbroken tally of record hot months has grown incredibly long. July itself, in NASA’s most recent announcement, has come in at about 1.06 C hotter than 1880s averages (and 0.84 C hotter than NASA’s 20th-century baseline). This makes the month we just went through the hottest month ever recorded in the global climate record by a substantial 0.1 C margin (beating out July of 2011 as the previous record-holder).


(Due to strong land-surface warming during summer in the Northern Hemisphere, July is typically the hottest month of the year. July 2016 was both the hottest July on record and the hottest ever month in the past 136 years of recordkeeping. Image source: NASA.)

At this point, you have to go all the way back to September of 2015 to find a month that isn’t now a new record-holder. And, as you can see in the month-to-month comparison graph above by NASA, many of the recent records have been very strong indeed.

Such heat has brought with it every manner of trouble. From droughts in the Amazon rainforest, to record-low sea ice levels, to worsening droughts, to a global rash of floods and wildfires, to the longest-running coral bleaching event ever recorded, to expanding ocean dead zones and lakes and riverways choked with algae, to tropical viruses like Zika marching northward as anthrax-carrying deer are coughed up out of the thawing permafrost, to the loss and destabilization of glacial ice around the planet, the picture of the world in 2016 is one of a place suffering far greater and wider-ranging climate disruptions than during 1998.

Now, given the considerable difference in impacts over just an 18-year time period and an approximate 0.3 C temperature increase, imagine what another 18 years and another 0.3 C or greater would unleash.

Portrait of the Hottest Month Ever — More Arctic Warming

July was just one part of this big upward jump in global temperatures and related extreme climate conditions. The distribution of that heat showed that climate-change-related polar amplification was still in full swing up north.

Above-average temperatures continued to concentrate near the vulnerable Arctic. NASA shows that temperatures in the region of 75 to 90° North Latitude ranged from around 1.4 to 2.1 C above normal. Such record-warm readings were likely due to loss of sea ice and consequent albedo reductions in the region of the Beaufort Sea and the Canadian Arctic Archipelago (see Arctic map here). Peak temperature departures in this zone hit as high as 7.7 C above average for the month — pretty extreme for northern polar July.

Conversely, a small pool of slightly cooler-than-normal readings hovered over the East Siberian Sea. But this small region was far milder, achieving only a peak 2 C departure below 20th-century norms.

GISS Temperature Map July 2016

(The hottest month on record globally shows highest above-average temperatures exactly where we don’t need them — in the Arctic north of Alaska, Canada, and Greenland, near the Yamal Peninsula and the Kara Sea, and in the south over West Antarctica. Image source: NASA.)

The broader region from Latitudes 35° S to 75° N saw temperatures ranging between 0.7 and 1.4 C above the NASA 20th-century baseline. This included the Equator at around 0.8 C above average despite the cooling effects of the Eastern Pacific which was starting to tilt toward La Nina conditions.

From 35° S to the pole, temperatures rapidly fall off for July with the region from 75° to 90° S seeing 1 to 1.6 C negative temperature departures. It’s worth noting that this Antarctic region was the only area to experience widespread below-average temperatures on the globe. Even so, West Antarctica stood as a noted warm outlier in this single large cool pool, with temperatures for most of the Antarctic Peninsula and adjacent inland regions hitting 4 C or more above normal.

Outlook — Predicted La Nina is Weak; Northern Polar Amplification is Strong

Cooler surface waters in the Equatorial Pacific are predicted to produce a weak, late La Nina for 2016 and early 2017. This event is not expected to be anywhere near as strong as the significant 2010 to 2012 La Nina. As a result, it will likely have a lesser overall downward effect on global surface temperatures.

GFS global temperature tracking

(GFS global temperature tracking indicates that August is likely to be as warm or slightly warmer than July, which puts this month within striking distance of another consecutive monthly global high temperature record. Image source: Karsten Haustein Climate Reanalysis.)

On the other hand, as August and September roll into October and November, Northern Hemisphere polar amplification is likely to intensify and this will tend to further buffer the downward temperature swing typically produced by La Nina. Therefore, it’s not likely that August to December temperatures will fall outside of the 0.95 to 1.15 C June-July temperature differential from 1880s ranges.

Current GFS model tracking for August (see image above) hints at a likely range between 1.05 and 1.15 C above 1880s values, which means that August is currently on track to challenge previous all-time temperature records for the month and that 2016 is continuing to solidify its extreme heat gains.



Gavin Schmidt

Karsten Haustein Climate Reanalysis

BOM ENSO Forecast


Hat tip to Colorado Bob

Hat tip to DT Lange

Hat tip to Ridley Jack

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