February marked a potential turning point in the inexorable march of a warming planet.
According to NASA, the Japan Meteorological Agency and other research groups, February was the globe's warmest seasonally adjusted month on record, and the most unusually warm month since instrument records began in 1880.
The magnitude of the warming seen in February was astounding even to scientists who, for good reason, tend to downplay the significance of an individual month in the context of the longer-term climate record.
Gavin Schmidt, who leads NASA's Goddard Institute for Space Studies, reacted on Twitter with the comment of, simply: "Wow."
Here are the top five takeaway messages of the new climate data:
1. The numbers are shocking
The NASA and Japan Meteorological Agency data show that the combination of a record strong El Niño event in the tropical Pacific Ocean and human-caused global warming drove global temperatures to levels never before seen since instrument records began in 1880.
The NASA data, which was released on Saturday and is subject to adjustment as scientists refine their analysis, shows that February had a global average surface temperature of 1.35 degrees Celsius above the 1951 to 1980 average, or 2.43 degrees Fahrenheit above average.
Image: NASA GISS
The 1.35-degree Celsius temperature anomaly in February beat the anomaly recorded in January, which itself was a record high departure from average for any month.
This means that temperatures in February 2016 had the largest departure from average of any month in NASA's records since 1880.
To put it more plainly, February stands out for its unusual heat more than any other month in the modern climate record.
The previous warmest February, according to NASA, was in 1998, which was also a year with an extremely strong El Niño.
During El Niño events, an area of milder than average ocean waters in the equatorial tropical Pacific Ocean increases the flow of heat from the ocean to the atmosphere, boosting global average temperatures.
Image: NASA GISS
Typically, El Niño's strength, which is measured in sea surface temperature anomalies, peaks in the oceans a few months before the warming influence is maximized in the atmosphere.
This year, the oceans hit their mildest levels in November, before cooling off slightly.
This means that the atmospheric warming effect from El Niño was stronger in February, giving global average surface temperatures an additional boost on top of long-term human-caused global warming.
2. It's not just NASA's readings
On Monday, the Japan Meteorological Agency (JMA) weighed in with its own findings on the global average surface temperatures during February.
The JMA compares average temperatures to a different baseline than NASA uses — that of 1981-2010. It also does not weigh warmth in the Arctic as heavily as NASA's analysis tends to.
Image: Japan Meteorological agency
Still, the JMA found that this was the mildest February on record, with a monthly anomaly of 0.62 degrees Celsius, or 1.11 degrees Fahrenheit, above the 1981-2010 average, and 1.04 degrees Celsius, or 1.9 degrees Fahrenheit, above the 20th century average.
This was the mildest February since JMA's data began in 1891.
In addition, the JMA found this was the mildest February since the El Niño February of 1998, with average global surface temperatures of 0.19 degrees Celsius, or 0.34 degrees Fahrenheit, milder than in 1998.
However, the JMA did not find that February 2016 had the largest temperature anomaly of any month on record, compared to the 1981-2010 average.
The February climate record is also backed up by information from satellites, which showed record high amounts of atmospheric heat in February.
According to data from the University of Alabama at Huntsville, the planet had a global average temperature that was 0.83 degrees Celsius, or 1.5 degrees Fahrenheit, above average during the month of February. (Satellites don't measure surface temperature in the same way a backyard thermometer does. Rather, they detect levels of atmospheric heat.)
That reading was a significant increase above the 0.3 degrees Celsius anomaly, or 0.54 degrees Fahrenheit, from satellite-based temperatures in January, which also set a record.
Another satellite database maintained by Remote Sensing Systems also showed a huge warming spike in February.
3. A glimpse into a 2-degree Celsius future?
As Penn State climate scientist Michael Mann has pointed out via social media, the NASA February temperature findings are especially significant when compared to preindustrial temperatures.
Before humans began pumping carbon dioxide into the air from burning fossil fuels like coal and oil, global average surface temperatures were far cooler.
When compared to those conditions, Mann says, February was probably about 2 degrees Celsius, or 3.6 degrees Fahrenheit, above the preindustrial average for the globe.
However, more reliable calculations made using data from the northern hemisphere only show that average surface temperatures during February were about 2.5 degrees Celsius, or 4.5 degrees Fahrenheit, above average for this region.
This is potentially significant since the 2-degree target is the official global temperature target adopted by global leaders in the Paris Climate Agreement in December. The fact that this threshold may have been briefly eclipsed is significant, Mann said in an email.
Mann compared the February data to the first time global atmospheric concentrations of carbon dioxide, or CO2, eclipsed 400 parts per million, which is a symbolic milestone and the highest levels on record in human history.
"The takeaway message here is that this is much like when we first briefly crossed the 400 ppm threshold of atmospheric CO2 a few years ago over the course of the annual CO2 cycle, or when the King tides first started to breach the seawalls of Miami Beach," he said.
"This is the first time we’ve temporarily breached the 2C warming threshold, but it will become more common and eventually perpetual if we do nothing to stem the tide."
4. Don't blame it all on El Niño
The ongoing El Niño event, which is among the strongest ever recorded, is not the most important factor behind the February temperature milestone, experts told Mashable.
In fact, as a general rule, both El Niño and its cooling effect sibling, La Niña, are getting milder over time as human-caused global warming continues to accelerate.
Image: climate Central
"Yes, of course El Niño has a hand in the February and other monthly temperatures records we've been observing, but not the only hand, not even the winning hand," Jessica Blunden of the National Center for Environmental Information in Asheville, told Mashable in an email.
"During the last big El Niño event of 97/98, temperatures departures from average were much lower compared with what we're seeing now with this comparable event, which shows us that general warming is occurring over time," she said.
Blunden noted that even February 2015 beat the temperatures seen during February 1998, even though there was no official El Niño taking place in 2015.
Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research in Boulder, Colorado, said El Niño's peak in November probably added about 0.23 degrees Celsius, or 0.41 degrees Fahrenheit, to the global average surface temperature in February.
He said the warming influence of an El Niño "is not trivial at all."
Think of El Niño events and La Niña events like gas pedals and brakes on car that is climbing a hill. The car keeps going higher, but when an El Niño is present, the driver steps on the gas and goes up faster.
When a La Niña — characterized by cooler than average ocean temperatures in the tropical Pacific — is present, that warming temporarily slows down, like when a driver hits the brake pedal.
"When we have the La Niña's the Earth gets a bit of a reprieve from the warming, but when we have El Niños, the warming is enhanced and exacerbates the physical changes already happening, sometimes irreversibly," Blunden said.
Mann, who directs Penn State's Earth systems science center, published a study earlier this year that showed the record warm years of 1998, 2005, 2010, 2014 and now 2015 would not have occurred without human-caused global warming.
"I think it’s important to step back and ask how likely these individual temperature records would be in the absence of human-caused global warming," he said.
5. Warming may slow a bit by next year
El Niño forecasts show the current event is likely to weaken to so-called "neutral" conditions by the spring and summer, followed by the potential development of a La Niña cool phase.
This would tend to dampen down the rate of global warming temporarily, which could yield fewer monthly records like February of 2016.
As Trenberth told Mashable, "It won't be long before that [El Niño bounce] disappears and it won't continue throughout 2016. I will still take bets that 2015 will be warmer than 2016."
However, if this occurs, it won't mean that long-term global warming has stopped or reversed, but that it has just temporarily dialed back, likely to speed up again soon afterward.